1 files changed, 87 insertions, 0 deletions
diff --git a/apps/web/src/services/waveform-cache/service.ts b/apps/web/src/services/waveform-cache/service.ts
new file mode 100644
index 00000000..3b7d34f3
--- /dev/null
+++ b/apps/web/src/services/waveform-cache/service.ts
@@ -0,0 +1,87 @@
+"use client";
+
+import { createAudioContext } from "@/lib/media/audio";
+import {
+	buildSourceWaveformSummary,
+	type SourceWaveformSummary,
+} from "@/lib/media/waveform-summary";
+
+interface GetSourceWaveformSummaryArgs {
+	sourceKey: string;
+	audioBuffer?: AudioBuffer;
+	sourceFile?: File;
+	audioUrl?: string;
+}
+
+export class WaveformCache {
+	private summaries = new Map<string, Promise<SourceWaveformSummary>>();
+
+	getSourceSummary({
+		sourceKey,
+		audioBuffer,
+		sourceFile,
+		audioUrl,
+	}: GetSourceWaveformSummaryArgs): Promise<SourceWaveformSummary> {
+		const existing = this.summaries.get(sourceKey);
+		if (existing) {
+			return existing;
+		}
+
+		const promise = this.buildSummary({
+			sourceKey,
+			audioBuffer,
+			sourceFile,
+			audioUrl,
+		}).catch((error) => {
+			this.summaries.delete(sourceKey);
+			throw error;
+		});
+
+		this.summaries.set(sourceKey, promise);
+		return promise;
+	}
+
+	clearSource({ sourceKey }: { sourceKey: string }): void {
+		this.summaries.delete(sourceKey);
+	}
+
+	clearAll(): void {
+		this.summaries.clear();
+	}
+
+	private async buildSummary({
+		sourceKey,
+		audioBuffer,
+		sourceFile,
+		audioUrl,
+	}: GetSourceWaveformSummaryArgs): Promise<SourceWaveformSummary> {
+		if (audioBuffer) {
+			return buildSourceWaveformSummary({ sourceKey, buffer: audioBuffer });
+		}
+
+		let arrayBuffer: ArrayBuffer | null = null;
+		if (sourceFile) {
+			arrayBuffer = await sourceFile.arrayBuffer();
+		} else if (audioUrl) {
+			const response = await fetch(audioUrl);
+			if (!response.ok) {
+				throw new Error(`Failed to fetch waveform source: ${response.status}`);
+			}
+			arrayBuffer = await response.arrayBuffer();
+		}
+
+		if (!arrayBuffer) {
+			throw new Error(`No waveform source available for ${sourceKey}`);
+		}
+
+		const audioContext = createAudioContext();
+		try {
+			const buffer = await audioContext.decodeAudioData(arrayBuffer.slice(0));
+			return buildSourceWaveformSummary({ sourceKey, buffer });
+		} finally {
+			void audioContext.close();
+		}
+	}
+}
+
+export const waveformCache = new WaveformCache();