rlsp-yaml 0.1.3

// SPDX-License-Identifier: MIT

use std::collections::HashSet;

use saphyr::YamlOwned;
use tower_lsp::lsp_types::{
    CompletionItem, CompletionItemKind, CompletionItemTag, Documentation, InsertTextFormat,
    MarkupContent, MarkupKind, Position,
};

use crate::schema::{JsonSchema, SchemaType};

// Maximum number of completion items returned.
const MAX_COMPLETION_ITEMS: usize = 100;
// Maximum number of allOf/anyOf/oneOf branches walked for property collection.
const MAX_BRANCH_COUNT: usize = 20;
// Maximum number of Unicode characters in a description shown in documentation.
const MAX_DESCRIPTION_LEN: usize = 200;
// Maximum number of Unicode characters in an enum label.
const MAX_ENUM_LABEL_LEN: usize = 50;

/// Compute completion items for the given YAML text and cursor position.
///
/// When `schema` is provided, schema-defined properties and enum values are
/// merged with structural (document-based) suggestions. Falls back to structural
/// completion when `schema` is `None` or has no relevant properties.
///
/// Returns an empty list when the document is empty, the AST is unavailable,
/// the position is out of bounds, or the cursor is on a comment or separator.
#[must_use]
pub fn complete_at(
    text: &str,
    documents: Option<&Vec<YamlOwned>>,
    position: Position,
    schema: Option<&JsonSchema>,
) -> Vec<CompletionItem> {
    let lines: Vec<&str> = text.lines().collect();
    let line_idx = position.line as usize;
    let col_idx = position.character as usize;

    let Some(line) = lines.get(line_idx) else {
        return Vec::new();
    };

    // For completion, the cursor is often at or just past the end of the line
    // (where the user is typing). Only reject positions well beyond the line.
    // We clamp to line length for further processing.
    if col_idx > line.len() + 1 {
        return Vec::new();
    }
    let col_idx = col_idx.min(line.len());

    let trimmed = line.trim();

    if trimmed.starts_with('#') {
        return Vec::new();
    }

    if trimmed == "---" || trimmed == "..." {
        return Vec::new();
    }

    // Blank line: schema key completions if schema is available, otherwise empty.
    if trimmed.is_empty() {
        if let Some(s) = schema {
            let current_indent = indentation_level(line);
            let path = build_key_path(&lines, line_idx, current_indent);
            let resolved = resolve_schema_path(s, &path);
            if let Some(resolved_schema) = resolved {
                let present = collect_present_keys_at_indent(&lines, line_idx, current_indent);
                return schema_key_completions(resolved_schema, &present);
            }
        }
        return Vec::new();
    }

    // Structural completion requires a parsed AST.
    let Some(documents) = documents else {
        return Vec::new();
    };
    if documents.is_empty() {
        return Vec::new();
    }

    let current_indent = indentation_level(line);
    let cursor_context = classify_cursor(line, col_idx);

    match cursor_context {
        CursorContext::Key(current_key) => {
            let structural = suggest_sibling_keys(&lines, line_idx, current_indent, &current_key);
            if let Some(s) = schema {
                let path = build_key_path(&lines, line_idx, current_indent);
                let resolved = resolve_schema_path(s, &path);
                if let Some(resolved_schema) = resolved
                    && schema_has_properties(resolved_schema)
                {
                    let present = collect_present_keys_at_indent(&lines, line_idx, current_indent);
                    let schema_items = schema_key_completions(resolved_schema, &present);
                    // Filter structural items by the same present-keys set so
                    // schema-defined properties that are already present don't
                    // re-appear through the structural fallback.
                    let filtered_structural: Vec<CompletionItem> = structural
                        .into_iter()
                        .filter(|i| !present.contains(i.label.as_str()))
                        .collect();
                    merge_completions(filtered_structural, schema_items)
                } else {
                    structural
                }
            } else {
                structural
            }
        }
        CursorContext::Value(key_name) => schema.map_or_else(
            || suggest_values_for_key(&lines, line_idx, &key_name),
            |s| {
                let path = build_value_key_path(&lines, line_idx, current_indent, &key_name);
                resolve_schema_path(s, &path).map_or_else(
                    || suggest_values_for_key(&lines, line_idx, &key_name),
                    |prop_schema| {
                        let schema_items = schema_value_completions(prop_schema);
                        if schema_items.is_empty() {
                            suggest_values_for_key(&lines, line_idx, &key_name)
                        } else {
                            schema_items
                        }
                    },
                )
            },
        ),
    }
}

/// Merge structural and schema-sourced key completion items, deduplicating by
/// label and capping at `MAX_COMPLETION_ITEMS`.
fn merge_completions(
    structural: Vec<CompletionItem>,
    schema_items: Vec<CompletionItem>,
) -> Vec<CompletionItem> {
    let mut seen: HashSet<String> = HashSet::new();
    let mut result: Vec<CompletionItem> = Vec::new();

    // Schema items first (richer metadata), then structural fallback.
    for item in schema_items.into_iter().chain(structural) {
        if seen.insert(item.label.clone()) {
            result.push(item);
            if result.len() >= MAX_COMPLETION_ITEMS {
                break;
            }
        }
    }
    result
}

/// Build the ancestor key path (from root to the parent of the cursor line).
///
/// Returns the sequence of mapping keys that describe the nesting context of
/// the current line. For a cursor inside `a:\n  b:\n    <cursor>`, this returns
/// `["a", "b"]`. Sequence items are represented as `"[]"` sentinels so that the
/// path walker can descend into `items` schemas.
fn build_key_path(lines: &[&str], cursor_line: usize, cursor_indent: usize) -> Vec<String> {
    let cursor_trimmed = lines.get(cursor_line).map_or("", |l| l.trim());
    let cursor_in_seq = cursor_trimmed.starts_with("- ");

    // If cursor_indent is 0 and not in a sequence item, path is empty (top-level).
    if cursor_indent == 0 && !cursor_in_seq {
        return Vec::new();
    }

    let mut path: Vec<String> = Vec::new();
    let mut target_indent = cursor_indent;

    for i in (0..cursor_line).rev() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        let indent = indentation_level(line);

        if indent >= target_indent {
            continue;
        }

        // This line is at a lower indent — it must be the parent.
        let effective = trimmed.strip_prefix("- ").unwrap_or(trimmed);
        if let Some(key) = extract_key(effective).or_else(|| extract_key(trimmed)) {
            path.push(key);
        } else if trimmed.starts_with("- ") || trimmed == "-" {
            path.push("[]".to_string());
        }

        target_indent = indent;
        if target_indent == 0 {
            break;
        }
    }

    path.reverse();

    // If the cursor line itself is a sequence item (starts with "- "), the keys
    // within it are inside an array element — append "[]" to descend into `items`.
    if cursor_in_seq {
        path.push("[]".to_string());
    }

    path
}

/// Build the key path for a value position: same as `build_key_path` but
/// appends the key whose value the cursor is on.
fn build_value_key_path(
    lines: &[&str],
    cursor_line: usize,
    cursor_indent: usize,
    key_name: &str,
) -> Vec<String> {
    let mut path = build_key_path(lines, cursor_line, cursor_indent);
    path.push(key_name.to_string());
    path
}

/// Walk the schema tree following `path`, returning the sub-schema at that
/// path if it exists. Returns `None` when the path exceeds the schema depth.
fn resolve_schema_path<'a>(schema: &'a JsonSchema, path: &[String]) -> Option<&'a JsonSchema> {
    let [key, rest @ ..] = path else {
        return Some(schema);
    };

    // Array item descent.
    if key == "[]" {
        if let Some(items) = &schema.items {
            return resolve_schema_path(items, rest);
        }
        return None;
    }

    // Direct property lookup.
    if let Some(Some(prop_schema)) = schema.properties.as_ref().map(|p| p.get(key.as_str())) {
        return resolve_schema_path(prop_schema, rest);
    }

    // Walk composition branches (capped).
    [&schema.all_of, &schema.any_of, &schema.one_of]
        .into_iter()
        .flatten()
        .flat_map(|v| v.iter())
        .take(MAX_BRANCH_COUNT)
        .find_map(|branch| resolve_schema_path(branch, path))
}

/// Collect keys already present in the document at `cursor_indent`, to exclude
/// them from schema suggestions.
fn collect_present_keys_at_indent(
    lines: &[&str],
    cursor_line: usize,
    cursor_indent: usize,
) -> HashSet<String> {
    let mut keys = HashSet::new();
    let (doc_start, doc_end) = document_range(lines, cursor_line);

    for (i, line) in lines
        .get(doc_start..=doc_end)
        .unwrap_or_default()
        .iter()
        .enumerate()
        .map(|(i, l)| (i + doc_start, l))
    {
        let trimmed = line.trim();
        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }
        let indent = indentation_level(line);
        if indent != cursor_indent {
            continue;
        }
        let effective = trimmed.strip_prefix("- ").unwrap_or(trimmed);
        if let Some(colon_pos) = find_mapping_colon(effective) {
            let key = effective[..colon_pos].trim();
            let value = effective[colon_pos + 1..].trim();
            if key.is_empty() {
                continue;
            }
            // Always exclude the cursor line's key (the one being typed).
            // For other lines, only exclude keys that have a non-empty value;
            // a key with an empty value is still worth suggesting (the user
            // may want enum hints or type info for it).
            if i == cursor_line || !value.is_empty() {
                keys.insert(key.to_string());
            }
        }
    }
    keys
}

/// Return true if the schema has any properties to suggest (direct or via composition).
fn schema_has_properties(schema: &JsonSchema) -> bool {
    if schema.properties.as_ref().is_some_and(|p| !p.is_empty()) {
        return true;
    }
    [&schema.all_of, &schema.any_of, &schema.one_of]
        .into_iter()
        .flatten()
        .any(|branch_list| branch_list.iter().any(schema_has_properties))
}

/// Produce key completion items from a resolved schema, excluding already-present keys.
fn schema_key_completions(schema: &JsonSchema, present: &HashSet<String>) -> Vec<CompletionItem> {
    let mut items: Vec<CompletionItem> = Vec::new();
    collect_schema_properties(schema, present, &mut items, 0);

