gami-web/app/stores/firstOrderDiscount.ts

import { defineStore } from 'pinia'
import { skillApi } from '~/api/skill'
import type { FirstOrderDiscountChanceVo } from '~/types/api'

/**
 * Store for first-order discount (首单1折) chance.
 * Bound to the current user; refresh on app start after login and when order status changes.
 */
export const useFirstOrderDiscountStore = defineStore('firstOrderDiscount', {
  state: (): FirstOrderDiscountChanceVo => ({
    hasChance: false,
    discountRate: 0,
    eligiblePrice: 0,
  }),

  getters: {
    /**
     * Format discount rate for display: e.g. 0.1 (1折) => "90%" (90% off).
     */
    discountRatePercent: (state) => {
      const rate = state.discountRate
      if (rate <= 0 || rate >= 1)
        return '0%'
      return `${Math.round((1 - rate) * 100)}%`
    },

    /**
     * Get display price for a skill: apply discount when has chance, skill is eligible, and not own.
     * @param price - Original price (coins)
     * @param ownerUserNo - Skill owner userNo (optional)
     * @param currentUserNo - Current user's userNo; when equal to ownerUserNo, discount is not applied
     */
    getDisplayPrice: state => (price: number, ownerUserNo?: string, currentUserNo?: string) => {
      if (!state.hasChance || state.discountRate <= 0)
        return price
      if (ownerUserNo && currentUserNo && ownerUserNo === currentUserNo)
        return price
      if (state.eligiblePrice > 0 && price !== state.eligiblePrice)
        return price
      return Math.round(price * state.discountRate)
    },

    /** Whether discount is applied for this skill (for showing original + discounted) */
    isDiscountEligible: state => (price: number, ownerUserNo?: string, currentUserNo?: string) => {
      if (!state.hasChance || state.discountRate <= 0)
        return false
      if (ownerUserNo && currentUserNo && ownerUserNo === currentUserNo)
        return false
      if (state.eligiblePrice > 0 && price !== state.eligiblePrice)
        return false
      return true
    },
  },

  actions: {
    setChance(data: FirstOrderDiscountChanceVo) {
      this.hasChance = data.hasChance
      this.discountRate = data.discountRate
      this.eligiblePrice = data.eligiblePrice
    },

    clear() {
      this.hasChance = false
      this.discountRate = 0
      this.eligiblePrice = 0
    },

    /** Fetch current user's first-order discount chance. Call when logged in. */
    async fetchChance() {
      try {
        const data = await skillApi.firstOrderDiscountChance()
        this.setChance(data)
        return data
      }
      catch {
        this.clear()
        return null
      }
    },
  },
})