import axios from 'axios';
import https from 'https';
import { GITEA_TOKEN, GITEA_COMMENT_TOKEN, GITEA_SERVER_URL, GITEA_REPOSITORY, GITEA_SKIP_TLS_VERIFY, PR_NUMBER, PR_HEAD_SHA, PR_HEAD_BRANCH } from './config.js';
import { line, ok, warn } from './log.js';

const httpsAgent = GITEA_SKIP_TLS_VERIFY ? new https.Agent({ rejectUnauthorized: false }) : undefined;
const headers = (token = GITEA_TOKEN) => ({ Authorization: `token ${token}`, 'Content-Type': 'application/json' });
const api = (path) => `${GITEA_SERVER_URL.replace(/\/$/, '')}/api/v1${path}`;

function extractCommitMessage(payload) {
  return payload?.message
    || payload?.commit?.message
    || payload?.commit?.commit?.message
    || '';
}

export function getBotReviewOutcome(message) {
  const match = String(message || '').match(/\[ai-review-bot\](?:\[(success|failure)\])?/i);
  return match?.[1]?.toLowerCase() || 'unknown';
}

/**
 * 取得 PR 的 Git Diff 內容，已自動排除 .gitea/ 資料夾。
 */
export async function getPRDiff() {
  const resp = await axios.get(api(`/repos/${GITEA_REPOSITORY}/pulls/${PR_NUMBER}.diff`), { headers: headers(), timeout: 60000, httpsAgent });
  return filterDiff(resp.data, [
    '.amazonq/',
    '.agents/',
    '.antigravity/',
    '.claude/',
    '.codex/',
    '.gemini/',
    '.gitea/',
    '.github/',
    'AGENTS.md',
    'ANTIGRAVITY.md',
    'CLAUDE.md',
    'GEMINI.md',
    'README.md',
    'TODO.md',
  ]);
}

export async function getCommitMessageBySha(sha) {
  if (!sha) return '';
  try {
    const resp = await axios.get(api(`/repos/${GITEA_REPOSITORY}/git/commits/${encodeURIComponent(sha)}`), {
      headers: headers(),
      timeout: 30000,
      httpsAgent,
    });
    const message = extractCommitMessage(resp.data);
    line(`bot-check commit api: sha=${sha} keys=${Object.keys(resp.data || {}).join(',') || 'empty'} message=${message ? 'found' : 'empty'}`);
    return message;
  } catch (e) {
    warn(`bot-check commit api 失敗: sha=${sha} error=${e.message}`);
    return '';
  }
}

export async function getBranchHeadCommitMessage(branch = PR_HEAD_BRANCH) {
  if (!branch) return '';
  try {
    const resp = await axios.get(api(`/repos/${GITEA_REPOSITORY}/branches/${encodeURIComponent(branch)}`), {
      headers: headers(),
      timeout: 30000,
      httpsAgent,
    });
    const sha = resp.data?.commit?.id || resp.data?.commit?.sha || '';
    line(`bot-check branch api: branch=${branch} keys=${Object.keys(resp.data || {}).join(',') || 'empty'} sha=${sha || 'empty'} message=${extractCommitMessage(resp.data?.commit) ? 'found' : 'empty'}`);
    return await getCommitMessageBySha(sha);
  } catch (e) {
    warn(`bot-check branch api 失敗: branch=${branch} error=${e.message}`);
    return '';
  }
}

export async function shouldSkipBotCommit({ sha = PR_HEAD_SHA || process.env.GITHUB_SHA, branch = PR_HEAD_BRANCH } = {}) {
  line(`bot-check start: PR_HEAD_SHA=${PR_HEAD_SHA || 'empty'} GITHUB_SHA=${process.env.GITHUB_SHA || 'empty'} sha=${sha || 'empty'} branch=${branch || 'empty'}`);

  const shaMessage = await getCommitMessageBySha(sha);
  if (sha) {
    line(`bot-check sha: sha=${sha} message=${shaMessage ? 'found' : 'empty'} outcome=${getBotReviewOutcome(shaMessage)}`);
    if (shaMessage.includes('[ai-review-bot]')) {
      ok('bot-check matched commit sha marker');
      return true;
    }
  } else {
    line('bot-check skip sha lookup because sha is empty');
  }

  const branchMessage = await getBranchHeadCommitMessage(branch);
  if (branch) {
    line(`bot-check branch: branch=${branch} head_message=${branchMessage ? 'found' : 'empty'} outcome=${getBotReviewOutcome(branchMessage)}`);
    if (branchMessage.includes('[ai-review-bot]')) {
      ok('bot-check matched branch head marker');
      return true;
    }
  } else {
    line('bot-check skip branch lookup because branch is empty');
  }

  line('bot-check no [ai-review-bot] marker found');
  return false;
}

/**
 * 過濾 diff 內容，移除路徑符合 excludePrefixes 的區塊。
 * 每個區塊以 "diff --git a/<prefix>" 開頭判斷，使用 startsWith 精確比對前綴。
 */
export function filterDiff(diff, excludePrefixes) {
  return diff.split(/(?=^diff --git )/m)
    .filter(block => !excludePrefixes.some(p => {
      const prefix = `diff --git a/${p}`;
      const singleFile = `diff --git a/${p} b/${p}`;
      return block.startsWith(prefix) || block.startsWith(singleFile);
    }))
    .join('');
}

export async function postComment(body) {
  const resp = await axios.post(
    api(`/repos/${GITEA_REPOSITORY}/issues/${PR_NUMBER}/comments`),
    { body },
    { headers: headers(GITEA_COMMENT_TOKEN || GITEA_TOKEN), timeout: 30000, httpsAgent },
  );
  return resp.data;
}