//! Parsing logic for story YAML front matter and todo checkboxes.
use serde::Deserialize;
use std::fs;
use std::path::Path;

use super::types::{QaMode, StoryMetaError, StoryMetadata};

#[derive(Debug, Deserialize)]
pub(super) struct FrontMatter {
    pub name: Option<String>,
    pub coverage_baseline: Option<String>,
    pub merge_failure: Option<String>,
    pub agent: Option<String>,
    pub review_hold: Option<bool>,
    /// Configurable QA mode field: "human", "server", or "agent".
    pub qa: Option<String>,
    /// Number of times this story has been retried at its current pipeline stage.
    pub retry_count: Option<u32>,
    /// When `true`, auto-assign will skip this story (retry limit exceeded).
    pub blocked: Option<bool>,
    /// Story numbers this story depends on.
    pub depends_on: Option<Vec<u32>>,
    /// When `true`, the story is frozen.
    pub frozen: Option<bool>,
    /// Set to `true` when an agent's `run_tests` call returns `passed=true`.
    /// Used by the bug-645 salvage path to distinguish a genuine test-passing
    /// session from one that merely compiled.
    pub run_tests_passed: Option<bool>,
    /// Item type: "story", "bug", "spike", or "refactor".
    #[serde(rename = "type")]
    pub item_type: Option<String>,
    /// Set to `true` when the auto-assigner has already spawned a mergemaster
    /// session for a content-conflict failure.
    pub mergemaster_attempted: Option<bool>,
    /// Epic this item belongs to (numeric ID as string, e.g. "880").
    pub epic: Option<String>,
}

/// Parse the YAML front matter block from a story markdown string.
pub fn parse_front_matter(contents: &str) -> Result<StoryMetadata, StoryMetaError> {
    let mut lines = contents.lines();

    let first = lines.next().unwrap_or_default().trim();
    if first != "---" {
        return Err(StoryMetaError::MissingFrontMatter);
    }

    let mut front_lines = Vec::new();
    for line in &mut lines {
        let trimmed = line.trim();
        if trimmed == "---" {
            let raw = front_lines.join("\n");
            let front: FrontMatter = serde_yaml::from_str(&raw)
                .map_err(|e| StoryMetaError::InvalidFrontMatter(e.to_string()))?;
            return Ok(build_metadata(front));
        }
        front_lines.push(line);
    }

    Err(StoryMetaError::InvalidFrontMatter(
        "Missing closing front matter delimiter".to_string(),
    ))
}

fn build_metadata(front: FrontMatter) -> StoryMetadata {
    let qa = front.qa.as_deref().and_then(QaMode::from_str);

    StoryMetadata {
        name: front.name,
        coverage_baseline: front.coverage_baseline,
        merge_failure: front.merge_failure,
        agent: front.agent,
        review_hold: front.review_hold,
        qa,
        retry_count: front.retry_count,
        blocked: front.blocked,
        depends_on: front.depends_on,
        frozen: front.frozen,
        run_tests_passed: front.run_tests_passed,
        item_type: front.item_type,
        mergemaster_attempted: front.mergemaster_attempted,
        epic: front.epic,
    }
}

/// Parse unchecked todo items (`- [ ] ...`) from a markdown string.
pub fn parse_unchecked_todos(contents: &str) -> Vec<String> {
    contents
        .lines()
        .filter_map(|line| {
            let trimmed = line.trim();
            trimmed.strip_prefix("- [ ] ").map(|text| text.to_string())
        })
        .collect()
}

/// Resolve the effective QA mode for a story file.
///
/// Reads the `qa` front matter field. If absent, falls back to `default`.
/// Spikes are **not** handled here — the caller is responsible for overriding
/// to `Human` for spikes.
pub fn resolve_qa_mode(path: &Path, default: QaMode) -> QaMode {
    let contents = match fs::read_to_string(path) {
        Ok(c) => c,
        Err(_) => return default,
    };
    match parse_front_matter(&contents) {
        Ok(meta) => meta.qa.unwrap_or(default),
        Err(_) => default,
    }
}

/// Resolve the effective QA mode for a story by story ID.
///
/// Checks the typed `qa_mode` CRDT register first.  If the register holds a
/// recognised value (`"server"`, `"agent"`, or `"human"`), returns it.
/// Otherwise falls back to parsing the `qa` YAML front-matter field from
/// `contents`.  If neither source provides a value, returns `default`.
pub fn resolve_qa_mode_from_content(story_id: &str, contents: &str, default: QaMode) -> QaMode {
    // CRDT register takes precedence over YAML front matter.
    if let Some(view) = crate::crdt_state::read_item(story_id)
        && let Some(ref s) = view.qa_mode
        && let Some(mode) = QaMode::from_str(s)
    {
        return mode;
    }
    // Fall back to YAML front matter for backward compatibility.
    match parse_front_matter(contents) {
        Ok(meta) => meta.qa.unwrap_or(default),
        Err(_) => default,
    }
}

