/**
 * Queue API Endpoints
 * 
 * Provides HTTP interface for queue operations:
 * - POST /api/queue - Enqueue Instagram URL for processing
 * - GET /api/queue - List all queue items with optional status filtering
 */

import { json, error } from '@sveltejs/kit';
import { queueManager } from '$lib/server/queue/QueueManager';
import type { RequestHandler } from './$types';

/**
 * POST /api/queue - Enqueue Instagram URL
 * 
 * Body: { url: string }
 * Returns: { id: string, url: string, status: string, enqueuedAt: string }
 * 
 * Validates Instagram URL format and enqueues for processing.
 * Returns 400 for invalid URLs, 500 for server errors.
 */
export const POST: RequestHandler = async ({ request }) => {
  try {
    // Parse JSON body with proper error handling
    let body;
    try {
      body = await request.json();
    } catch (jsonError) {
      return error(400, { message: 'Invalid JSON in request body' });
    }
    
    // Validate request body
    if (!body || typeof body !== 'object') {
      return error(400, { message: 'Request body must be JSON object' });
    }
    
    const { url } = body;
    
    // Validate URL presence
    if (!url || typeof url !== 'string') {
      return error(400, { message: 'URL is required and must be a string' });
    }
    
    // Validate Instagram URL format
    const instagramUrlPattern = /^https:\/\/(www\.)?instagram\.com\/p\/[a-zA-Z0-9_-]+\/?$/;
    if (!instagramUrlPattern.test(url)) {
      return error(400, { 
        message: 'Invalid Instagram URL format. Expected: https://instagram.com/p/{post-id}' 
      });
    }
    
    // Enqueue the URL
    const queueItem = queueManager.enqueue(url);
    
    // Return minimal response (full details available at GET /api/queue/{id})
    return json({
      id: queueItem.id,
      url: queueItem.url,
      status: queueItem.status,
      enqueuedAt: queueItem.enqueuedAt
    });
    
  } catch (err) {
    console.error('Failed to enqueue URL:', err);
    return error(500, { message: 'Internal server error' });
  }
};

/**
 * GET /api/queue - List queue items
 * 
 * Query params:
 * - status?: string - Filter by status (pending, in_progress, success, unhealthy, error)
 * - limit?: number - Maximum items to return (default: 50, max: 200)
 * - offset?: number - Pagination offset (default: 0)
 * 
 * Returns: { items: QueueItem[], total: number, hasMore: boolean }
 */
export const GET: RequestHandler = async ({ url }) => {
  try {
    const searchParams = url.searchParams;
    
    // Parse query parameters
    const statusFilter = searchParams.get('status');
    const limitParam = searchParams.get('limit');
    const offsetParam = searchParams.get('offset');
    
    // Validate and parse limit
    let limit = 50; // default
    if (limitParam) {
      const parsedLimit = parseInt(limitParam, 10);
      if (isNaN(parsedLimit) || parsedLimit < 1) {
        return error(400, { message: 'Limit must be a positive integer' });
      }
      if (parsedLimit > 200) {
        return error(400, { message: 'Limit cannot exceed 200' });
      }
      limit = parsedLimit;
    }
    
    // Validate and parse offset
    let offset = 0; // default
    if (offsetParam) {
      const parsedOffset = parseInt(offsetParam, 10);
      if (isNaN(parsedOffset) || parsedOffset < 0) {
        return error(400, { message: 'Offset must be a non-negative integer' });
      }
      offset = parsedOffset;
    }
    
    // Validate status filter
    const validStatuses = ['pending', 'in_progress', 'success', 'unhealthy', 'error'];
    if (statusFilter && !validStatuses.includes(statusFilter)) {
      return error(400, { 
        message: `Invalid status filter. Must be one of: ${validStatuses.join(', ')}` 
      });
    }
    
    // Get all items
    let items = queueManager.getAll();
    const totalCount = items.length;
    
    // Apply status filter
    if (statusFilter) {
      items = items.filter(item => item.status === statusFilter);
    }
    
    // Sort by enqueued time (newest first)
    items.sort((a, b) => new Date(b.enqueuedAt).getTime() - new Date(a.enqueuedAt).getTime());
    
    // Apply pagination
    const paginatedItems = items.slice(offset, offset + limit);
    const hasMore = (offset + limit) < items.length;
    
    return json({
      items: paginatedItems,
      total: statusFilter ? items.length : totalCount,
      hasMore,
      pagination: {
        offset,
        limit,
        count: paginatedItems.length
      }
    });
    
  } catch (err) {
    console.error('Failed to list queue items:', err);
    return error(500, { message: 'Internal server error' });
  }
};