export type SubscriptionTier = 'free' | 'pro' | 'proplus';
export type SubscriptionStatus = 'none' | 'active' | 'expired' | 'cancelled';
export type NodeStatus = 'done' | 'current' | 'locked' | 'chest';
export type LeaderboardScope = 'region' | 'topic';
export type RewardSource = 'ad' | 'check_in' | 'subscription' | 'admin_grant' | 'debug';
export type SubscriptionPlatform = 'huawei' | 'apple' | 'google';

export interface RegionDto {
  code: string;
  name: string;
  shortName: string;
  parentCode: string | null;
  level: number;
  sortOrder: number;
  enabled: boolean;
}

export interface RegionsConfigDto {
  version: string;
  countryCode: 'CN';
  hierarchy: 'flat';
  updatedAt: string;
  regions: readonly RegionDto[];
}

export interface UserRegionDto {
  code: string;
  name: string;
  shortName: string;
  selectedAt: string | null;
  nextChangeAllowedAt: string | null;
}

export interface UserBriefDto {
  id: string;
  nickname: string;
  avatarUrl: string | null;
  tier: SubscriptionTier;
  level: number;
  region: UserRegionDto | null;
}

export interface SubscriptionDto {
  status: SubscriptionStatus;
  tier: SubscriptionTier;
  expiresAt: string | null;
  autoRenew?: boolean;
}

export interface ProgressSummaryDto {
  hearts: number;
  maxHearts: number;
  nextHeartRestoreAt: string | null;
  dailyAttemptsLeft: number;
  dailyAttemptsMax: number;
  nextAttemptResetAt: string | null;
  highRewardSessionsLeft: number;
  highRewardSessionsMax: number;
  xp: number;
  level: number;
  xpToNextLevel: number;
  streakDays: number;
  checkInDays: number;
  streakProtectedUntil: string | null;
  activeTrackId: string | null;
  isSubscribed: boolean;
}

export interface ThemeNodeDto {
  id: string;
  title: string;
  status: NodeStatus;
  reward: string;
  questionCount: number;
}

export interface ThemeTrackDto {
  id: string;
  name: string;
  icon: string;
  progress: number;
  nodes: ThemeNodeDto[];
}

export interface ShopBenefitDto {
  id: string;
  type: 'hearts' | 'attempts' | 'streak' | 'subscription';
  title: string;
  description: string;
  enabled: boolean;
  requiresAd: boolean;
}

export type ShopProductType = 'item' | 'cosmetic';
export type ShopProductId =
  | 'hint-feather'
  | 'heart-supply'
  | 'double-xp-potion'
  | 'streak-shield'
  | 'mascot-outfit-starter';

export interface ShopProductDto {
  id: ShopProductId;
  type: ShopProductType;
  itemId: string;
  title: string;
  description: string;
  priceCoins: number;
  quantity: number;
  enabled: boolean;
}

export interface ShopCatalogDto {
  benefits: readonly ShopBenefitDto[];
  products: readonly ShopProductDto[];
}

export interface ShopPurchaseResultDto {
  product: ShopProductDto;
  coinsSpent: number;
  coinsBalance: number;
  item: {
    itemId: string;
    quantity: number;
    activeUntil: string | null;
    metadata: Record<string, unknown> | null;
  };
  rewards: ReadonlyArray<{
    type: string;
    source?: string;
    amount?: number;
    itemId?: string;
    quantity?: number;
    title?: string;
  }>;
}

export interface WalletDto {
  coinsBalance: number;
}

export interface InventoryItemDto {
  itemId: string;
  quantity: number;
  activeUntil: string | null;
  metadata: Record<string, unknown> | null;
}

export interface InventoryDto {
  items: readonly InventoryItemDto[];
}

export type UsableInventoryItemId = 'streak_shield' | 'double_xp_potion' | 'heart_supply' | 'hint_feather';

export interface UseInventoryItemResultDto {
  itemId: UsableInventoryItemId;
  quantityRemaining: number;
  effect: {
    type: 'restore_hearts' | 'double_xp' | 'hint' | 'streak_protection';
    activeUntil?: string | null;
    hearts?: number;
    excludedOptions?: readonly string[];
    streakProtectedUntil?: string | null;
  };
}

export interface BootstrapDto {
  user: UserBriefDto;
  progress: ProgressSummaryDto;
  tracks: ThemeTrackDto[];
  shopBenefits: readonly ShopBenefitDto[];
  shop: ShopCatalogDto;
  wallet: WalletDto;
  inventory: InventoryDto;
  subscription: SubscriptionDto;
}

export interface ChallengeQuestionDto {
  challengeId: string;
  trackId: string;
  nodeId: string;
  question: {
    id: string;
    prompt: string;
    options: ReadonlyArray<{ id: string; text: string }>;
  };
}

export interface ChallengeSessionDto {
  challengeId: string;
  trackId: string;
  nodeId: string;
  totalQuestions: number;
  highRewardEligible: boolean;
  questions: readonly ChallengeQuestionDto[];
  /** 已提交过答案的题目 ID（用于 session 续答场景，客户端据此跳到下一道未答题）。 */
  answeredQuestionIds: readonly string[];
}

/** 知识卡查看事件响应：返回本次发放的 XP 奖励和最新进度。 */
export interface KnowledgeCardViewDto {
  cardId: string;
  rewards: ReadonlyArray<{
    type: string;
    source?: string;
    amount?: number;
    title?: string;
  }>;
  progress: ProgressSummaryDto;
}

export interface AnswerRequestDto {
  challengeId: string;
  questionId: string;
  selectedOptionId: string;
  timeMs: number;
  submitRequestId?: string;
}

export interface AnswerResultDto {
  answerState: 'correct' | 'wrong';
  correctOptionId: string;
  xpDelta: number;
  progress: {
    hearts: number;
    dailyAttemptsLeft: number;
    highRewardSessionsLeft: number;
    highRewardSessionsMax: number;
    xp: number;
    streakDays: number;
  };
  knowledgeCard: {
    id: string;
    title: string;
    summary: string;
    fact: string;
  };
  rewards: ReadonlyArray<{
    type: string;
    source?: string;
    amount?: number;
    itemId?: string;
    quantity?: number;
    title?: string;
  }>;
}

export interface LeaderboardEntryDto {
  rank: number;
  userId: string;
  displayName: string;
  avatarUrl: string | null;
  xp: number;
  badge: string;
  isMe: boolean;
}

/** 周榜元信息，附带在排行榜响应中。 */
export interface LeaderboardMetaDto {
  weekStart: string;
  weekEnd: string;
  nextRefreshAt: string;
  groupId: string | null;
  requiresRegionSelection?: boolean;
  selectedRegion?: UserRegionDto | null;
  viewRegion?: RegionDto | null;
  /** 当前用户组内排名（仅 /leaderboards/me 返回）。 */
  rank?: number;
  /** 当前周奖励预览：各组前 3 名的金币奖励。 */
  rewardPreview: Array<{ rank: number; coins: number }>;
}