package task

import (
	"context"
	"encoding/json"
	stderrors "errors"
	"sync/atomic"
	"time"

	"go.uber.org/zap"

	cardapp "github.com/break/junhong_cmp_fiber/internal/application/cardobservation"
	carddomain "github.com/break/junhong_cmp_fiber/internal/domain/cardobservation"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
)

// IngestExecutor 消费轮询观测入库消息（topic card.ingest）：复用卡观测应用服务写库，按采集 ID 去重；
// 可重试错误按退避延迟重投且不设次数上限，业务性错误记录后丢弃。
type IngestExecutor struct {
	base        *PollingBase
	observation *cardapp.Service
	timeout     time.Duration
	// lastLagMS 是最近处理消息的发布到开始处理的等待时长，供积压监控读取。
	lastLagMS atomic.Int64
}

// NewIngestExecutor 创建入库消费者。
func NewIngestExecutor(base *PollingBase, observation *cardapp.Service, timeout time.Duration) *IngestExecutor {
	if timeout <= 0 {
		timeout = constants.PollingIngestDefaultTimeout
	}
	return &IngestExecutor{base: base, observation: observation, timeout: timeout}
}

// LastLag 返回最近处理的入库消息从发布到开始处理的等待时长。
func (e *IngestExecutor) LastLag() time.Duration {
	if e == nil {
		return 0
	}
	return time.Duration(e.lastLagMS.Load()) * time.Millisecond
}

// Handle 处理一条入库消息，返回 0 表示确认，正数表示按该延迟重投。
func (e *IngestExecutor) Handle(ctx context.Context, body []byte, attempts uint16, _ func()) time.Duration {
	var msg IngestMessage
	if err := json.Unmarshal(body, &msg); err != nil || !msg.valid() {
		e.base.logger.Warn("入库消息无效，丢弃", zap.ByteString("body", body))
		return 0
	}
	if !msg.PublishedAt.IsZero() {
		e.lastLagMS.Store(time.Since(msg.PublishedAt).Milliseconds())
	}
	if e.alreadyDone(ctx, msg.ObservationID) {
		return 0
	}
	taskCtx, cancel := context.WithTimeout(ctx, e.timeout)
	defer cancel()
	taskCtx = withPollingWorkerAuditContext(taskCtx, msg.TaskType, pollingPriorityTaskName(msg.TaskType), msg.ObservationID)
	changed, err := e.apply(taskCtx, msg)
	if err != nil {
		return e.onFailure(msg, attempts, err)
	}
	e.markDone(msg.ObservationID)
	if changed && msg.Kind == ingestKindTraffic {
		e.markFlowEvaluated(msg.CardID)
	}
	return 0
}

// apply 按观测类型调用卡观测应用服务，返回流量是否产生增量或跨月。
func (e *IngestExecutor) apply(ctx context.Context, msg IngestMessage) (bool, error) {
	if e.observation == nil {
		return false, errors.New(errors.CodeInternalError, "卡观测能力未配置")
	}
	switch msg.Kind {
	case ingestKindTraffic:
		decision, err := e.observation.ApplyTrafficObservation(ctx, carddomain.TrafficObservation{
			CardID: msg.CardID, GatewayReadingMB: msg.Traffic.ReadingMB, ReadingResult: msg.Traffic.ReadingResult,
			ResetDay: msg.Traffic.ResetDay, Raw: msg.Raw, ICCID: msg.ICCID, CarrierID: msg.CarrierID,
			Failure:  &carddomain.CollectionFailure{DurationMS: msg.Traffic.DurationMS},
			Metadata: msg.metadata(),
		})
		return decision.IncrementMB > 0 || decision.CrossMonth, err
	case ingestKindNetwork:
		_, err := e.observation.ApplyNetworkObservation(ctx, carddomain.NetworkObservation{
			CardID: msg.CardID, GatewayStatus: msg.Network.Status, GatewayExtend: msg.Network.Extend,
			GatewayIMEI: msg.Network.IMEI, Metadata: msg.metadata(),
		})
		return false, err
	case ingestKindRealname:
		_, err := e.observation.ApplyCardObservation(ctx, carddomain.RealnameObservation{
			CardID: msg.CardID, Verified: msg.Realname.Verified, Metadata: msg.metadata(),
		})
		return false, err
	}
	return false, errors.New(errors.CodeInvalidParam, "未知的入库观测类型")
}

