use std::path::{Path, PathBuf};
use std::process::Command;

use crate::io::story_metadata::clear_front_matter_field;
use crate::slog;

#[allow(dead_code)]
fn item_type_from_id(item_id: &str) -> &'static str {
    // New format: {digits}_{type}_{slug}
    let after_num = item_id.trim_start_matches(|c: char| c.is_ascii_digit());
    if after_num.starts_with("_bug_") {
        "bug"
    } else if after_num.starts_with("_spike_") {
        "spike"
    } else {
        "story"
    }
}

/// Return the source directory path for a work item (always work/1_upcoming/).
fn item_source_dir(project_root: &Path, _item_id: &str) -> PathBuf {
    project_root.join(".story_kit").join("work").join("1_upcoming")
}

/// Return the done directory path for a work item (always work/5_done/).
fn item_archive_dir(project_root: &Path, _item_id: &str) -> PathBuf {
    project_root.join(".story_kit").join("work").join("5_done")
}

/// Move a work item (story, bug, or spike) from `work/1_upcoming/` to `work/2_current/`.
///
/// Idempotent: if the item is already in `2_current/`, returns Ok without committing.
/// If the item is not found in `1_upcoming/`, logs a warning and returns Ok.
pub fn move_story_to_current(project_root: &Path, story_id: &str) -> Result<(), String> {
    let sk = project_root.join(".story_kit").join("work");
    let current_dir = sk.join("2_current");
    let current_path = current_dir.join(format!("{story_id}.md"));

    if current_path.exists() {
        // Already in 2_current/ — idempotent, nothing to do.
        return Ok(());
    }

    let source_dir = item_source_dir(project_root, story_id);
    let source_path = source_dir.join(format!("{story_id}.md"));

    if !source_path.exists() {
        slog!(
            "[lifecycle] Work item '{story_id}' not found in {}; skipping move to 2_current/",
            source_dir.display()
        );
        return Ok(());
    }

    std::fs::create_dir_all(&current_dir)
        .map_err(|e| format!("Failed to create work/2_current/ directory: {e}"))?;

    std::fs::rename(&source_path, &current_path)
        .map_err(|e| format!("Failed to move '{story_id}' to 2_current/: {e}"))?;

    slog!(
        "[lifecycle] Moved '{story_id}' from {} to work/2_current/",
        source_dir.display()
    );

    Ok(())
}

/// Check whether a feature branch `feature/story-{story_id}` exists and has
/// commits that are not yet on master.  Returns `true` when there is unmerged
/// work, `false` when there is no branch or all its commits are already
/// reachable from master.
pub fn feature_branch_has_unmerged_changes(project_root: &Path, story_id: &str) -> bool {
    let branch = format!("feature/story-{story_id}");

    // Check if the branch exists.
    let branch_check = Command::new("git")
        .args(["rev-parse", "--verify", &branch])
        .current_dir(project_root)
        .output();
    match branch_check {
        Ok(out) if out.status.success() => {}
        _ => return false, // No feature branch → nothing to merge.
    }

    // Check if the branch has commits not reachable from master.
    let log = Command::new("git")
        .args(["log", &format!("master..{branch}"), "--oneline"])
        .current_dir(project_root)
        .output();
    match log {
        Ok(out) => {
            let stdout = String::from_utf8_lossy(&out.stdout);
            !stdout.trim().is_empty()
        }
        Err(_) => false,
    }
}

