config_disassembler/xml/handlers/

reassemble.rs

//! Reassemble XML from disassembled directory.

use crate::xml::builders::{build_xml_string, merge_xml_elements, reorder_root_keys};
use crate::xml::multi_level::{ensure_segment_files_structure, load_multi_level_config};
use crate::xml::parsers::parse_to_xml_object;
use crate::xml::types::{MultiLevelRule, SidecarSpec, XmlElement};
use crate::xml::utils::normalize_path_unix;
use serde_json::Value;
use std::collections::HashSet;
use std::ffi::OsString;
use std::future::Future;
use std::path::{Path, PathBuf};
use std::pin::Pin;
use tokio::fs;

/// Read a `.key_order.json` file (if present) and parse it as a list of root key names.
async fn read_key_order(path: &Path) -> Option<Vec<String>> {
    let bytes = fs::read(path).await.ok()?;
    serde_json::from_slice::<Vec<String>>(&bytes).ok()
}

/// Remove @xmlns from an object so the reassembled segment wrapper (e.g. programProcesses) has no xmlns.
fn strip_xmlns_from_value(v: Value) -> Value {
    match v {
        Value::Object(obj) => {
            Value::Object(obj.into_iter().filter(|(k, _)| k != "@xmlns").collect())
        }
        other => other,
    }
}

/// When recursing into a nested multi-level rule's `path_segment`, the
/// deeper-level recursion needs the *sibling* rules — every rule
/// except the one we just matched — so a sub-directory that happens
/// to share its parent's `path_segment` doesn't re-enter the same
/// rule. Returns the cloned slice with the matched segment filtered
/// out. Pure helper extracted from
/// `reassemble_multi_level_segment_inner`.
fn deeper_candidate_rules(
    all_rules: &[MultiLevelRule],
    exclude_path_segment: &str,
) -> Vec<MultiLevelRule> {
    all_rules
        .iter()
        .filter(|r| r.path_segment != exclude_path_segment)
        .cloned()
        .collect()
}

/// True when the current directory is the disassembly root for any
/// of the supplied multi-level rules. Each rule stores the base path
/// it was disassembled from; if `dir_path` matches one, the caller is
/// allowed to match that rule's child segments. Pure helper extracted
/// from `process_files_in_directory` so the `dir_path == base`
/// equality is testable without a temporary directory tree.
fn is_at_base_path(dir_path: &str, base_segments: &[(String, String, bool)]) -> bool {
    base_segments.iter().any(|(base, _, _)| dir_path == base)
}

type ProcessDirFuture<'a> = Pin<
    Box<
        dyn Future<Output = Result<Vec<XmlElement>, Box<dyn std::error::Error + Send + Sync>>>
            + Send
            + 'a,
    >,
>;

type SegmentFuture<'a> =
    Pin<Box<dyn Future<Output = Result<(), Box<dyn std::error::Error + Send + Sync>>> + Send + 'a>>;

pub struct ReassembleXmlFileHandler;

impl ReassembleXmlFileHandler {
    pub fn new() -> Self {
        Self
    }

    pub async fn reassemble(
        &self,
        file_path: &str,
        file_extension: Option<&str>,
        post_purge: bool,
        sidecar_specs: Option<&[SidecarSpec]>,
    ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
        let file_path = normalize_path_unix(file_path);
        if !self.validate_directory(&file_path).await? {
            return Ok(());
        }

        let path = Path::new(&file_path);
        let config = load_multi_level_config(path).await;
        if let Some(ref config) = config {
            // Process each rule whose path_segment exists as a directory at the
            // disassembly root. Inner-only rules (whose segment lives nested under another
            // rule's item dir) are handled dynamically when the parent rule walks its
            // items; we hand them in as `nested_rules` candidates here.
            for (i, rule) in config.rules.iter().enumerate() {
                let segment_path = path.join(&rule.path_segment);
                if !segment_path.is_dir() {
                    continue;
                }
                let nested: Vec<MultiLevelRule> = config
                    .rules
                    .iter()
                    .enumerate()
                    .filter(|(j, _)| *j != i)
                    .map(|(_, r)| r.clone())
                    .collect();
                self.reassemble_multi_level_segment(&segment_path, rule, &nested)
                    .await?;
            }
        }

