feat(sync): add canonical room media state

2026-09-04 15:05:20 +00:00 · 2026-08-20 17:27:08 +02:00
parent 1e41d98c2f
commit c064953cca
16 changed files with 1191 additions and 15 deletions
@@ -0,0 +1,87 @@
+import { EVENTS, MAX_MEDIA_TIME } from '../shared/constants.js';
+
+function clampMediaTime(value) {
+    if (typeof value !== 'number' || !Number.isFinite(value)) return null;
+    return Math.max(0, Math.min(MAX_MEDIA_TIME, value));
+}
+
+export function effectiveMediaPosition(mediaState, now = Date.now()) {
+    if (!mediaState) return null;
+    const currentTime = clampMediaTime(mediaState.currentTime);
+    if (currentTime === null) return null;
+    if (mediaState.playbackState !== 'playing') return currentTime;
+    const updatedAt = typeof mediaState.updatedAt === 'number' && Number.isFinite(mediaState.updatedAt)
+        ? mediaState.updatedAt
+        : now;
+    return clampMediaTime(currentTime + Math.max(0, now - updatedAt) / 1000);
+}
+
+export function snapshotMediaState(mediaState, now = Date.now()) {
+    if (!mediaState) return null;
+    const currentTime = effectiveMediaPosition(mediaState, now);
+    if (currentTime === null
+        || !Number.isSafeInteger(mediaState.revision)
+        || mediaState.revision < 1
+        || (mediaState.playbackState !== 'playing' && mediaState.playbackState !== 'paused')) {
+        return null;
+    }
+    return {
+        revision: mediaState.revision,
+        playbackState: mediaState.playbackState,
+        currentTime,
+        updatedBy: mediaState.updatedBy
+    };
+}
+
+function commitMediaState(room, playbackState, currentTime, updatedBy, now) {
+    const normalizedTime = clampMediaTime(currentTime);
+    if (normalizedTime === null
+        || (playbackState !== 'playing' && playbackState !== 'paused')
+        || typeof updatedBy !== 'string'
+        || !updatedBy) {
+        return false;
+    }
+    room.mediaState = {
+        revision: (room.mediaState?.revision || 0) + 1,
+        playbackState,
+        currentTime: normalizedTime,
+        updatedAt: now,
+        updatedBy
+    };
+    return true;
+}
+
+export function updateMediaStateFromControl(room, eventName, payload, senderPeerId, {
+    now = Date.now(),
+    senderPlaybackState = null
+} = {}) {
+    if (!room || !payload || typeof payload !== 'object') return false;
+
+    if (eventName === EVENTS.PLAY || eventName === EVENTS.PAUSE) {
+        const eventPosition = clampMediaTime(payload.currentTime);
+        const currentTime = eventPosition ?? effectiveMediaPosition(room.mediaState, now);
+        if (currentTime === null) return false;
+        return commitMediaState(
+            room,
+            eventName === EVENTS.PLAY ? 'playing' : 'paused',
+            currentTime,
+            senderPeerId,
+            now
+        );
+    }
+
+    if (eventName === EVENTS.SEEK) {
+        const targetTime = clampMediaTime(payload.targetTime) ?? clampMediaTime(payload.currentTime);
+        const playbackState = payload.playbackState === 'playing' || payload.playbackState === 'paused'
+            ? payload.playbackState
+            : (room.mediaState?.playbackState || senderPlaybackState);
+        if (targetTime === null) return false;
+        return commitMediaState(room, playbackState, targetTime, senderPeerId, now);
+    }
+
+    return false;
+}
+
+export function commitForceSyncMediaState(room, targetTime, senderPeerId, now = Date.now()) {
+    return commitMediaState(room, 'playing', targetTime, senderPeerId, now);
+}