export type StoryPlaybackPhase = 'timer' | 'narration' | 'media' | null;
export type StoryPlaybackState = {
    currentTime: number;
    duration: number;
    playState: 'playing' | 'paused' | 'idle';
    isBuffering: boolean;
    phase: StoryPlaybackPhase;
};
type PlaybackClockDeps = {
    now?: () => number;
    setIntervalFn?: typeof setInterval;
    clearIntervalFn?: typeof clearInterval;
    tickMs?: number;
};
type TimerPhaseConfig = {
    kind: 'timer';
    offsetSec?: number;
    durationSec: number;
    onComplete?: () => void;
};
type ExternalPhaseConfig = {
    kind: 'narration' | 'media';
    offsetSec?: number;
    durationSec: number;
    sourceStartSec: number;
    getCurrentTime: () => number | null | undefined;
    onComplete?: () => void;
};
type StateListener = (state: StoryPlaybackState) => void;
export declare class StoryPlaybackClock {
    state: StoryPlaybackState;
    private readonly now;
    private readonly setIntervalFn;
    private readonly clearIntervalFn;
    private readonly tickMs;
    private timerId;
    private phase;
    private phaseStartedAtMs;
    private phaseElapsedAtStartSec;
    private listeners;
    constructor(deps?: PlaybackClockDeps);
    getState(): StoryPlaybackState;
    /**
     * Returns the current presentation time recomputed from the wall clock at the
     * moment of the call, without mutating state or notifying listeners. The
     * ticking loop only updates `state.currentTime` ~20×/s; a render loop can call
     * this every animation frame to drive the camera at the display refresh rate.
     */
    getLiveCurrentTime(): number;
    subscribe(listener: StateListener): () => void;
    destroy(): void;
    loadChapter(durationSec: number): void;
    setBuffering(isBuffering: boolean): void;
    startTimerPhase(config: Omit<TimerPhaseConfig, 'kind'>): void;
    startNarrationPhase(config: Omit<ExternalPhaseConfig, 'kind'>): void;
    startMediaPhase(config: Omit<ExternalPhaseConfig, 'kind'>): void;
    play(): void;
    pause(): void;
    stop(): void;
    private setPhase;
    private startTickLoop;
    private stopTickLoop;
    private tick;
    private computePhaseElapsedSec;
    private applyState;
}
export declare const createStoryPlaybackClock: (deps?: PlaybackClockDeps) => StoryPlaybackClock;
export {};