data-protocol-validator 0.1.0

use std::collections::{HashMap, HashSet};

use serde_json::Value;

use crate::errors::create_error;
use crate::format::validate_format;
use crate::suggestions::{
    suggest_array_fix, suggest_missing_required, suggest_number_fix, suggest_remove_additional,
    suggest_string_fix, suggest_type_fix,
};
use crate::types::{
    Suggestion, ValidationError, ValidationOptions, ValidationResult, ValidationStats,
};

// ---------------------------------------------------------------------------
// Walker context
// ---------------------------------------------------------------------------

struct WalkerContext<'a> {
    errors: Vec<ValidationError>,
    root_schema: &'a Value,
    fields_checked: u64,
    fields_valid: u64,
    fields_invalid: u64,
    options: ValidationOptions,
}

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

/// Return the JSON type name for a value, compatible with the TypeScript
/// implementation's `getJsonType`.
fn get_json_type(value: &Value) -> &'static str {
    match value {
        Value::Null => "null",
        Value::Bool(_) => "boolean",
        Value::Number(_) => "number",
        Value::String(_) => "string",
        Value::Array(_) => "array",
        Value::Object(_) => "object",
    }
}

/// Check whether a value matches a single schema type keyword.
fn matches_type(type_name: &str, data: &Value) -> bool {
    match type_name {
        "string" => data.is_string(),
        "number" => data.is_number(),
        "integer" => data.is_number() && data.as_f64().map(|n| n.fract() == 0.0).unwrap_or(false),
        "boolean" => data.is_boolean(),
        "null" => data.is_null(),
        "object" => data.is_object(),
        "array" => data.is_array(),
        _ => false,
    }
}

/// Check whether `current_path` is relevant in partial validation mode.
fn is_in_partial_paths(current_path: &str, paths: &[String]) -> bool {
    paths.iter().any(|p| {
        current_path == p
            || current_path.starts_with(&format!("{}/", p))
            || p.starts_with(&format!("{}/", current_path))
    })
}

/// Add an error to the context, optionally attaching a suggestion.
fn add_error(ctx: &mut WalkerContext, mut error: ValidationError, suggestion: Option<Suggestion>) {
    if let Some(s) = suggestion {
        error.suggestion = Some(s);
    }
    ctx.errors.push(error);
    ctx.fields_invalid += 1;
}

/// Resolve a `$ref` string against the root schema's `$defs`.
fn resolve_ref<'a>(ref_str: &str, root_schema: &'a Value) -> Option<&'a Value> {
    let prefix = "#/$defs/";
    if !ref_str.starts_with(prefix) {
        return None;
    }
    let def_name = &ref_str[prefix.len()..];
    root_schema.get("$defs").and_then(|defs| defs.get(def_name))
}

// ---------------------------------------------------------------------------
// Core recursive walker
// ---------------------------------------------------------------------------

fn walk_schema(schema: &Value, data: &Value, path: &str, ctx: &mut WalkerContext) {
    // Partial mode: skip paths not in the paths list
    if ctx.options.mode == "partial" && !ctx.options.paths.is_empty() && !is_in_partial_paths(path, &ctx.options.paths) {
        return;
    }

    // Resolve $ref
    if let Some(ref_str) = schema.get("$ref").and_then(|v| v.as_str()) {
        match resolve_ref(ref_str, ctx.root_schema) {
            Some(resolved) => {
                walk_schema(resolved, data, path, ctx);
                return;
            }
            None => {
                let mut context = HashMap::new();
                context.insert("ref", ref_str.to_string());
                add_error(ctx, create_error("E011", path, context), None);
                return;
            }
        }
    }

    // Check x-deprecated (warning only)
    if let Some(dep) = schema.get("x-deprecated") {
        if !dep.is_null() && dep.as_bool() != Some(false) {
            let reason = if let Some(s) = dep.as_str() {
                s.to_string()
            } else {
                "deprecated".to_string()
            };
            let mut context = HashMap::new();
            context.insert("field", path.to_string());
            context.insert("reason", reason);
            let warning = create_error("W001", path, context);
            ctx.errors.push(warning);
        }
    }