// onFailure 业务性错误丢弃，其余按退避重投；第 10 次起每次重投记 ERROR。
func (e *IngestExecutor) onFailure(msg IngestMessage, attempts uint16, err error) time.Duration {
	fields := []zap.Field{zap.String("kind", msg.Kind), zap.Uint("card_id", msg.CardID),
		zap.String("observation_id", msg.ObservationID), zap.Uint16("attempts", attempts), zap.Error(err)}
	if ingestBusinessError(err) {
		e.base.logger.Warn("入库遇到业务性错误，丢弃消息", fields...)
		return 0
	}
	delay := ingestRetryDelay(attempts)
	fields = append(fields, zap.Duration("retry_after", delay))
	if attempts >= constants.PollingIngestErrorLogFromAttempt {
		e.base.logger.Error("入库持续失败，继续重投", fields...)
	} else {
		e.base.logger.Warn("入库失败，延迟重投", fields...)
	}
	return delay
}

// ingestBusinessError 判断错误是否为重试也不会成功的业务性错误（卡不存在、观测数据校验失败）。
func ingestBusinessError(err error) bool {
	var appErr *errors.AppError
	if !stderrors.As(err, &appErr) {
		return false
	}
	switch appErr.Code {
	case errors.CodeNotFound, errors.CodeInvalidParam, errors.CodeInvalidStatus:
		return true
	}
	return false
}

func (e *IngestExecutor) alreadyDone(ctx context.Context, observationID string) bool {
	if e.base.redis == nil {
		return false
	}
	exists, err := e.base.redis.Exists(ctx, constants.RedisPollingIngestDoneKey(observationID)).Result()
	return err == nil && exists > 0
}

func (e *IngestExecutor) markDone(observationID string) {
	if e.base.redis == nil {
		return
	}
	markCtx, cancel := pollingFallbackContext()
	defer cancel()
	if err := e.base.redis.Set(markCtx, constants.RedisPollingIngestDoneKey(observationID), "1", constants.PollingIngestDoneTTL).Err(); err != nil {
		e.base.logger.Warn("写入库已处理标记失败，重投时由业务幂等兜底", zap.String("observation_id", observationID), zap.Error(err))
	}
}

// markFlowEvaluated 流量入库产生增量或跨月时写评估标记，有效期取该卡套餐检查间隔；套餐步骤据此跳过。
func (e *IngestExecutor) markFlowEvaluated(cardID uint) {
	if e.base.redis == nil {
		return
	}
	markCtx, cancel := pollingFallbackContext()
	defer cancel()
	ttl := constants.PollingFlowEvaluatedFallbackTTL
	if card, err := e.base.getCardWithCache(markCtx, cardID); err == nil && e.base.configMgr != nil {
		info, ok := e.base.configMgr.MergedTaskIntervals(card)[constants.TaskTypePollingPackage]
		if !ok || info.Interval <= 0 {
			return
		}
		ttl = time.Duration(info.Interval) * time.Second
	}
	if err := e.base.redis.Set(markCtx, constants.RedisPollingFlowEvaluatedKey(cardID), "1", ttl).Err(); err != nil {
		e.base.logger.Debug("写流量评估标记失败", zap.Uint("card_id", cardID), zap.Error(err))
	}
}

// flowEvaluatedRecently 判断入库段是否在套餐检查间隔内写过流量评估标记。
func (b *PollingBase) flowEvaluatedRecently(ctx context.Context, cardID uint) bool {
	if b == nil || b.redis == nil {
		return false
	}
	exists, err := b.redis.Exists(ctx, constants.RedisPollingFlowEvaluatedKey(cardID)).Result()
	return err == nil && exists > 0
}