        // Build one base-segment entry per multi-level rule so the recursive walker can
        // recognize each rule's path_segment under the disassembly root.
        let base_segments: Vec<(String, String, bool)> = config
            .as_ref()
            .map(|c| {
                c.rules
                    .iter()
                    .map(|r| (file_path.clone(), r.path_segment.clone(), true))
                    .collect()
            })
            .unwrap_or_default();
        // When multi-level reassembly is done, purge the entire disassembled directory
        let post_purge_final = post_purge || config.is_some();
        self.reassemble_plain(
            &file_path,
            file_extension,
            post_purge_final,
            &base_segments,
            sidecar_specs,
        )
        .await
    }

    /// Reassemble a single multi-level segment directory.
    ///
    /// For each item directory under `segment_path` (e.g. each `<dialog>/` under
    /// `botDialogs/`):
    ///
    /// 1. **Phase 1 — nested rules first.** For every immediate sub-directory whose name
    ///    matches a `nested_rules` candidate's `path_segment`, recursively reassemble
    ///    that sub-directory as its own segment. This wraps each per-step file in
    ///    `<wrap_root_element><inner_segment>...</inner_segment></wrap_root_element>` *before*
    ///    the outer-level merge sees it, so multiple inner items survive as siblings
    ///    rather than collapsing into a single bag of leaves.
    ///
    /// 2. **Phase 2 — flat sub-directories.** Any remaining sub-directory (anything not
    ///    consumed by phase 1) is collapsed into a per-item `.xml` at the parent level
    ///    via [`Self::reassemble_plain`], the original behaviour for things like
    ///    decompose-rule outputs.
    ///
    /// 3. **Phase 3 — merge item.** Everything in the item directory (the `.xml` files
    ///    written by phases 1 and 2 plus any leaf `.xml` already there) is merged into
    ///    a single `.xml` at the parent level.
    ///
    /// Finally, [`ensure_segment_files_structure`] wraps every `.xml` in `segment_path`
    /// in `<wrap_root_element><path_segment>...</path_segment></wrap_root_element>` so
    /// the parent reassembly sees correctly-wrapped siblings.
    fn reassemble_multi_level_segment<'a>(
        &'a self,
        segment_path: &'a Path,
        rule: &'a MultiLevelRule,
        nested_rules: &'a [MultiLevelRule],
    ) -> SegmentFuture<'a> {
        let segment_path = segment_path.to_path_buf();
        let rule = rule.clone();
        let nested_rules = nested_rules.to_vec();
        Box::pin(async move {
            self.reassemble_multi_level_segment_inner(&segment_path, &rule, &nested_rules)
                .await
        })
    }

    async fn reassemble_multi_level_segment_inner(
        &self,
        segment_path: &Path,
        rule: &MultiLevelRule,
        nested_rules: &[MultiLevelRule],
    ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
        if !segment_path.is_dir() {
            return Ok(());
        }
        let mut entries = Vec::new();
        let mut read_dir = fs::read_dir(segment_path).await?;
        while let Some(entry) = read_dir.next_entry().await? {
            entries.push(entry);
        }
        entries.sort_by_key(|e| e.file_name());
        for entry in entries {
            let process_path = entry.path();
            if !process_path.is_dir() {
                continue;
            }
            let process_path_str = normalize_path_unix(&process_path.to_string_lossy());
            let mut sub_entries = Vec::new();
            let mut sub_read = fs::read_dir(&process_path).await?;
            while let Some(e) = sub_read.next_entry().await? {
                sub_entries.push(e);
            }
            sub_entries.sort_by_key(|e| e.file_name());