    // If 2+ required properties are missing, offer a snippet that inserts them all at once.
    if let Some(required) = &schema.required {
        let missing: Vec<&String> = required
            .iter()
            .filter(|r| !present.contains(r.as_str()))
            .collect();
        if missing.len() >= 2 {
            let snippet_body: String = missing
                .iter()
                .enumerate()
                .map(|(idx, key)| {
                    let n = idx + 1;
                    let default = schema
                        .properties
                        .as_ref()
                        .and_then(|props| props.get(*key))
                        .map_or("", snippet_default);
                    if default.is_empty() {
                        format!("{key}: ${{{n}:}}")
                    } else {
                        format!("{key}: ${{{n}:{default}}}")
                    }
                })
                .collect::<Vec<_>>()
                .join("\n");
            items.push(CompletionItem {
                label: "(all required)".to_string(),
                kind: Some(CompletionItemKind::SNIPPET),
                insert_text_format: Some(InsertTextFormat::SNIPPET),
                insert_text: Some(snippet_body),
                sort_text: Some("!".to_string()),
                detail: Some(format!("{} required properties", missing.len())),
                ..CompletionItem::default()
            });
        }
    }

    items
}

/// Return the snippet placeholder default for a schema based on its type.
fn snippet_default(schema: &JsonSchema) -> &'static str {
    match schema.schema_type.as_ref() {
        Some(SchemaType::Single(t)) => match t.as_str() {
            "string" => "\"\"",
            "integer" | "number" => "0",
            "boolean" => "false",
            "object" => "{}",
            "array" => "[]",
            _ => "",
        },
        _ => "",
    }
}

/// Recursively collect property names from a schema and its composition branches.
fn collect_schema_properties(
    schema: &JsonSchema,
    present: &HashSet<String>,
    items: &mut Vec<CompletionItem>,
    depth: usize,
) {
    if depth >= MAX_BRANCH_COUNT {
        return;
    }

    if let Some(props) = &schema.properties {
        for (key, prop_schema) in props {
            if present.contains(key.as_str()) {
                continue;
            }
            if items.len() >= MAX_COMPLETION_ITEMS {
                return;
            }
            let detail = type_label(prop_schema);
            let documentation = prop_schema.description.as_deref().map(|d| {
                Documentation::MarkupContent(MarkupContent {
                    kind: MarkupKind::Markdown,
                    value: truncate_description(d),
                })
            });
            let (tags, sort_text) = if prop_schema.deprecated == Some(true) {
                (
                    Some(vec![CompletionItemTag::DEPRECATED]),
                    Some(format!("~{key}")),
                )
            } else {
                (None, None)
            };
            items.push(CompletionItem {
                label: key.clone(),
                kind: Some(CompletionItemKind::FIELD),
                detail,
                documentation,
                tags,
                sort_text,
                ..CompletionItem::default()
            });
        }
    }

    // Walk composition branches, capped.
    let branch_lists = [&schema.all_of, &schema.any_of, &schema.one_of];
    let mut branch_count = 0;
    for branch_list in branch_lists.into_iter().flatten() {
        for branch in branch_list {
            if branch_count >= MAX_BRANCH_COUNT {
                return;
            }
            collect_schema_properties(branch, present, items, depth + 1);
            branch_count += 1;
        }
    }
}

/// Produce value completion items from a schema (enum values or boolean type).
fn schema_value_completions(schema: &JsonSchema) -> Vec<CompletionItem> {
    // Enum values take priority.
    if let Some(enum_vals) = &schema.enum_values {
        let detail = type_label(schema);
        return enum_vals
            .iter()
            .filter_map(|v| {
                let label = json_value_to_yaml_label(v)?;
                let label = truncate_enum_label(&label);
                Some(CompletionItem {
                    label,
                    kind: Some(CompletionItemKind::VALUE),
                    detail: detail.clone(),
                    ..CompletionItem::default()
                })
            })
            .collect();
    }

    // Boolean type → suggest "true" and "false".
    if matches!(&schema.schema_type, Some(SchemaType::Single(t)) if t == "boolean") {
        return vec![
            CompletionItem {
                label: "true".to_string(),
                kind: Some(CompletionItemKind::VALUE),
                ..CompletionItem::default()
            },
            CompletionItem {
                label: "false".to_string(),
                kind: Some(CompletionItemKind::VALUE),
                ..CompletionItem::default()
            },
        ];
    }

    Vec::new()
}

/// Convert a `serde_json::Value` to a YAML scalar label string.
/// Returns `None` for values that have no natural YAML scalar representation
/// (arrays, objects).
fn json_value_to_yaml_label(v: &serde_json::Value) -> Option<String> {
    match v {
        serde_json::Value::String(s) => Some(s.clone()),
        serde_json::Value::Bool(b) => Some(b.to_string()),
        serde_json::Value::Number(n) => Some(n.to_string()),
        serde_json::Value::Null => Some("null".to_string()),
        serde_json::Value::Array(_) | serde_json::Value::Object(_) => None,
    }
}

/// Return the type label string for a schema (e.g. `"string"`, `"integer"`),
/// or `None` if no type is defined.
fn type_label(schema: &JsonSchema) -> Option<String> {
    match &schema.schema_type {
        Some(SchemaType::Single(t)) => Some(t.clone()),
        Some(SchemaType::Multiple(ts)) => Some(ts.join(" | ")),
        None => None,
    }
}

/// Truncate a description so the result (including ellipsis) is at most
/// `MAX_DESCRIPTION_LEN` Unicode characters.
fn truncate_description(desc: &str) -> String {
    if desc.chars().count() <= MAX_DESCRIPTION_LEN {
        return desc.to_string();
    }
    // Keep MAX_DESCRIPTION_LEN-1 chars, then append "…" (1 char) = MAX_DESCRIPTION_LEN total.
    let keep = MAX_DESCRIPTION_LEN - 1;
    let boundary = desc.char_indices().nth(keep).map_or(desc.len(), |(i, _)| i);
    format!("{}…", &desc[..boundary])
}

/// Truncate an enum label so the result (including ellipsis) is at most
/// `MAX_ENUM_LABEL_LEN` Unicode characters.
fn truncate_enum_label(label: &str) -> String {
    if label.chars().count() <= MAX_ENUM_LABEL_LEN {
        return label.to_string();
    }
    // Keep MAX_ENUM_LABEL_LEN-1 chars, then append "…" (1 char) = MAX_ENUM_LABEL_LEN total.
    let keep = MAX_ENUM_LABEL_LEN - 1;
    let boundary = label
        .char_indices()
        .nth(keep)
        .map_or(label.len(), |(i, _)| i);
    format!("{}…", &label[..boundary])
}

/// Whether the cursor is on a key or a value.
enum CursorContext {
    Key(String),
    Value(String),
}

/// Classify where the cursor is on the line: key position or value position.
fn classify_cursor(line: &str, col: usize) -> CursorContext {
    let trimmed = line.trim();

    // Handle sequence item lines: "  - key: value"
    let effective_line = trimmed.strip_prefix("- ").unwrap_or(trimmed);

    if let Some(colon_pos) = find_mapping_colon(line) {
        let key = line[..colon_pos].trim();
        // Strip "- " prefix from key if present
        let key = key.strip_prefix("- ").unwrap_or(key);
        let value_start = colon_pos + 1;
        let value_part = line[value_start..].trim();

        if col > colon_pos && !value_part.is_empty() {
            return CursorContext::Value(key.to_string());
        }
        // Cursor on key side, or value is empty (suggest keys)
        if value_part.is_empty() && col > colon_pos {
            return CursorContext::Value(key.to_string());
        }
        return CursorContext::Key(key.to_string());
    }

    // Sequence item with key-value inside: "- key: value"
    if let Some(colon_pos) = find_mapping_colon(effective_line) {
        let key = effective_line[..colon_pos].trim();
        return CursorContext::Key(key.to_string());
    }

    CursorContext::Key(trimmed.to_string())
}

/// Suggest sibling keys at the same indentation level, excluding the current key.
fn suggest_sibling_keys(
    lines: &[&str],
    current_line: usize,
    current_indent: usize,
    current_key: &str,
) -> Vec<CompletionItem> {
    // Determine if we're inside a sequence item
    let in_sequence = is_in_sequence_item(lines, current_line, current_indent);

    if in_sequence {
        return suggest_keys_for_sequence_item(lines, current_line, current_indent);
    }

    // Collect all sibling keys at the same indent level in the same mapping block
    let sibling_keys = collect_sibling_keys(lines, current_line, current_indent);

    sibling_keys
        .into_iter()
        .filter(|k| k != current_key)
        .map(|k| CompletionItem {
            label: k,
            kind: Some(CompletionItemKind::FIELD),
            ..CompletionItem::default()
        })
        .collect()
}

/// Check if the current line is inside a sequence item (preceded by a "- " at same or parent indent).
fn is_in_sequence_item(lines: &[&str], current_line: usize, current_indent: usize) -> bool {
    // Check if current line starts with "- "
    let current_trimmed = lines.get(current_line).map_or("", |l| l.trim());
    if current_trimmed.starts_with("- ") {
        return true;
    }

    // Walk backwards to find if we're a continuation of a sequence item
    for i in (0..current_line).rev() {
        let prev_line = lines.get(i).map_or("", |l| *l);
        let prev_trimmed = prev_line.trim();

        if prev_trimmed.is_empty() || prev_trimmed.starts_with('#') {
            continue;
        }

        if is_document_separator(prev_trimmed) {
            break;
        }

        let prev_indent = indentation_level(prev_line);

        if prev_indent < current_indent {
            // Parent level - check if it's a sequence item
            if prev_trimmed.starts_with("- ") {
                return true;
            }
            break;
        }

        if prev_indent == current_indent {
            // Same level - if it's a sequence item start, we're in a sequence
            if prev_trimmed.starts_with("- ") {
                return true;
            }
        }
    }

    false
}

/// Suggest keys for a sequence item by looking at sibling sequence items' keys.
fn suggest_keys_for_sequence_item(
    lines: &[&str],
    current_line: usize,
    current_indent: usize,
) -> Vec<CompletionItem> {
    // Find all keys in the current sequence item
    let current_item_keys = collect_current_sequence_item_keys(lines, current_line, current_indent);

    // Find the start of the sequence (parent with "- " items)
    let sequence_indent = find_sequence_indent(lines, current_line, current_indent);

