package polling

import (
	"context"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/redis/go-redis/v9"

	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/internal/model/dto"
	"github.com/break/junhong_cmp_fiber/internal/store/postgres"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
)

// 分钟计数 Hash 字段（与 gatewaylimit.Guard 写入口径一致）。
const (
	statAttempts    = "attempts"
	statDurationSum = "duration_ms_sum"
	statWouldLimit  = "would_limit"
	statPrefixDur   = "duration_le:"
	statPrefixExem  = "exempt:"
	statPrefixUp    = "upstream:"
)

// statDurationBuckets 与写入端分桶上界一致（毫秒）。
var statDurationBuckets = []string{"100", "300", "500", "1000", "3000", "10000", "60000", "inf"}

// ListStopResumeRecords 按条件查询停复机记录；时间范围必填且跨度不超过 31 天。
func (s *GatewayRateLimitService) ListStopResumeRecords(ctx context.Context, req *dto.StopResumeRecordListRequest) (*dto.StopResumeRecordPageResult, error) {
	if err := requirePlatformReader(ctx); err != nil {
		return nil, err
	}
	if req.StartTime.IsZero() || req.EndTime.IsZero() {
		return nil, errors.New(errors.CodeInvalidParam, "停复机记录查询参数不合法：开始时间与结束时间必填")
	}
	if !req.EndTime.After(req.StartTime) || req.EndTime.Sub(req.StartTime) > time.Duration(constants.StopResumeRecordQueryMaxDays)*24*time.Hour {
		return nil, errors.New(errors.CodeInvalidParam, "停复机记录查询参数不合法：时间跨度须大于 0 且不超过 31 天")
	}
	page, size := normalizePage(req.Page, req.PageSize)
	return s.listRecords(ctx, postgres.StopResumeRecordFilter{
		ICCID: strings.TrimSpace(req.ICCID), CarrierID: req.CarrierID, Action: req.Action, Source: req.Source,
		Result: req.Result, ErrorCategory: req.ErrorCategory, StartTime: req.StartTime, EndTime: req.EndTime,
		Page: page, PageSize: size,
	})
}

// ListCardStopResumeRecords 查询单卡停复机历史；未传时间默认最近 31 天。
func (s *GatewayRateLimitService) ListCardStopResumeRecords(ctx context.Context, req *dto.CardStopResumeRecordListRequest) (*dto.StopResumeRecordPageResult, error) {
	if err := requirePlatformReader(ctx); err != nil {
		return nil, err
	}
	var count int64
	if err := s.db.WithContext(ctx).Model(&model.IotCard{}).Where("id = ?", req.ID).Count(&count).Error; err != nil {
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询 IoT 卡失败")
	}
	if count == 0 {
		return nil, errors.New(errors.CodeNotFound, "IoT 卡不存在")
	}
	end := req.EndTime
	if end.IsZero() {
		end = time.Now()
	}
	start := req.StartTime
	if start.IsZero() {
		start = end.AddDate(0, 0, -constants.StopResumeRecordQueryMaxDays)
	}
	if !end.After(start) || end.Sub(start) > time.Duration(constants.StopResumeRecordQueryMaxDays)*24*time.Hour {
		return nil, errors.New(errors.CodeInvalidParam, "停复机记录查询参数不合法：时间跨度须大于 0 且不超过 31 天")
	}
	page, size := normalizePage(req.Page, req.PageSize)
	cardID := req.ID
	return s.listRecords(ctx, postgres.StopResumeRecordFilter{CardID: &cardID, StartTime: start, EndTime: end, Page: page, PageSize: size})
}