/// Move a story from `work/2_current/` to `work/5_done/` and auto-commit.
///
/// * If the story is in `2_current/`, it is moved to `5_done/` and committed.
/// * If the story is in `4_merge/`, it is moved to `5_done/` and committed.
/// * If the story is already in `5_done/` or `6_archived/`, this is a no-op (idempotent).
/// * If the story is not found in `2_current/`, `4_merge/`, `5_done/`, or `6_archived/`, an error is returned.
pub fn move_story_to_archived(project_root: &Path, story_id: &str) -> Result<(), String> {
    let sk = project_root.join(".story_kit").join("work");
    let current_path = sk.join("2_current").join(format!("{story_id}.md"));
    let merge_path = sk.join("4_merge").join(format!("{story_id}.md"));
    let done_dir = sk.join("5_done");
    let done_path = done_dir.join(format!("{story_id}.md"));
    let archived_path = sk.join("6_archived").join(format!("{story_id}.md"));

    if done_path.exists() || archived_path.exists() {
        // Already in done or archived — idempotent, nothing to do.
        return Ok(());
    }

    // Check 2_current/ first, then 4_merge/
    let source_path = if current_path.exists() {
        current_path.clone()
    } else if merge_path.exists() {
        merge_path.clone()
    } else {
        return Err(format!(
            "Story '{story_id}' not found in work/2_current/ or work/4_merge/. Cannot accept story."
        ));
    };

    std::fs::create_dir_all(&done_dir)
        .map_err(|e| format!("Failed to create work/5_done/ directory: {e}"))?;
    std::fs::rename(&source_path, &done_path)
        .map_err(|e| format!("Failed to move story '{story_id}' to 5_done/: {e}"))?;

    // Strip stale merge_failure from front matter now that the story is done.
    if let Err(e) = clear_front_matter_field(&done_path, "merge_failure") {
        slog!("[lifecycle] Warning: could not clear merge_failure from '{story_id}': {e}");
    }

    let from_dir = if source_path == current_path {
        "work/2_current/"
    } else {
        "work/4_merge/"
    };
    slog!("[lifecycle] Moved story '{story_id}' from {from_dir} to work/5_done/");

    Ok(())
}

/// Move a story/bug from `work/2_current/` or `work/3_qa/` to `work/4_merge/`.
///
/// This stages a work item as ready for the mergemaster to pick up and merge into master.
/// Idempotent: if already in `4_merge/`, returns Ok without committing.
pub fn move_story_to_merge(project_root: &Path, story_id: &str) -> Result<(), String> {
    let sk = project_root.join(".story_kit").join("work");
    let current_path = sk.join("2_current").join(format!("{story_id}.md"));
    let qa_path = sk.join("3_qa").join(format!("{story_id}.md"));
    let merge_dir = sk.join("4_merge");
    let merge_path = merge_dir.join(format!("{story_id}.md"));

    if merge_path.exists() {
        // Already in 4_merge/ — idempotent, nothing to do.
        return Ok(());
    }

    // Accept from 2_current/ (manual trigger) or 3_qa/ (pipeline advancement from QA stage).
    let source_path = if current_path.exists() {
        current_path.clone()
    } else if qa_path.exists() {
        qa_path.clone()
    } else {
        return Err(format!(
            "Work item '{story_id}' not found in work/2_current/ or work/3_qa/. Cannot move to 4_merge/."
        ));
    };

    std::fs::create_dir_all(&merge_dir)
        .map_err(|e| format!("Failed to create work/4_merge/ directory: {e}"))?;
    std::fs::rename(&source_path, &merge_path)
        .map_err(|e| format!("Failed to move '{story_id}' to 4_merge/: {e}"))?;

    let from_dir = if source_path == current_path {
        "work/2_current/"
    } else {
        "work/3_qa/"
    };
    slog!("[lifecycle] Moved '{story_id}' from {from_dir} to work/4_merge/");