            // Phase 1: drain any sub-directory that matches a nested rule's
            // `path_segment` so it is re-wrapped before the outer merge runs.
            let mut handled: HashSet<OsString> = HashSet::new();
            for sub_entry in &sub_entries {
                let sub_path: PathBuf = sub_entry.path();
                if !sub_path.is_dir() {
                    continue;
                }
                let sub_name = sub_path.file_name().and_then(|n| n.to_str()).unwrap_or("");
                let Some(nested_rule) = nested_rules.iter().find(|r| r.path_segment == sub_name)
                else {
                    continue;
                };
                // Pass everything *except* the rule we just matched as deeper candidates.
                // Sibling rules remain candidates further down the tree without re-entering
                // the same rule on a sub-dir that happens to share its name.
                let deeper = deeper_candidate_rules(nested_rules, &nested_rule.path_segment);
                self.reassemble_multi_level_segment(&sub_path, nested_rule, &deeper)
                    .await?;
                handled.insert(sub_entry.file_name());
            }

            // Phase 2: collapse remaining sub-directories into per-item .xml files at
            // the parent level (preserves existing behaviour for non-nested-rule subdirs).
            for sub_entry in &sub_entries {
                let sub_path = sub_entry.path();
                if !sub_path.is_dir() {
                    continue;
                }
                if handled.contains(&sub_entry.file_name()) {
                    continue;
                }
                let sub_path_str = normalize_path_unix(&sub_path.to_string_lossy());
                self.reassemble_plain(&sub_path_str, Some("xml"), true, &[], None)
                    .await?;
            }

            // Phase 3: merge everything in the item dir into a single .xml at the parent.
            self.reassemble_plain(&process_path_str, Some("xml"), true, &[], None)
                .await?;
        }
        ensure_segment_files_structure(
            segment_path,
            &rule.wrap_root_element,
            &rule.path_segment,
            &rule.wrap_xmlns,
        )
        .await?;
        Ok(())
    }

    /// Merge and write reassembled XML (no multi-level pre-step). Used internally.
    /// `base_segments` carries one tuple `(base_path, segment_name, extract_inner)` per
    /// multi-level rule. When the recursive walker reaches `base_path` and finds a subdir
    /// whose name matches one of the segment_names, that subdir's XML files are folded
    /// into a single array under the segment_name key. When extract_inner is true, each
    /// file's structure is `document_root > segment_name > content` and only the content
    /// is collected; otherwise the whole root is kept.
    async fn reassemble_plain(
        &self,
        file_path: &str,
        file_extension: Option<&str>,
        post_purge: bool,
        base_segments: &[(String, String, bool)],
        sidecar_specs: Option<&[SidecarSpec]>,
    ) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
        let file_path = normalize_path_unix(file_path);
        log::debug!("Parsing directory to reassemble: {}", file_path);
        let parsed_objects = self
            .process_files_in_directory(file_path.to_string(), base_segments.to_vec())
            .await?;

        if parsed_objects.is_empty() {
            log::error!(
                "No files under {} were parsed successfully. A reassembled XML file was not created.",
                file_path
            );
            return Ok(());
        }

        // merge_xml_elements only returns None when every parsed element is empty or
        // declaration-only (no usable root). Treat that the same as "nothing parsed"
        // rather than emitting an `<root></root>` stub.
        let Some(mut merged) = merge_xml_elements(&parsed_objects) else {
            log::error!(
                "No usable root element found while merging files under {}. A reassembled XML file was not created.",
                file_path
            );
            return Ok(());
        };

        // Resolve sidecar specs: use the caller-supplied slice when non-empty,
        // otherwise auto-detect from .sidecars.json written by disassembly.
        let auto_specs: Vec<crate::xml::types::SidecarSpec>;
        let effective_specs: Option<&[crate::xml::types::SidecarSpec]> =
            if sidecar_specs.is_some_and(|s| !s.is_empty()) {
                sidecar_specs
            } else {
                let meta_path = Path::new(&file_path).join(".sidecars.json");
                if let Ok(content) = fs::read_to_string(&meta_path).await {
                    if let Ok(parsed) =
                        serde_json::from_str::<Vec<crate::xml::types::SidecarSpec>>(&content)
                    {
                        auto_specs = parsed;
                        Some(auto_specs.as_slice())
                    } else {
                        None
                    }
                } else {
                    None
                }
            };

