import { json, type RequestHandler } from '@sveltejs/kit';
import { BackendAuth } from '$lib/auth/backend';

const backendAuth = new BackendAuth(
  {
    clientId: process.env.CLIENT_ID,
    tenantId: process.env.TENANT_ID,
    clientSecret: process.env.CLIENT_SECRET,
  },
  process.env.PB_DB
);

export const POST: RequestHandler = async ({ request }) => {
  try {
    const body = await request.json();
    const pbToken = body.pbToken;
    
    // Get Graph token
    const { token: graphToken, expiresOnISO: graphExpires } = await backendAuth.graphTokenManager.getTokenWithExpiry();
    
    if (!graphToken) {
      return json({ success: false, error: 'Failed to acquire Graph token' }, { status: 500 });
    }
    
    // Decode both tokens to compare
    const decodeJWT = (token: string) => {
      try {
        const parts = token.split('.');
        if (parts.length !== 3) return null;
        return JSON.parse(Buffer.from(parts[1], 'base64').toString());
      } catch {
        return null;
      }
    };

    const graphPayload = decodeJWT(graphToken);
    
    // Validate PB token to get actual user
    let authenticatedUser = 'Unknown';
    if (pbToken) {
      try {
        const isValid = await backendAuth.pbValidator.validateUserToken(pbToken);
        if (isValid) {
          const userRecord = await backendAuth.pbValidator.getUserRecord(pbToken);
          authenticatedUser = userRecord?.email || userRecord?.id || 'Unknown';
        }
      } catch {
        authenticatedUser = 'Token invalid or expired';
      }
    }
    
    return json({
      success: true,
      comparison: {
        graph_token: {
          issuer: graphPayload?.iss || 'N/A',
          audience: graphPayload?.aud || 'N/A',
          app: graphPayload?.app_displayname || 'N/A',
          scopes: graphPayload?.scp || 'N/A',
          issued_at: graphPayload?.iat ? new Date(graphPayload.iat * 1000).toISOString() : 'N/A',
          expires_at: graphPayload?.exp ? new Date(graphPayload.exp * 1000).toISOString() : 'N/A',
          type: 'Microsoft Graph Token (Backend/App-only)',
          source: '@azure/msal-node',
          purpose: 'Backend API calls to Microsoft Graph',
        },
        pocketbase_token: {
          note: 'User token from PocketBase OAuth2',
          type: 'PocketBase User Token (Frontend/User)',
          source: 'PocketBase OAuth2 flow',
          purpose: 'User authentication and authorization',
          authenticated_user: authenticatedUser,
        },
        are_different: true,
        explanation: 'These are completely different tokens from different systems: Graph token is for app-to-app Microsoft API access, PocketBase token is for user authentication in the application.',
      },
    });
  } catch (error) {
    return json(
      { success: false, error: error instanceof Error ? error.message : 'Failed to compare tokens' },
      { status: 500 }
    );
  }
};