package cloud

import (
	"encoding/json"
	"fmt"
	"math"
	"sort"
	"strconv"
	"strings"
)

// FetchDailyBill 拉取指定日期的腾讯云日账单，并按产品和地域汇总。 // Logan.Li
func (p *TencentProvider) FetchDailyBill(billingDate string) ([]CloudBillingRecord, error) {
	if len(billingDate) != 10 {
		return nil, fmt.Errorf("账单日期格式应为 YYYY-MM-DD")
	}

	type aggregationKey struct {
		service string
		region  string
	}
	aggregation := map[aggregationKey]float64{}
	const pageSize = 100

	for offset := 0; ; offset += pageSize {
		// DescribeBillDetail 不支持 Day 参数，使用账期和起止时间限定单日范围。 // Logan.Li
		body, err := p.callService("billing", "billing.tencentcloudapi.com", "2018-07-09", "DescribeBillDetail", "", map[string]interface{}{
			"Month":         billingDate[:7],
			"BeginTime":     billingDate + " 00:00:00",
			"EndTime":       billingDate + " 23:59:59",
			"Offset":        offset,
			"Limit":         pageSize,
			"NeedRecordNum": 1,
		})
		if err != nil {
			return nil, err
		}

		var response tencentBillDetailResponse
		if err := json.Unmarshal(body, &response); err != nil {
			return nil, fmt.Errorf("解析腾讯云账单响应失败: %w", err)
		}
		for _, detail := range response.Response.DetailSet {
			cost := tencentBillAmount(detail.RealTotalCost)
			if cost == 0 {
				cost = tencentBillAmount(detail.RealCost)
			}
			if cost == 0 {
				cost = tencentBillAmount(detail.CashPayAmount)
			}
			if cost == 0 {
				// 腾讯云明细账单将组件费用放在 ComponentSet，逐项汇总实际费用。 // Logan.Li
				for _, component := range detail.ComponentSet {
					componentCost := tencentBillAmount(component.RealCost)
					if componentCost == 0 {
						componentCost = tencentBillAmount(component.CashPayAmount)
					}
					cost += componentCost
				}
			}
			if cost <= 0 {
				continue
			}
			service := firstNonEmpty(detail.ProductCodeName, detail.BusinessCodeName, detail.ProductCode, "其他")
			region := firstNonEmpty(detail.RegionName, "全局")
			aggregation[aggregationKey{service: service, region: region}] += cost
		}

		if len(response.Response.DetailSet) < pageSize || (response.Response.Total > 0 && offset+pageSize >= response.Response.Total) {
			break
		}
	}

	keys := make([]aggregationKey, 0, len(aggregation))
	for key := range aggregation {
		keys = append(keys, key)
	}
	sort.Slice(keys, func(i, j int) bool {
		if keys[i].service == keys[j].service {
			return keys[i].region < keys[j].region
		}
		return keys[i].service < keys[j].service
	})

	records := make([]CloudBillingRecord, 0, len(keys))
	for _, key := range keys {
		records = append(records, CloudBillingRecord{
			BillingDate: billingDate,
			Provider:    "tencent",
			Cost:        math.Round(aggregation[key]*100) / 100,
			Currency:    "CNY",
			Service:     key.service,
			Region:      key.region,
			Description: "云 API 自动同步（腾讯云 DescribeBillDetail）",
		})
	}
	return records, nil
}

// tencentBillDetailResponse 描述腾讯云费用中心明细账单响应。 // Logan.Li
type tencentBillDetailResponse struct {
	Response struct {
		Total     int `json:"Total"`
		DetailSet []struct {
			ProductCode      string          `json:"ProductCode"`
			ProductCodeName  string          `json:"ProductCodeName"`
			BusinessCodeName string          `json:"BusinessCodeName"`
			RegionName       string          `json:"RegionName"`
			RealTotalCost    json.RawMessage `json:"RealTotalCost"`
			RealCost         json.RawMessage `json:"RealCost"`
			CashPayAmount    json.RawMessage `json:"CashPayAmount"`
			ComponentSet     []struct {
				RealCost      json.RawMessage `json:"RealCost"`
				CashPayAmount json.RawMessage `json:"CashPayAmount"`
			} `json:"ComponentSet"`
		} `json:"DetailSet"`
	} `json:"Response"`
}

// tencentBillAmount 兼容腾讯云账单金额字段为字符串或数字的响应。 // Logan.Li
func tencentBillAmount(raw json.RawMessage) float64 {
	value := strings.Trim(strings.TrimSpace(string(raw)), "\"")
	amount, err := strconv.ParseFloat(value, 64)
	if err != nil {
		return 0
	}
	return amount
}

// firstNonEmpty 返回首个非空文本，用于兼容不同账单产品字段。 // Logan.Li
func firstNonEmpty(values ...string) string {
	for _, value := range values {
		if text := strings.TrimSpace(value); text != "" {
			return text
		}
	}
	return ""
}