        // Inject sidecar element content before key reordering so the element
        // lands at its original position rather than being appended at the end.
        if let Some(specs) = effective_specs {
            inject_sidecar_elements(&file_path, &mut merged, specs).await?;
        }

        // Apply stored key order so reassembled XML matches original document order.
        let key_order_path = Path::new(&file_path).join(".key_order.json");
        if let Some(reordered) = read_key_order(&key_order_path)
            .await
            .and_then(|order| reorder_root_keys(&merged, &order))
        {
            merged = reordered;
        }

        let final_xml = build_xml_string(&merged);
        let output_path = self.get_output_path(&file_path, file_extension);

        fs::write(&output_path, &final_xml).await?;

        // Remove sidecar files and metadata after successful injection. They are
        // decomposition artifacts: the content is now inside the reassembled XML.
        // Only done when post_purge is requested.
        if post_purge {
            if let Some(specs) = effective_specs {
                let path = Path::new(&file_path);
                let base = path
                    .file_name()
                    .and_then(|n| n.to_str())
                    .unwrap_or("output");
                for spec in specs {
                    let sidecar = path.join(format!("{}.{}", base, spec.extension));
                    fs::remove_file(&sidecar).await.ok();
                }
            }
            fs::remove_dir_all(file_path).await.ok();
        }

        Ok(())
    }

    fn process_files_in_directory<'a>(
        &'a self,
        dir_path: String,
        base_segments: Vec<(String, String, bool)>,
    ) -> ProcessDirFuture<'a> {
        Box::pin(async move {
            let mut parsed = Vec::new();
            let mut entries = Vec::new();
            let mut read_dir = fs::read_dir(&dir_path).await?;
            while let Some(entry) = read_dir.next_entry().await? {
                entries.push(entry);
            }
            // Sort by full filename for deterministic cross-platform ordering
            entries.sort_by(|a, b| {
                let a_name = a.file_name().to_string_lossy().to_string();
                let b_name = b.file_name().to_string_lossy().to_string();
                a_name.cmp(&b_name)
            });

            // We are at the disassembly root for a given rule when our dir_path matches
            // the base_path stored on that rule. Each rule shares the same base_path in
            // the current implementation, but tracking them per-entry keeps the door open
            // for future per-rule base_paths without another signature change.
            let is_base = is_at_base_path(&dir_path, &base_segments);

            for entry in entries {
                let path = entry.path();
                let file_path = normalize_path_unix(&path.to_string_lossy()).to_string();

                if path.is_file() {
                    let name = path.file_name().and_then(|n| n.to_str()).unwrap_or("");
                    if !name.starts_with('.') && self.is_parsable_file(name) {
                        if let Some(parsed_obj) = parse_to_xml_object(&file_path).await {
                            parsed.push(parsed_obj);
                        }
                    }
                } else {
                    // Anything not a regular file is treated as a directory; symlinks and
                    // other exotic entries simply recurse via read_dir below.
                    let dir_name = path.file_name().and_then(|n| n.to_str()).unwrap_or("");
                    let matched_segment = if is_base {
                        base_segments
                            .iter()
                            .find(|(_, seg_name, _)| seg_name == dir_name)
                            .cloned()
                    } else {
                        None
                    };
                    if let Some((_, segment_name, extract_inner)) = matched_segment {
                        let segment_element = self
                            .collect_segment_as_array(&file_path, &segment_name, extract_inner)
                            .await?;
                        if let Some(el) = segment_element {
                            parsed.push(el);
                        }
                    } else {
                        let sub_parsed = self
                            .process_files_in_directory(file_path, base_segments.clone())
                            .await?;
                        parsed.extend(sub_parsed);
                    }
                }
            }

