// Git 状态收集（异步 + 缓存）
// 分支名由 pi 的 footerData.getGitBranch() 提供（带文件监听），此处仅收集
// status / ahead / behind / sha，避免阻塞 footer 渲染

import { spawn } from "node:child_process";

export type GitStatus = "clean" | "dirty" | "conflicts";

/** 额外 git 状态（分支名除外） */
export interface GitExtra {
  status: GitStatus;
  ahead: number;
  behind: number;
  sha?: string;
}

type CacheEntry = GitExtra | null; // null = 非 git 仓库

/** 运行 git 命令，返回 stdout 字符串（失败返回空串） */
function runGit(args: string[], cwd: string): Promise<string> {
  return new Promise((resolve) => {
    let out = "";
    try {
      const child = spawn("git", args, {
        cwd,
        stdio: ["ignore", "pipe", "ignore"],
        windowsHide: true,
      });
      child.stdout.on("data", (d: Buffer) => {
        out += d.toString();
      });
      child.on("error", () => resolve(""));
      child.on("close", () => resolve(out.trim()));
    } catch {
      resolve("");
    }
  });
}

/** 判断是否为 git 仓库 */
async function isRepo(cwd: string): Promise<boolean> {
  const r = await runGit(["--no-optional-locks", "rev-parse", "--git-dir"], cwd);
  return r.length > 0 && !r.toLowerCase().startsWith("fatal");
}

/** 收集额外 git 状态（异步） */
async function collectGitExtra(cwd: string, showSha: boolean): Promise<CacheEntry> {
  if (!(await isRepo(cwd))) return null;

  const statusOut = await runGit(["--no-optional-locks", "status", "--porcelain"], cwd);
  let status: GitStatus = "clean";
  if (statusOut.trim()) {
    // 冲突标记：UU / AA / DD（任一列）
    status = /(^|\n)(UU|AA|DD)/.test(statusOut) ? "conflicts" : "dirty";
  }

  const aheadStr = await runGit(["--no-optional-locks", "rev-list", "--count", "@{u}..HEAD"], cwd);
  const behindStr = await runGit(["--no-optional-locks", "rev-list", "--count", "HEAD..@{u}"], cwd);
  const ahead = parseInt(aheadStr, 10) || 0;
  const behind = parseInt(behindStr, 10) || 0;

  let sha: string | undefined;
  if (showSha) {
    const s = await runGit(["--no-optional-locks", "rev-parse", "--short=7", "HEAD"], cwd);
    if (s) sha = s;
  }

  return { status, ahead, behind, sha };
}

/** Git 状态缓存：render 时同步读取，后台异步刷新 */
export class GitCache {
  private cache = new Map<string, CacheEntry>();
  private inflight = new Map<string, Promise<void>>();
  private lastRefresh = new Map<string, number>();
  private showSha = false;
  /** 刷新节流间隔（毫秒），避免渲染时频繁调用 git */
  private throttleMs = 15_000;

  setShowSha(v: boolean): void {
    this.showSha = v;
  }

  /** 同步读取缓存：undefined=未加载，null=非仓库，对象=已加载 */
  get(cwd: string): CacheEntry | undefined {
    return this.cache.get(cwd);
  }

  /** 异步刷新；force=true 绕过节流（用于 turn 结束等事件） */
  async refresh(cwd: string, onUpdate?: () => void, force = false): Promise<void> {
    const now = Date.now();
    if (
      !force &&
      this.lastRefresh.has(cwd) &&
      now - (this.lastRefresh.get(cwd) ?? 0) < this.throttleMs
    ) {
      return; // 节流跳过
    }
    if (this.inflight.has(cwd)) return this.inflight.get(cwd);

    const p = (async () => {
      try {
        const r = await collectGitExtra(cwd, this.showSha);
        this.cache.set(cwd, r);
        this.lastRefresh.set(cwd, Date.now());
      } catch {
        this.cache.set(cwd, null);
      }
      this.inflight.delete(cwd);
      onUpdate?.();
    })();
    this.inflight.set(cwd, p);
    return p;
  }

  dispose(): void {
    this.cache.clear();
    this.inflight.clear();
    this.lastRefresh.clear();
  }
}