    // Collect keys from all sibling sequence items
    let mut all_keys: HashSet<String> = HashSet::new();
    collect_all_sequence_item_keys(lines, current_line, sequence_indent, &mut all_keys);

    // Exclude keys already present in current item
    all_keys
        .into_iter()
        .filter(|k| !current_item_keys.contains(k))
        .map(|k| CompletionItem {
            label: k,
            kind: Some(CompletionItemKind::FIELD),
            ..CompletionItem::default()
        })
        .collect()
}

/// Collect keys in the current sequence item.
fn collect_current_sequence_item_keys(
    lines: &[&str],
    current_line: usize,
    current_indent: usize,
) -> HashSet<String> {
    let mut keys = HashSet::new();

    // Find the start of the current sequence item (walk back to the "- " line)
    let item_start = find_current_item_start(lines, current_line, current_indent);

    // The indent for keys within this item
    let key_indent = current_indent;

    // Walk from item_start forward through the current item
    for i in item_start..lines.len() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        let indent = indentation_level(line);

        // If we've hit a line at a lower indent or a new sequence item at the sequence level, stop
        if i > item_start && indent < key_indent {
            // Check if this is a new sequence item at the same sequence level
            break;
        }
        if i > item_start && indent == key_indent && trimmed.starts_with("- ") {
            break;
        }
        // Also stop if we find a sibling "- " at the item start indent
        if i > item_start {
            let start_line = lines.get(item_start).map_or("", |l| *l);
            let start_indent = indentation_level(start_line);
            if indent == start_indent && trimmed.starts_with("- ") {
                break;
            }
        }

        if let Some(key) = extract_key(trimmed) {
            keys.insert(key);
        }
    }

    keys
}

/// Find the start line of the current sequence item.
fn find_current_item_start(lines: &[&str], current_line: usize, current_indent: usize) -> usize {
    let current_trimmed = lines.get(current_line).map_or("", |l| l.trim());
    if current_trimmed.starts_with("- ") {
        return current_line;
    }

    for i in (0..current_line).rev() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        let indent = indentation_level(line);

        if indent < current_indent && trimmed.starts_with("- ") {
            return i;
        }
        if indent < current_indent {
            break;
        }
        if indent == current_indent && trimmed.starts_with("- ") {
            return i;
        }
    }

    current_line
}

/// Find the indent level of the sequence (the "- " lines).
fn find_sequence_indent(lines: &[&str], current_line: usize, current_indent: usize) -> usize {
    let current_trimmed = lines.get(current_line).map_or("", |l| l.trim());
    if current_trimmed.starts_with("- ") {
        return current_indent;
    }

    for i in (0..current_line).rev() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        let indent = indentation_level(line);

        if indent < current_indent && trimmed.starts_with("- ") {
            return indent;
        }
        if indent < current_indent {
            break;
        }
    }

    current_indent
}

/// Collect keys from all sequence items at the given sequence indent.
fn collect_all_sequence_item_keys(
    lines: &[&str],
    current_line: usize,
    sequence_indent: usize,
    all_keys: &mut HashSet<String>,
) {
    // Walk backwards to find the start of the sequence
    let mut seq_start = current_line;
    for i in (0..current_line).rev() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        let indent = indentation_level(line);

        if indent < sequence_indent {
            break;
        }
        if indent == sequence_indent && trimmed.starts_with("- ") {
            seq_start = i;
        }
    }

    // Walk forward from seq_start collecting keys from all items
    let key_indent = sequence_indent + 2; // keys inside "- " are indented by dash + space
    let mut in_sequence = false;

    for i in seq_start..lines.len() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        let indent = indentation_level(line);

        if indent < sequence_indent {
            break;
        }

        if indent == sequence_indent && trimmed.starts_with("- ") {
            in_sequence = true;
            // Extract key from "- key: value"
            if let Some(after_dash) = trimmed.strip_prefix("- ")
                && let Some(key) = extract_key(after_dash)
            {
                all_keys.insert(key);
            }
            continue;
        }

        if in_sequence
            && indent >= key_indent
            && let Some(key) = extract_key(trimmed)
        {
            all_keys.insert(key);
        }
    }
}

/// Collect sibling keys at the same indent level in the same mapping block.
fn collect_sibling_keys(lines: &[&str], current_line: usize, current_indent: usize) -> Vec<String> {
    let mut keys = Vec::new();
    let mut seen = HashSet::new();

    // Walk backwards from current line
    for i in (0..current_line).rev() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        if is_document_separator(trimmed) {
            break;
        }

        let indent = indentation_level(line);

        if indent < current_indent {
            break;
        }

        if indent == current_indent
            && let Some(key) = extract_key(trimmed)
            && seen.insert(key.clone())
        {
            keys.push(key);
        }
    }

    // Walk forward from current line
    for i in (current_line + 1)..lines.len() {
        let line = lines.get(i).map_or("", |l| *l);
        let trimmed = line.trim();

        if trimmed.is_empty() || trimmed.starts_with('#') {
            continue;
        }

        if is_document_separator(trimmed) {
            break;
        }

        let indent = indentation_level(line);

        if indent < current_indent {
            break;
        }

        if indent == current_indent
            && let Some(key) = extract_key(trimmed)
            && seen.insert(key.clone())
        {
            keys.push(key);
        }
    }

    keys
}

/// Suggest values for a key by finding the same key name elsewhere in the same document.
fn suggest_values_for_key(
    lines: &[&str],
    cursor_line: usize,
    key_name: &str,
) -> Vec<CompletionItem> {
    let mut seen = HashSet::new();
    let (doc_start, doc_end) = document_range(lines, cursor_line);
    lines
        .get(doc_start..=doc_end)
        .unwrap_or_default()
        .iter()
        .filter_map(|line| {
            let trimmed = line.trim();
            let effective = trimmed.strip_prefix("- ").unwrap_or(trimmed);
            let colon_pos = find_mapping_colon(effective)?;
            let k = effective[..colon_pos].trim();
            if k != key_name {
                return None;
            }
            let val = effective[colon_pos + 1..].trim();
            if val.is_empty() || !seen.insert(val.to_string()) {
                return None;
            }
            Some(CompletionItem {
                label: val.to_string(),
                kind: Some(CompletionItemKind::VALUE),
                ..CompletionItem::default()
            })
        })
        .collect()
}

/// Return true if the trimmed line is a YAML document separator (`---` or `...`).
fn is_document_separator(trimmed: &str) -> bool {
    trimmed == "---" || trimmed == "..."
}

/// Return the `(start, end)` line index range (both inclusive) for the document
/// containing `cursor_line`.  The range is bounded by `---`/`...` separators
/// immediately before and after the cursor line.
fn document_range(lines: &[&str], cursor_line: usize) -> (usize, usize) {
    let start = (0..cursor_line)
        .rev()
        .find(|&i| {
            lines
                .get(i)
                .is_some_and(|l| is_document_separator(l.trim()))
        })
        .map_or(0, |sep| sep + 1);

    let end = (cursor_line + 1..lines.len())
        .find(|&i| {
            lines
                .get(i)
                .is_some_and(|l| is_document_separator(l.trim()))
        })
        .map_or_else(
            || lines.len().saturating_sub(1),
            |sep| sep.saturating_sub(1),
        );

    (start, end)
}

/// Get the indentation level (number of leading spaces) of a line.
fn indentation_level(line: &str) -> usize {
    line.len() - line.trim_start().len()
}

/// Extract the key from a YAML line like "key: value" or "- key: value".
fn extract_key(trimmed_line: &str) -> Option<String> {
    let line = trimmed_line.strip_prefix("- ").unwrap_or(trimmed_line);

    if let Some(colon_pos) = find_mapping_colon(line) {
        let key = line[..colon_pos].trim();
        if !key.is_empty() {
            return Some(key.to_string());
        }
    }
    None
}

/// Find the position of the mapping colon in a YAML line.
/// Skips colons inside quoted strings.
fn find_mapping_colon(line: &str) -> Option<usize> {
    let mut in_single_quote = false;
    let mut in_double_quote = false;

    for (i, ch) in line.char_indices() {
        match ch {
            '\'' if !in_double_quote => in_single_quote = !in_single_quote,
            '"' if !in_single_quote => in_double_quote = !in_double_quote,
            ':' if !in_single_quote && !in_double_quote => {
                let rest = &line[i + 1..];
                if rest.is_empty() || rest.starts_with(' ') || rest.starts_with('\t') {
                    return Some(i);
                }
            }
            _ => {}
        }
    }
    None
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::schema::{JsonSchema, SchemaType};
    use serde_json::json;
    use tower_lsp::lsp_types::Documentation;

    fn pos(line: u32, character: u32) -> Position {
        Position::new(line, character)
    }

    fn parse_docs(text: &str) -> Option<Vec<YamlOwned>> {
        use saphyr::LoadableYamlNode;
        YamlOwned::load_from_str(text).ok()
    }

    fn labels(items: &[CompletionItem]) -> Vec<&str> {
        items.iter().map(|i| i.label.as_str()).collect()
    }

    fn string_schema() -> JsonSchema {
        JsonSchema {
            schema_type: Some(SchemaType::Single("string".to_string())),
            ..JsonSchema::default()
        }
    }

    fn integer_schema() -> JsonSchema {
        JsonSchema {
            schema_type: Some(SchemaType::Single("integer".to_string())),
            ..JsonSchema::default()
        }
    }

    fn boolean_schema() -> JsonSchema {
        JsonSchema {
            schema_type: Some(SchemaType::Single("boolean".to_string())),
            ..JsonSchema::default()
        }
    }

    fn object_schema(props: Vec<(&str, JsonSchema)>) -> JsonSchema {
        JsonSchema {
            schema_type: Some(SchemaType::Single("object".to_string())),
            properties: Some(props.into_iter().map(|(k, v)| (k.to_string(), v)).collect()),
            ..JsonSchema::default()
        }
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Backward-Compatibility Tests (Tests 1–15): None schema
    // ══════════════════════════════════════════════════════════════════════════

    // Test 1
    #[test]
    fn should_suggest_sibling_keys_not_yet_present() {
        let text = "name: Alice\nage: 30\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"age"),
            "should suggest sibling key 'age', got: {labels:?}"
        );
        assert!(
            !labels.contains(&"name"),
            "should not suggest the key at cursor position"
        );
        assert!(
            result
                .iter()
                .all(|i| i.kind == Some(CompletionItemKind::FIELD)),
            "key completions should have FIELD kind"
        );
    }