    // Composition: allOf, anyOf, oneOf
    if let Some(all_of) = schema.get("allOf").and_then(|v| v.as_array()) {
        validate_all_of(all_of, data, path, ctx);
    }
    if let Some(any_of) = schema.get("anyOf").and_then(|v| v.as_array()) {
        validate_any_of(any_of, data, path, ctx);
    }
    if let Some(one_of) = schema.get("oneOf").and_then(|v| v.as_array()) {
        validate_one_of(one_of, data, path, ctx);
    }

    // Enum
    if let Some(enum_values) = schema.get("enum").and_then(|v| v.as_array()) {
        ctx.fields_checked += 1;
        if !enum_values.iter().any(|e| e == data) {
            let data_str = serde_json::to_string(data).unwrap_or_default();
            let enum_str = enum_values
                .iter()
                .map(|e| serde_json::to_string(e).unwrap_or_default())
                .collect::<Vec<_>>()
                .join(", ");
            let mut context = HashMap::new();
            context.insert("value", data_str);
            context.insert("constraint", format!("enum [{}]", enum_str));
            add_error(ctx, create_error("E009", path, context), None);
        } else {
            ctx.fields_valid += 1;
        }
        return;
    }

    // Const
    if schema.get("const").is_some() {
        let const_val = &schema["const"];
        ctx.fields_checked += 1;
        if const_val != data {
            let data_str = serde_json::to_string(data).unwrap_or_default();
            let const_str = serde_json::to_string(const_val).unwrap_or_default();
            let mut context = HashMap::new();
            context.insert("value", data_str);
            context.insert("constraint", format!("const {}", const_str));
            add_error(ctx, create_error("E009", path, context), None);
        } else {
            ctx.fields_valid += 1;
        }
        return;
    }

    // Type check
    if let Some(type_val) = schema.get("type") {
        let types: Vec<String> = if let Some(arr) = type_val.as_array() {
            arr.iter()
                .filter_map(|v| v.as_str().map(|s| s.to_string()))
                .collect()
        } else if let Some(s) = type_val.as_str() {
            vec![s.to_string()]
        } else {
            vec![]
        };

        let type_matches = types.iter().any(|t| matches_type(t, data));

        if !type_matches {
            ctx.fields_checked += 1;
            let actual_type = get_json_type(data);
            let suggestion = suggest_type_fix(data, &types[0]);
            let mut context = HashMap::new();
            context.insert("expected", types.join(" | "));
            context.insert("actual", actual_type.to_string());
            add_error(ctx, create_error("E001", path, context), suggestion);
            return; // Don't check constraints if type doesn't match
        }
    }

    // Type-specific constraint validation
    let actual_type = get_json_type(data);

    match actual_type {
        "string" => {
            if let Some(s) = data.as_str() {
                validate_string(schema, s, path, ctx);
            }
        }
        "number" => {
            if let Some(n) = data.as_f64() {
                validate_number(schema, n, path, ctx);
            }
        }
        "array" => {
            if let Some(arr) = data.as_array() {
                validate_array(schema, arr, path, ctx);
            }
        }
        "object" => {
            if let Some(obj) = data.as_object() {
                validate_object(schema, obj, path, ctx);
            }
        }
        _ => {
            // Primitive types with no constraints (boolean, null)
            ctx.fields_checked += 1;
            ctx.fields_valid += 1;
        }
    }
}

