codebase overhaul (#697)

1 files changed, 335 insertions, 0 deletions

diff --git a/apps/web/src/core/managers/audio-manager.ts b/apps/web/src/core/managers/audio-manager.ts
new file mode 100644
index 00000000..621cca18
--- /dev/null
+++ b/apps/web/src/core/managers/audio-manager.ts
@@ -0,0 +1,335 @@
+import type { EditorCore } from "@/core";
+import type { AudioClipSource } from "@/lib/media/audio";
+import { createAudioContext, collectAudioClips } from "@/lib/media/audio";
+import {
+	ALL_FORMATS,
+	AudioBufferSink,
+	BlobSource,
+	Input,
+	type WrappedAudioBuffer,
+} from "mediabunny";
+
+export class AudioManager {
+	private audioContext: AudioContext | null = null;
+	private masterGain: GainNode | null = null;
+	private playbackStartTime = 0;
+	private playbackStartContextTime = 0;
+	private scheduleTimer: number | null = null;
+	private lookaheadSeconds = 2;
+	private scheduleIntervalMs = 500;
+	private clips: AudioClipSource[] = [];
+	private sinks = new Map<string, AudioBufferSink>();
+	private inputs = new Map<string, Input>();
+	private activeClipIds = new Set<string>();
+	private clipIterators = new Map<
+		string,
+		AsyncGenerator<WrappedAudioBuffer, void, unknown>
+	>();
+	private queuedSources = new Set<AudioBufferSourceNode>();
+	private playbackSessionId = 0;
+	private lastIsPlaying = false;
+	private lastVolume = 1;
+	private unsubscribers: Array<() => void> = [];
+
+	constructor(private editor: EditorCore) {
+		this.lastVolume = this.editor.playback.getVolume();
+
+		this.unsubscribers.push(
+			this.editor.playback.subscribe(this.handlePlaybackChange),
+			this.editor.timeline.subscribe(this.handleTimelineChange),
+			this.editor.media.subscribe(this.handleTimelineChange),
+		);
+		if (typeof window !== "undefined") {
+			window.addEventListener("playback-seek", this.handleSeek);
+		}
+	}
+
+	dispose(): void {
+		this.stopPlayback();
+		for (const unsub of this.unsubscribers) {
+			unsub();
+		}
+		this.unsubscribers = [];
+		if (typeof window !== "undefined") {
+			window.removeEventListener("playback-seek", this.handleSeek);
+		}
+		this.disposeSinks();
+		if (this.audioContext) {
+			void this.audioContext.close();
+			this.audioContext = null;
+			this.masterGain = null;
+		}
+	}
+
+	private handlePlaybackChange = (): void => {
+		const isPlaying = this.editor.playback.getIsPlaying();
+		const volume = this.editor.playback.getVolume();
+
+		if (volume !== this.lastVolume) {
+			this.lastVolume = volume;
+			this.updateGain();
+		}
+
+		if (isPlaying !== this.lastIsPlaying) {
+			this.lastIsPlaying = isPlaying;
+			if (isPlaying) {
+				void this.startPlayback({
+					time: this.editor.playback.getCurrentTime(),
+				});
+			} else {
+				this.stopPlayback();
+			}
+		}
+	};
+
+	private handleSeek = (event: Event): void => {
+		const detail = (event as CustomEvent<{ time: number }>).detail;
+		if (!detail) return;
+
+		if (this.editor.playback.getIsPlaying()) {
+			void this.startPlayback({ time: detail.time });
+			return;
+		}
+
+		this.stopPlayback();
+	};
+
+	private handleTimelineChange = (): void => {
+		this.disposeSinks();
+
+		if (!this.editor.playback.getIsPlaying()) return;
+
+		void this.startPlayback({ time: this.editor.playback.getCurrentTime() });
+	};
+
+	private ensureAudioContext(): AudioContext | null {
+		if (this.audioContext) return this.audioContext;
+		if (typeof window === "undefined") return null;
+
+		this.audioContext = createAudioContext();
+		this.masterGain = this.audioContext.createGain();
+		this.masterGain.gain.value = this.lastVolume;
+		this.masterGain.connect(this.audioContext.destination);
+		return this.audioContext;
+	}
+
+	private updateGain(): void {
+		if (!this.masterGain) return;
+		this.masterGain.gain.value = this.lastVolume;
+	}
+
+	private getPlaybackTime(): number {
+		if (!this.audioContext) return this.playbackStartTime;
+		const elapsed = this.audioContext.currentTime - this.playbackStartContextTime;
+		return this.playbackStartTime + elapsed;
+	}
+
+	private async startPlayback({ time }: { time: number }): Promise<void> {
+		const audioContext = this.ensureAudioContext();
+		if (!audioContext) return;
+
+		this.stopPlayback();
+		this.playbackSessionId++;
+
+		const tracks = this.editor.timeline.getTracks();
+		const mediaAssets = this.editor.media.getAssets();
+		const duration = this.editor.timeline.getTotalDuration();
+
+		if (duration <= 0) return;
+
+		if (audioContext.state === "suspended") {
+			await audioContext.resume();
+		}
+
+		this.clips = await collectAudioClips({ tracks, mediaAssets });
+		if (!this.editor.playback.getIsPlaying()) return;
+
+		this.playbackStartTime = time;
+		this.playbackStartContextTime = audioContext.currentTime;
+
+		this.scheduleUpcomingClips();
+
+		if (typeof window !== "undefined") {
+			this.scheduleTimer = window.setInterval(() => {
+				this.scheduleUpcomingClips();