func (s *GatewayRateLimitService) listRecords(ctx context.Context, filter postgres.StopResumeRecordFilter) (*dto.StopResumeRecordPageResult, error) {
	rows, total, err := postgres.NewCardStopResumeRecordStore(s.db).List(ctx, filter)
	if err != nil {
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询停复机记录失败")
	}
	items := make([]dto.StopResumeRecordResponse, 0, len(rows))
	for _, row := range rows {
		items = append(items, dto.StopResumeRecordResponse{
			ID: row.ID, CardID: row.CardID, ICCID: row.ICCID, CarrierID: row.CarrierID, Action: row.Action,
			ActionName: stopResumeActionName(row.Action), Source: row.Source, Scene: row.Scene, Reason: row.Reason,
			CommandID: row.CommandID, Attempt: row.Attempt, Result: row.Result, ErrorCategory: row.ErrorCategory,
			ErrorCategoryName: errorCategoryName(row.ErrorCategory), ProviderCode: row.ProviderCode,
			ProviderMessage: row.ProviderMessage, DurationMS: row.DurationMS, CreatedAt: row.CreatedAt,
		})
	}
	return &dto.StopResumeRecordPageResult{List: items, Total: total, Page: filter.Page, PageSize: filter.PageSize}, nil
}

// CarrierCallStats 汇总最近若干分钟各运营商账户的网关调用（只返回有调用的账户）。
func (s *GatewayRateLimitService) CarrierCallStats(ctx context.Context, redisClient *redis.Client, req *dto.GatewayCallStatsRequest) (*dto.GatewayCallStatsResponse, error) {
	if err := requirePlatformReader(ctx); err != nil {
		return nil, err
	}
	minutes := req.Minutes
	if minutes <= 0 {
		minutes = 15
	}
	names, err := s.carrierNames(ctx)
	if err != nil {
		return nil, err
	}
	carrierIDs := []uint{0}
	for id := range names {
		carrierIDs = append(carrierIDs, id)
	}
	sort.Slice(carrierIDs, func(i, j int) bool { return carrierIDs[i] < carrierIDs[j] })
	stamps := minuteStamps(time.Now(), minutes)
	data, err := loadStatHashes(ctx, redisClient, carrierIDs, stamps)
	if err != nil {
		return nil, err
	}
	resp := &dto.GatewayCallStatsResponse{Mode: s.currentMode(ctx), Minutes: minutes, Carriers: []dto.GatewayCarrierStat{}}
	for _, carrierID := range carrierIDs {
		var ops []dto.GatewayOperationStat
		for _, op := range constants.GatewayCardOperations {
			stat := aggregateOperation(op, data[statKey{carrierID, op}], len(stamps))
			if stat.Attempts > 0 || stat.RateLimited > 0 || stat.WouldLimit > 0 {
				ops = append(ops, stat)
			}
		}
		if len(ops) == 0 {
			continue
		}
		name := names[carrierID]
		if carrierID == 0 {
			name = "未知账户"
		}
		resp.Carriers = append(resp.Carriers, dto.GatewayCarrierStat{CarrierID: carrierID, CarrierName: name, Operations: ops})
	}
	return resp, nil
}

// CarrierCallTrend 返回单个运营商账户按时间桶聚合的网关调用趋势。
func (s *GatewayRateLimitService) CarrierCallTrend(ctx context.Context, redisClient *redis.Client, req *dto.GatewayCallTrendRequest) (*dto.GatewayCallTrendResponse, error) {
	if err := requirePlatformReader(ctx); err != nil {
		return nil, err
	}
	minutes, bucket := req.Minutes, req.BucketMinutes
	if minutes <= 0 {
		minutes = 60
	}
	if bucket <= 0 {
		bucket = 1
	}
	stamps := minuteStamps(time.Now(), minutes)
	data, err := loadStatHashes(ctx, redisClient, []uint{req.CarrierID}, stamps)
	if err != nil {
		return nil, err
	}
	resp := &dto.GatewayCallTrendResponse{CarrierID: req.CarrierID, Points: []dto.GatewayCallTrendPoint{}}
	for start := 0; start < len(stamps); start += bucket {
		end := start + bucket
		if end > len(stamps) {
			end = len(stamps)
		}
		point := dto.GatewayCallTrendPoint{Time: formatStamp(stamps[start]), Operations: []dto.GatewayOperationStat{}}
		for _, op := range constants.GatewayCardOperations {
			series := data[statKey{req.CarrierID, op}]
			if series == nil {
				continue
			}
			stat := aggregateOperation(op, series[start:end], end-start)
			if stat.Attempts > 0 || stat.RateLimited > 0 || stat.WouldLimit > 0 {
				point.Operations = append(point.Operations, stat)
			}
		}
		resp.Points = append(resp.Points, point)
	}
	return resp, nil
}

