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, 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, [
    '.gitea/',
    '.github/',
    '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 extractCommitMessage(resp.data);
  } catch (e) {
    warn(`取得 commit 訊息失敗: 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 || '';
    return await getCommitMessageBySha(sha);
  } catch (e) {
    warn(`取得分支 head 訊息失敗: branch=${branch} error=${e.message}`);
    return '';
  }
}

/** 檢查 PR head（commit sha 或分支 head）的訊息是否帶 [ai-review-bot] 標記，是則代表本次是自動提交、應跳過審查。 */
export async function shouldSkipBotCommit({ sha = PR_HEAD_SHA || process.env.GITHUB_SHA, branch = PR_HEAD_BRANCH } = {}) {
  const shaMessage = await getCommitMessageBySha(sha);
  if (sha && shaMessage.includes('[ai-review-bot]')) return true;

  const branchMessage = await getBranchHeadCommitMessage(branch);
  if (branch && branchMessage.includes('[ai-review-bot]')) return true;

  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;
}

/**
 * 在 PR 指定檔案的指定行數發布行內 review comment（標註程式碼位置）。
 * 透過 Gitea 的 pull reviews API，以 new_position 對應新版檔案的行號。
 * 若該行不在 diff 範圍內，Gitea 會回傳錯誤，由呼叫端決定是否降級為一般 comment。
 */
export async function postPullReviewComment({ path: filePath, line, body }) {
  const resp = await axios.post(
    api(`/repos/${GITEA_REPOSITORY}/pulls/${PR_NUMBER}/reviews`),
    {
      commit_id: PR_HEAD_SHA || undefined,
      event: 'COMMENT',
      body: '',
      comments: [{ path: filePath, body, new_position: line }],
    },
    { headers: headers(GITEA_COMMENT_TOKEN || GITEA_TOKEN), timeout: 30000, httpsAgent },
  );
  return resp.data;
}

/**
 * 建立一個 PR review，本文放統計摘要，comments 放多筆行內 review comments。
 */
export async function postPullReview({ body, comments = [] }) {
  const resp = await axios.post(
    api(`/repos/${GITEA_REPOSITORY}/pulls/${PR_NUMBER}/reviews`),
    {
      commit_id: PR_HEAD_SHA || undefined,
      event: 'COMMENT',
      body,
      comments,
    },
    { headers: headers(GITEA_COMMENT_TOKEN || GITEA_TOKEN), timeout: 30000, httpsAgent },
  );
  return resp.data;
}

/**
 * 取得 PR 上所有的 review（每個 review 可含多個行內 comment）。
 */
export async function listPullReviews() {
  const resp = await axios.get(
    api(`/repos/${GITEA_REPOSITORY}/pulls/${PR_NUMBER}/reviews`),
    { headers: headers(), timeout: 30000, httpsAgent },
  );
  return Array.isArray(resp.data) ? resp.data : [];
}

/**
 * 取得單一 review 底下的所有行內 comment。
 */
export async function getPullReviewComments(reviewId) {
  const resp = await axios.get(
    api(`/repos/${GITEA_REPOSITORY}/pulls/${PR_NUMBER}/reviews/${reviewId}/comments`),
    { headers: headers(), timeout: 30000, httpsAgent },
  );
  return Array.isArray(resp.data) ? resp.data : [];
}

/**
 * 取得 PR 上所有 review 的行內 comment，展平成單一陣列。
 * 單一 review 取 comment 失敗時記錄警告並略過，不中斷整體流程。
 */
export async function listAllReviewComments() {
  const reviews = await listPullReviews();
  const all = [];
  for (const review of reviews) {
    if (!review?.id) continue;
    try {
      all.push(...await getPullReviewComments(review.id));
    } catch (e) {
      warn(`取得 review #${review.id} 的 comments 失敗（略過）: ${e.message}`);
    }
  }
  line(`取得 PR review comments: reviews=${reviews.length} comments=${all.length}`);
  return all;
}

/**
 * 解決（resolve）一個 review comment 所屬的對話。
 * 對應 Gitea 官方 API：POST /repos/{repo}/pulls/comments/{id}/resolve。
 */
export async function resolvePullReviewComment(commentId) {
  const resp = await axios.post(
    api(`/repos/${GITEA_REPOSITORY}/pulls/comments/${commentId}/resolve`),
    {},
    { headers: headers(GITEA_COMMENT_TOKEN || GITEA_TOKEN), timeout: 30000, httpsAgent },
  );
  return resp.data;
}

/**
 * 取得指定 ref（預設 PR head）下某檔案的最新文字內容；
 * Gitea contents API 回傳 base64，這裡解碼成字串。檔案不存在或非文字時回傳空字串。
 */
export async function getFileContentAtRef(filePath, ref = PR_HEAD_SHA || PR_HEAD_BRANCH) {
  try {
    const resp = await axios.get(
      api(`/repos/${GITEA_REPOSITORY}/contents/${encodeURIComponent(filePath).replace(/%2F/g, '/')}`),
      { headers: headers(), params: ref ? { ref } : undefined, timeout: 30000, httpsAgent },
    );
    const { content, encoding } = resp.data || {};
    if (typeof content !== 'string') return '';
    return encoding === 'base64' ? Buffer.from(content, 'base64').toString('utf8') : content;
  } catch (e) {
    warn(`取得檔案內容失敗（視為空）: ${filePath}@${ref || 'head'} error=${e.message}`);
    return '';
  }
}