    Ok(())
}

/// Move a story/bug from `work/2_current/` to `work/3_qa/` and auto-commit.
///
/// This stages a work item for QA review before merging to master.
/// Idempotent: if already in `3_qa/`, returns Ok without committing.
pub fn move_story_to_qa(project_root: &Path, story_id: &str) -> Result<(), String> {
    let sk = project_root.join(".story_kit").join("work");
    let current_path = sk.join("2_current").join(format!("{story_id}.md"));
    let qa_dir = sk.join("3_qa");
    let qa_path = qa_dir.join(format!("{story_id}.md"));

    if qa_path.exists() {
        // Already in 3_qa/ — idempotent, nothing to do.
        return Ok(());
    }

    if !current_path.exists() {
        return Err(format!(
            "Work item '{story_id}' not found in work/2_current/. Cannot move to 3_qa/."
        ));
    }

    std::fs::create_dir_all(&qa_dir)
        .map_err(|e| format!("Failed to create work/3_qa/ directory: {e}"))?;
    std::fs::rename(&current_path, &qa_path)
        .map_err(|e| format!("Failed to move '{story_id}' to 3_qa/: {e}"))?;

    slog!("[lifecycle] Moved '{story_id}' from work/2_current/ to work/3_qa/");

    Ok(())
}

/// Move a bug from `work/2_current/` or `work/1_upcoming/` to `work/5_done/` and auto-commit.
///
/// * If the bug is in `2_current/`, it is moved to `5_done/` and committed.
/// * If the bug is still in `1_upcoming/` (never started), it is moved directly to `5_done/`.
/// * If the bug is already in `5_done/`, this is a no-op (idempotent).
/// * If the bug is not found anywhere, an error is returned.
pub fn close_bug_to_archive(project_root: &Path, bug_id: &str) -> Result<(), String> {
    let sk = project_root.join(".story_kit").join("work");
    let current_path = sk.join("2_current").join(format!("{bug_id}.md"));
    let upcoming_path = sk.join("1_upcoming").join(format!("{bug_id}.md"));
    let archive_dir = item_archive_dir(project_root, bug_id);
    let archive_path = archive_dir.join(format!("{bug_id}.md"));

    if archive_path.exists() {
        return Ok(());
    }

    let source_path = if current_path.exists() {
        current_path.clone()
    } else if upcoming_path.exists() {
        upcoming_path.clone()
    } else {
        return Err(format!(
            "Bug '{bug_id}' not found in work/2_current/ or work/1_upcoming/. Cannot close bug."
        ));
    };

    std::fs::create_dir_all(&archive_dir)
        .map_err(|e| format!("Failed to create work/5_done/ directory: {e}"))?;
    std::fs::rename(&source_path, &archive_path)
        .map_err(|e| format!("Failed to move bug '{bug_id}' to 5_done/: {e}"))?;

    slog!(
        "[lifecycle] Closed bug '{bug_id}' → work/5_done/"
    );

    Ok(())
}

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

    // ── move_story_to_current tests ────────────────────────────────────────────

    #[test]
    fn move_story_to_current_moves_file() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let upcoming = root.join(".story_kit/work/1_upcoming");
        let current = root.join(".story_kit/work/2_current");
        fs::create_dir_all(&upcoming).unwrap();
        fs::create_dir_all(&current).unwrap();
        fs::write(upcoming.join("10_story_foo.md"), "test").unwrap();

        move_story_to_current(root, "10_story_foo").unwrap();

        assert!(!upcoming.join("10_story_foo.md").exists());
        assert!(current.join("10_story_foo.md").exists());
    }

    #[test]
    fn move_story_to_current_is_idempotent_when_already_current() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let current = root.join(".story_kit/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(current.join("11_story_foo.md"), "test").unwrap();

        move_story_to_current(root, "11_story_foo").unwrap();
        assert!(current.join("11_story_foo.md").exists());
    }

    #[test]
    fn move_story_to_current_noop_when_not_in_upcoming() {
        let tmp = tempfile::tempdir().unwrap();
        assert!(move_story_to_current(tmp.path(), "99_missing").is_ok());
    }