    // Test 2
    #[test]
    fn should_not_suggest_keys_already_present_in_mapping() {
        let text = "name: Alice\nage: 30\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), None);

        let labels = labels(&result);
        assert!(
            !labels.contains(&"name"),
            "should not suggest 'name' which is at the cursor line"
        );
    }

    // Test 3
    #[test]
    fn should_suggest_nested_sibling_keys() {
        let text = "server:\n  host: localhost\n  port: 8080\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 2), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"port"),
            "should suggest sibling key 'port', got: {labels:?}"
        );
        assert!(
            !labels.contains(&"server"),
            "should not suggest parent key 'server'"
        );
        assert!(
            !labels.contains(&"host"),
            "should not suggest the key at cursor line"
        );
    }

    // Test 4
    #[test]
    fn should_suggest_keys_from_deeply_nested_mapping() {
        let text = "a:\n  b:\n    c: 1\n    d: 2\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(2, 4), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"d"),
            "should suggest sibling key 'd', got: {labels:?}"
        );
        assert!(
            !labels.contains(&"a"),
            "should not suggest ancestor key 'a'"
        );
        assert!(!labels.contains(&"b"), "should not suggest parent key 'b'");
        assert!(
            !labels.contains(&"c"),
            "should not suggest the key at cursor line"
        );
    }

    // Test 5
    #[test]
    fn should_suggest_keys_from_sibling_sequence_items() {
        let text = "items:\n  - name: Alice\n    age: 30\n  - name: Bob\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(3, 4), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"age"),
            "should suggest 'age' from sibling sequence item, got: {labels:?}"
        );
    }

    // Test 6
    #[test]
    fn should_not_suggest_keys_already_in_current_sequence_item() {
        let text = "items:\n  - name: Alice\n    age: 30\n  - name: Bob\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(3, 4), None);

        let labels = labels(&result);
        assert!(
            !labels.contains(&"name"),
            "should not suggest 'name' already present in current sequence item"
        );
    }

    // Test 7
    #[test]
    fn should_suggest_values_seen_for_same_key_name() {
        let text = "items:\n  - env: production\n  - env: staging\n  - env: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(3, 10), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"production"),
            "should suggest value 'production', got: {labels:?}"
        );
        assert!(
            labels.contains(&"staging"),
            "should suggest value 'staging', got: {labels:?}"
        );
        assert!(
            result
                .iter()
                .all(|i| i.kind == Some(CompletionItemKind::VALUE)),
            "value completions should have VALUE kind"
        );
    }

    // Test 8
    #[test]
    fn should_not_suggest_duplicate_values() {
        let text = "items:\n  - env: production\n  - env: production\n  - env: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(3, 10), None);

        let labels = labels(&result);
        let production_count = labels.iter().filter(|&&l| l == "production").count();
        assert_eq!(
            production_count, 1,
            "should deduplicate: 'production' should appear only once, got: {labels:?}"
        );
    }

    // Test 9
    #[test]
    fn should_return_empty_for_empty_document() {
        let text = "";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), None);

        assert!(result.is_empty(), "should return empty for empty document");
    }

    // Test 10
    #[test]
    fn should_return_empty_when_ast_is_none() {
        let text = "key: [bad";
        let result = complete_at(text, None, pos(0, 0), None);

        assert!(
            result.is_empty(),
            "should return empty when AST is None (failed parse)"
        );
    }

    // Test 11
    #[test]
    fn should_return_empty_for_comment_line() {
        let text = "# comment\nkey: value\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), None);

        assert!(result.is_empty(), "should return empty for comment line");
    }

    // Test 12
    #[test]
    fn should_return_empty_for_document_separator() {
        let text = "key1: v1\n---\nkey2: v2\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 0), None);

        assert!(
            result.is_empty(),
            "should return empty for document separator"
        );
    }

    // Test 13
    #[test]
    fn should_return_empty_for_position_beyond_document_lines() {
        let text = "key: value\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(10, 0), None);

        assert!(
            result.is_empty(),
            "should return empty for position beyond document lines"
        );
    }

    // Test 14
    #[test]
    fn should_return_empty_for_position_beyond_line_length() {
        let text = "key: value\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 100), None);

        assert!(
            result.is_empty(),
            "should return empty for position beyond line length"
        );
    }

    // Test 15
    #[test]
    fn should_return_empty_for_no_documents() {
        let text = "key: value\n";
        let empty: Vec<YamlOwned> = Vec::new();
        let result = complete_at(text, Some(&empty), pos(0, 0), None);

        assert!(
            result.is_empty(),
            "should return empty for empty documents vector"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group B — Schema Key Completion at Key Positions
    // ══════════════════════════════════════════════════════════════════════════

    // Test 17
    #[test]
    fn should_suggest_schema_properties_at_top_level_key_position() {
        let schema = object_schema(vec![("name", string_schema()), ("age", integer_schema())]);
        let text = "name: Alice\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"age"),
            "should suggest schema property 'age', got: {labels:?}"
        );
        assert!(
            !labels.contains(&"name"),
            "should not suggest 'name' which is already present"
        );
        assert!(
            result
                .iter()
                .any(|i| i.kind == Some(CompletionItemKind::FIELD)),
            "schema key completions should have FIELD kind"
        );
    }

    // Test 18
    #[test]
    fn should_include_schema_detail_and_documentation_in_key_suggestion() {
        let schema = object_schema(vec![(
            "name",
            JsonSchema {
                schema_type: Some(SchemaType::Single("string".to_string())),
                description: Some("The user's name".to_string()),
                ..JsonSchema::default()
            },
        )]);
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let item = result.iter().find(|i| i.label == "name");
        assert!(
            item.is_some(),
            "should suggest 'name', got: {:?}",
            labels(&result)
        );
        let item = item.unwrap();
        assert_eq!(
            item.detail.as_deref(),
            Some("string"),
            "detail should be the type 'string'"
        );
        let has_description = match &item.documentation {
            Some(Documentation::String(s)) => s.contains("The user's name"),
            Some(Documentation::MarkupContent(m)) => m.value.contains("The user's name"),
            None => false,
        };
        assert!(
            has_description,
            "documentation should contain 'The user's name'"
        );
    }

    // Test 19
    #[test]
    fn should_suggest_all_schema_properties_when_mapping_is_empty() {
        let schema = object_schema(vec![
            ("host", JsonSchema::default()),
            ("port", JsonSchema::default()),
            ("timeout", JsonSchema::default()),
        ]);
        let text = "host: localhost\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(labels.contains(&"port"), "should suggest 'port'");
        assert!(labels.contains(&"timeout"), "should suggest 'timeout'");
        assert!(
            !labels.contains(&"host"),
            "should not suggest 'host' (already present)"
        );
    }

    // Test 20
    #[test]
    fn should_not_suggest_schema_properties_already_in_document() {
        let schema = object_schema(vec![
            ("a", JsonSchema::default()),
            ("b", JsonSchema::default()),
            ("c", JsonSchema::default()),
        ]);
        let text = "a: 1\nb: 2\nc: \n";
        let docs = parse_docs(text);
        // cursor on line 2 ("c:"), key position
        let result = complete_at(text, docs.as_ref(), pos(2, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            !labels.contains(&"a"),
            "should not suggest 'a' (already present)"
        );
        assert!(
            !labels.contains(&"b"),
            "should not suggest 'b' (already present)"
        );
        assert!(
            !labels.contains(&"c"),
            "should not suggest 'c' (current line)"
        );
    }

    // Test 21
    #[test]
    fn should_suggest_schema_properties_for_nested_key_position() {
        let schema = object_schema(vec![(
            "server",
            object_schema(vec![("host", string_schema()), ("port", integer_schema())]),
        )]);
        let text = "server:\n  host: localhost\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 2), Some(&schema));

        let labels = labels(&result);
        assert!(labels.contains(&"port"), "should suggest nested 'port'");
        assert!(
            !labels.contains(&"host"),
            "should not suggest 'host' (already present)"
        );
        assert!(
            !labels.contains(&"server"),
            "should not suggest parent 'server'"
        );
    }

    // Test 22
    #[test]
    fn should_merge_schema_and_structural_suggestions() {
        let schema = object_schema(vec![("kind", string_schema())]);
        let text = "name: Alice\nkind: \n";
        let docs = parse_docs(text);
        // cursor at key position on line 0 ("name:")
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"kind"),
            "schema property 'kind' should appear"
        );
        assert!(
            !labels.contains(&"name"),
            "current key 'name' should not appear"
        );
    }

    // Test 23
    #[test]
    fn should_deduplicate_when_schema_and_structure_both_suggest_same_key() {
        let schema = object_schema(vec![("env", string_schema())]);
        let text = "env: production\nregion: us-east\n";
        let docs = parse_docs(text);
        // cursor at key position on line 1 ("region:")
        let result = complete_at(text, docs.as_ref(), pos(1, 0), Some(&schema));

        let labels = labels(&result);
        let env_count = labels.iter().filter(|&&l| l == "env").count();
        assert!(
            env_count <= 1,
            "'env' should appear at most once, got: {labels:?}"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group C — Schema Enum Completion at Value Positions
    // ══════════════════════════════════════════════════════════════════════════

    // Test 24
    #[test]
    fn should_suggest_enum_values_at_value_position() {
        let schema = object_schema(vec![(
            "env",
            JsonSchema {
                enum_values: Some(vec![
                    json!("production"),
                    json!("staging"),
                    json!("development"),
                ]),
                ..JsonSchema::default()
            },
        )]);
        let text = "env: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 5), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"production"),
            "should suggest 'production'"
        );
        assert!(labels.contains(&"staging"), "should suggest 'staging'");
        assert!(
            labels.contains(&"development"),
            "should suggest 'development'"
        );
        assert!(
            result
                .iter()
                .any(|i| i.kind == Some(CompletionItemKind::VALUE)),
            "enum completions should have VALUE kind"
        );
    }

