psn-js/src/decoder.ts

import { Decoders } from './index.js';
import {
	type DataPacketChunk,
	type InfoPacketChunk,
	type Tracker,
	TrackerFromData,
	TrackerFromInfo,
} from './models/index.js';

export class Decoder {
	infoPacketFrames: { [key: number]: InfoPacketChunk[] } = {};

	dataPacketFrames: { [key: number]: DataPacketChunk[] } = {};

	trackers: { [key: string]: Tracker } = {};

	systemName: string = '';

	updateInfo(framePackets: InfoPacketChunk[]) {
		framePackets.forEach((packet) => {
			if (packet.data.systemName?.data) {
				this.systemName = packet.data.systemName?.data.systemName;
			}

			if (packet.data.trackerList?.data) {
				packet.data.trackerList.data.trackers.forEach((infoTrackerChunk) => {
					if (!this.trackers[infoTrackerChunk.chunk.header.id]) {
						const tracker = TrackerFromInfo(infoTrackerChunk);
						if (tracker) {
							this.trackers[infoTrackerChunk.chunk.header.id] = tracker;
						}
					}
					const tracker = this.trackers[infoTrackerChunk.chunk.header.id];
					tracker.updateInfo(infoTrackerChunk);
				});
			}
		});
	}

	updateData(framePackets: DataPacketChunk[]) {
		framePackets.forEach((packet) => {
			if (packet.data.trackerList) {
				packet.data.trackerList?.data.trackers.forEach((dataTrackerChunk) => {
					if (!this.trackers[dataTrackerChunk.chunk.header.id]) {
						const tracker = TrackerFromData(dataTrackerChunk);
						if (tracker) {
							this.trackers[dataTrackerChunk.chunk.header.id] = tracker;
						}
					}
					const tracker = this.trackers[dataTrackerChunk.chunk.header.id];
					tracker.updateData(dataTrackerChunk);
				});
			}
		});
	}

	// TODO(jwetzell): add invalid frame id decoding. Scenario where a frame id is reused before one is complete
	decode(packetBuf: Uint8Array) {
		const packet = Decoders.Chunk(packetBuf);
		if (packet === undefined) {
			return packet;
		}

		if (packet.header.id === 0x6756) {
			const infoPacket = Decoders.InfoPacketChunk(packetBuf);
			if (infoPacket?.chunk.header.hasSubchunks) {
				const currentInfoPacketHeader = infoPacket.data.packetHeader;
				if (!currentInfoPacketHeader) {
					// NOTE(jwetzell): not sure that info packets without a header subchunk are valid?
					throw new Error('malformed packet');
				}

				const systemSubChunk = infoPacket.data.systemName;
				if (!systemSubChunk) {
					// NOTE(jwetzell): not sure that info packets without a system subchunk are valid?
					throw new Error('malformed packet');
				}
				if (currentInfoPacketHeader.data.frameId) {
					if (
						this.infoPacketFrames[currentInfoPacketHeader.data.frameId] ===
						undefined
					) {
						this.infoPacketFrames[currentInfoPacketHeader.data.frameId] = [];
					}
					this.infoPacketFrames[currentInfoPacketHeader.data.frameId].push(
						infoPacket
					);

					if (
						this.infoPacketFrames[currentInfoPacketHeader.data.frameId]
							.length === currentInfoPacketHeader.data.framePacketCount
					) {
						this.updateInfo(
							this.infoPacketFrames[currentInfoPacketHeader.data.frameId]
						);
						delete this.infoPacketFrames[currentInfoPacketHeader.data.frameId];
					}
				}
			}
		} else if (packet.header.id === 0x6755) {
			const dataPacket = Decoders.DataPacketChunk(packetBuf);
			if (dataPacket.chunk.header.hasSubchunks) {
				const currentDataPacketHeader = dataPacket.data.packetHeader;
				if (!currentDataPacketHeader) {
					// NOTE(jwetzell): not sure that info packets without a header subchunk are valid?
					throw new Error('malformed packet');
				}

				if (currentDataPacketHeader.data.frameId) {
					if (
						this.dataPacketFrames[currentDataPacketHeader.data.frameId] ===
						undefined
					) {
						this.dataPacketFrames[currentDataPacketHeader.data.frameId] = [];
					}
					this.dataPacketFrames[currentDataPacketHeader.data.frameId].push(
						dataPacket
					);
					if (
						this.dataPacketFrames[currentDataPacketHeader.data.frameId]
							.length === currentDataPacketHeader.data.framePacketCount
					) {
						this.updateData(
							this.dataPacketFrames[currentDataPacketHeader.data.frameId]
						);
						delete this.dataPacketFrames[currentDataPacketHeader.data.frameId];
					}
				}
			}
		}
	}
}