package cloud

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

// FetchDailyBill 拉取指定日期的阿里云日账单（按产品+地域聚合） // Logan.Li
func (a *AliyunProvider) FetchDailyBill(billingDate string) ([]CloudBillingRecord, error) {
	if len(billingDate) != 10 {
		return nil, fmt.Errorf("账单日期格式应为 YYYY-MM-DD")
	}
	billingCycle := billingDate[:7]

	type aggKey struct {
		service string
		region  string
	}
	agg := map[aggKey]float64{}
	currency := "CNY"

	pageNum := 1
	pageSize := 300
	totalCount := -1

	for {
		body, err := a.callBSS("QueryInstanceBill", map[string]string{
			"BillingCycle":     billingCycle,
			"BillingDate":      billingDate,
			"Granularity":      "DAILY",
			"PageNum":          strconv.Itoa(pageNum),
			"PageSize":         strconv.Itoa(pageSize),
			"IsHideZeroCharge": "true",
		})
		if err != nil {
			return nil, err
		}

		var resp aliyunInstanceBillResponse
		if err := json.Unmarshal(body, &resp); err != nil {
			return nil, fmt.Errorf("解析账单响应失败: %w", err)
		}
		if !resp.Success && resp.Code != "Success" {
			msg := resp.Message
			if msg == "" {
				msg = string(body)
			}
			return nil, fmt.Errorf("阿里云账单 API 错误: %s", msg)
		}

		if totalCount < 0 {
			totalCount = resp.Data.TotalCount
		}

		items := normalizeBillItems(resp.Data.Items.Item)
		for _, it := range items {
			amount := it.PretaxAmount
			if amount <= 0 {
				amount = it.PaymentAmount
			}
			if amount <= 0 {
				continue
			}
			service := strings.TrimSpace(it.ProductName)
			if service == "" {
				service = strings.TrimSpace(it.ProductCode)
			}
			if service == "" {
				service = "其他"
			}
			region := strings.TrimSpace(it.Region)
			if region == "" {
				region = "全局"
			}
			key := aggKey{service: service, region: region}
			agg[key] += amount
			if it.Currency != "" {
				currency = it.Currency
			}
		}

		if len(items) == 0 || pageNum*pageSize >= totalCount {
			break
		}
		pageNum++
	}

	records := make([]CloudBillingRecord, 0, len(agg))
	for key, cost := range agg {
		records = append(records, CloudBillingRecord{
			BillingDate: billingDate,
			Provider:    "aliyun",
			Cost:        math.Round(cost*100) / 100,
			Currency:    currency,
			Service:     key.service,
			Region:      key.region,
			Description: "云API自动同步（阿里云 QueryInstanceBill）",
		})
	}
	return records, nil
}

type aliyunInstanceBillResponse struct {
	Code    string `json:"Code"`
	Message string `json:"Message"`
	Success bool   `json:"Success"`
	Data    struct {
		TotalCount int `json:"TotalCount"`
		Items      struct {
			Item json.RawMessage `json:"Item"`
		} `json:"Items"`
	} `json:"Data"`
}

type aliyunBillItem struct {
	ProductCode   string  `json:"ProductCode"`
	ProductName   string  `json:"ProductName"`
	Region        string  `json:"Region"`
	PretaxAmount  float64 `json:"PretaxAmount"`
	PaymentAmount float64 `json:"PaymentAmount"`
	Currency      string  `json:"Currency"`
}

// normalizeBillItems 兼容 Item 为对象或数组两种返回格式 // Logan.Li
func normalizeBillItems(raw json.RawMessage) []aliyunBillItem {
	if len(raw) == 0 || string(raw) == "null" {
		return nil
	}
	var items []aliyunBillItem
	if err := json.Unmarshal(raw, &items); err == nil {
		return items
	}
	var one aliyunBillItem
	if err := json.Unmarshal(raw, &one); err == nil {
		return []aliyunBillItem{one}
	}
	return nil
}