func (s *GatewayRateLimitService) currentMode(ctx context.Context) string {
	if s.runtime == nil {
		return constants.RateLimitModeObserve
	}
	return s.runtime.Settings.Current(ctx).Mode
}

type statKey struct {
	carrierID uint
	op        string
}

// minuteStamps 返回从最早到最近的分钟标识（上海时区 yyyyMMddHHmm）。
func minuteStamps(now time.Time, minutes int) []string {
	location := shanghaiLocation()
	current := now.In(location).Truncate(time.Minute)
	stamps := make([]string, minutes)
	for i := 0; i < minutes; i++ {
		stamps[minutes-1-i] = current.Add(-time.Duration(i) * time.Minute).Format("200601021504")
	}
	return stamps
}

func formatStamp(stamp string) string {
	t, err := time.ParseInLocation("200601021504", stamp, shanghaiLocation())
	if err != nil {
		return stamp
	}
	return t.Format("2006-01-02 15:04")
}

// loadStatHashes 用管道批量读取分钟计数；返回每个账户 × 操作按分钟顺序的 Hash 列表。
func loadStatHashes(ctx context.Context, redisClient *redis.Client, carrierIDs []uint, stamps []string) (map[statKey][]map[string]string, error) {
	result := map[statKey][]map[string]string{}
	if redisClient == nil {
		return result, nil
	}
	type pending struct {
		key statKey
		idx int
		cmd *redis.MapStringStringCmd
	}
	pipe := redisClient.Pipeline()
	cmds := make([]pending, 0, len(carrierIDs)*len(constants.GatewayCardOperations)*len(stamps))
	for _, carrierID := range carrierIDs {
		for _, op := range constants.GatewayCardOperations {
			key := statKey{carrierID, op}
			result[key] = make([]map[string]string, len(stamps))
			for idx, stamp := range stamps {
				cmds = append(cmds, pending{key: key, idx: idx, cmd: pipe.HGetAll(ctx, constants.RedisGatewayCallStatKey(carrierID, op, stamp))})
			}
		}
	}
	if _, err := pipe.Exec(ctx); err != nil && err != redis.Nil {
		return nil, errors.Wrap(errors.CodeRedisError, err, "读取网关调用统计失败")
	}
	for _, item := range cmds {
		values, err := item.cmd.Result()
		if err == nil && len(values) > 0 {
			result[item.key][item.idx] = values
		}
	}
	return result, nil
}

// aggregateOperation 汇总一个操作在若干分钟内的计数。
func aggregateOperation(op string, minutes []map[string]string, minuteCount int) dto.GatewayOperationStat {
	stat := dto.GatewayOperationStat{Operation: op, OperationName: constants.GatewayOperationName(op), Failures: map[string]int64{}, Exempt: map[string]int64{}}
	buckets := map[string]int64{}
	var durationSum int64
	for _, values := range minutes {
		var minuteAttempts int64
		for field, raw := range values {
			value, err := strconv.ParseInt(raw, 10, 64)
			if err != nil {
				continue
			}
			switch {
			case field == statAttempts:
				stat.Attempts += value
				minuteAttempts = value
			case field == statDurationSum:
				durationSum += value
			case field == statWouldLimit:
				stat.WouldLimit += value
			case field == constants.GatewayErrorRateLimited:
				stat.RateLimited += value
			case field == constants.GatewayResultSuccess:
				stat.Success += value
			case strings.HasPrefix(field, statPrefixDur):
				buckets[strings.TrimPrefix(field, statPrefixDur)] += value
			case strings.HasPrefix(field, statPrefixExem):
				stat.Exempt[strings.TrimPrefix(field, statPrefixExem)] += value
			default:
				stat.Failures[field] += value
			}
		}
		if qps := float64(minuteAttempts) / 60; qps > stat.PeakMinuteQPS {
			stat.PeakMinuteQPS = qps
		}
	}
	if minuteCount > 0 {
		stat.AvgQPS = float64(stat.Attempts) / float64(minuteCount*60)
	}
	if stat.Attempts > 0 {
		stat.SuccessRate = float64(stat.Success) / float64(stat.Attempts)
		stat.AvgDurationMS = float64(durationSum) / float64(stat.Attempts)
		stat.P95DurationMS = percentileBucket(buckets, stat.Attempts, 0.95)
	}
	return stat
}