    // Test 25
    #[test]
    fn should_include_schema_detail_in_enum_suggestion() {
        let schema = object_schema(vec![(
            "env",
            JsonSchema {
                schema_type: Some(SchemaType::Single("string".to_string())),
                enum_values: Some(vec![json!("prod"), json!("dev")]),
                description: Some("Deployment target".to_string()),
                ..JsonSchema::default()
            },
        )]);
        let text = "env: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 5), Some(&schema));

        assert!(!result.is_empty(), "should have enum suggestions");
        assert!(
            result
                .iter()
                .any(|i| i.detail.as_deref().is_some_and(|d| d.contains("string"))),
            "at least one suggestion should have detail containing 'string'"
        );
    }

    // Test 26
    #[test]
    fn should_not_duplicate_enum_value_already_used_in_same_key() {
        let schema = object_schema(vec![(
            "env",
            JsonSchema {
                enum_values: Some(vec![json!("production"), json!("staging")]),
                ..JsonSchema::default()
            },
        )]);
        let text = "env: production\nenv: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 5), Some(&schema));

        let labels = labels(&result);
        let prod_count = labels.iter().filter(|&&l| l == "production").count();
        assert!(prod_count <= 1, "'production' should appear at most once");
    }

    // Test 27
    #[test]
    fn should_fall_back_to_structural_value_suggestions_when_no_schema_enum() {
        let schema = object_schema(vec![("env", string_schema())]);
        let text = "env: production\nenv: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 5), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"production"),
            "structural value 'production' should still appear as fallback"
        );
    }

    // Test 28
    #[test]
    fn should_suggest_boolean_values_for_boolean_schema_type() {
        let schema = object_schema(vec![("enabled", boolean_schema())]);
        let text = "enabled: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 9), Some(&schema));

        let labels = labels(&result);
        assert!(labels.contains(&"true"), "should suggest 'true'");
        assert!(labels.contains(&"false"), "should suggest 'false'");
        assert!(
            result
                .iter()
                .any(|i| i.kind == Some(CompletionItemKind::VALUE)),
            "boolean completions should have VALUE kind"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group D — Path Resolution
    // ══════════════════════════════════════════════════════════════════════════

    // Test 29
    #[test]
    fn should_resolve_nested_path_for_schema_property_completion() {
        let schema = object_schema(vec![(
            "database",
            object_schema(vec![("host", string_schema()), ("port", integer_schema())]),
        )]);
        let text = "database:\n  host: localhost\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 2), Some(&schema));

        let labels = labels(&result);
        assert!(labels.contains(&"port"), "should suggest nested 'port'");
        assert!(
            !labels.contains(&"database"),
            "should not suggest parent 'database'"
        );
    }

    // Test 30
    #[test]
    fn should_resolve_array_items_schema_for_key_completion() {
        let schema = object_schema(vec![(
            "servers",
            JsonSchema {
                schema_type: Some(SchemaType::Single("array".to_string())),
                items: Some(Box::new(object_schema(vec![
                    ("host", string_schema()),
                    ("port", integer_schema()),
                ]))),
                ..JsonSchema::default()
            },
        )]);
        let text = "servers:\n  - host: localhost\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 4), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"port"),
            "should suggest 'port' from items schema"
        );
    }

    // Test 31
    #[test]
    fn should_resolve_path_to_third_level_nesting() {
        let schema = object_schema(vec![(
            "a",
            object_schema(vec![(
                "b",
                object_schema(vec![("c", string_schema()), ("d", integer_schema())]),
            )]),
        )]);
        let text = "a:\n  b:\n    c: v\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(2, 4), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"d"),
            "should suggest deep schema property 'd'"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group E — Composition Schemas
    // ══════════════════════════════════════════════════════════════════════════

    // Test 32
    #[test]
    fn should_suggest_properties_from_allof_branches() {
        let schema = JsonSchema {
            all_of: Some(vec![
                object_schema(vec![("name", string_schema())]),
                object_schema(vec![("age", integer_schema())]),
            ]),
            ..JsonSchema::default()
        };
        let text = "name: Alice\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"age"),
            "should suggest 'age' merged from allOf branches"
        );
    }

    // Test 33
    #[test]
    fn should_suggest_properties_from_anyof_branches() {
        let schema = JsonSchema {
            any_of: Some(vec![
                object_schema(vec![("host", string_schema())]),
                object_schema(vec![("socket", string_schema())]),
            ]),
            ..JsonSchema::default()
        };
        let text = "host: localhost\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"socket"),
            "should suggest 'socket' merged from anyOf branches"
        );
    }

    // Test 34
    #[test]
    fn should_suggest_properties_from_oneof_branches() {
        let schema = JsonSchema {
            one_of: Some(vec![
                object_schema(vec![("url", string_schema())]),
                object_schema(vec![("path", string_schema())]),
            ]),
            ..JsonSchema::default()
        };
        let text = "url: http://example.com\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"path"),
            "should suggest 'path' from oneOf branches"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group F — Fallback Behavior
    // ══════════════════════════════════════════════════════════════════════════

    // Test 35
    #[test]
    fn should_fall_back_to_structural_completion_when_schema_is_none() {
        let text = "name: Alice\nage: 30\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"age"),
            "structural sibling 'age' should appear when schema is None"
        );
    }

    // Test 36
    #[test]
    fn should_fall_back_to_structural_when_schema_has_no_properties() {
        let schema = JsonSchema::default();
        let text = "name: Alice\nage: 30\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"age"),
            "structural sibling 'age' should appear when schema has no properties"
        );
    }

    // Test 37
    #[test]
    fn should_offer_schema_property_when_structural_has_no_siblings() {
        // Schema has "unrelated"; document only has "name" (no siblings for structural).
        let schema = object_schema(vec![("unrelated", JsonSchema::default())]);
        let text = "name: Alice\n";
        let docs = parse_docs(text);
        // cursor at key position on the only key "name"; no structural siblings, but schema
        // offers "unrelated"
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"unrelated"),
            "schema property 'unrelated' should appear even when no structural siblings"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group G — Edge Cases
    // ══════════════════════════════════════════════════════════════════════════

    // Test 38
    #[test]
    fn should_return_empty_for_schema_completion_on_empty_document() {
        let schema = object_schema(vec![("name", string_schema())]);
        let docs: Option<Vec<YamlOwned>> = None;
        let result = complete_at("", docs.as_ref(), pos(0, 0), Some(&schema));

        assert!(result.is_empty(), "should return empty for empty document");
    }

    // Test 39
    #[test]
    fn should_return_empty_for_schema_completion_on_comment_line() {
        let schema = object_schema(vec![("name", string_schema())]);
        let text = "# comment\nkey: value\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        assert!(result.is_empty(), "should return empty for comment line");
    }

    // Test 40
    #[test]
    fn should_return_empty_for_schema_completion_on_document_separator() {
        let schema = object_schema(vec![("name", string_schema())]);
        let text = "key1: v1\n---\nkey2: v2\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 0), Some(&schema));

        assert!(
            result.is_empty(),
            "should return empty for document separator"
        );
    }

    // Test 41
    #[test]
    fn should_handle_schema_property_with_no_type_gracefully() {
        let schema = object_schema(vec![("data", JsonSchema::default())]);
        let text = "name: Alice\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let item = result.iter().find(|i| i.label == "data");
        assert!(item.is_some(), "should suggest 'data' without panicking");
        // detail may be None or empty — no type to show
        let item = item.unwrap();
        if let Some(detail) = &item.detail {
            assert!(
                detail.is_empty(),
                "detail should be empty when schema has no type, got: {detail:?}"
            );
        }
    }

    // Test 42
    #[test]
    fn should_handle_enum_completion_with_partial_value_at_cursor() {
        let schema = object_schema(vec![(
            "env",
            JsonSchema {
                enum_values: Some(vec![json!("production"), json!("staging")]),
                ..JsonSchema::default()
            },
        )]);
        // Cursor after "pro" — value position with partial input
        let text = "env: pro\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 8), Some(&schema));

        let labels = labels(&result);
        // LSP filtering is client-side; server should return all enum options
        assert!(
            labels.contains(&"production") || labels.contains(&"staging"),
            "should return enum suggestions even with partial value at cursor"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Security Tests (Tests 43–50)
    // ══════════════════════════════════════════════════════════════════════════

    // Test 43 — description truncated at 200 Unicode chars
    #[test]
    fn should_truncate_description_at_200_chars_in_completion_documentation() {
        let long_desc = "x".repeat(500);
        let schema = object_schema(vec![(
            "name",
            JsonSchema {
                description: Some(long_desc),
                ..JsonSchema::default()
            },
        )]);
        let text = "age: 30\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let item = result.iter().find(|i| i.label == "name");
        assert!(item.is_some(), "should suggest 'name'");
        if let Some(item) = item {
            let doc_char_count = match &item.documentation {
                Some(Documentation::String(s)) => s.chars().count(),
                Some(Documentation::MarkupContent(m)) => m.value.chars().count(),
                None => 0,
            };
            assert!(
                doc_char_count <= 200,
                "documentation should be truncated to 200 chars, got {}",
                doc_char_count
            );
        }
    }

    // Test 44 — item count cap at 100
    #[test]
    fn should_cap_completion_items_at_100_when_schema_has_many_properties() {
        let properties: std::collections::HashMap<String, JsonSchema> = (0..150)
            .map(|i| (format!("prop_{i:03}"), JsonSchema::default()))
            .collect();
        let schema = JsonSchema {
            schema_type: Some(SchemaType::Single("object".to_string())),
            properties: Some(properties),
            ..JsonSchema::default()
        };
        let text = "prop_000: x\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        assert!(
            result.len() <= 100,
            "completion items should be capped at 100, got {}",
            result.len()
        );
    }

    // Test 45 — allOf branch walking capped at MAX_BRANCH_COUNT (20)
    #[test]
    fn should_cap_allof_branch_walking_at_max_branch_count() {
        // 30 branches — only MAX_BRANCH_COUNT (20) should be walked
        let branches: Vec<JsonSchema> = (0..30)
            .map(|i| JsonSchema {
                properties: Some(
                    std::iter::once((format!("field_{i}"), JsonSchema::default())).collect(),
                ),
                ..JsonSchema::default()
            })
            .collect();
        let schema = JsonSchema {
            all_of: Some(branches),
            ..JsonSchema::default()
        };
        let text = "irrelevant: x\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        // At most 20 branches walked → at most 20 distinct schema-sourced properties
        let schema_prop_count = result
            .iter()
            .filter(|i| i.kind == Some(CompletionItemKind::FIELD))
            .count();
        assert!(
            schema_prop_count <= 20,
            "at most 20 allOf branches should be walked, got {} schema props",
            schema_prop_count
        );
    }