+			}, this.scheduleIntervalMs);
+		}
+	}
+
+	private scheduleUpcomingClips(): void {
+		if (!this.editor.playback.getIsPlaying()) return;
+
+		const currentTime = this.getPlaybackTime();
+		const windowEnd = currentTime + this.lookaheadSeconds;
+
+		for (const clip of this.clips) {
+			if (clip.muted) continue;
+			if (this.activeClipIds.has(clip.id)) continue;
+
+			const clipEnd = clip.startTime + clip.duration;
+			if (clipEnd <= currentTime) continue;
+			if (clip.startTime > windowEnd) continue;
+
+			this.activeClipIds.add(clip.id);
+			void this.runClipIterator({ clip, startTime: currentTime, sessionId: this.playbackSessionId });
+		}
+	}
+
+	private stopPlayback(): void {
+		if (this.scheduleTimer && typeof window !== "undefined") {
+			window.clearInterval(this.scheduleTimer);
+		}
+		this.scheduleTimer = null;
+
+		for (const iterator of this.clipIterators.values()) {
+			void iterator.return();
+		}
+		this.clipIterators.clear();
+		this.activeClipIds.clear();
+
+		for (const source of this.queuedSources) {
+			try {
+				source.stop();
+			} catch {}
+			source.disconnect();
+		}
+		this.queuedSources.clear();
+	}
+
+	private async runClipIterator({
+		clip,
+		startTime,
+		sessionId,
+	}: {
+		clip: AudioClipSource;
+		startTime: number;
+		sessionId: number;
+	}): Promise<void> {
+		const audioContext = this.ensureAudioContext();
+		if (!audioContext) return;
+
+		const sink = await this.getAudioSink({ clip });
+		if (!sink || !this.editor.playback.getIsPlaying()) return;
+		if (sessionId !== this.playbackSessionId) return;
+
+		const clipStart = clip.startTime;
+		const clipEnd = clip.startTime + clip.duration;
+
+		const iteratorStartTime = Math.max(startTime, clipStart);
+		const sourceStartTime =
+			clip.trimStart + (iteratorStartTime - clip.startTime);
+
+		const iterator = sink.buffers(sourceStartTime);
+		this.clipIterators.set(clip.id, iterator);
+
+		for await (const { buffer, timestamp } of iterator) {
+			if (!this.editor.playback.getIsPlaying()) return;
+			if (sessionId !== this.playbackSessionId) return;
+
+			const timelineTime = clip.startTime + (timestamp - clip.trimStart);
+			if (timelineTime >= clipEnd) break;
+
+			const node = audioContext.createBufferSource();
+			node.buffer = buffer;
+			node.connect(this.masterGain ?? audioContext.destination);
+
+			const startTimestamp =
+				this.playbackStartContextTime +
+				(timelineTime - this.playbackStartTime);
+
+			if (startTimestamp >= audioContext.currentTime) {
+				node.start(startTimestamp);
+			} else {
+				const offset = audioContext.currentTime - startTimestamp;
+				if (offset < buffer.duration) {
+					node.start(audioContext.currentTime, offset);
+				} else {
+					continue;
+				}
+			}
+
+			this.queuedSources.add(node);
+			node.addEventListener("ended", () => {
+				node.disconnect();
+				this.queuedSources.delete(node);
+			});
+
+			const aheadTime = timelineTime - this.getPlaybackTime();
+			if (aheadTime >= 1) {
+				await this.waitUntilCaughtUp({ timelineTime, targetAhead: 1 });
+				if (sessionId !== this.playbackSessionId) return;
+			}
+		}
+
+		this.clipIterators.delete(clip.id);
+		// don't remove from activeClipIds - prevents scheduler from restarting this clip
+		// the set is cleared on stopPlayback anyway
+	}
+
+	private waitUntilCaughtUp({
+		timelineTime,
+		targetAhead,
+	}: {
+		timelineTime: number;
+		targetAhead: number;
+	}): Promise<void> {
+		return new Promise((resolve) => {
+			const checkInterval = setInterval(() => {
+				if (!this.editor.playback.getIsPlaying()) {
+					clearInterval(checkInterval);
+					resolve();
+					return;
+				}
+
+				const playbackTime = this.getPlaybackTime();
+				if (timelineTime - playbackTime < targetAhead) {
+					clearInterval(checkInterval);
+					resolve();
+				}
+			}, 100);
+		});
+	}
+
+	private disposeSinks(): void {
+		for (const iterator of this.clipIterators.values()) {
+			void iterator.return();
+		}
+		this.clipIterators.clear();
+		this.activeClipIds.clear();
+
+		for (const input of this.inputs.values()) {
+			input.dispose();
+		}
+		this.inputs.clear();
+		this.sinks.clear();
+	}
+
+	private async getAudioSink({
+		clip,
+	}: {
+		clip: AudioClipSource;
+	}): Promise<AudioBufferSink | null> {
+		const existingSink = this.sinks.get(clip.sourceKey);
+		if (existingSink) return existingSink;
+
+		try {
+			const input = new Input({
+				source: new BlobSource(clip.file),
+				formats: ALL_FORMATS,
+			});
+			const audioTrack = await input.getPrimaryAudioTrack();
+			if (!audioTrack) {
+				input.dispose();
+				return null;
+			}
+
+			const sink = new AudioBufferSink(audioTrack);
+			this.inputs.set(clip.sourceKey, input);
+			this.sinks.set(clip.sourceKey, sink);
+			return sink;
+		} catch (error) {
+			console.warn("Failed to initialize audio sink:", error);
+			return null;
+		}
+	}
+}