// ---------------------------------------------------------------------------
// String validation
// ---------------------------------------------------------------------------

fn validate_string(schema: &Value, data: &str, path: &str, ctx: &mut WalkerContext) {
    ctx.fields_checked += 1;
    let mut valid = true;

    if let Some(min_len) = schema.get("minLength").and_then(|v| v.as_u64()) {
        if (data.len() as u64) < min_len {
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("minLength {}, got length {}", min_len, data.len()),
            );
            add_error(ctx, create_error("E004", path, context), None);
            valid = false;
        }
    }

    if let Some(max_len) = schema.get("maxLength").and_then(|v| v.as_u64()) {
        if (data.len() as u64) > max_len {
            let suggestion = suggest_string_fix(data, schema);
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("maxLength {}, got length {}", max_len, data.len()),
            );
            add_error(ctx, create_error("E004", path, context), suggestion);
            valid = false;
        }
    }

    if let Some(pattern) = schema.get("pattern").and_then(|v| v.as_str()) {
        if let Ok(re) = regex::Regex::new(pattern) {
            if !re.is_match(data) {
                let mut context = HashMap::new();
                context.insert(
                    "constraint",
                    format!("pattern \"{}\" does not match", pattern),
                );
                add_error(ctx, create_error("E004", path, context), None);
                valid = false;
            }
        }
    }

    if let Some(format) = schema.get("format").and_then(|v| v.as_str()) {
        if !validate_format(data, format) {
            let mut context = HashMap::new();
            context.insert("format", format.to_string());
            context.insert("value", data.to_string());
            add_error(ctx, create_error("E008", path, context), None);
            valid = false;
        }
    }

    if valid {
        ctx.fields_valid += 1;
    }
}

// ---------------------------------------------------------------------------
// Number validation
// ---------------------------------------------------------------------------

fn validate_number(schema: &Value, data: f64, path: &str, ctx: &mut WalkerContext) {
    ctx.fields_checked += 1;
    let mut valid = true;

    if let Some(min) = schema.get("minimum").and_then(|v| v.as_f64()) {
        if data < min {
            let suggestion = suggest_number_fix(data, schema);
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("minimum {}, got {}", format_num(min), format_num(data)),
            );
            add_error(ctx, create_error("E005", path, context), suggestion);
            valid = false;
        }
    }

    if let Some(max) = schema.get("maximum").and_then(|v| v.as_f64()) {
        if data > max {
            let suggestion = suggest_number_fix(data, schema);
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("maximum {}, got {}", format_num(max), format_num(data)),
            );
            add_error(ctx, create_error("E005", path, context), suggestion);
            valid = false;
        }
    }

    if let Some(exc_min) = schema.get("exclusiveMinimum").and_then(|v| v.as_f64()) {
        if data <= exc_min {
            let suggestion = suggest_number_fix(data, schema);
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!(
                    "exclusiveMinimum {}, got {}",
                    format_num(exc_min),
                    format_num(data)
                ),
            );
            add_error(ctx, create_error("E005", path, context), suggestion);
            valid = false;
        }
    }

    if let Some(exc_max) = schema.get("exclusiveMaximum").and_then(|v| v.as_f64()) {
        if data >= exc_max {
            let suggestion = suggest_number_fix(data, schema);
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!(
                    "exclusiveMaximum {}, got {}",
                    format_num(exc_max),
                    format_num(data)
                ),
            );
            add_error(ctx, create_error("E005", path, context), suggestion);
            valid = false;
        }
    }

    if let Some(multiple_of) = schema.get("multipleOf").and_then(|v| v.as_f64()) {
        let remainder = (data % multiple_of).abs();
        let tolerance = 1e-10;
        if remainder > tolerance && (remainder - multiple_of).abs() > tolerance {
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!(
                    "multipleOf {}, got {}",
                    format_num(multiple_of),
                    format_num(data)
                ),
            );
            add_error(ctx, create_error("E005", path, context), None);
            valid = false;
        }
    }

    if valid {
        ctx.fields_valid += 1;
    }
}

/// Format a number for display in error messages, matching JS behaviour.
fn format_num(n: f64) -> String {
    if n.fract() == 0.0 && n.abs() < 1e15 {
        format!("{}", n as i64)
    } else {
        format!("{}", n)
    }
}

