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import { encodePacket, encodePacketToBinary } from "./encodePacket.js";
import { decodePacket } from "./decodePacket.js";
import { ERROR_PACKET, } from "./commons.js";
const SEPARATOR = String.fromCharCode(30); // see https://en.wikipedia.org/wiki/Delimiter#ASCII_delimited_text
const encodePayload = (packets, callback) => {
// some packets may be added to the array while encoding, so the initial length must be saved
const length = packets.length;
const encodedPackets = new Array(length);
let count = 0;
packets.forEach((packet, i) => {
// force base64 encoding for binary packets
encodePacket(packet, false, (encodedPacket) => {
encodedPackets[i] = encodedPacket;
if (++count === length) {
callback(encodedPackets.join(SEPARATOR));
}
});
});
};
const decodePayload = (encodedPayload, binaryType) => {
const encodedPackets = encodedPayload.split(SEPARATOR);
const packets = [];
for (let i = 0; i < encodedPackets.length; i++) {
const decodedPacket = decodePacket(encodedPackets[i], binaryType);
packets.push(decodedPacket);
if (decodedPacket.type === "error") {
break;
}
}
return packets;
};
export function createPacketEncoderStream() {
// @ts-expect-error
return new TransformStream({
transform(packet, controller) {
encodePacketToBinary(packet, (encodedPacket) => {
const payloadLength = encodedPacket.length;
let header;
// inspired by the WebSocket format: https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers#decoding_payload_length
if (payloadLength < 126) {
header = new Uint8Array(1);
new DataView(header.buffer).setUint8(0, payloadLength);
}
else if (payloadLength < 65536) {
header = new Uint8Array(3);
const view = new DataView(header.buffer);
view.setUint8(0, 126);
view.setUint16(1, payloadLength);
}
else {
header = new Uint8Array(9);
const view = new DataView(header.buffer);
view.setUint8(0, 127);
view.setBigUint64(1, BigInt(payloadLength));
}
// first bit indicates whether the payload is plain text (0) or binary (1)
if (packet.data && typeof packet.data !== "string") {
header[0] |= 0x80;
}
controller.enqueue(header);
controller.enqueue(encodedPacket);
});
},
});
}
let TEXT_DECODER;
function totalLength(chunks) {
return chunks.reduce((acc, chunk) => acc + chunk.length, 0);
}
function concatChunks(chunks, size) {
if (chunks[0].length === size) {
return chunks.shift();
}
const buffer = new Uint8Array(size);
let j = 0;
for (let i = 0; i < size; i++) {
buffer[i] = chunks[0][j++];
if (j === chunks[0].length) {
chunks.shift();
j = 0;
}
}
if (chunks.length && j < chunks[0].length) {
chunks[0] = chunks[0].slice(j);
}
return buffer;
}
export function createPacketDecoderStream(maxPayload, binaryType) {
if (!TEXT_DECODER) {
TEXT_DECODER = new TextDecoder();
}
const chunks = [];
let state = 0 /* READ_HEADER */;
let expectedLength = -1;
let isBinary = false;
// @ts-expect-error
return new TransformStream({
transform(chunk, controller) {
chunks.push(chunk);
while (true) {
if (state === 0 /* READ_HEADER */) {
if (totalLength(chunks) < 1) {
break;
}
const header = concatChunks(chunks, 1);
isBinary = (header[0] & 0x80) === 0x80;
expectedLength = header[0] & 0x7f;
if (expectedLength < 126) {
state = 3 /* READ_PAYLOAD */;
}
else if (expectedLength === 126) {
state = 1 /* READ_EXTENDED_LENGTH_16 */;
}
else {
state = 2 /* READ_EXTENDED_LENGTH_64 */;
}
}
else if (state === 1 /* READ_EXTENDED_LENGTH_16 */) {
if (totalLength(chunks) < 2) {
break;
}
const headerArray = concatChunks(chunks, 2);
expectedLength = new DataView(headerArray.buffer, headerArray.byteOffset, headerArray.length).getUint16(0);
state = 3 /* READ_PAYLOAD */;
}
else if (state === 2 /* READ_EXTENDED_LENGTH_64 */) {
if (totalLength(chunks) < 8) {
break;
}
const headerArray = concatChunks(chunks, 8);
const view = new DataView(headerArray.buffer, headerArray.byteOffset, headerArray.length);
const n = view.getUint32(0);
if (n > Math.pow(2, 53 - 32) - 1) {
// the maximum safe integer in JavaScript is 2^53 - 1
controller.enqueue(ERROR_PACKET);
break;
}
expectedLength = n * Math.pow(2, 32) + view.getUint32(4);
state = 3 /* READ_PAYLOAD */;
}
else {
if (totalLength(chunks) < expectedLength) {
break;
}
const data = concatChunks(chunks, expectedLength);
controller.enqueue(decodePacket(isBinary ? data : TEXT_DECODER.decode(data), binaryType));
state = 0 /* READ_HEADER */;
}
if (expectedLength === 0 || expectedLength > maxPayload) {
controller.enqueue(ERROR_PACKET);
break;
}
}
},
});
}
export const protocol = 4;
export { encodePacket, encodePayload, decodePacket, decodePayload, };
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