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,
  getLLMConfig,
} from './config.js';
import { verifyRemoteAccess } from './git.js';
import { step, line, ok, error } from './log.js';

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

function giteaErr(e) {
  const status = e.response?.status;
  return status ? `HTTP ${status} ${e.message}` : e.message;
}

/** 檢查必要環境變數是否齊全；可傳入覆寫值供測試使用 */
export function checkRequiredEnv({ token = GITEA_TOKEN, repo = GITEA_REPOSITORY, pr = PR_NUMBER } = {}) {
  const missing = [];
  if (!token) missing.push('GITEA_TOKEN');
  if (!repo) missing.push('GITEA_REPOSITORY');
  if (!pr) missing.push('PR_NUMBER');
  return { ok: missing.length === 0, missing };
}

/** 用 GITEA_TOKEN 讀取此 repo，同時驗證 token 有效與有讀取權限 */
export async function verifyGiteaToken(token = GITEA_TOKEN, repo = GITEA_REPOSITORY) {
  try {
    await axios.get(api(`/repos/${repo}`), { headers: giteaHeaders(token), timeout: 30000, httpsAgent });
    return { ok: true };
  } catch (e) {
    return { ok: false, error: giteaErr(e) };
  }
}

/** 若有提供 comment token，用它呼叫 /user 驗證可用；沒提供則略過 */
export async function verifyCommentToken(token = GITEA_COMMENT_TOKEN) {
  if (!token) return { ok: true, skipped: true };
  try {
    await axios.get(api('/user'), { headers: giteaHeaders(token), timeout: 30000, httpsAgent });
    return { ok: true };
  } catch (e) {
    return { ok: false, error: giteaErr(e) };
  }
}

/**
 * 驗證 LLM 設定可用：
 * - 須已選定一個 provider
 * - Ollama 檢查 base URL 是否可連線
 * - 其餘 provider 以最小請求驗證認證，多把 Key 只要一把成功即可
 */
export async function verifyLLM() {
  const { provider, apiKeys, baseURL, model } = getLLMConfig();
  if (!provider) return { ok: false, error: '未設定任何 LLM provider 或 API Key' };
  if (!baseURL) return { ok: false, provider, error: `${provider} 缺少 base URL` };

  const base = baseURL.replace(/\/$/, '');

  if (provider === 'ollama') {
    try {
      await axios.get(`${base}/models`, { timeout: 30000 });
      return { ok: true, provider };
    } catch (e) {
      return { ok: false, provider, error: `Ollama base URL 無法連線: ${e.message}` };
    }
  }

  const headers = { 'Content-Type': 'application/json' };
  if (provider === 'claude') headers['anthropic-version'] = '2023-06-01';
  const payload = { model, messages: [{ role: 'user', content: 'ping' }], max_tokens: 1, temperature: 0 };

  for (let i = 0; i < apiKeys.length; i++) {
    headers['Authorization'] = `Bearer ${apiKeys[i]}`;
    try {
      await axios.post(`${base}/chat/completions`, payload, { headers, timeout: 30000 });
      return { ok: true, provider, keyIndex: i + 1, total: apiKeys.length };
    } catch (e) {
      line(`[preflight] LLM key[${i + 1}/${apiKeys.length}] 驗證失敗: ${e.message}`);
    }
  }
  return { ok: false, provider, error: `所有 ${apiKeys.length} 把 ${provider} API Key 驗證失敗` };
}

/**
 * 集中執行所有驗證相關設定的前置檢查；全部通過回傳 true，任一失敗回傳 false。
 * 僅做唯讀的認證/連線確認，不發布任何 comment。
 */
export async function runPreflight(workspace = process.env.GITHUB_WORKSPACE || '/workspace') {
  step('Step1.5', '前置驗證（驗證相關設定）');

  const env = checkRequiredEnv();
  if (!env.ok) {
    error(`缺少必要環境變數: ${env.missing.join(', ')}`);
    return false;
  }
  ok('必要環境變數齊全 (GITEA_TOKEN, GITEA_REPOSITORY, PR_NUMBER)');

  const gitea = await verifyGiteaToken();
  if (!gitea.ok) {
    error(`GITEA_TOKEN 驗證失敗（無法讀取 repo ${GITEA_REPOSITORY}）: ${gitea.error}`);
    return false;
  }
  ok(`GITEA_TOKEN 可讀取 repo ${GITEA_REPOSITORY}`);

  const comment = await verifyCommentToken();
  if (!comment.ok) {
    error(`GITEA_COMMENT_TOKEN 驗證失敗: ${comment.error}`);
    return false;
  }
  if (comment.skipped) line('未提供 GITEA_COMMENT_TOKEN，comment 將沿用 GITEA_TOKEN');
  else ok('GITEA_COMMENT_TOKEN 可用');

  const remote = verifyRemoteAccess(workspace);
  if (!remote.ok) {
    error(`git push 認證/連線驗證失敗（ls-remote）: ${remote.error}`);
    return false;
  }
  ok('git remote 認證可用（ls-remote 成功）');

  const llm = await verifyLLM();
  if (!llm.ok) {
    error(`LLM 驗證失敗: ${llm.error}`);
    return false;
  }
  if (llm.keyIndex) ok(`LLM provider=${llm.provider} 驗證通過（key ${llm.keyIndex}/${llm.total}）`);
  else ok(`LLM provider=${llm.provider} 連線正常`);

  ok('前置驗證通過');
  return true;
}