import {
  clampSessionTimerDurationMs,
  clampSessionTimerLayout,
  createInitialSessionTimerState,
  getSessionTimerRemainingMs,
  type SessionTimerEvent,
  type SessionTimerState,
} from '../../shared/types/sessionTimer';

export class TimerSessionStore {
  private state: SessionTimerState = createInitialSessionTimerState();

  getState(): SessionTimerState {
    return this.state;
  }

  clear(): SessionTimerState {
    this.state = createInitialSessionTimerState();
    return this.state;
  }

  dispatch(event: SessionTimerEvent, now = Date.now()): SessionTimerState {
    switch (event.kind) {
      case 'setDuration': {
        const durationMs = clampSessionTimerDurationMs(event.durationMs);
        if (this.state.running) {
          const remaining = getSessionTimerRemainingMs(this.state, now);
          this.state = {
            ...this.state,
            revision: this.state.revision + 1,
            durationMs,
            remainingMs: Math.min(remaining, durationMs),
            endsAt: now + Math.min(remaining, durationMs),
          };
        } else {
          this.state = {
            ...this.state,
            revision: this.state.revision + 1,
            durationMs,
            remainingMs: durationMs,
            endsAt: null,
            running: false,
          };
        }
        return this.state;
      }
      case 'start': {
        const remaining = getSessionTimerRemainingMs(this.state, now);
        if (remaining <= 0) {
          // Restart from full duration if already at zero.
          const durationMs = this.state.durationMs;
          this.state = {
            ...this.state,
            revision: this.state.revision + 1,
            remainingMs: durationMs,
            running: true,
            endsAt: now + durationMs,
          };
          return this.state;
        }
        this.state = {
          ...this.state,
          revision: this.state.revision + 1,
          running: true,
          endsAt: now + remaining,
          remainingMs: remaining,
        };
        return this.state;
      }
      case 'pause': {
        if (!this.state.running) return this.state;
        const remaining = getSessionTimerRemainingMs(this.state, now);
        this.state = {
          ...this.state,
          revision: this.state.revision + 1,
          running: false,
          endsAt: null,
          remainingMs: remaining,
        };
        return this.state;
      }
      case 'reset': {
        this.state = {
          ...this.state,
          revision: this.state.revision + 1,
          running: false,
          endsAt: null,
          remainingMs: this.state.durationMs,
        };
        return this.state;
      }
      case 'setVisibleToPlayers': {
        if (this.state.visibleToPlayers === event.visible) return this.state;
        this.state = {
          ...this.state,
          revision: this.state.revision + 1,
          visibleToPlayers: event.visible,
        };
        return this.state;
      }
      case 'layout.set': {
        const layout = clampSessionTimerLayout(event.layout);
        this.state = {
          ...this.state,
          revision: this.state.revision + 1,
          layout,
        };
        return this.state;
      }
      default: {
        const _exhaustive: never = event;
        return _exhaustive;
      }
    }
  }

  /** Когда running и время вышло — зафиксировать 00:00 (вызывается из UI/main по желанию). */
  settleIfExpired(now = Date.now()): SessionTimerState {
    if (!this.state.running) return this.state;
    const remaining = getSessionTimerRemainingMs(this.state, now);
    if (remaining > 0) return this.state;
    this.state = {
      ...this.state,
      revision: this.state.revision + 1,
      running: false,
      endsAt: null,
      remainingMs: 0,
    };
    return this.state;
  }

  /** Слепок: таймер на паузе, без абсолютного момента конца. */
  loadPaused(next: Pick<SessionTimerState, 'durationMs' | 'remainingMs' | 'visibleToPlayers' | 'layout'>): SessionTimerState {
    const durationMs = clampSessionTimerDurationMs(next.durationMs);
    const remainingMs = Math.max(0, Math.min(durationMs, Math.round(next.remainingMs)));
    this.state = {
      revision: this.state.revision + 1,
      durationMs,
      remainingMs,
      running: false,
      endsAt: null,
      visibleToPlayers: Boolean(next.visibleToPlayers),
      layout: clampSessionTimerLayout(next.layout),
    };
    return this.state;
  }
}