// percentileBucket 返回累计占比达到 p 的分桶上界；落在最后一个分桶时返回 -1。
func percentileBucket(buckets map[string]int64, total int64, p float64) int64 {
	threshold := int64(float64(total)*p + 0.5)
	var cumulative int64
	for _, upper := range statDurationBuckets {
		cumulative += buckets[upper]
		if cumulative >= threshold {
			if upper == "inf" {
				return -1
			}
			value, _ := strconv.ParseInt(upper, 10, 64)
			return value
		}
	}
	return -1
}

func shanghaiLocation() *time.Location {
	location, err := time.LoadLocation("Asia/Shanghai")
	if err != nil {
		return time.FixedZone("CST", 8*3600)
	}
	return location
}

func stopResumeActionName(action string) string {
	if action == constants.StopResumeActionStart {
		return "复机"
	}
	return "停机"
}

func errorCategoryName(category string) string {
	switch category {
	case "":
		return ""
	case constants.GatewayErrorNetwork:
		return "网络错误"
	case constants.GatewayErrorTimeout:
		return "请求超时"
	case constants.GatewayErrorHTTP:
		return "HTTP 异常"
	case constants.GatewayErrorInvalidResponse:
		return "响应无效"
	default:
		return constants.GatewayErrorClassName(category)
	}
}

// PollingOptions 返回轮询与网关限流相关的前端枚举，前端不写死取值。
func (s *GatewayRateLimitService) PollingOptions(ctx context.Context) (*dto.PollingOptionsResponse, error) {
	if err := requirePlatformReader(ctx); err != nil {
		return nil, err
	}
	resp := &dto.PollingOptionsResponse{}
	for _, op := range constants.GatewayCardOperations {
		resp.GatewayOperations = append(resp.GatewayOperations, dto.PollingOptionItem{Value: op, Label: constants.GatewayOperationName(op)})
	}
	for _, class := range constants.GatewayErrorClasses {
		resp.ErrorCategories = append(resp.ErrorCategories, dto.PollingOptionItem{Value: class, Label: constants.GatewayErrorClassName(class)})
	}
	resp.MatchTypes = []dto.PollingOptionItem{{Value: constants.GatewayMatchContains, Label: "包含"}, {Value: constants.GatewayMatchPrefix, Label: "前缀"}, {Value: constants.GatewayMatchRegex, Label: "正则"}}
	resp.RateLimitModes = []dto.PollingOptionItem{{Value: constants.RateLimitModeObserve, Label: "只统计不拦截"}, {Value: constants.RateLimitModeEnforce, Label: "拦截"}}
	resp.ExemptSources = []dto.PollingOptionItem{
		{Value: constants.RateLimitExemptManualClick, Label: "后台人工点击"}, {Value: constants.RateLimitExemptChannelThreshold, Label: "通道阈值"},
		{Value: constants.RateLimitExemptAutoRenewal, Label: "自动续费"}, {Value: constants.RateLimitExemptManualRefresh, Label: "手动刷新"},
	}
	resp.StopResumeResults = []dto.PollingOptionItem{
		{Value: constants.StopResumeRecordSuccess, Label: "成功"}, {Value: constants.StopResumeRecordFailed, Label: "失败"},
		{Value: constants.StopResumeRecordUnknown, Label: "结果未知"}, {Value: constants.StopResumeRecordAlreadyTarget, Label: "已是目标状态"},
		{Value: constants.StopResumeRecordSkipped, Label: "跳过"},
	}
	resp.StopResumeActions = []dto.PollingOptionItem{{Value: constants.StopResumeActionStop, Label: "停机"}, {Value: constants.StopResumeActionStart, Label: "复机"}}
	return resp, nil
}