kefu/im/backend/internal/app/pet_feed_pricing.go

package app

import (
	"context"
	"encoding/json"
	"net/http"
	"strconv"
	"strings"
)

// A price the app fills in for you has to be defensible: a cat in a small city
// is not a dog in Shenzhen. The table lives in config so operations can move it
// without a release, and the number stays editable — the suggestion is a
// starting point, not a rule.

type priceSuggestConfig struct {
	Base     map[string]int `json:"base"`     // 物种基准单价（分）
	Cities   map[string]int `json:"cities"`   // 城市系数（百分比），键是城市编码前两位或全码
	Minutes  map[string]int `json:"minutes"`  // 每次时长加价（分）
	DogWalk  int            `json:"dogWalk"`  // 含遛狗时的额外加价（分）
	Rounding int            `json:"rounding"` // 取整到多少分
}

const defaultPriceSuggest = `{
  "base": {"cat": 3000, "dog": 4500, "other": 3000},
  "cities": {"11": 120, "31": 120, "44": 115, "51": 105, "33": 110},
  "minutes": {"15": -300, "20": 0, "30": 500, "45": 1200},
  "dogWalk": 500,
  "rounding": 100
}`

func (a *App) priceSuggestConfig(ctx context.Context) priceSuggestConfig {
	parsed := priceSuggestConfig{}
	raw := strings.TrimSpace(a.configPlain(ctx, "pet.feed_price_suggest_json", ""))
	if raw == "" || json.Unmarshal([]byte(raw), &parsed) != nil {
		_ = json.Unmarshal([]byte(defaultPriceSuggest), &parsed)
	}
	if parsed.Rounding < 1 {
		parsed.Rounding = 100
	}
	return parsed
}

// suggestFeedPrice returns the per-visit price in cents, plus the band the
// server will accept, so the form can warn before the user submits.
func (a *App) suggestFeedPrice(ctx context.Context, species, cityCode string, minutes int, walking bool) (int, int, int) {
	config := a.priceSuggestConfig(ctx)
	price, ok := config.Base[species]
	if !ok {
		price = config.Base["other"]
	}
	if price <= 0 {
		price = 3000
	}
	// 先按城市系数缩放：同一件事在不同城市值不同的钱。
	factor := 0
	if code := strings.TrimSpace(cityCode); code != "" {
		if value, hit := config.Cities[code]; hit {
			factor = value
		} else if len(code) >= 2 {
			if value, hit = config.Cities[code[:2]]; hit {
				factor = value
			}
		}
	}
	if factor <= 0 {
		factor = 100
	}
	price = price * factor / 100
	if extra, hit := config.Minutes[strconv.Itoa(minutes)]; hit {
		price += extra
	}
	if walking {
		price += config.DogWalk
	}
	minPrice := a.configInt(ctx, "pet.feed_min_price_cent", 2000)
	maxPrice := a.configInt(ctx, "pet.feed_max_price_cent", 50000)
	price = (price / config.Rounding) * config.Rounding
	if price < minPrice {
		price = minPrice
	}
	if price > maxPrice {
		price = maxPrice
	}
	return price, minPrice, maxPrice
}

func (a *App) feedPriceSuggestion(w http.ResponseWriter, r *http.Request) {
	query := r.URL.Query()
	species := strings.TrimSpace(query.Get("species"))
	if petID, err := strconv.ParseInt(strings.TrimSpace(query.Get("petId")), 10, 64); err == nil && petID > 0 {
		var owned string
		if a.db.QueryRowContext(r.Context(), `SELECT species FROM pets WHERE id=? AND owner_user_id=? AND deleted_at IS NULL`,
			petID, current(r).ID).Scan(&owned) == nil {
			species = owned
		}
	}
	if _, ok := petSpecies[species]; !ok {
		species = "other"
	}
	minutes, _ := strconv.Atoi(strings.TrimSpace(query.Get("minMinutes")))
	if minutes <= 0 {
		minutes = 20
	}
	cityCode := strings.TrimSpace(query.Get("cityCode"))
	if cityCode == "" {
		if addressID, err := strconv.ParseInt(strings.TrimSpace(query.Get("addressId")), 10, 64); err == nil && addressID > 0 {
			_ = a.db.QueryRowContext(r.Context(), `SELECT city_code FROM pet_addresses WHERE id=? AND user_id=?`,
				addressID, current(r).ID).Scan(&cityCode)
		}
	}
	walking := strings.TrimSpace(query.Get("walk")) == "1" || species == "dog"

	price, minPrice, maxPrice := a.suggestFeedPrice(r.Context(), species, cityCode, minutes, walking)
	reply(w, map[string]any{
		"priceCent": price, "minPriceCent": minPrice, "maxPriceCent": maxPrice,
		"species": species, "cityCode": cityCode, "minMinutes": minutes,
		"feePercent": a.configInt(r.Context(), "pet.feed_platform_fee_percent", 15),
	})
}