// ---------------------------------------------------------------------------
// Array validation
// ---------------------------------------------------------------------------

fn validate_array(schema: &Value, data: &[Value], path: &str, ctx: &mut WalkerContext) {
    ctx.fields_checked += 1;
    let mut valid = true;

    if let Some(min_items) = schema.get("minItems").and_then(|v| v.as_u64()) {
        if (data.len() as u64) < min_items {
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("minItems {}, got {}", min_items, data.len()),
            );
            add_error(ctx, create_error("E006", path, context), None);
            valid = false;
        }
    }

    if let Some(max_items) = schema.get("maxItems").and_then(|v| v.as_u64()) {
        if (data.len() as u64) > max_items {
            let suggestion = suggest_array_fix(schema);
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("maxItems {}, got {}", max_items, data.len()),
            );
            add_error(ctx, create_error("E006", path, context), suggestion);
            valid = false;
        }
    }

    if schema
        .get("uniqueItems")
        .and_then(|v| v.as_bool())
        .unwrap_or(false)
    {
        let mut seen: Vec<&Value> = Vec::new();
        for item in data {
            if seen.contains(&item) {
                let mut context = HashMap::new();
                context.insert(
                    "constraint",
                    "uniqueItems: array contains duplicates".to_string(),
                );
                add_error(ctx, create_error("E006", path, context), None);
                valid = false;
                break;
            }
            seen.push(item);
        }
    }

    if valid {
        ctx.fields_valid += 1;
    }

    // Validate items
    if let Some(items_schema) = schema.get("items") {
        for (i, item) in data.iter().enumerate() {
            let item_path = format!("{}/{}", path, i);
            walk_schema(items_schema, item, &item_path, ctx);
        }
    }
}

// ---------------------------------------------------------------------------
// Object validation
// ---------------------------------------------------------------------------

fn validate_object(
    schema: &Value,
    data: &serde_json::Map<String, Value>,
    path: &str,
    ctx: &mut WalkerContext,
) {
    ctx.fields_checked += 1;
    let mut valid = true;
    let keys: Vec<&String> = data.keys().collect();

    // Required
    if let Some(required) = schema.get("required").and_then(|v| v.as_array()) {
        for prop in required {
            if let Some(prop_name) = prop.as_str() {
                if !data.contains_key(prop_name) {
                    let suggestion = suggest_missing_required(prop_name);
                    let mut context = HashMap::new();
                    context.insert("property", prop_name.to_string());
                    add_error(ctx, create_error("E002", path, context), Some(suggestion));
                    valid = false;
                }
            }
        }
    }

    // minProperties / maxProperties
    if let Some(min_props) = schema.get("minProperties").and_then(|v| v.as_u64()) {
        if (keys.len() as u64) < min_props {
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("minProperties {}, got {}", min_props, keys.len()),
            );
            add_error(ctx, create_error("E007", path, context), None);
            valid = false;
        }
    }

    if let Some(max_props) = schema.get("maxProperties").and_then(|v| v.as_u64()) {
        if (keys.len() as u64) > max_props {
            let mut context = HashMap::new();
            context.insert(
                "constraint",
                format!("maxProperties {}, got {}", max_props, keys.len()),
            );
            add_error(ctx, create_error("E007", path, context), None);
            valid = false;
        }
    }

    // additionalProperties
    if let Some(additional) = schema.get("additionalProperties") {
        if additional != &Value::Bool(true) {
            let defined: HashSet<&str> = schema
                .get("properties")
                .and_then(|v| v.as_object())
                .map(|obj| obj.keys().map(|k| k.as_str()).collect())
                .unwrap_or_default();

            for key in &keys {
                if !defined.contains(key.as_str()) {
                    if additional == &Value::Bool(false) {
                        let suggestion = suggest_remove_additional(key);
                        let mut context = HashMap::new();
                        context.insert("property", key.to_string());
                        add_error(ctx, create_error("E003", path, context), Some(suggestion));
                        valid = false;
                    } else if additional.is_object() {
                        // Validate against additionalProperties schema
                        let prop_path = format!("{}/{}", path, key);
                        walk_schema(additional, &data[key.as_str()], &prop_path, ctx);
                    }
                }
            }
        }
    }

    if valid {
        ctx.fields_valid += 1;
    }

    // Validate individual properties
    if let Some(properties) = schema.get("properties").and_then(|v| v.as_object()) {
        for (prop_name, prop_schema) in properties {
            if let Some(prop_data) = data.get(prop_name) {
                let prop_path = format!("{}/{}", path, prop_name);
                walk_schema(prop_schema, prop_data, &prop_path, ctx);
            }
        }
    }
}

