/// <reference lib="webworker" />
import { logger } from '$lib/core/utils/logger';
let chunks: Uint8Array[] = [];
let totalBytes = 0;
let expectedLength = -1;

self.onmessage = async (e) => {
	if (e.data.type === 'CHUNK') {
		const chunk = e.data.payload;
		chunks.push(chunk);
		totalBytes += chunk.length;

		// Loop to process complete messages
		while (true) {
			// 1. Try to get length header (need 4 bytes)
			if (expectedLength === -1 && totalBytes >= 4) {
				// Need a flat buffer just to read the header
				const headerBuf = concatChunks(chunks, 4);
				expectedLength = new DataView(headerBuf.buffer).getInt32(0, false);

				// Remove header bytes from our chunks array
				removeBytes(4);
			}

			// 2. Try to get payload
			if (expectedLength !== -1 && totalBytes >= expectedLength) {
				const payload = concatChunks(chunks, expectedLength);
				removeBytes(expectedLength);

				self.postMessage({ type: 'DATA', payload }, [payload.buffer]);

				expectedLength = -1; // Reset for next message
			} else {
				break; // Wait for more data
			}
		}
	}
};

// Helper: Concatenate only what we need
function concatChunks(chunks: Uint8Array[], length: number): Uint8Array {
	const result = new Uint8Array(length);
	let offset = 0;
	for (let i = 0; i < chunks.length && offset < length; i++) {
		const chunk = chunks[i];
		const toCopy = Math.min(chunk.length, length - offset);
		result.set(chunk.slice(0, toCopy), offset);
		// If we only used part of the chunk, we keep the rest in the array
		if (toCopy < chunk.length) {
			chunks[i] = chunk.slice(toCopy);
		} else {
			chunks.shift();
			i--;
		}
		offset += toCopy;
	}
	return result;
}

// Helper: Update total count
function removeBytes(n: number) {
	totalBytes -= n;
}