            Ok(parsed)
        })
    }

    /// Collect all .xml files in a directory, parse each, and build one element with
    /// root_key and single key segment_name whose value is array of each file's content.
    /// When extract_inner is true, each file has root > segment_name > content; we push that content.
    async fn collect_segment_as_array(
        &self,
        segment_dir: &str,
        segment_name: &str,
        extract_inner: bool,
    ) -> Result<Option<XmlElement>, Box<dyn std::error::Error + Send + Sync>> {
        let mut xml_files = Vec::new();
        let mut read_dir = fs::read_dir(segment_dir).await?;
        while let Some(entry) = read_dir.next_entry().await? {
            let path = entry.path();
            let name = path.file_name().and_then(|n| n.to_str()).unwrap_or("");
            if path.is_file() && !name.starts_with('.') && self.is_parsable_file(name) {
                xml_files.push(normalize_path_unix(&path.to_string_lossy()));
            }
        }
        xml_files.sort();

        let mut root_contents = Vec::new();
        let mut first_xml: Option<(String, Option<Value>)> = None;
        for file_path in &xml_files {
            // parse_to_xml_object always yields a JSON object on success; treat any other
            // shape (including parse failure) as a skip without branching explicitly.
            let Some(parsed) = parse_to_xml_object(file_path).await else {
                continue;
            };
            let obj_owned = parsed.as_object().cloned().unwrap_or_default();
            let obj = &obj_owned;
            let Some(root_key) = obj.keys().find(|k| *k != "?xml").cloned() else {
                continue;
            };
            let root_val = obj
                .get(&root_key)
                .cloned()
                .unwrap_or(Value::Object(serde_json::Map::new()));
            let mut content = if extract_inner {
                root_val
                    .get(segment_name)
                    .cloned()
                    .unwrap_or_else(|| Value::Object(serde_json::Map::new()))
            } else {
                root_val
            };
            // Inner segment element (e.g. programProcesses) should not have xmlns in output
            if extract_inner {
                content = strip_xmlns_from_value(content);
            }
            root_contents.push(content);
            if first_xml.is_none() {
                first_xml = Some((root_key, obj.get("?xml").cloned()));
            }
        }
        if root_contents.is_empty() {
            return Ok(None);
        }
        let (root_key, decl_opt) = first_xml.unwrap();
        let mut content = serde_json::Map::new();
        content.insert(segment_name.to_string(), Value::Array(root_contents));
        let mut top = serde_json::Map::new();
        if let Some(decl) = decl_opt {
            top.insert("?xml".to_string(), decl);
        } else {
            let mut d = serde_json::Map::new();
            d.insert("@version".to_string(), Value::String("1.0".to_string()));
            d.insert("@encoding".to_string(), Value::String("UTF-8".to_string()));
            top.insert("?xml".to_string(), Value::Object(d));
        }
        top.insert(root_key, Value::Object(content));
        Ok(Some(Value::Object(top)))
    }

    fn is_parsable_file(&self, file_name: &str) -> bool {
        let lower = file_name.to_lowercase();
        lower.ends_with(".xml")
            || lower.ends_with(".json")
            || lower.ends_with(".json5")
            || lower.ends_with(".yaml")
            || lower.ends_with(".yml")
    }

    async fn validate_directory(
        &self,
        path: &str,
    ) -> Result<bool, Box<dyn std::error::Error + Send + Sync>> {
        let meta = fs::metadata(path).await?;
        if !meta.is_dir() {
            log::error!(
                "The provided path to reassemble is not a directory: {}",
                path
            );
            return Ok(false);
        }
        Ok(true)
    }

    fn get_output_path(&self, dir_path: &str, extension: Option<&str>) -> String {
        let path = Path::new(dir_path);
        let parent = path.parent().unwrap_or(Path::new("."));
        let base_name = path
            .file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("output");
        let ext = extension.unwrap_or("xml");
        parent
            .join(format!("{}.{}", base_name, ext))
            .to_string_lossy()
            .to_string()
    }
}

impl Default for ReassembleXmlFileHandler {
    fn default() -> Self {
        Self::new()
    }
}

