/**
 * 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 } from '@sveltejs/kit';
import { queueManager } from '$lib/server/queue/QueueManager';
import { validateInstagramUrl } from '$lib/server/validation/instagram-url';
import { handleApiError } from '$lib/server/api/errorHandler';
import { ValidationError } from '$lib/server/api/errors';
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) {
			throw new ValidationError('Invalid JSON in request body');
		}

		// Validate request body
		if (!body || typeof body !== 'object') {
			throw new ValidationError('Request body must be JSON object');
		}

		const { url } = body;

		// Validate URL presence
		if (!url || typeof url !== 'string') {
			throw new ValidationError('URL is required and must be a string');
		}

		// Validate Instagram URL format using utility
		const validation = validateInstagramUrl(url);
		if (!validation.valid) {
			throw new ValidationError(validation.error || 'Invalid Instagram URL');
		}

		// Check for duplicate before enqueueing
		const existingItem = queueManager.findByUrl(url);

		if (existingItem) {
			// Return info response for duplicate
			return json({
				duplicate: true,
				message: 'This recipe is already in the queue',
				item: {
					id: existingItem.id,
					url: existingItem.url,
					status: existingItem.status,
					enqueuedAt: existingItem.enqueuedAt
				}
			}, { status: 200 }); // 200 OK, not an error
		}

		// Enqueue new URL
		const queueItem = queueManager.enqueue(url);

		// Return success response
		return json({
			duplicate: false,
			item: {
				id: queueItem.id,
				url: queueItem.url,
				status: queueItem.status,
				enqueuedAt: queueItem.enqueuedAt
			}
		});
	} catch (error) {
		return handleApiError(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) {
				throw new ValidationError('Limit must be a positive integer');
			}
			if (parsedLimit > 200) {
				throw new ValidationError('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) {
				throw new ValidationError('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)) {
			throw new ValidationError(
				`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 (error) {
		return handleApiError(error);
	}
};