    // Test 46 — enum labels truncated at 50 chars
    #[test]
    fn should_truncate_long_enum_labels_at_50_chars() {
        let long_val = "a".repeat(60);
        let schema = object_schema(vec![(
            "key",
            JsonSchema {
                enum_values: Some(vec![json!(long_val)]),
                ..JsonSchema::default()
            },
        )]);
        let text = "key: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 5), Some(&schema));

        assert!(!result.is_empty(), "should have enum suggestion");
        for item in &result {
            assert!(
                item.label.chars().count() <= 50,
                "enum label should be truncated to 50 chars, got {} chars: {}",
                item.label.chars().count(),
                item.label
            );
        }
    }

    // Test 47 — JSON boolean enum values produce YAML scalar labels "true"/"false"
    #[test]
    fn should_convert_json_boolean_enum_to_yaml_scalar_true_false() {
        let schema = object_schema(vec![(
            "enabled",
            JsonSchema {
                enum_values: Some(vec![json!(true), json!(false)]),
                ..JsonSchema::default()
            },
        )]);
        let text = "enabled: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 9), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"true"),
            "JSON boolean true should produce label 'true', got: {labels:?}"
        );
        assert!(
            labels.contains(&"false"),
            "JSON boolean false should produce label 'false', got: {labels:?}"
        );
        assert!(
            !labels.contains(&"\"true\""),
            "should not produce JSON-quoted string '\"true\"'"
        );
        assert!(
            !labels.contains(&"\"false\""),
            "should not produce JSON-quoted string '\"false\"'"
        );
    }

    // Test 48 — path depth exceeds schema depth: graceful bail, no panic
    #[test]
    fn should_return_no_schema_context_when_yaml_path_exceeds_schema_depth() {
        // Schema is only 2 levels deep; YAML cursor is 5 levels deep.
        // The path walker runs out of properties before reaching the cursor — must bail cleanly.
        let schema = object_schema(vec![("a", object_schema(vec![("b", string_schema())]))]);
        let text = "a:\n  b:\n    c:\n      d:\n        e: v\n";
        let docs = parse_docs(text);
        // Must not panic or hang regardless of result
        let _result = complete_at(text, docs.as_ref(), pos(4, 8), Some(&schema));
    }

    // Test 49 — already-present keys excluded from schema suggestions
    #[test]
    fn should_exclude_already_present_keys_from_schema_suggestions() {
        let schema = object_schema(vec![
            ("a", JsonSchema::default()),
            ("b", JsonSchema::default()),
            ("c", JsonSchema::default()),
        ]);
        let text = "a: 1\nb: 2\n";
        let docs = parse_docs(text);
        // cursor on a new blank line at indent 0, key position after "b"
        let result = complete_at(text, docs.as_ref(), pos(1, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            !labels.contains(&"a"),
            "'a' is already present, should not appear"
        );
        assert!(
            !labels.contains(&"b"),
            "'b' is on cursor line, should not appear"
        );
        assert!(labels.contains(&"c"), "'c' is not present, should appear");
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group H — Multi-Document Boundary Tests
    // ══════════════════════════════════════════════════════════════════════════

    // Test 51 — sibling keys must not cross --- boundary
    #[test]
    fn should_not_suggest_sibling_keys_from_other_document() {
        // doc1 has "alpha"; doc2 has "beta". Cursor on "beta" should not see "alpha".
        let text = "alpha: 1\n---\nbeta: 2\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(2, 0), None);

        let labels = labels(&result);
        assert!(
            !labels.contains(&"alpha"),
            "should not suggest 'alpha' from document 1 when cursor is in document 2, got: {labels:?}"
        );
    }

    // Test 52 — sibling keys must not cross ... boundary
    #[test]
    fn should_not_suggest_sibling_keys_across_document_end_marker() {
        let text = "alpha: 1\n...\nbeta: 2\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(2, 0), None);

        let labels = labels(&result);
        assert!(
            !labels.contains(&"alpha"),
            "should not suggest 'alpha' from before '...' separator, got: {labels:?}"
        );
    }

    // Test 53 — collect_present_keys_at_indent must not see keys from other document
    #[test]
    fn should_not_suppress_schema_key_present_only_in_other_document() {
        // doc1 has "name: Alice"; doc2 has only "age: 30".
        // Schema has "name" and "age". Cursor in doc2 — "name" should be suggested because
        // it is not present in doc2.
        let schema = object_schema(vec![("name", string_schema()), ("age", integer_schema())]);
        let text = "name: Alice\n---\nage: 30\n";
        let docs = parse_docs(text);
        // cursor on "age:" in doc2
        let result = complete_at(text, docs.as_ref(), pos(2, 0), Some(&schema));

        let labels = labels(&result);
        assert!(
            labels.contains(&"name"),
            "should suggest 'name' because it is absent from document 2, got: {labels:?}"
        );
    }

    // Test 54 — suggest_values_for_key must not include values from other document
    #[test]
    fn should_not_suggest_values_from_other_document() {
        // doc1 has "env: production"; doc2 has "env: " (cursor here).
        // Value completion for "env" in doc2 should not see "production" from doc1.
        let text = "env: production\n---\nenv: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(2, 5), None);

        let labels = labels(&result);
        assert!(
            !labels.contains(&"production"),
            "should not suggest 'production' from document 1 when cursor is in document 2, got: {labels:?}"
        );
    }

    // Test 55 — is_in_sequence_item must not cross --- boundary
    #[test]
    fn should_not_detect_sequence_context_from_other_document() {
        // doc1 has a sequence item "- name: Alice"; doc2 has a plain mapping "host: local".
        // Completion in doc2 should use mapping-sibling logic, not sequence-item logic.
        let text = "items:\n  - name: Alice\n---\nhost: local\nport: 8080\n";
        let docs = parse_docs(text);
        // cursor on "host:" in doc2
        let result = complete_at(text, docs.as_ref(), pos(3, 0), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"port"),
            "should suggest sibling key 'port' in document 2, got: {labels:?}"
        );
        assert!(
            !labels.contains(&"name"),
            "should not suggest 'name' from the sequence in document 1, got: {labels:?}"
        );
    }

    // Test 56 — cursor on first line (no separator before it)
    #[test]
    fn should_handle_cursor_on_first_line_of_multi_doc_file() {
        let text = "alpha: 1\n---\nbeta: 2\n";
        let docs = parse_docs(text);
        // cursor on "alpha:" — first line, no separator before it
        let result = complete_at(text, docs.as_ref(), pos(0, 0), None);

        let labels = labels(&result);
        assert!(
            !labels.contains(&"beta"),
            "should not suggest 'beta' from document 2 when cursor is on line 0, got: {labels:?}"
        );
    }

    // Test 57 — cursor on last line of file (no separator after it)
    #[test]
    fn should_handle_cursor_on_last_line_of_multi_doc_file() {
        let text = "alpha: 1\n---\nbeta: 2\ngamma: 3\n";
        let docs = parse_docs(text);
        // cursor on last line "gamma:"
        let result = complete_at(text, docs.as_ref(), pos(3, 0), None);

        let labels = labels(&result);
        assert!(
            labels.contains(&"beta"),
            "should suggest sibling 'beta' from the same document, got: {labels:?}"
        );
        assert!(
            !labels.contains(&"alpha"),
            "should not suggest 'alpha' from document 1, got: {labels:?}"
        );
    }

    // Test 58 — consecutive separators (empty document between them)
    #[test]
    fn should_handle_consecutive_document_separators() {
        let text = "alpha: 1\n---\n---\nbeta: 2\n";
        let docs = parse_docs(text);
        // cursor on "beta:" — the document between the two --- lines is empty
        let result = complete_at(text, docs.as_ref(), pos(3, 0), None);

        let labels = labels(&result);
        assert!(
            !labels.contains(&"alpha"),
            "should not suggest 'alpha' from document 1 through empty middle document, got: {labels:?}"
        );
    }

    // Test 59 — deprecated property gets DEPRECATED tag and tilde sort_text
    #[test]
    fn should_tag_deprecated_property_with_deprecated_tag_and_tilde_sort_text() {
        let schema = object_schema(vec![(
            "old_field",
            JsonSchema {
                deprecated: Some(true),
                ..JsonSchema::default()
            },
        )]);
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let item = result
            .iter()
            .find(|i| i.label == "old_field")
            .expect("should suggest old_field");
        assert_eq!(
            item.tags,
            Some(vec![CompletionItemTag::DEPRECATED]),
            "deprecated property should have DEPRECATED tag"
        );
        assert!(
            item.sort_text
                .as_deref()
                .map(|s| s.starts_with('~'))
                .unwrap_or(false),
            "deprecated property sort_text should start with '~', got: {:?}",
            item.sort_text
        );
    }

    // Test 60 — non-deprecated property has no tags and no sort_text
    #[test]
    fn should_not_tag_non_deprecated_property() {
        let schema = object_schema(vec![(
            "current_field",
            JsonSchema {
                deprecated: None,
                ..JsonSchema::default()
            },
        )]);
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let item = result
            .iter()
            .find(|i| i.label == "current_field")
            .expect("should suggest current_field");
        assert_eq!(
            item.tags, None,
            "non-deprecated property should have no tags"
        );
        assert_eq!(
            item.sort_text, None,
            "non-deprecated property should have no sort_text"
        );
    }

    // Test 61 — only deprecated property is tagged when mixed schema
    #[test]
    fn should_only_tag_deprecated_property_in_mixed_schema() {
        let schema = object_schema(vec![
            (
                "new_field",
                JsonSchema {
                    deprecated: None,
                    ..JsonSchema::default()
                },
            ),
            (
                "old_field",
                JsonSchema {
                    deprecated: Some(true),
                    ..JsonSchema::default()
                },
            ),
        ]);
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let new_item = result
            .iter()
            .find(|i| i.label == "new_field")
            .expect("should suggest new_field");
        let old_item = result
            .iter()
            .find(|i| i.label == "old_field")
            .expect("should suggest old_field");

        assert_eq!(
            new_item.tags, None,
            "non-deprecated 'new_field' should have no tags"
        );
        assert_eq!(
            old_item.tags,
            Some(vec![CompletionItemTag::DEPRECATED]),
            "deprecated 'old_field' should have DEPRECATED tag"
        );
    }