/// Read sidecar files and inject their content back into the merged XML value
/// before serialisation.
///
/// Each sidecar is located inside the decomposed directory itself
/// (e.g. `MySvc/MySvc.yaml`). If a sidecar is absent (element was not in
/// the original XML, or was never extracted), the spec is silently skipped.
///
/// The injected value uses the `{"#raw-text": content}` shape that `build_xml_string`
/// writes with `partial_escape`: mandatory XML chars (`<`, `>`, `&`) are escaped
/// but `"` is left as-is so YAML content round-trips without `&quot;` inflation.
async fn inject_sidecar_elements(
    dir_path: &str,
    merged: &mut XmlElement,
    specs: &[SidecarSpec],
) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    let path = Path::new(dir_path);
    let base = path
        .file_name()
        .and_then(|n| n.to_str())
        .unwrap_or("output");

    let root_key = merged
        .as_object()
        .and_then(|o| o.keys().find(|k| *k != "?xml").cloned());
    let Some(root_key) = root_key else {
        return Ok(());
    };

    if let Some(root_val) = merged.as_object_mut().and_then(|o| o.get_mut(&root_key)) {
        if let Some(root_obj) = root_val.as_object_mut() {
            for spec in specs {
                let sidecar_path = path.join(format!("{}.{}", base, spec.extension));
                let Ok(content) = fs::read_to_string(&sidecar_path).await else {
                    continue;
                };
                root_obj.insert(
                    spec.element.clone(),
                    serde_json::json!({ "#raw-text": content }),
                );
            }
        }
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    #[test]
    #[allow(clippy::default_constructed_unit_structs)]
    fn reassemble_handler_default_equals_new() {
        let _ = ReassembleXmlFileHandler::default();
    }

    #[test]
    fn strip_xmlns_from_value_passes_non_object_through() {
        let s = Value::String("hello".to_string());
        assert_eq!(
            strip_xmlns_from_value(s),
            Value::String("hello".to_string())
        );
        let arr = json!([1, 2]);
        assert_eq!(strip_xmlns_from_value(arr.clone()), arr);
    }

    #[test]
    fn strip_xmlns_from_value_removes_xmlns_key() {
        let obj = json!({ "@xmlns": "ns", "child": 1 });
        let stripped = strip_xmlns_from_value(obj);
        let map = stripped.as_object().unwrap();
        assert!(map.get("@xmlns").is_none());
        assert_eq!(map.get("child").and_then(|v| v.as_i64()), Some(1));
    }

    #[test]
    fn is_parsable_file_recognises_supported_extensions() {
        let h = ReassembleXmlFileHandler::new();
        assert!(h.is_parsable_file("a.xml"));
        assert!(h.is_parsable_file("a.json"));
        assert!(h.is_parsable_file("a.json5"));
        assert!(h.is_parsable_file("a.yaml"));
        assert!(h.is_parsable_file("a.yml"));
        assert!(h.is_parsable_file("A.XML"));
        assert!(!h.is_parsable_file("a.txt"));
    }

    #[test]
    fn get_output_path_appends_extension_and_uses_parent_dir() {
        let h = ReassembleXmlFileHandler::new();
        let out = h.get_output_path("/tmp/foo", Some("xml"));
        assert!(out.ends_with("foo.xml"));
        let out_default = h.get_output_path("/tmp/bar", None);
        assert!(out_default.ends_with("bar.xml"));
        // No parent - uses "." fallback
        assert_eq!(h.get_output_path("only", Some("json")), "only.json");
    }

    #[tokio::test]
    async fn reassemble_multi_level_segment_noop_when_not_dir() {
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        let file = tmp.path().join("not_a_dir.txt");
        tokio::fs::write(&file, "hi").await.unwrap();
        let rule = crate::xml::types::MultiLevelRule {
            file_pattern: String::new(),
            root_to_strip: String::new(),
            unique_id_elements: String::new(),
            path_segment: String::new(),
            wrap_root_element: "Root".to_string(),
            wrap_xmlns: String::new(),
        };
        h.reassemble_multi_level_segment(&file, &rule, &[])
            .await
            .unwrap();
    }