/// Return `true` if the story has `frozen: true` in the content store.
///
/// Used by the pipeline advance code to suppress stage transitions for frozen stories.
pub fn is_story_frozen_in_store(story_id: &str) -> bool {
    let contents = match crate::db::read_content(story_id) {
        Some(c) => c,
        None => return false,
    };
    parse_front_matter(&contents)
        .ok()
        .and_then(|m| m.frozen)
        .unwrap_or(false)
}

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

    #[test]
    fn parses_front_matter_metadata() {
        let input = r#"---
name: Establish the TDD Workflow and Gates
workflow: tdd
---
# Story 26
"#;

        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(
            meta.name.as_deref(),
            Some("Establish the TDD Workflow and Gates")
        );
        assert_eq!(meta.coverage_baseline, None);
    }

    #[test]
    fn parses_coverage_baseline_from_front_matter() {
        let input = "---\nname: Test Story\ncoverage_baseline: 78.5%\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.coverage_baseline.as_deref(), Some("78.5%"));
    }

    #[test]
    fn rejects_missing_front_matter() {
        let input = "# Story 26\n";
        assert_eq!(
            parse_front_matter(input),
            Err(StoryMetaError::MissingFrontMatter)
        );
    }

    #[test]
    fn rejects_unclosed_front_matter() {
        let input = "---\nname: Test\n";
        assert!(matches!(
            parse_front_matter(input),
            Err(StoryMetaError::InvalidFrontMatter(_))
        ));
    }

    #[test]
    fn parse_unchecked_todos_mixed() {
        let input = "## AC\n- [ ] First thing\n- [x] Done thing\n- [ ] Second thing\n";
        assert_eq!(
            parse_unchecked_todos(input),
            vec!["First thing", "Second thing"]
        );
    }

    #[test]
    fn parse_unchecked_todos_all_checked() {
        let input = "- [x] Done\n- [x] Also done\n";
        assert!(parse_unchecked_todos(input).is_empty());
    }

    #[test]
    fn parse_unchecked_todos_no_checkboxes() {
        let input = "# Story\nSome text\n- A bullet\n";
        assert!(parse_unchecked_todos(input).is_empty());
    }

    #[test]
    fn parse_unchecked_todos_leading_whitespace() {
        let input = "  - [ ] Indented item\n";
        assert_eq!(parse_unchecked_todos(input), vec!["Indented item"]);
    }

    #[test]
    fn parses_review_hold_from_front_matter() {
        let input = "---\nname: Spike\nreview_hold: true\n---\n# Spike\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.review_hold, Some(true));
    }

    #[test]
    fn review_hold_defaults_to_none() {
        let input = "---\nname: Story\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.review_hold, None);
    }

    #[test]
    fn parses_qa_mode_from_front_matter() {
        let input = "---\nname: Story\nqa: server\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.qa, Some(QaMode::Server));

        let input = "---\nname: Story\nqa: agent\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.qa, Some(QaMode::Agent));

        let input = "---\nname: Story\nqa: human\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.qa, Some(QaMode::Human));
    }

    #[test]
    fn qa_mode_defaults_to_none() {
        let input = "---\nname: Story\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.qa, None);
    }

    #[test]
    fn resolve_qa_mode_uses_file_value() {
        let tmp = tempfile::tempdir().unwrap();
        let path = tmp.path().join("story.md");
        std::fs::write(&path, "---\nname: Test\nqa: human\n---\n# Story\n").unwrap();
        assert_eq!(resolve_qa_mode(&path, QaMode::Server), QaMode::Human);
    }

    #[test]
    fn resolve_qa_mode_falls_back_to_default() {
        let tmp = tempfile::tempdir().unwrap();
        let path = tmp.path().join("story.md");
        std::fs::write(&path, "---\nname: Test\n---\n# Story\n").unwrap();
        assert_eq!(resolve_qa_mode(&path, QaMode::Server), QaMode::Server);
        assert_eq!(resolve_qa_mode(&path, QaMode::Agent), QaMode::Agent);
    }

    #[test]
    fn resolve_qa_mode_missing_file_uses_default() {
        let path = std::path::Path::new("/nonexistent/story.md");
        assert_eq!(resolve_qa_mode(path, QaMode::Server), QaMode::Server);
    }

    #[test]
    fn parses_depends_on_from_front_matter() {
        let input = "---\nname: Story\ndepends_on: [477, 478]\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.depends_on, Some(vec![477, 478]));
    }

    #[test]
    fn depends_on_defaults_to_none() {
        let input = "---\nname: Story\n---\n# Story\n";
        let meta = parse_front_matter(input).expect("front matter");
        assert_eq!(meta.depends_on, None);
    }
}