//! Git API endpoints — status and diff.

use axum::{
    extract::{Query, State},
    http::StatusCode,
    Json,
};
use serde::{Deserialize, Serialize};

use crate::AppState;

type ApiResult<T> = Result<Json<T>, (StatusCode, Json<serde_json::Value>)>;

fn api_err(msg: impl std::fmt::Display) -> (StatusCode, Json<serde_json::Value>) {
    (
        StatusCode::INTERNAL_SERVER_ERROR,
        Json(serde_json::json!({ "error": msg.to_string() })),
    )
}

// ── Types ─────────────────────────────────────────────────────────────────────

#[derive(Debug, Serialize)]
pub struct GitFileStatus {
    pub path: String,
    pub status: String, // "M", "A", "D", "?", "R", etc.
}

#[derive(Debug, Deserialize)]
pub struct DiffQuery {
    pub path: Option<String>,
}

// ── Handlers ──────────────────────────────────────────────────────────────────

/// GET /api/git/status — returns list of changed files.
pub async fn git_status(
    State(state): State<AppState>,
) -> ApiResult<Vec<GitFileStatus>> {
    let project_path = &state.config.project_path;

    let output = tokio::process::Command::new("git")
        .args(["status", "--porcelain"])
        .current_dir(project_path)
        .output()
        .await
        .map_err(|e| api_err(format!("git status failed: {e}")))?;

    let stdout = String::from_utf8_lossy(&output.stdout);
    let mut files = Vec::new();

    for line in stdout.lines() {
        if line.len() < 4 {
            continue;
        }
        let xy = &line[..2];
        let path = line[3..].trim();
        // Handle renames: "old -> new"
        let file_path = if let Some(arrow) = path.find(" -> ") {
            &path[arrow + 4..]
        } else {
            path
        };

        // Determine status badge: prefer index status (first char)
        let status = if xy.starts_with('M') || xy.ends_with('M') {
            "M"
        } else if xy.starts_with('A') || xy.starts_with('?') {
            "A"
        } else if xy.starts_with('D') || xy.ends_with('D') {
            "D"
        } else if xy.starts_with('R') {
            "R"
        } else {
            "M"
        };

        files.push(GitFileStatus {
            path: file_path.to_string(),
            status: status.to_string(),
        });
    }

    Ok(Json(files))
}

/// GET /api/git/diff?path=<file> — returns unified diff.
pub async fn git_diff(
    State(state): State<AppState>,
    Query(q): Query<DiffQuery>,
) -> ApiResult<String> {
    let project_path = &state.config.project_path;

    let mut cmd = tokio::process::Command::new("git");
    cmd.arg("diff").current_dir(project_path);

    if let Some(ref path) = q.path {
        cmd.arg("--").arg(path);
    }

    let output = cmd
        .output()
        .await
        .map_err(|e| api_err(format!("git diff failed: {e}")))?;

    let diff = String::from_utf8_lossy(&output.stdout).to_string();
    Ok(Json(diff))
}