import axios from 'axios';
import logger from '@/utils/logger.js';
import { getApiBaseUrl } from '@/utils/environment.js';
import { OAuthConfigService } from '@/services/auth/oauth-config.service.js';
import type { GitHubUserInfo, GitHubEmailInfo, OAuthUserData } from '@/types/auth.js';
import { OAuthProvider } from './base.provider.js';

/**
 * GitHub OAuth Service
 * Handles all GitHub OAuth operations including URL generation, token exchange, and user info retrieval
 */
export class GitHubOAuthProvider implements OAuthProvider {
  private static instance: GitHubOAuthProvider;

  private constructor() {
    // Initialize OAuth helpers if needed
  }

  public static getInstance(): GitHubOAuthProvider {
    if (!GitHubOAuthProvider.instance) {
      GitHubOAuthProvider.instance = new GitHubOAuthProvider();
    }
    return GitHubOAuthProvider.instance;
  }

  /**
   * Generate GitHub OAuth authorization URL
   */
  async generateOAuthUrl(state?: string): Promise<string> {
    const oAuthConfigService = OAuthConfigService.getInstance();
    const config = await oAuthConfigService.getConfigByProvider('github');

    if (!config) {
      throw new Error('GitHub OAuth not configured');
    }

    const selfBaseUrl = getApiBaseUrl();

    if (config?.useSharedKey) {
      if (!state) {
        logger.warn('Shared GitHub OAuth called without state parameter');
        throw new Error('State parameter is required for shared GitHub OAuth');
      }
      // Use shared keys if configured
      const cloudBaseUrl = process.env.CLOUD_API_HOST || 'https://api.insforge.dev';
      const redirectUri = `${selfBaseUrl}/api/auth/oauth/shared/callback/${state}`;
      const response = await axios.get(
        `${cloudBaseUrl}/auth/v1/shared/github?redirect_uri=${encodeURIComponent(redirectUri)}`,
        {
          headers: {
            'Content-Type': 'application/json',
          },
        }
      );
      return response.data.auth_url || response.data.url || '';
    }

    logger.debug('GitHub OAuth Config (fresh from DB):', {
      clientId: config.clientId ? 'SET' : 'NOT SET',
    });

    const authUrl = new URL('https://github.com/login/oauth/authorize');
    authUrl.searchParams.set('client_id', config.clientId ?? '');
    authUrl.searchParams.set('redirect_uri', `${selfBaseUrl}/api/auth/oauth/github/callback`);
    authUrl.searchParams.set('scope', config.scopes ? config.scopes.join(' ') : 'user:email');
    if (state) {
      authUrl.searchParams.set('state', state);
    }

    return authUrl.toString();
  }

  /**
   * Exchange GitHub code for access token
   */
  async exchangeCodeToToken(code: string): Promise<string> {
    const oAuthConfigService = OAuthConfigService.getInstance();
    const config = await oAuthConfigService.getConfigByProvider('github');

    if (!config) {
      throw new Error('GitHub OAuth not configured');
    }

    try {
      logger.info('Exchanging GitHub code for token', {
        hasCode: !!code,
        clientId: config.clientId?.substring(0, 10) + '...',
      });

      const clientSecret = await oAuthConfigService.getClientSecretByProvider('github');
      const selfBaseUrl = getApiBaseUrl();
      const response = await axios.post(
        'https://github.com/login/oauth/access_token',
        {
          client_id: config.clientId,
          client_secret: clientSecret,
          code,
          redirect_uri: `${selfBaseUrl}/api/auth/oauth/github/callback`,
        },
        {
          headers: {
            Accept: 'application/json',
          },
        }
      );

      if (!response.data.access_token) {
        throw new Error('Failed to get access token from GitHub');
      }

      return response.data.access_token;
    } catch (error) {
      if (axios.isAxiosError(error) && error.response) {
        logger.error('GitHub token exchange failed', {
          status: error.response.status,
          error: error.response.data,
        });
        throw new Error(`GitHub OAuth error: ${JSON.stringify(error.response.data)}`);
      }
      throw error;
    }
  }

  /**
   * Get GitHub user info
   */
  async getUserInfo(accessToken: string): Promise<GitHubUserInfo> {
    try {
      const userResponse = await axios.get('https://api.github.com/user', {
        headers: {
          Authorization: `Bearer ${accessToken}`,
        },
      });

      // GitHub doesn't always return email in user endpoint
      let email = userResponse.data.email;

      if (!email) {
        const emailResponse = await axios.get('https://api.github.com/user/emails', {
          headers: {
            Authorization: `Bearer ${accessToken}`,
          },
        });

        const primaryEmail = emailResponse.data.find((e: GitHubEmailInfo) => e.primary);
        email = primaryEmail ? primaryEmail.email : emailResponse.data[0]?.email;
      }

      return {
        id: userResponse.data.id,
        login: userResponse.data.login,
        name: userResponse.data.name,
        email: email || `${userResponse.data.login}@users.noreply.github.com`,
        avatar_url: userResponse.data.avatar_url,
      };
    } catch (error) {
      logger.error('GitHub user info retrieval failed:', error);
      throw new Error(`Failed to get GitHub user info: ${error}`);
    }
  }

  /**
   * Handle GitHub OAuth callback
   */
  async handleCallback(payload: { code?: string; token?: string }): Promise<OAuthUserData> {
    if (!payload.code) {
      throw new Error('No authorization code provided');
    }

    const accessToken = await this.exchangeCodeToToken(payload.code);
    const githubUserInfo = await this.getUserInfo(accessToken);

    // Transform GitHub user info to generic format
    const userName = githubUserInfo.name || githubUserInfo.login;
    const email = githubUserInfo.email || `${githubUserInfo.login}@users.noreply.github.com`;
    return {
      provider: 'github',
      providerId: githubUserInfo.id.toString(),
      email,
      userName,
      avatarUrl: githubUserInfo.avatar_url || '',
      identityData: githubUserInfo,
    };
  }

  /**
   * Handle shared callback payload transformation
   */
  handleSharedCallback(payloadData: Record<string, unknown>): OAuthUserData {
    const providerId = String(payloadData.providerId ?? '');
    const name = String(payloadData.name ?? '');
    const login = String(payloadData.login ?? '');
    const emailField = String(payloadData.email ?? '');
    const avatar = String(payloadData.avatar ?? '');

    const userName = name || login;
    const email = emailField || `${login}@users.noreply.github.com`;

    return {
      provider: 'github',
      providerId,
      email,
      userName,
      avatarUrl: avatar,
      identityData: payloadData,
    };
  }
}