    // Test 50 — lock ordering: document_store released before schema_associations
    #[test]
    #[ignore]
    fn lock_ordering_document_store_released_before_schema_associations() {
        // Structural/code-review enforcement test — not executable at unit test level.
        //
        // The completion handler in server.rs must acquire locks in this order:
        //   document_store → schema_associations → schema_cache
        // Each lock must be fully released (guard dropped) before the next is acquired.
        // No std::sync::Mutex guard may be held across an .await point.
        // Enforcement: code review + the lock ordering comment on the Backend struct.
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group I — Multi-Required Snippet Completion
    // ══════════════════════════════════════════════════════════════════════════

    fn schema_with_required(props: Vec<(&str, JsonSchema)>, required: Vec<&str>) -> JsonSchema {
        JsonSchema {
            schema_type: Some(SchemaType::Single("object".to_string())),
            properties: Some(props.into_iter().map(|(k, v)| (k.to_string(), v)).collect()),
            required: Some(required.into_iter().map(str::to_string).collect()),
            ..JsonSchema::default()
        }
    }

    // Test 62 — 3 required props all missing → snippet item with all 3 tab-stops
    #[test]
    fn should_offer_all_required_snippet_when_three_required_props_missing() {
        let schema = schema_with_required(
            vec![
                ("name", string_schema()),
                ("age", integer_schema()),
                ("enabled", boolean_schema()),
            ],
            vec!["name", "age", "enabled"],
        );
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let snippet = result
            .iter()
            .find(|i| i.label == "(all required)")
            .expect("should offer '(all required)' snippet item");

        let insert_text = snippet
            .insert_text
            .as_deref()
            .expect("snippet item must have insert_text");

        assert!(
            insert_text.contains("${1:"),
            "snippet must contain tab-stop ${{1:...}}, got: {insert_text}"
        );
        assert!(
            insert_text.contains("${2:"),
            "snippet must contain tab-stop ${{2:...}}, got: {insert_text}"
        );
        assert!(
            insert_text.contains("${3:"),
            "snippet must contain tab-stop ${{3:...}}, got: {insert_text}"
        );
        assert!(
            insert_text.contains("name:"),
            "snippet must mention 'name', got: {insert_text}"
        );
        assert!(
            insert_text.contains("age:"),
            "snippet must mention 'age', got: {insert_text}"
        );
        assert!(
            insert_text.contains("enabled:"),
            "snippet must mention 'enabled', got: {insert_text}"
        );
    }

    // Test 63 — 3 required, 2 already present → no snippet (only 1 missing)
    #[test]
    fn should_not_offer_snippet_when_only_one_required_prop_missing() {
        let schema = schema_with_required(
            vec![
                ("name", string_schema()),
                ("age", integer_schema()),
                ("enabled", boolean_schema()),
            ],
            vec!["name", "age", "enabled"],
        );
        // "name" and "age" are already present; only "enabled" is missing
        let text = "name: Alice\nage: 30\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let has_snippet = result.iter().any(|i| i.label == "(all required)");
        assert!(
            !has_snippet,
            "should not offer snippet when only 1 required prop is missing"
        );
    }

    // Test 64 — schema with 0 required → no snippet
    #[test]
    fn should_not_offer_snippet_when_no_required_props() {
        let schema = object_schema(vec![("name", string_schema()), ("age", integer_schema())]);
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let has_snippet = result.iter().any(|i| i.label == "(all required)");
        assert!(
            !has_snippet,
            "should not offer snippet when schema has no required array"
        );
    }

    // Test 65 — type-aware defaults: string → "", integer → 0, boolean → false
    #[test]
    fn should_use_type_aware_defaults_in_snippet() {
        let schema = schema_with_required(
            vec![
                ("title", string_schema()),
                ("count", integer_schema()),
                ("active", boolean_schema()),
            ],
            vec!["title", "count", "active"],
        );
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let snippet = result
            .iter()
            .find(|i| i.label == "(all required)")
            .expect("should offer snippet");

        let insert_text = snippet
            .insert_text
            .as_deref()
            .expect("must have insert_text");

        assert!(
            insert_text.contains("\"\""),
            "string type should default to \"\", got: {insert_text}"
        );
        assert!(
            insert_text.contains(":0")
                || insert_text.contains(": 0")
                || insert_text.contains("{1:0}")
                || insert_text.contains("{2:0}")
                || insert_text.contains("{3:0}"),
            "integer type should default to 0, got: {insert_text}"
        );
        assert!(
            insert_text.contains("false"),
            "boolean type should default to false, got: {insert_text}"
        );
    }

    // Test 66 — snippet item has InsertTextFormat::SNIPPET
    #[test]
    fn should_set_insert_text_format_to_snippet() {
        let schema = schema_with_required(
            vec![("name", string_schema()), ("age", integer_schema())],
            vec!["name", "age"],
        );
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let snippet = result
            .iter()
            .find(|i| i.label == "(all required)")
            .expect("should offer snippet");

        assert_eq!(
            snippet.insert_text_format,
            Some(InsertTextFormat::SNIPPET),
            "snippet item must have InsertTextFormat::SNIPPET"
        );
    }

    // Test 67 — snippet item sort_text is "!" (sorts to top)
    #[test]
    fn should_set_snippet_sort_text_to_exclamation() {
        let schema = schema_with_required(
            vec![("name", string_schema()), ("age", integer_schema())],
            vec!["name", "age"],
        );
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let snippet = result
            .iter()
            .find(|i| i.label == "(all required)")
            .expect("should offer snippet");

        assert_eq!(
            snippet.sort_text.as_deref(),
            Some("!"),
            "snippet sort_text should be '!' to sort to top"
        );
    }

    // ══════════════════════════════════════════════════════════════════════════
    // Group J — Previously Uncovered Paths
    // ══════════════════════════════════════════════════════════════════════════

    // Line 74: blank line with no schema → returns empty vec
    #[test]
    fn should_return_empty_for_blank_line_when_no_schema() {
        let text = "key: value\n\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 0), None);

        assert!(
            result.is_empty(),
            "blank line with no schema should return empty"
        );
    }

    // Lines 191-192: sequence item with no key in build_key_path pushes "[]"
    // A bare "- " line in the parent triggers the [] sentinel.
    #[test]
    fn should_build_path_with_sequence_sentinel_for_bare_sequence_parent() {
        // "servers" is a sequence; items have "host" and "port".
        // Schema resolves via "servers" → [] → items schema.
        let schema = object_schema(vec![(
            "servers",
            JsonSchema {
                schema_type: Some(SchemaType::Single("array".to_string())),
                items: Some(Box::new(object_schema(vec![
                    ("host", string_schema()),
                    ("port", integer_schema()),
                ]))),
                ..JsonSchema::default()
            },
        )]);
        // Bare sequence item "- " with no inline key, then indented key below it
        let text = "servers:\n  -\n    host: localhost\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(2, 4), Some(&schema));

        let ls = labels(&result);
        assert!(
            ls.contains(&"port"),
            "should suggest 'port' via sequence [] path, got: {ls:?}"
        );
    }

    // Lines 361-365: snippet_default for object/array/unknown types
    #[test]
    fn should_use_object_default_in_snippet_for_object_type_required_field() {
        // Need 2+ required missing for snippet; pair with a string field
        let schema = schema_with_required(
            vec![
                (
                    "config",
                    JsonSchema {
                        schema_type: Some(SchemaType::Single("object".to_string())),
                        ..JsonSchema::default()
                    },
                ),
                ("name", string_schema()),
            ],
            vec!["config", "name"],
        );
        let schema2 = schema_with_required(
            vec![
                (
                    "tags",
                    JsonSchema {
                        schema_type: Some(SchemaType::Single("array".to_string())),
                        ..JsonSchema::default()
                    },
                ),
                ("name", string_schema()),
            ],
            vec!["tags", "name"],
        );

        let text = "\n";
        let docs = parse_docs(text);

        let result1 = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));
        let snippet1 = result1.iter().find(|i| i.label == "(all required)");
        assert!(
            snippet1.is_some(),
            "should offer snippet for object-typed field"
        );
        let insert1 = snippet1.unwrap().insert_text.as_deref().unwrap_or("");
        assert!(
            insert1.contains("{}"),
            "object type default should be '{{}}', got: {insert1}"
        );

        let result2 = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema2));
        let snippet2 = result2.iter().find(|i| i.label == "(all required)");
        assert!(
            snippet2.is_some(),
            "should offer snippet for array-typed field"
        );
        let insert2 = snippet2.unwrap().insert_text.as_deref().unwrap_or("");
        assert!(
            insert2.contains("[]"),
            "array type default should be '[]', got: {insert2}"
        );
    }

    // Line 332: required field with no-default type (None type) → bare tab-stop format
    #[test]
    fn should_use_bare_tab_stop_in_snippet_for_field_with_no_type() {
        // Need 2+ required missing to trigger snippet; pair no-type "data" with typed "name"
        let schema = schema_with_required(
            vec![("data", JsonSchema::default()), ("name", string_schema())],
            vec!["data", "name"],
        );
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let snippet = result.iter().find(|i| i.label == "(all required)");
        assert!(snippet.is_some(), "should offer snippet");
        let insert = snippet.unwrap().insert_text.as_deref().unwrap_or("");
        // "data" has no type so default is "" → produces "data: ${N:}" (bare tab-stop)
        assert!(
            insert.contains("data: ${"),
            "no-type field should have a tab-stop, got: {insert}"
        );
    }

    // Line 377: collect_schema_properties depth cap
    #[test]
    fn should_not_panic_when_allof_depth_exceeds_max_branch_count() {
        // Build a deeply recursive schema via allOf to hit the depth guard
        fn deep_schema(depth: usize) -> JsonSchema {
            if depth == 0 {
                return object_schema(vec![("leaf", JsonSchema::default())]);
            }
            JsonSchema {
                all_of: Some(vec![deep_schema(depth - 1)]),
                ..JsonSchema::default()
            }
        }
        // 25 levels deep — exceeds MAX_BRANCH_COUNT (20)
        let schema = deep_schema(25);
        let text = "\n";
        let docs = parse_docs(text);
        // Must not panic or hang
        let _result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));
    }

