wehub-resource-sync
74 lines
2.4 KiB
TypeScript
74 lines
2.4 KiB
TypeScript
/**
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* Playback cursor — resolve the current action from a `(sceneIndex, actionIndex)`
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* cursor over a scene list.
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*
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* Moved verbatim from the app's `lib/playback/engine-cursor.ts` so the app
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* runtime and the video exporter walk scenes identically. Pure — types come
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* from `@openmaic/dsl`, no runtime dependencies.
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*/
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import type { Action, SceneCore } from '@openmaic/dsl';
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/**
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* Synthetic dwell beat yielded for a scene that carries no actions. It is an
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* empty-text speech, so the engine routes it through the same reading-timer
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* dwell a blank speech clip already uses — the slide shows for a short beat
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* instead of being skipped (which would make it vanish from playback). A scene
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* with `actions: []` thus behaves exactly like one carrying a single blank
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* speech clip.
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*/
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export const EMPTY_SCENE_DWELL: Action = {
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id: '__empty_scene_dwell__',
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type: 'speech',
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text: '',
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} as Action;
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export interface CursorResult {
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action: Action;
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sceneId: string;
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/** The (possibly advanced) scene cursor the engine should adopt. */
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sceneIndex: number;
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/** The (possibly advanced) action cursor the engine should adopt. */
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actionIndex: number;
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}
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/**
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* Resolve the current playback action from a `(sceneIndex, actionIndex)` cursor,
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* advancing past scenes whose actions are exhausted. A scene with no actions
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* yields one {@link EMPTY_SCENE_DWELL} beat (when its action cursor is still 0)
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* rather than being skipped. Returns `null` once every scene is consumed.
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*
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* Pure: it does not mutate inputs; the caller adopts the returned cursor. Typed
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* against {@link SceneCore} (only `id` + `actions` are read), so an app-widened
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* `Scene` (extra content kinds) is accepted without casting.
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*/
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export function resolvePlaybackCursor(
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scenes: SceneCore[],
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sceneIndex: number,
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actionIndex: number,
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): CursorResult | null {
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let si = sceneIndex;
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let ai = actionIndex;
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while (si < scenes.length) {
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const actions = scenes[si].actions ?? [];
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if (actions.length === 0) {
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if (ai === 0) {
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return {
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action: EMPTY_SCENE_DWELL,
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sceneId: scenes[si].id,
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sceneIndex: si,
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actionIndex: ai,
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};
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}
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si++;
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ai = 0;
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continue;
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}
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if (ai < actions.length) {
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return { action: actions[ai], sceneId: scenes[si].id, sceneIndex: si, actionIndex: ai };
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}
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si++;
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ai = 0;
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}
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return null;
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}
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