    #[test]
    fn move_bug_to_current_moves_from_upcoming() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let upcoming = root.join(".story_kit/work/1_upcoming");
        let current = root.join(".story_kit/work/2_current");
        fs::create_dir_all(&upcoming).unwrap();
        fs::create_dir_all(&current).unwrap();
        fs::write(upcoming.join("1_bug_test.md"), "# Bug 1\n").unwrap();

        move_story_to_current(root, "1_bug_test").unwrap();

        assert!(!upcoming.join("1_bug_test.md").exists());
        assert!(current.join("1_bug_test.md").exists());
    }

    // ── close_bug_to_archive tests ─────────────────────────────────────────────

    #[test]
    fn close_bug_moves_from_current_to_archive() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let current = root.join(".story_kit/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(current.join("2_bug_test.md"), "# Bug 2\n").unwrap();

        close_bug_to_archive(root, "2_bug_test").unwrap();

        assert!(!current.join("2_bug_test.md").exists());
        assert!(root.join(".story_kit/work/5_done/2_bug_test.md").exists());
    }

    #[test]
    fn close_bug_moves_from_upcoming_when_not_started() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let upcoming = root.join(".story_kit/work/1_upcoming");
        fs::create_dir_all(&upcoming).unwrap();
        fs::write(upcoming.join("3_bug_test.md"), "# Bug 3\n").unwrap();

        close_bug_to_archive(root, "3_bug_test").unwrap();

        assert!(!upcoming.join("3_bug_test.md").exists());
        assert!(root.join(".story_kit/work/5_done/3_bug_test.md").exists());
    }

    // ── item_type_from_id tests ────────────────────────────────────────────────

    #[test]
    fn item_type_from_id_detects_types() {
        assert_eq!(item_type_from_id("1_bug_test"), "bug");
        assert_eq!(item_type_from_id("1_spike_research"), "spike");
        assert_eq!(item_type_from_id("50_story_my_story"), "story");
        assert_eq!(item_type_from_id("1_story_simple"), "story");
    }

    // ── move_story_to_merge tests ──────────────────────────────────────────────

    #[test]
    fn move_story_to_merge_moves_file() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let current = root.join(".story_kit/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(current.join("20_story_foo.md"), "test").unwrap();

        move_story_to_merge(root, "20_story_foo").unwrap();

        assert!(!current.join("20_story_foo.md").exists());
        assert!(root.join(".story_kit/work/4_merge/20_story_foo.md").exists());
    }

    #[test]
    fn move_story_to_merge_from_qa_dir() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let qa_dir = root.join(".story_kit/work/3_qa");
        fs::create_dir_all(&qa_dir).unwrap();
        fs::write(qa_dir.join("40_story_test.md"), "test").unwrap();

        move_story_to_merge(root, "40_story_test").unwrap();

        assert!(!qa_dir.join("40_story_test.md").exists());
        assert!(root.join(".story_kit/work/4_merge/40_story_test.md").exists());
    }

    #[test]
    fn move_story_to_merge_idempotent_when_already_in_merge() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let merge_dir = root.join(".story_kit/work/4_merge");
        fs::create_dir_all(&merge_dir).unwrap();
        fs::write(merge_dir.join("21_story_test.md"), "test").unwrap();

        move_story_to_merge(root, "21_story_test").unwrap();
        assert!(merge_dir.join("21_story_test.md").exists());
    }

    #[test]
    fn move_story_to_merge_errors_when_not_in_current_or_qa() {
        let tmp = tempfile::tempdir().unwrap();
        let result = move_story_to_merge(tmp.path(), "99_nonexistent");
        assert!(result.unwrap_err().contains("not found in work/2_current/ or work/3_qa/"));
    }

    // ── move_story_to_qa tests ────────────────────────────────────────────────

    #[test]
    fn move_story_to_qa_moves_file() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let current = root.join(".story_kit/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(current.join("30_story_qa.md"), "test").unwrap();

        move_story_to_qa(root, "30_story_qa").unwrap();

        assert!(!current.join("30_story_qa.md").exists());
        assert!(root.join(".story_kit/work/3_qa/30_story_qa.md").exists());
    }