    #[tokio::test]
    async fn reassemble_multi_level_segment_skips_files_in_segment_root() {
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        let segment = tmp.path().join("segment");
        tokio::fs::create_dir(&segment).await.unwrap();
        // A bare file inside the segment dir should be skipped (not a subdir).
        tokio::fs::write(segment.join("stray.txt"), "x")
            .await
            .unwrap();
        let rule = crate::xml::types::MultiLevelRule {
            file_pattern: String::new(),
            root_to_strip: String::new(),
            unique_id_elements: String::new(),
            path_segment: "segment".to_string(),
            wrap_root_element: "Root".to_string(),
            wrap_xmlns: "http://example.com".to_string(),
        };
        h.reassemble_multi_level_segment(&segment, &rule, &[])
            .await
            .unwrap();
    }

    #[tokio::test]
    async fn collect_segment_as_array_returns_none_for_empty_dir() {
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        let out = h
            .collect_segment_as_array(tmp.path().to_str().unwrap(), "seg", true)
            .await
            .unwrap();
        assert!(out.is_none());
    }

    #[tokio::test]
    async fn collect_segment_as_array_skips_unparseable_and_empty_roots() {
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        // Unparseable XML
        tokio::fs::write(tmp.path().join("bad.xml"), "<<")
            .await
            .unwrap();
        // Valid XML but only declaration and no root after parse
        tokio::fs::write(tmp.path().join("only-decl.xml"), "")
            .await
            .unwrap();
        // Hidden file is skipped
        tokio::fs::write(tmp.path().join(".hidden.xml"), "<r/>")
            .await
            .unwrap();
        let out = h
            .collect_segment_as_array(tmp.path().to_str().unwrap(), "seg", false)
            .await
            .unwrap();
        assert!(out.is_none());
    }

    #[tokio::test]
    async fn collect_segment_as_array_without_xml_decl_inserts_default_decl() {
        // XML files without a `<?xml ?>` declaration: the `else` branch in
        // collect_segment_as_array must synthesize a default declaration with
        // version="1.0" and encoding="UTF-8".
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        tokio::fs::write(
            tmp.path().join("a.xml"),
            r#"<Root><seg><x>1</x></seg></Root>"#,
        )
        .await
        .unwrap();
        let out = h
            .collect_segment_as_array(tmp.path().to_str().unwrap(), "seg", true)
            .await
            .unwrap()
            .unwrap();
        let obj = out.as_object().unwrap();
        let decl = obj
            .get("?xml")
            .and_then(|v| v.as_object())
            .expect("default declaration must be inserted when XML has none");
        assert_eq!(decl.get("@version").and_then(|v| v.as_str()), Some("1.0"));
        assert_eq!(
            decl.get("@encoding").and_then(|v| v.as_str()),
            Some("UTF-8")
        );
    }

    #[tokio::test]
    async fn collect_segment_as_array_with_xml_decl_preserves_it() {
        // XML file WITH a `<?xml ?>` declaration: `decl_opt` is Some → line 438
        // `top.insert("?xml", decl)` is executed (the `if let Some(decl)` branch).
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        tokio::fs::write(
            tmp.path().join("a.xml"),
            r#"<?xml version="1.0" encoding="UTF-8"?><Root><seg><x>1</x></seg></Root>"#,
        )
        .await
        .unwrap();
        let out = h
            .collect_segment_as_array(tmp.path().to_str().unwrap(), "seg", true)
            .await
            .unwrap()
            .unwrap();
        let obj = out.as_object().unwrap();
        let decl = obj
            .get("?xml")
            .and_then(|v| v.as_object())
            .expect("?xml declaration must be preserved from source");
        assert_eq!(decl.get("@version").and_then(|v| v.as_str()), Some("1.0"));
        assert_eq!(
            decl.get("@encoding").and_then(|v| v.as_str()),
            Some("UTF-8")
        );
    }

