package cloud

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

type huaweiBillRecord struct {
	ServiceTypeCode      string          `json:"service_type_code"`
	ServiceTypeName      string          `json:"service_type_name"`
	CloudServiceType     string          `json:"cloud_service_type"`
	CloudServiceTypeName string          `json:"cloud_service_type_name"`
	ResourceTypeName     string          `json:"resource_type_name"`
	RegionCode           string          `json:"region_code"`
	Region               string          `json:"region"`
	RegionName           string          `json:"region_name"`
	Amount               json.RawMessage `json:"amount"`
	ConsumeAmount        json.RawMessage `json:"consume_amount"`
	OfficialAmount       json.RawMessage `json:"official_amount"`
	DiscountAmount       json.RawMessage `json:"discount_amount"`
}

type huaweiBillPage struct {
	TotalCount int                `json:"total_count"`
	Currency   string             `json:"currency"`
	Records    []huaweiBillRecord `json:"records"`
	FeeRecords []huaweiBillRecord `json:"fee_records"`
}

// FetchDailyBill 通过华为云 BSS 费用流水接口拉取单日账单。 // Logan.Li
func (p *HuaweiProvider) FetchDailyBill(billingDate string) ([]CloudBillingRecord, error) {
	if _, err := time.Parse("2006-01-02", billingDate); err != nil {
		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{}
	currency := "CNY"
	const pageSize = 1000
	for offset := 0; ; offset += pageSize {
		query := url.Values{
			"bill_cycle":      {billingDate[:7]},
			"bill_date_begin": {billingDate},
			"bill_date_end":   {billingDate},
			"offset":          {strconv.Itoa(offset)},
			"limit":           {strconv.Itoa(pageSize)},
		}
		body, err := p.signedGet("https://bss.myhuaweicloud.com/v2/bills/customer-bills/fee-records?"+query.Encode(), "bss")
		if err != nil {
			return nil, err
		}
		page, err := decodeHuaweiBillPage(body)
		if err != nil {
			return nil, err
		}
		if page.Currency != "" {
			currency = page.Currency
		}
		records := page.Records
		if len(records) == 0 {
			records = page.FeeRecords
		}
		for _, item := range records {
			cost := huaweiBillRecordCost(item)
			if cost == 0 {
				continue
			}
			service := firstNonEmpty(item.ServiceTypeName, item.CloudServiceTypeName, item.ResourceTypeName, item.ServiceTypeCode, item.CloudServiceType, "其他")
			region := firstNonEmpty(item.RegionName, item.RegionCode, item.Region, "全局")
			aggregation[aggregationKey{service: service, region: region}] += cost
		}
		if len(records) < pageSize || (page.TotalCount > 0 && offset+pageSize >= page.TotalCount) {
			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: "huawei", Cost: math.Round(aggregation[key]*100) / 100,
			Currency: currency, Service: key.service, Region: key.region,
			Description: "云 API 自动同步（华为云 BSS）",
		})
	}
	return records, nil
}

// decodeHuaweiBillPage 兼容华为云 records 与旧版 fee_records 响应。 // Logan.Li
func decodeHuaweiBillPage(body []byte) (huaweiBillPage, error) {
	var page huaweiBillPage
	if err := json.Unmarshal(body, &page); err != nil {
		return page, fmt.Errorf("解析华为云 BSS 响应失败: %w", err)
	}
	return page, nil
}

// huaweiBillRecordCost 依次读取实际消费、流水金额和官网价减优惠。 // Logan.Li
func huaweiBillRecordCost(item huaweiBillRecord) float64 {
	if cost := huaweiBillAmount(item.ConsumeAmount); cost != 0 {
		return cost
	}
	if cost := huaweiBillAmount(item.Amount); cost != 0 {
		return cost
	}
	return huaweiBillAmount(item.OfficialAmount) - huaweiBillAmount(item.DiscountAmount)
}

// huaweiBillAmount 兼容华为云金额字段的字符串和数字格式。 // Logan.Li
func huaweiBillAmount(raw json.RawMessage) float64 {
	value := strings.Trim(strings.TrimSpace(string(raw)), "\"")
	amount, err := strconv.ParseFloat(value, 64)
	if err != nil {
		return 0
	}
	return amount
}