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

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

/**
 * 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/',
    '.claude/',
    '.codex/',
    '.gemini/',
    '.gitea/',
    '.github/',
    '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,
    });
    return resp.data?.message || '';
  } catch {
    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 || '';
    return await getCommitMessageBySha(sha);
  } catch {
    return '';
  }
}

export async function shouldSkipBotCommit({ sha = PR_HEAD_SHA || process.env.GITHUB_SHA, branch = PR_HEAD_BRANCH } = {}) {
  const candidates = [
    await getCommitMessageBySha(sha),
    await getBranchHeadCommitMessage(branch),
  ].filter(Boolean);
  return candidates.some(message => message.includes('[ai-review-bot]'));
}

/**
 * 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(), timeout: 30000, httpsAgent });
  return resp.data;
}