// ---------------------------------------------------------------------------
// Composition
// ---------------------------------------------------------------------------

fn create_sub_context<'a>(parent_ctx: &WalkerContext<'a>) -> WalkerContext<'a> {
    WalkerContext {
        errors: Vec::new(),
        root_schema: parent_ctx.root_schema,
        fields_checked: 0,
        fields_valid: 0,
        fields_invalid: 0,
        options: parent_ctx.options.clone(),
    }
}

fn validate_all_of(schemas: &[Value], data: &Value, path: &str, ctx: &mut WalkerContext) {
    for sub_schema in schemas {
        let mut sub_ctx = create_sub_context(ctx);
        walk_schema(sub_schema, data, path, &mut sub_ctx);
        if !sub_ctx.errors.is_empty() {
            let mut context = HashMap::new();
            context.insert("keyword", "allOf".to_string());
            add_error(ctx, create_error("E010", path, context), None);
            return;
        }
    }
}

fn validate_any_of(schemas: &[Value], data: &Value, path: &str, ctx: &mut WalkerContext) {
    for sub_schema in schemas {
        let mut sub_ctx = create_sub_context(ctx);
        walk_schema(sub_schema, data, path, &mut sub_ctx);
        if sub_ctx.errors.is_empty() {
            return; // at least one matched
        }
    }
    let mut context = HashMap::new();
    context.insert("keyword", "anyOf".to_string());
    add_error(ctx, create_error("E010", path, context), None);
}

fn validate_one_of(schemas: &[Value], data: &Value, path: &str, ctx: &mut WalkerContext) {
    let mut match_count = 0;
    for sub_schema in schemas {
        let mut sub_ctx = create_sub_context(ctx);
        walk_schema(sub_schema, data, path, &mut sub_ctx);
        if sub_ctx.errors.is_empty() {
            match_count += 1;
        }
    }
    if match_count != 1 {
        let mut context = HashMap::new();
        context.insert("keyword", "oneOf".to_string());
        add_error(ctx, create_error("E010", path, context), None);
    }
}

// ---------------------------------------------------------------------------
// Public API
// ---------------------------------------------------------------------------

/// Validate data against a full protocol envelope (must have a `schema` key).
pub fn validate(
    data: &Value,
    protocol: &Value,
    options: Option<ValidationOptions>,
) -> ValidationResult {
    let schema = protocol
        .get("schema")
        .cloned()
        .unwrap_or(Value::Object(serde_json::Map::new()));

    let opts = options.unwrap_or(ValidationOptions {
        mode: "full".to_string(),
        paths: vec![],
    });

    let mut ctx = WalkerContext {
        errors: Vec::new(),
        root_schema: &schema,
        fields_checked: 0,
        fields_valid: 0,
        fields_invalid: 0,
        options: opts.clone(),
    };

    walk_schema(&schema, data, "", &mut ctx);

    ValidationResult {
        valid: ctx.errors.iter().filter(|e| e.severity == "error").count() == 0,
        mode: opts.mode,
        errors: ctx.errors,
        stats: ValidationStats {
            fields_checked: ctx.fields_checked,
            fields_valid: ctx.fields_valid,
            fields_invalid: ctx.fields_invalid,
        },
    }
}

/// Validate data against a bare schema (no protocol envelope).
pub fn validate_schema(
    data: &Value,
    schema: &Value,
    options: Option<ValidationOptions>,
) -> ValidationResult {
    let protocol = serde_json::json!({
        "$protocol": "https://dataprotocol.dev/v1",
        "name": "__inline__",
        "version": "0.0.0",
        "schema": schema
    });
    validate(data, &protocol, options)
}