import { 
  UserType, 
  CallType, 
  TranslationType, 
  BillingRule, 
  UserAccount, 
  CallRecord,
  BILLING_CONFIG 
} from '../types/billing';

export class BillingService {
  private static instance: BillingService;
  private billingRules: BillingRule[] = [];
  private userAccount: UserAccount | null = null;

  private constructor() {
    this.initializeDefaultRules();
  }

  public static getInstance(): BillingService {
    if (!BillingService.instance) {
      BillingService.instance = new BillingService();
    }
    return BillingService.instance;
  }

  // 初始化默认计费规则
  private initializeDefaultRules() {
    this.billingRules = [
      // 普通用户规则
      {
        id: 'individual_voice_text',
        name: '语音通话+文字翻译',
        callType: CallType.VOICE,
        translationType: TranslationType.TEXT,
        pricePerMinute: 50,
        minimumCharge: 50,
        userType: UserType.INDIVIDUAL,
      },
      {
        id: 'individual_video_sign',
        name: '视频通话+手语翻译',
        callType: CallType.VIDEO,
        translationType: TranslationType.SIGN_LANGUAGE,
        pricePerMinute: 100,
        minimumCharge: 100,
        userType: UserType.INDIVIDUAL,
      },
      {
        id: 'individual_video_human',
        name: '视频通话+真人翻译',
        callType: CallType.VIDEO,
        translationType: TranslationType.HUMAN_INTERPRETER,
        pricePerMinute: 200,
        minimumCharge: 200,
        userType: UserType.INDIVIDUAL,
      },
      // 企业用户规则（相同但可能有优惠）
      {
        id: 'enterprise_voice_text',
        name: '语音通话+文字翻译',
        callType: CallType.VOICE,
        translationType: TranslationType.TEXT,
        pricePerMinute: 40, // 企业优惠价
        minimumCharge: 40,
        userType: UserType.ENTERPRISE,
      },
      {
        id: 'enterprise_video_sign',
        name: '视频通话+手语翻译',
        callType: CallType.VIDEO,
        translationType: TranslationType.SIGN_LANGUAGE,
        pricePerMinute: 80,
        minimumCharge: 80,
        userType: UserType.ENTERPRISE,
      },
      {
        id: 'enterprise_video_human',
        name: '视频通话+真人翻译',
        callType: CallType.VIDEO,
        translationType: TranslationType.HUMAN_INTERPRETER,
        pricePerMinute: 160,
        minimumCharge: 160,
        userType: UserType.ENTERPRISE,
      },
    ];
  }

  // 设置用户账户
  setUserAccount(account: UserAccount) {
    this.userAccount = account;
  }

  // 获取用户账户
  getUserAccount(): UserAccount | null {
    return this.userAccount;
  }

  // 获取计费规则
  getBillingRule(callType: CallType, translationType: TranslationType, userType: UserType): BillingRule | null {
    return this.billingRules.find(rule => 
      rule.callType === callType && 
      rule.translationType === translationType && 
      rule.userType === userType
    ) || null;
  }

  // 计算通话费用
  calculateCallCost(
    callType: CallType, 
    translationType: TranslationType, 
    durationMinutes: number,
    interpreterRate?: number
  ): number {
    if (!this.userAccount) return 0;

    const rule = this.getBillingRule(callType, translationType, this.userAccount.userType);
    if (!rule) return 0;

    // 向上取整分钟数
    const roundedMinutes = Math.ceil(durationMinutes);
    
    // 基础费用
    let baseCost = Math.max(roundedMinutes * rule.pricePerMinute, rule.minimumCharge);
    
    // 如果有翻译员费用，额外计算
    let interpreterCost = 0;
    if (interpreterRate && translationType === TranslationType.HUMAN_INTERPRETER) {
      interpreterCost = roundedMinutes * interpreterRate;
    }

    return baseCost + interpreterCost;
  }

  // 检查余额是否足够
  checkBalance(
    callType: CallType, 
    translationType: TranslationType, 
    minutes: number = 1,
    interpreterRate?: number
  ): {
    sufficient: boolean;
    requiredAmount: number;
    currentBalance: number;
  } {
    if (!this.userAccount) {
      return { sufficient: false, requiredAmount: 0, currentBalance: 0 };
    }

    const requiredAmount = this.calculateCallCost(callType, translationType, minutes, interpreterRate);
    
    return {
      sufficient: this.userAccount.balance >= requiredAmount,
      requiredAmount,
      currentBalance: this.userAccount.balance,
    };
  }

  // 检查是否需要低余额警告
  shouldShowLowBalanceWarning(
    callType: CallType, 
    translationType: TranslationType,
    interpreterRate?: number
  ): boolean {
    const thresholdCost = this.calculateCallCost(
      callType, 
      translationType, 
      BILLING_CONFIG.LOW_BALANCE_THRESHOLD_MINUTES,
      interpreterRate
    );
    
    return this.userAccount ? this.userAccount.balance < thresholdCost : true;
  }

  // 扣费
  deductBalance(amount: number): boolean {
    if (!this.userAccount || this.userAccount.balance < amount) {
      return false;
    }

    this.userAccount.balance -= amount;
    return true;
  }

  // 充值
  recharge(amount: number): void {
    if (this.userAccount) {
      this.userAccount.balance += amount;
    }
  }

  // 格式化金额（分转元）
  formatAmount(cents: number): string {
    return `¥${(cents / 100).toFixed(2)}`;
  }

  // 获取所有计费规则
  getAllBillingRules(): BillingRule[] {
    return this.billingRules;
  }

  // 获取用户可用的计费规则
  getUserBillingRules(): BillingRule[] {
    if (!this.userAccount) return [];
    return this.billingRules.filter(rule => rule.userType === this.userAccount!.userType);
  }

  // 充值账户
  rechargeAccount(amount: number): boolean {
    if (!this.userAccount || amount <= 0) {
      return false;
    }

    this.userAccount.balance += amount;
    return true;
  }
}