    #[tokio::test]
    async fn collect_segment_as_array_without_extract_inner_wraps_root() {
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        tokio::fs::write(tmp.path().join("a.xml"), r#"<Root><child>1</child></Root>"#)
            .await
            .unwrap();
        let out = h
            .collect_segment_as_array(tmp.path().to_str().unwrap(), "seg", false)
            .await
            .unwrap()
            .unwrap();
        let obj = out.as_object().unwrap();
        assert!(obj.contains_key("?xml"));
        let root = obj.get("Root").and_then(|r| r.as_object()).unwrap();
        assert!(root.get("seg").and_then(|v| v.as_array()).is_some());
    }

    fn rule_with_segment(segment: &str) -> MultiLevelRule {
        MultiLevelRule {
            file_pattern: String::new(),
            root_to_strip: String::new(),
            unique_id_elements: String::new(),
            path_segment: segment.to_string(),
            wrap_root_element: String::new(),
            wrap_xmlns: String::new(),
        }
    }

    #[test]
    fn deeper_candidate_rules_excludes_the_matched_segment() {
        // The matched rule must be filtered out, otherwise the
        // recursion would re-enter that rule when a child directory
        // happens to share its `path_segment`.
        let rules = vec![rule_with_segment("seg_a"), rule_with_segment("seg_b")];
        let deeper = deeper_candidate_rules(&rules, "seg_a");
        assert_eq!(deeper.len(), 1);
        assert_eq!(deeper[0].path_segment, "seg_b");
    }

    #[test]
    fn deeper_candidate_rules_keeps_all_when_no_segment_matches() {
        // When `exclude_path_segment` doesn't correspond to any rule
        // the input is forwarded unchanged. Pins the `!= -> ==` mutant
        // which would otherwise return an empty vec here.
        let rules = vec![rule_with_segment("seg_a"), rule_with_segment("seg_b")];
        let deeper = deeper_candidate_rules(&rules, "missing");
        assert_eq!(deeper.len(), 2);
    }

    #[test]
    fn deeper_candidate_rules_returns_empty_for_empty_input() {
        let deeper: Vec<MultiLevelRule> = deeper_candidate_rules(&[], "anything");
        assert!(deeper.is_empty());
    }

    #[test]
    fn is_at_base_path_true_when_dir_matches_any_segment() {
        let segs = vec![
            ("/base/other".to_string(), "seg1".to_string(), false),
            ("/base/here".to_string(), "seg2".to_string(), false),
        ];
        assert!(is_at_base_path("/base/here", &segs));
    }

    #[test]
    fn is_at_base_path_false_when_dir_matches_nothing() {
        let segs = vec![("/base/a".to_string(), "seg".to_string(), false)];
        assert!(!is_at_base_path("/base/b", &segs));
    }

    #[test]
    fn is_at_base_path_false_for_empty_segments() {
        let segs: Vec<(String, String, bool)> = Vec::new();
        assert!(!is_at_base_path("/anywhere", &segs));
    }

    // Pins the `delete ! in is_some_and(|s| !s.is_empty())` mutant at line 299.
    // When sidecar_specs is Some(&[]) the caller supplied nothing useful, so the
    // code must fall through to auto-detect via .sidecars.json — not treat the
    // empty slice as authoritative.
    #[tokio::test]
    async fn reassemble_plain_some_empty_sidecar_specs_falls_through_to_auto_detect() {
        let h = ReassembleXmlFileHandler::new();
        let tmp = tempfile::tempdir().unwrap();
        let dir = tmp.path().join("mydir");
        tokio::fs::create_dir(&dir).await.unwrap();

        tokio::fs::write(
            dir.join("a.xml"),
            r#"<?xml version="1.0" encoding="UTF-8"?><Root><Child>hello</Child></Root>"#,
        )
        .await
        .unwrap();

        tokio::fs::write(
            dir.join(".sidecars.json"),
            r#"[{"element":"Notes","extension":"yaml"}]"#,
        )
        .await
        .unwrap();

        // Sidecar file name = directory name + extension (matches inject_sidecar_elements logic).
        tokio::fs::write(dir.join("mydir.yaml"), "key: value")
            .await
            .unwrap();

        h.reassemble_plain(dir.to_str().unwrap(), Some("xml"), false, &[], Some(&[]))
            .await
            .unwrap();

        let output = tokio::fs::read_to_string(tmp.path().join("mydir.xml"))
            .await
            .unwrap();
        assert!(
            output.contains("key: value"),
            "sidecar content missing — auto-detect did not run:\n{output}"
        );
    }
}