export type DevPlanTaskStatus = 'TODO' | 'IN_PROGRESS' | 'DEVELOPED' | 'RELEASED';
export type DevPlanVersionStatus = 'PENDING' | 'IN_PROGRESS' | 'TESTING' | 'RELEASED';

export function computeDurationMinutes(
  devStartedAt: Date | null | undefined,
  devCompletedAt: Date | null | undefined,
): number | null {
  if (!devStartedAt || !devCompletedAt) return null;
  const ms = devCompletedAt.getTime() - devStartedAt.getTime();
  if (ms < 0) return null;
  return Math.round(ms / 60000);
}

export function versionStatusTimestamps(
  prev: DevPlanVersionStatus,
  next: DevPlanVersionStatus,
  current: {
    devStartedAt?: Date | null;
    devCompletedAt?: Date | null;
    releasedAt?: Date | null;
  },
): {
  devStartedAt?: Date | null;
  devCompletedAt?: Date | null;
  releasedAt?: Date | null;
  durationMinutes?: number | null;
} {
  const patch: {
    devStartedAt?: Date | null;
    devCompletedAt?: Date | null;
    releasedAt?: Date | null;
    durationMinutes?: number | null;
  } = {};
  const now = new Date();

  if (next === 'IN_PROGRESS' && !current.devStartedAt) {
    patch.devStartedAt = now;
  }
  if (next === 'TESTING' && !current.devCompletedAt) {
    patch.devCompletedAt = now;
  }
  if (next === 'RELEASED' && !current.releasedAt) {
    patch.releasedAt = now;
  }

  const started = patch.devStartedAt ?? current.devStartedAt ?? null;
  const completed = patch.devCompletedAt ?? current.devCompletedAt ?? null;
  const duration = computeDurationMinutes(started, completed);
  if (duration != null) patch.durationMinutes = duration;

  void prev;
  return patch;
}

export function taskCompletedAtOnStatus(
  prev: DevPlanTaskStatus,
  next: DevPlanTaskStatus,
  currentCompletedAt?: Date | null,
): Date | null | undefined {
  if (next === 'RELEASED' && !currentCompletedAt) return new Date();
  void prev;
  return undefined;
}

const TASK_STATUS_RANK: Record<DevPlanTaskStatus, number> = {
  TODO: 0,
  IN_PROGRESS: 1,
  DEVELOPED: 2,
  RELEASED: 3,
};

/** 版本状态 → 任务状态：待开始/开发中/测试中/已发布 ↔ 待处理/进行中/已开发/已发布 */
export function taskStatusFromVersionStatus(status: DevPlanVersionStatus): DevPlanTaskStatus {
  switch (status) {
    case 'PENDING':
      return 'TODO';
    case 'IN_PROGRESS':
      return 'IN_PROGRESS';
    case 'TESTING':
      return 'DEVELOPED';
    case 'RELEASED':
      return 'RELEASED';
  }
}

/** 任务挂多个版本时取进度最高的对应状态 */
export function resolveTaskStatusFromVersions(
  versionStatuses: DevPlanVersionStatus[],
): DevPlanTaskStatus | null {
  if (!versionStatuses.length) return null;
  return versionStatuses
    .map(taskStatusFromVersionStatus)
    .reduce((highest, current) =>
      TASK_STATUS_RANK[current] > TASK_STATUS_RANK[highest] ? current : highest,
    );
}