package service

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"strings"
	"time"
	"unicode/utf8"

	"cmautobuy/admin/model"
	"cmautobuy/admin/repository"
)

const maxShopeeSKUFieldRunes = 500

// UpdateShopeeSKUManual 保存采购员对现有蝦皮规格的人工修正。
// 只修改颜色、尺码和建议说明；规格原文、身份字段和既有采购数据保持不变。
func UpdateShopeeSKUManual(db *sql.DB, actor *model.User, goodsID, skuRecordID,
	color, size, advice string, now time.Time) error {
	if actor == nil || actor.Status != model.UserActive {
		return ErrUnauthenticated
	}
	goodsID = strings.TrimSpace(goodsID)
	skuRecordID = strings.TrimSpace(skuRecordID)
	color = strings.TrimSpace(color)
	size = strings.TrimSpace(size)
	advice = strings.TrimSpace(advice)
	if goodsID == "" {
		return invalidFieldInput("shopee_goods_id", "蝦皮商品编号不能为空")
	}
	if skuRecordID == "" {
		return invalidFieldInput("sku_record_id", "蝦皮规格记录编号不能为空")
	}
	if color == "" {
		return invalidFieldInput("color", "颜色不能为空")
	}
	if size == "" {
		return invalidFieldInput("size", "尺码不能为空")
	}
	for _, field := range []struct {
		name, label, value string
	}{{"color", "颜色", color}, {"size", "尺码", size}, {"advice", "建议说明", advice}} {
		if utf8.RuneCountInString(field.value) > maxShopeeSKUFieldRunes {
			return invalidFieldInput(field.name, "%s最多 500 个字符", field.label)
		}
	}

	tx, err := db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	state, err := repository.GetShopeeSKUManualState(tx, skuRecordID)
	if err != nil {
		return err
	}
	if state == nil || state.GoodsID != goodsID {
		return invalidFieldInput("sku_record_id", "蝦皮规格不存在或不属于当前商品，请刷新页面后重试")
	}
	sources, err := decodeShopeeSKUProvenance(state.FieldSources)
	if err != nil {
		return fmt.Errorf("读取蝦皮规格字段来源失败: %w", err)
	}
	observedTimes, err := decodeShopeeSKUProvenance(state.FieldObservedAt)
	if err != nil {
		return fmt.Errorf("读取蝦皮规格字段时间失败: %w", err)
	}
	at := now.UTC().Format(model.TimeLayout)
	for _, field := range []string{"color", "size", "advice"} {
		sources[field] = "manual"
		observedTimes[field] = at
	}
	sourcesJSON, err := json.Marshal(sources)
	if err != nil {
		return err
	}
	timesJSON, err := json.Marshal(observedTimes)
	if err != nil {
		return err
	}
	updated, err := repository.UpdateShopeeSKUManualFields(tx, skuRecordID, goodsID,
		color, size, advice, string(sourcesJSON), string(timesJSON), at)
	if err != nil {
		return err
	}
	if !updated {
		return invalidFieldInput("sku_record_id", "蝦皮规格已发生变化，请刷新页面后重试")
	}
	return tx.Commit()
}

func decodeShopeeSKUProvenance(raw string) (map[string]string, error) {
	values := map[string]string{}
	if strings.TrimSpace(raw) == "" {
		return values, nil
	}
	if err := json.Unmarshal([]byte(raw), &values); err != nil {
		return nil, err
	}
	return values, nil
}