import { spawnSync } from 'child_process';
import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import { GITEA_SERVER_URL, GITEA_REPOSITORY, GITEA_TOKEN, PR_HEAD_BRANCH, FINDINGS_PATH } from './config.js';

const ACTION_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const GENERATED_SYNC_PATHS = [FINDINGS_PATH, '.gitea/ai-review/exclusions.json'];
const remoteUrl = `${GITEA_SERVER_URL.replace(/\/$/, '')}/${GITEA_REPOSITORY}.git`;
export const SYNC_PATHS = [
  '.amazonq/rules/triage-findings.md',
  '.codex/skills/triage-findings/SKILL.md',
  '.codex/skills/triage-findings/agents/openai.yaml',
  '.claude/skills/triage-findings/SKILL.md',
  '.gemini/skills/triage-findings/SKILL.md',
  '.github/copilot-instructions.md',
  '.github/skills/triage-findings/SKILL.md',
  'CLAUDE.md',
  'GEMINI.md',
];

function makeRunner(spawn) {
  return function run(args, cwd, env) {
    const opts = { cwd, encoding: 'utf8' };
    if (env) opts.env = env;
    const result = spawn('git', args, opts);
    if (result.error) throw result.error;
    if (result.status !== 0) throw new Error((result.stderr || result.stdout || '').trim());
    return (result.stdout || '').trim();
  };
}

function withAskpass(workspace, fn) {
  const askpassScript = path.join(workspace, '.git-askpass.sh');
  fs.writeFileSync(askpassScript, '#!/bin/sh\necho "$GIT_TOKEN"\n', { mode: 0o700 });
  const credEnv = { ...process.env, GIT_ASKPASS: askpassScript, GIT_USERNAME: 'x-token', GIT_TOKEN: GITEA_TOKEN };
  try {
    return fn(credEnv);
  } finally {
    try { fs.unlinkSync(askpassScript); } catch {}
  }
}

function readGitOutput(run, args, cwd, env) {
  try {
    return run(args, cwd, env);
  } catch {
    return '';
  }
}

export function getRepoState(repoDir, _spawnSync = spawnSync) {
  const run = makeRunner(_spawnSync);
  const headSha = readGitOutput(run, ['rev-parse', 'HEAD'], repoDir);
  const shortSha = readGitOutput(run, ['rev-parse', '--short', 'HEAD'], repoDir);
  const branch = readGitOutput(run, ['branch', '--show-current'], repoDir);
  const commitTime = readGitOutput(run, ['show', '-s', '--format=%cI', 'HEAD'], repoDir);
  return { repoDir, branch, headSha, shortSha, commitTime };
}

/**
 * Clone PR head branch to workspace/repo (idempotent)
 */
export function cloneRepo(workspace, _spawnSync = spawnSync) {
  const run = makeRunner(_spawnSync);
  const repoDir = path.join(workspace, 'repo');

  return withAskpass(workspace, credEnv => {
    if (!fs.existsSync(repoDir)) {
      run(['clone', '--depth=1', '--branch', PR_HEAD_BRANCH, remoteUrl, repoDir], workspace, credEnv);
      console.log(`  ✅ repo cloned to ${repoDir}`);
    } else {
      run(['fetch', 'origin', PR_HEAD_BRANCH], repoDir, credEnv);
      run(['checkout', PR_HEAD_BRANCH], repoDir);
      console.log(`  ✅ repo already exists, fetched latest`);
    }
    return repoDir;
  });
}

export async function commitAndPush(workspace, repoDir, _spawnSync = spawnSync, sourceRoot = ACTION_ROOT) {
  const run = makeRunner(_spawnSync);

  try {
    await withAskpass(workspace, async credEnv => {
      run(['config', 'user.email', 'ai-review[bot]@gitea'], repoDir);
      run(['config', 'user.name', 'AI Review Bot'], repoDir);
      if (PR_HEAD_BRANCH) {
        run(['fetch', 'origin', PR_HEAD_BRANCH], repoDir, credEnv);
        run(['reset', '--hard', `origin/${PR_HEAD_BRANCH}`], repoDir);
      }

      const existingSyncPaths = [];

      // Copy action skill files into the target repo. Existing files are overwritten;
      // missing source files are ignored so we do not delete target repo content.
      for (const relPath of SYNC_PATHS) {
        const src = path.join(sourceRoot, relPath);
        const dest = path.join(repoDir, relPath);
        if (fs.existsSync(src)) {
          fs.mkdirSync(path.dirname(dest), { recursive: true });
          fs.copyFileSync(src, dest);
          existingSyncPaths.push(relPath);
        }
      }

      if (existingSyncPaths.length > 0) {
        run(['add', ...existingSyncPaths], repoDir);
      }
      const generatedSyncPaths = GENERATED_SYNC_PATHS.filter(relPath => fs.existsSync(path.join(workspace, relPath)));
      if (generatedSyncPaths.length > 0) {
        for (const relPath of generatedSyncPaths) {
          const src = path.join(workspace, relPath);
          const dest = path.join(repoDir, relPath);
          fs.mkdirSync(path.dirname(dest), { recursive: true });
          fs.copyFileSync(src, dest);
        }
        run(['add', ...generatedSyncPaths], repoDir);
      }

      const status = run(['status', '--porcelain'], repoDir);
      if (!status) {
        console.log('  sync files 無變更，跳過 commit');
        return;
      }

      const out = run(['commit', '-m', 'chore: update ai-review findings [skip ci]'], repoDir);
      const commitHash = out.match(/\[.+ ([a-f0-9]+)\]/)?.[1] || 'unknown';
      try {
        run(['push', remoteUrl, PR_HEAD_BRANCH], repoDir, credEnv);
        console.log(`  ✅ persisted findings  commit=${commitHash}  push=${PR_HEAD_BRANCH}`);
      } catch (pushErr) {
        console.log(`  ⚠️  Step7 commit 成功但 push 失敗: commit=${commitHash} push=${PR_HEAD_BRANCH} error=${pushErr.message}`);
      }
    });
  } catch (e) {
    console.log(`  ⚠️  Runner failed: commit/push 失敗: ${e.message}`);
  }
}