File size: 2,682 Bytes
65d68f5 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 | // ─── Video Engine V1 — on-device progress (resume) ───────────────────────────
// Saves playback position on the student's device so they can resume later.
// Bounded to the 50 most-recent videos (LRU) to stay light.
const KEY_PREFIX = "docdoe_video_progress_";
const INDEX_KEY = "docdoe_video_progress_index";
const MAX_ENTRIES = 50;
export type SavedVideoProgress = {
video_id: string;
current_segment_index: number;
current_segment_elapsed: number; // seconds into the current segment
completed_segment_ids: string[];
updated_at: string;
};
function canUseStorage(): boolean {
return typeof window !== "undefined" && !!window.localStorage;
}
function readIndex(): string[] {
if (!canUseStorage()) return [];
try {
const raw = window.localStorage.getItem(INDEX_KEY);
const parsed = raw ? (JSON.parse(raw) as unknown) : [];
return Array.isArray(parsed) ? parsed.filter((v): v is string => typeof v === "string") : [];
} catch {
return [];
}
}
function writeIndex(ids: string[]): void {
if (!canUseStorage()) return;
try {
window.localStorage.setItem(INDEX_KEY, JSON.stringify(ids));
} catch {
/* storage full / blocked — ignore */
}
}
function touch(videoId: string): void {
let index = readIndex().filter((id) => id !== videoId);
index.unshift(videoId);
// Evict least-recently-used beyond the cap.
if (index.length > MAX_ENTRIES) {
const evicted = index.slice(MAX_ENTRIES);
index = index.slice(0, MAX_ENTRIES);
for (const id of evicted) {
try {
window.localStorage.removeItem(`${KEY_PREFIX}${id}`);
} catch {
/* ignore */
}
}
}
writeIndex(index);
}
export function loadVideoProgress(videoId: string): SavedVideoProgress | null {
if (!canUseStorage()) return null;
try {
const raw = window.localStorage.getItem(`${KEY_PREFIX}${videoId}`);
if (!raw) return null;
return JSON.parse(raw) as SavedVideoProgress;
} catch {
return null;
}
}
export function saveVideoProgress(progress: SavedVideoProgress): void {
if (!canUseStorage()) return;
try {
window.localStorage.setItem(
`${KEY_PREFIX}${progress.video_id}`,
JSON.stringify({ ...progress, updated_at: new Date().toISOString() }),
);
touch(progress.video_id);
} catch {
/* storage full / blocked — degrade silently */
}
}
export function clearVideoProgress(videoId: string): void {
if (!canUseStorage()) return;
try {
window.localStorage.removeItem(`${KEY_PREFIX}${videoId}`);
writeIndex(readIndex().filter((id) => id !== videoId));
} catch {
/* ignore */
}
}
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