    // Lines 475-477: json_value_to_yaml_label for Number, Null, Array, Object
    #[test]
    fn should_render_number_and_null_enum_values_as_yaml_labels() {
        let schema = object_schema(vec![(
            "value",
            JsonSchema {
                enum_values: Some(vec![
                    serde_json::Value::Number(serde_json::Number::from(42)),
                    serde_json::Value::Null,
                    serde_json::Value::Number(serde_json::Number::from_f64(3.14).unwrap()),
                ]),
                ..JsonSchema::default()
            },
        )]);
        // "value: " is 7 chars; colon at index 5; col=6 puts cursor in value position
        let text = "value: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 6), Some(&schema));

        let ls = labels(&result);
        assert!(ls.contains(&"42"), "should render integer 42, got: {ls:?}");
        assert!(ls.contains(&"null"), "should render null, got: {ls:?}");
        assert!(
            ls.iter().any(|l| l.starts_with("3.14") || *l == "3.14"),
            "should render float 3.14, got: {ls:?}"
        );
    }

    #[test]
    fn should_skip_array_and_object_enum_values() {
        let schema = object_schema(vec![(
            "value",
            JsonSchema {
                enum_values: Some(vec![
                    serde_json::json!("valid"),
                    serde_json::json!(["a", "b"]), // array — skipped
                    serde_json::json!({"k": "v"}), // object — skipped
                ]),
                ..JsonSchema::default()
            },
        )]);
        // col=6: cursor in value position (after "value: ")
        let text = "value: \n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 6), Some(&schema));

        let ls = labels(&result);
        assert!(
            ls.contains(&"valid"),
            "string enum value should appear, got: {ls:?}"
        );
        assert_eq!(
            ls.len(),
            1,
            "array and object enum values should be skipped, got: {ls:?}"
        );
    }

    // Line 486: SchemaType::Multiple in type_label
    #[test]
    fn should_render_multiple_type_label_as_pipe_separated_string() {
        let schema = object_schema(vec![(
            "value",
            JsonSchema {
                schema_type: Some(SchemaType::Multiple(vec![
                    "string".to_string(),
                    "null".to_string(),
                ])),
                ..JsonSchema::default()
            },
        )]);
        let text = "name: x\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        let item = result.iter().find(|i| i.label == "value");
        assert!(item.is_some(), "should suggest 'value'");
        assert_eq!(
            item.unwrap().detail.as_deref(),
            Some("string | null"),
            "multiple types should be joined with ' | '"
        );
    }

    // Lines 538-542: find_mapping_colon single-quote handling
    #[test]
    fn should_find_colon_after_single_quoted_key_containing_colon() {
        // Key with colon inside single quotes; the mapping colon is after the closing quote
        let line = "'key:with:colons': value";
        let pos_colon = find_mapping_colon(line);
        assert!(
            pos_colon.is_some(),
            "should find mapping colon after closing quote, got: {pos_colon:?}"
        );
        let colon_pos = pos_colon.unwrap();
        assert_eq!(
            &line[..colon_pos],
            "'key:with:colons'",
            "key should be the single-quoted string"
        );
    }

    #[test]
    fn should_return_none_when_colon_is_inside_single_quotes() {
        // Line like "'no: colon here'" — no mapping colon outside quotes
        let line = "'no: colon here'";
        assert_eq!(
            find_mapping_colon(line),
            None,
            "colon inside single quotes should not count as mapping colon"
        );
    }

    // Lines 599, 611, 619, 621: is_in_sequence_item edge cases
    // Line 599: prev line is a document separator → break
    #[test]
    fn should_not_detect_sequence_context_across_document_separator() {
        let text = "items:\n  - name: Alice\n---\nhost: local\n";
        let docs = parse_docs(text);
        // "host:" is in a plain mapping in doc2; is_in_sequence_item should return false
        let result = complete_at(text, docs.as_ref(), pos(3, 0), None);
        let ls = labels(&result);
        // Should suggest sibling from same doc, not from sequence in doc1
        assert!(
            !ls.contains(&"name"),
            "should not suggest sequence key 'name' from doc1, got: {ls:?}"
        );
    }

    // Line 611: prev line at lower indent is NOT a "- " → break (no sequence detected)
    #[test]
    fn should_not_detect_sequence_context_when_parent_is_plain_mapping() {
        // "server:\n  host:" — parent is a plain mapping key, not a sequence item
        let text = "server:\n  host: localhost\n  port: 8080\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 2), None);
        let ls = labels(&result);
        assert!(
            ls.contains(&"port"),
            "should suggest sibling 'port', not sequence keys, got: {ls:?}"
        );
    }

    // Lines 619, 621: same-level "- " line in is_in_sequence_item → true
    // A same-indent previous "- " line means we're in a sequence context.
    #[test]
    fn should_detect_sequence_context_when_same_indent_sibling_is_sequence_item() {
        // Sequence items indented under a parent key
        // cursor on "  - name: Bob" (second item, which starts with "- ")
        let text = "people:\n  - name: Alice\n    age: 30\n  - name: Bob\n";
        let docs = parse_docs(text);
        // cursor on "  - name: Bob" (line 3), col=4 (inside key area)
        let result = complete_at(text, docs.as_ref(), pos(3, 4), None);
        let ls = labels(&result);
        assert!(
            ls.contains(&"age"),
            "should suggest 'age' from sibling sequence item via same-indent '- ' detection, got: {ls:?}"
        );
    }

    // Lines 675-733: find_current_item_start and find_sequence_indent
    #[test]
    fn should_suggest_sibling_sequence_item_keys_for_multiline_sequence_item() {
        // Sequence item spans multiple lines; cursor is inside an item
        // (not the first "- " line)
        let text = "items:\n  - name: Alice\n    age: 30\n    city: NY\n  - name: Bob\n";
        let docs = parse_docs(text);
        // cursor on line 4 ("  - name: Bob"), which is itself a "- " line
        let result = complete_at(text, docs.as_ref(), pos(4, 4), None);
        let ls = labels(&result);
        assert!(
            ls.contains(&"age") || ls.contains(&"city"),
            "should suggest keys from sibling sequence item, got: {ls:?}"
        );
    }

    #[test]
    fn should_find_sequence_indent_when_cursor_is_not_on_sequence_line() {
        // Cursor is on a key inside a sequence item (not the "- " line itself).
        // The sibling item has "score" which the current item doesn't — exercises
        // find_sequence_indent walking back from a non-"- " line.
        let text = "list:\n  - id: 1\n    label: a\n  - id: 2\n    score: 99\n";
        let docs = parse_docs(text);
        // cursor on line 2 ("    label: a") — inside the first sequence item
        let result = complete_at(text, docs.as_ref(), pos(2, 4), None);
        let ls = labels(&result);
        assert!(
            ls.contains(&"score"),
            "should suggest 'score' from sibling sequence item, got: {ls:?}"
        );
    }

    // Lines 778-827: collect_all_sequence_item_keys — walking backward to find
    // sequence start, then forward collecting keys
    #[test]
    fn should_collect_keys_from_all_sequence_items_including_those_before_cursor() {
        // Three sequence items; cursor on third. Keys from items 1 and 2 should appear.
        let text = "- kind: A\n  color: red\n- kind: B\n  size: large\n- kind: C\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(4, 2), None);
        let ls = labels(&result);
        assert!(
            ls.contains(&"color") || ls.contains(&"size"),
            "should collect keys from all prior sequence items, got: {ls:?}"
        );
    }

    // Lines 950, 969-971, 981-993: find_mapping_colon quote-aware edge cases
    #[test]
    fn should_find_colon_after_double_quoted_key_containing_colon() {
        let line = "\"key:with:colons\": value";
        let pos_colon = find_mapping_colon(line);
        assert!(
            pos_colon.is_some(),
            "should find mapping colon after closing double-quote, got: {pos_colon:?}"
        );
        let colon_pos = pos_colon.unwrap();
        assert_eq!(&line[..colon_pos], "\"key:with:colons\"");
    }

    #[test]
    fn should_return_none_for_line_with_no_colon() {
        assert_eq!(find_mapping_colon("just a plain value"), None);
    }

    #[test]
    fn should_return_none_for_colon_not_followed_by_space() {
        // "key:value" — colon not followed by space, not a mapping colon
        assert_eq!(
            find_mapping_colon("key:value"),
            None,
            "colon not followed by space should not be a mapping colon"
        );
    }

    #[test]
    fn should_return_none_for_colon_inside_double_quotes() {
        let line = "\"no: colon here\"";
        assert_eq!(
            find_mapping_colon(line),
            None,
            "colon inside double quotes should not count as mapping colon"
        );
    }

    // classify_cursor: Key context from sequence item line (lines 549-551)
    #[test]
    fn should_classify_cursor_as_key_for_sequence_item_with_key_colon() {
        // "- key: value" — effective_line is "key: value", find_mapping_colon on effective_line
        let result = classify_cursor("- mykey: value", 2);
        assert!(
            matches!(result, CursorContext::Key(k) if k == "mykey"),
            "should classify as Key with 'mykey'"
        );
    }

    // classify_cursor: Key context when line has no colon at all (line 554)
    #[test]
    fn should_classify_cursor_as_key_when_no_colon_on_line() {
        let result = classify_cursor("justtext", 0);
        assert!(
            matches!(result, CursorContext::Key(k) if k == "justtext"),
            "should classify bare text as Key"
        );
    }

    // complete_at with blank line + schema → schema_key_completions path (lines 64-74)
    #[test]
    fn should_suggest_schema_keys_on_blank_line_when_schema_is_present() {
        let schema = object_schema(vec![("host", string_schema()), ("port", integer_schema())]);
        let text = "host: localhost\n\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(1, 0), Some(&schema));

        let ls = labels(&result);
        assert!(
            ls.contains(&"port"),
            "should suggest 'port' on blank line with schema, got: {ls:?}"
        );
    }

    // blank line + schema but schema has no properties → returns empty (lines 68-74)
    #[test]
    fn should_return_empty_on_blank_line_when_schema_has_no_matching_path() {
        // Schema has "database" which has no sub-properties at top level cursor
        let schema = JsonSchema::default();
        let text = "\n";
        let docs = parse_docs(text);
        let result = complete_at(text, docs.as_ref(), pos(0, 0), Some(&schema));

        assert!(
            result.is_empty(),
            "blank line with schema having no properties should return empty"
        );
    }
}