//! Resolves the on-disk path to a Claude Code session transcript JSONL file.

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

/// Resolve the path to a Claude Code session transcript.
///
/// Claude Code stores each session's transcript at
/// `$HOME/.claude/projects/<mangled-cwd>/<session_id>.jsonl`, where
/// `<mangled-cwd>` is the absolute working directory with every `/` and `.`
/// replaced by `-` (e.g. `/workspace/.huskies/worktrees/1186` becomes
/// `-workspace--huskies-worktrees-1186`).
pub fn transcript_path(cwd: &Path, session_id: &str) -> PathBuf {
    let home = std::env::var("HOME").unwrap_or_else(|_| "/home/huskies".to_string());
    transcript_path_under_home(Path::new(&home), cwd, session_id)
}

/// Same as [`transcript_path`] but takes an explicit `$HOME` directory,
/// keeping the path-joining logic testable without mutating process env vars.
fn transcript_path_under_home(home: &Path, cwd: &Path, session_id: &str) -> PathBuf {
    let mangled = mangle_cwd(&cwd.to_string_lossy());
    home.join(".claude")
        .join("projects")
        .join(mangled)
        .join(format!("{session_id}.jsonl"))
}

/// Replace every `/` and `.` in an absolute path string with `-`, matching
/// the directory-naming convention Claude Code uses under `~/.claude/projects/`.
fn mangle_cwd(cwd: &str) -> String {
    cwd.chars()
        .map(|c| if c == '/' || c == '.' { '-' } else { c })
        .collect()
}

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

    #[test]
    fn mangles_worktree_path_matching_observed_convention() {
        // Verified against this very worktree's own transcript directory.
        assert_eq!(
            mangle_cwd("/workspace/.huskies/worktrees/1186"),
            "-workspace--huskies-worktrees-1186"
        );
    }

    #[test]
    fn mangles_simple_home_path() {
        assert_eq!(mangle_cwd("/home/huskies"), "-home-huskies");
    }

    #[test]
    fn transcript_path_joins_home_projects_dir_and_session_file() {
        let path = transcript_path_under_home(
            Path::new("/home/testuser"),
            Path::new("/workspace/proj"),
            "abc-123",
        );
        assert_eq!(
            path,
            PathBuf::from("/home/testuser/.claude/projects/-workspace-proj/abc-123.jsonl")
        );
    }
}
