import { NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/app/api/auth/[...nextauth]/route';
import { ListBucketsCommand, ListObjectsV2Command } from '@aws-sdk/client-s3';
import { createUserFolderStructure } from '@/lib/s3';

// Import the configured S3 client and config from lib/s3.ts
import { s3Client } from '@/lib/s3';
import { S3_CONFIG } from '@/lib/s3';

// Simple in-memory cache with consistent expiration
const CACHE_TTL = 2 * 60 * 1000; // 2 minutes
const folderCache = new Map();

export async function GET() {
  try {
    const session = await getServerSession(authOptions);
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
    }

    const userId = session.user.id;
    const cacheKey = `folders:${userId}`;

    // Check cache first
    const cachedData = folderCache.get(cacheKey);
    if (cachedData && (Date.now() - cachedData.timestamp < CACHE_TTL)) {
      console.log(`Using cached folders for user ${userId}`);
      return NextResponse.json({
        status: 'ready',
        folders: cachedData.folders
      });
    }

    // Verify S3 connectivity
    try {
      await s3Client.send(new ListBucketsCommand({}));
    } catch (error) {
      console.error('S3 connectivity issue:', error);
      return NextResponse.json({
        status: 'error',
        error: 'Storage service is unavailable'
      }, { status: 503 });
    }

    // List folders in the user's path
    try {
      // Using the user prefix to list all folders
      const prefix = `user-${userId}/`;
      const command = new ListObjectsV2Command({
        Bucket: S3_CONFIG.bucket,
        Prefix: prefix,
        Delimiter: '/'
      });
      
      const response = await s3Client.send(command);
      const prefixes = response.CommonPrefixes || [];
      
      // Extract folder names and convert to display format
      let folders = prefixes
        .map(prefix => {
          // Extract folder name from path (e.g., user-123/notes/ → notes)
          const folderName = prefix.Prefix?.split('/')[1] || '';
          
          // Format folder name for display (capitalize first letter)
          return folderName.charAt(0).toUpperCase() + folderName.slice(1);
        })
        .filter(Boolean); // Remove any empty strings
      
      console.log(`Found ${folders.length} folders for user ${userId}`);
      
      // If no folders, create the standard structure
      if (folders.length === 0) {
        console.log(`No folders found, creating structure for user ${userId}`);
        await createUserFolderStructure(userId);
        
        // Use standard folder list for display
        folders = ['Notes', 'Diary', 'Health', 'Contacts'];
      }
      
      // Update cache with the results
      folderCache.set(cacheKey, {
        folders,
        timestamp: Date.now()
      });
      
      // Return the folder list
      return NextResponse.json({
        status: 'ready',
        folders
      });
    } catch (error) {
      console.error('Error listing folders:', error);
      return NextResponse.json({ 
        status: 'error',
        error: 'Failed to list folders' 
      }, { status: 500 });
    }
  } catch (error) {
    console.error('Status endpoint error:', error);
    return NextResponse.json({
      status: 'error',
      error: 'Internal server error'
    }, { status: 500 });
  }
}