#!/usr/bin/env node
/**
 * 开发分支工作区初始化脚本
 *
 * 用于创建基于远端分支或新建的开发分支工作区。
 */

import { execFileSync } from "node:child_process";
import { existsSync, mkdirSync } from "node:fs";
import { resolve, relative } from "node:path";
import { createInterface } from "node:readline";

function git(args, opts) {
  return execFileSync("git", args, { encoding: "utf-8", stdio: "pipe", ...opts });
}

function getRootDir() {
  try {
    return resolve(git(["rev-parse", "--show-toplevel"]).trim());
  } catch {
    console.error("错误: 不在 git 仓库中");
    process.exit(1);
  }
}

function fetchRemote() {
  try {
    git(["fetch", "--quiet"]);
  } catch {
    console.warn("警告: 无法获取远端信息，继续使用本地数据");
  }
}

function listRemoteBranches() {
  try {
    return git(["branch", "-r"])
      .trim()
      .split(/\r?\n/)
      .map((l) => l.trim())
      .filter((l) => l && !l.includes(" -> "));
  } catch {
    return [];
  }
}

function matchingRemoteBranches(name) {
  return listRemoteBranches().filter((l) => l.endsWith(`/${name}`));
}

function localBranchExists(name) {
  try {
    git(["show-ref", "--verify", "--quiet", `refs/heads/${name}`]);
    return true;
  } catch {
    return false;
  }
}

function worktreeExists(worktreeDir) {
  try {
    const out = git(["worktree", "list"]);
    const target = resolve(worktreeDir);
    return out
      .split(/\r?\n/)
      .some((line) => {
        const fields = line.trim().split(/\s+/);
        return fields.length > 0 && resolve(fields[0]) === target;
      });
  } catch {
    return false;
  }
}

function shortBranchName(remoteRef) {
  const idx = remoteRef.indexOf("/");
  return idx === -1 ? remoteRef : remoteRef.slice(idx + 1);
}

function assertCanCreate(name, dir) {
  if (existsSync(dir)) {
    throw new Error(`工作区已存在于 ${dir}`);
  }
  if (worktreeExists(dir)) {
    throw new Error(`工作区 '${name}' 已存在`);
  }
  if (localBranchExists(name)) {
    throw new Error(`本地分支 '${name}' 已存在`);
  }
}

function addWorktree(name, dir, base) {
  const args = ["worktree", "add", "-b", name, dir];
  if (base) args.push(base);
  git(args);
}

function addWorktreeSafe(name, dir, base) {
  assertCanCreate(name, dir);
  addWorktree(name, dir, base);
  console.log(`工作区已创建于 ${dir}`);
}

function ask(rl, prompt) {
  return new Promise((resolve) => rl.question(prompt, resolve));
}

async function selectFromList(items, prompt, allowCreate) {
  if (items.length === 0) return null;

  console.log(prompt);
  items.forEach((item, i) => console.log(`     ${i + 1}\t${item}`));
  if (allowCreate) console.log(`     ${items.length + 1}\t创建新分支`);
  console.log();

  const max = allowCreate ? items.length + 1 : items.length;
  const rl = createInterface({ input: process.stdin, output: process.stdout });

  let cancelled = false;
  rl.on("close", () => { cancelled = true; });

  while (true) {
    const raw = await ask(rl, `请选择 (1-${max}): `);
    if (cancelled) {
      rl.close();
      process.exit(1);
    }
    const n = Number.parseInt(raw, 10);
    if (Number.isNaN(n) || n < 1 || n > max) {
      console.log(`错误: 请输入 1-${max} 之间的数字`);
      continue;
    }
    if (n <= items.length) {
      const sel = items[n - 1];
      console.log(`已选择: ${sel}`);
      rl.close();
      return sel;
    }
    rl.close();
    return null;
  }
}

async function inputBranchName() {
  const rl = createInterface({ input: process.stdin, output: process.stdout });

  let cancelled = false;
  rl.on("close", () => { cancelled = true; });

  while (true) {
    const name = (await ask(rl, "请输入新分支名称: ")).trim();
    if (cancelled) {
      rl.close();
      process.exit(1);
    }
    if (name) {
      rl.close();
      return name;
    }
    console.log("错误: 分支名称不能为空");
  }
}

async function handleWithName(name, worktreesDir) {
  const dir = resolve(worktreesDir, name);

  try {
    assertCanCreate(name, dir);
  } catch (e) {
    console.error(`错误: ${e.message}`);
    process.exit(1);
  }

  const remotes = matchingRemoteBranches(name);

  try {
    if (remotes.length > 0) {
      const base = await selectFromList(remotes, "找到远端分支:", true);
      addWorktree(name, dir, base ?? undefined);
    } else {
      console.log("未找到远端分支，创建新分支");
      addWorktree(name, dir);
    }
    console.log(`工作区已创建于 ${dir}`);
  } catch (e) {
    console.error(`错误: ${e.message}`);
    process.exit(1);
  }
}

async function handleWithoutName(worktreesDir) {
  const remotes = listRemoteBranches();

  if (remotes.length === 0) {
    console.log("未找到远端分支");
    process.exit(1);
  }

  const selected = await selectFromList(remotes, "远端分支列表:", true);

  if (selected) {
    const name = shortBranchName(selected);
    const dir = resolve(worktreesDir, name);
    try {
      addWorktreeSafe(name, dir, selected);
    } catch (e) {
      console.error(`错误: ${e.message}`);
      process.exit(1);
    }
  } else {
    const name = await inputBranchName();
    const dir = resolve(worktreesDir, name);
    try {
      addWorktreeSafe(name, dir);
    } catch (e) {
      console.error(`错误: ${e.message}`);
      process.exit(1);
    }
  }
}

process.on("SIGINT", () => process.exit(1));

async function main() {
  const branchName = process.argv[2];

  const rootDir = getRootDir();
  const worktreesDir = resolve(rootDir, ".worktrees");
  mkdirSync(worktreesDir, { recursive: true });

  console.log("正在从远端获取最新分支信息...");
  fetchRemote();

  if (branchName) {
    await handleWithName(branchName, worktreesDir);
  } else {
    await handleWithoutName(worktreesDir);
  }
}

main().catch((e) => {
  console.error(`错误: ${e.message}`);
  process.exit(1);
});