import { logger } from '$lib/core/utils/logger';
import { error, json } from '@sveltejs/kit';
import type { RequestEvent } from '@sveltejs/kit';
import { verifyAuthToken } from '$lib/server/auth';

// In-memory store for streamed catalog data
// Format: { batchId: { chunks: [...], status: 'collecting'|'complete'|'error' } }
const streamCache = new Map<string, any>();
const MAX_CACHE_SIZE = 200; // max number of batches in cache
const MAX_CHUNKS_PER_BATCH = 500;

export async function POST({ request }: RequestEvent) {
	try {
		await verifyAuthToken(request);

		const data = await request.json();
		const { batch_id, msg, content, current_chunk, total_chunks } = data.payload ?? {};

		// Input validation
		if (!batch_id || typeof batch_id !== 'string') {
			throw error(400, 'Missing or invalid batch_id');
		}
		if (!msg || typeof msg !== 'string') {
			throw error(400, 'Missing or invalid msg');
		}
		if (content !== undefined && content !== null && typeof content !== 'string') {
			throw error(400, 'content must be a string');
		}

		// Enforce cache size limit — evict oldest batches when over capacity
		if (!streamCache.has(batch_id) && streamCache.size >= MAX_CACHE_SIZE) {
			const oldestKey = streamCache.keys().next().value;
			if (oldestKey !== undefined) {
				streamCache.delete(oldestKey);
				logger.warn(`[API] Evicted oldest batch "${oldestKey}" — cache full`);
			}
		}

		// Initialize or update batch
		if (!streamCache.has(batch_id)) {
			const cappedTotal = typeof total_chunks === 'number' && total_chunks > 0
				? Math.min(total_chunks, MAX_CHUNKS_PER_BATCH)
				: MAX_CHUNKS_PER_BATCH;
			streamCache.set(batch_id, {
				chunks: [],
				status: 'collecting',
				total_chunks: cappedTotal,
				createdAt: Date.now()
			});
		}

		const batch = streamCache.get(batch_id);

		// Handle different message types
		if (msg === 'start') {
			logger.info(`[API] Stream started for batch ${batch_id}`);
		} else if (msg === 'chunk') {
			if (batch.chunks.length >= MAX_CHUNKS_PER_BATCH) {
				logger.warn(`[API] Max chunks reached for batch ${batch_id}, ignoring chunk`);
				return json({ status: 'received', batch_id, warning: 'max_chunks_reached' });
			}
			batch.chunks.push(content);
			logger.info(`[API] Received chunk ${current_chunk}/${total_chunks} for batch ${batch_id}`);
		} else if (msg === 'end') {
			batch.status = 'complete';
			logger.info(`[API] Stream complete for batch ${batch_id}, total chunks: ${batch.chunks.length}`);
		} else if (msg === 'error') {
			batch.status = 'error';
			batch.error = content;
			logger.info(`[API] Stream error for batch ${batch_id}:`, content);
		}

		return json({ status: 'received', batch_id });
	} catch (error) {
		logger.error('[API] Error processing stream:', error);
		return json({ status: 'error', message: String(error) }, { status: 500 });
	}
}

export async function GET({ request, url }: RequestEvent) {
	// Verify authentication
	await verifyAuthToken(request);

	const batchId = url.searchParams.get('batch_id');

	// Clean up old cache entries (older than 5 minutes)
	const now = Date.now();
	for (const [key, value] of streamCache.entries()) {
		if (now - value.createdAt > 5 * 60 * 1000) {
			streamCache.delete(key);
		}
	}

	// If batch_id specified, return that specific batch
	if (batchId) {
		const batch = streamCache.get(batchId);

		if (!batch) {
			return json({ status: 'not_found' }, { status: 404 });
		}

		return json({
			batch_id: batchId,
			status: batch.status,
			chunks: batch.chunks,
			total_chunks: batch.total_chunks,
			error: batch.error || null,
			createdAt: new Date(batch.createdAt).toISOString()
		});
	}

	// Otherwise return list of all recent batches
	const batches = Array.from(streamCache.entries()).map(([batchId, batch]) => ({
		batch_id: batchId,
		status: batch.status,
		chunks_count: batch.chunks.length,
		total_chunks: batch.total_chunks,
		error: batch.error || null,
		createdAt: new Date(batch.createdAt).toISOString()
	}));

	return json({
		status: 'success',
		batches: batches.sort(
			(a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime()
		)
	});
}