    #[test]
    fn move_story_to_qa_idempotent_when_already_in_qa() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let qa_dir = root.join(".story_kit/work/3_qa");
        fs::create_dir_all(&qa_dir).unwrap();
        fs::write(qa_dir.join("31_story_test.md"), "test").unwrap();

        move_story_to_qa(root, "31_story_test").unwrap();
        assert!(qa_dir.join("31_story_test.md").exists());
    }

    #[test]
    fn move_story_to_qa_errors_when_not_in_current() {
        let tmp = tempfile::tempdir().unwrap();
        let result = move_story_to_qa(tmp.path(), "99_nonexistent");
        assert!(result.unwrap_err().contains("not found in work/2_current/"));
    }

    // ── move_story_to_archived tests ──────────────────────────────────────────

    #[test]
    fn move_story_to_archived_finds_in_merge_dir() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();
        let merge_dir = root.join(".story_kit/work/4_merge");
        fs::create_dir_all(&merge_dir).unwrap();
        fs::write(merge_dir.join("22_story_test.md"), "test").unwrap();

        move_story_to_archived(root, "22_story_test").unwrap();

        assert!(!merge_dir.join("22_story_test.md").exists());
        assert!(root.join(".story_kit/work/5_done/22_story_test.md").exists());
    }

    #[test]
    fn move_story_to_archived_error_when_not_in_current_or_merge() {
        let tmp = tempfile::tempdir().unwrap();
        let result = move_story_to_archived(tmp.path(), "99_nonexistent");
        assert!(result.unwrap_err().contains("4_merge"));
    }

    // ── feature_branch_has_unmerged_changes tests ────────────────────────────

    fn init_git_repo(repo: &std::path::Path) {
        Command::new("git")
            .args(["init"])
            .current_dir(repo)
            .output()
            .unwrap();
        Command::new("git")
            .args(["config", "user.email", "test@test.com"])
            .current_dir(repo)
            .output()
            .unwrap();
        Command::new("git")
            .args(["config", "user.name", "Test"])
            .current_dir(repo)
            .output()
            .unwrap();
        Command::new("git")
            .args(["commit", "--allow-empty", "-m", "init"])
            .current_dir(repo)
            .output()
            .unwrap();
    }

    /// Bug 226: feature_branch_has_unmerged_changes returns true when the
    /// feature branch has commits not on master.
    #[test]
    fn feature_branch_has_unmerged_changes_detects_unmerged_code() {
        use std::fs;
        use tempfile::tempdir;

        let tmp = tempdir().unwrap();
        let repo = tmp.path();
        init_git_repo(repo);

        // Create a feature branch with a code commit.
        Command::new("git")
            .args(["checkout", "-b", "feature/story-50_story_test"])
            .current_dir(repo)
            .output()
            .unwrap();
        fs::write(repo.join("feature.rs"), "fn main() {}").unwrap();
        Command::new("git")
            .args(["add", "."])
            .current_dir(repo)
            .output()
            .unwrap();
        Command::new("git")
            .args(["commit", "-m", "add feature"])
            .current_dir(repo)
            .output()
            .unwrap();
        Command::new("git")
            .args(["checkout", "master"])
            .current_dir(repo)
            .output()
            .unwrap();

        assert!(
            feature_branch_has_unmerged_changes(repo, "50_story_test"),
            "should detect unmerged changes on feature branch"
        );
    }

    /// Bug 226: feature_branch_has_unmerged_changes returns false when no
    /// feature branch exists.
    #[test]
    fn feature_branch_has_unmerged_changes_false_when_no_branch() {
        use tempfile::tempdir;

        let tmp = tempdir().unwrap();
        let repo = tmp.path();
        init_git_repo(repo);

        assert!(
            !feature_branch_has_unmerged_changes(repo, "99_nonexistent"),
            "should return false when no feature branch"
        );
    }
}