package task

import (
	"context"
	"time"

	"github.com/hibiken/asynq"
	"go.uber.org/zap"
	"gorm.io/gorm"

	"github.com/break/junhong_cmp_fiber/internal/gateway"
	"github.com/break/junhong_cmp_fiber/internal/model"
	iot_card_svc "github.com/break/junhong_cmp_fiber/internal/service/iot_card"
	packagepkg "github.com/break/junhong_cmp_fiber/internal/service/package"
	"github.com/break/junhong_cmp_fiber/internal/store/postgres"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
)

// PollingCarddataHandler 流量检查任务处理器
// 职责：调 Gateway 查流量 → 写 DB → 扣减套餐流量 → 调 EvaluateAndAct 判断停复机
// 不做：直接停复机决策，委托给 StopResumeService.EvaluateAndAct
type PollingCarddataHandler struct {
	base          *PollingBase
	gateway       *gateway.Client
	iotCardStore  *postgres.IotCardStore
	carrierStore  *postgres.CarrierStore
	usageService  *packagepkg.UsageService
	stopResumeSvc iot_card_svc.StopResumeServiceInterface
}

// NewPollingCarddataHandler 创建流量检查任务处理器
func NewPollingCarddataHandler(
	base *PollingBase,
	gw *gateway.Client,
	iotCardStore *postgres.IotCardStore,
	carrierStore *postgres.CarrierStore,
	usageService *packagepkg.UsageService,
	stopResumeSvc iot_card_svc.StopResumeServiceInterface,
) *PollingCarddataHandler {
	return &PollingCarddataHandler{
		base:          base,
		gateway:       gw,
		iotCardStore:  iotCardStore,
		carrierStore:  carrierStore,
		usageService:  usageService,
		stopResumeSvc: stopResumeSvc,
	}
}

// Handle 处理流量检查任务
func (h *PollingCarddataHandler) Handle(ctx context.Context, t *asynq.Task) error {
	startTime := time.Now()

	cardID, ok := parseTaskPayload(t.Payload(), h.base.logger)
	if !ok {
		return nil
	}

	if !h.base.acquireConcurrency(ctx, constants.TaskTypePollingCarddata) {
		h.base.logger.Debug("并发已满，重新入队", zap.Uint("card_id", cardID))
		return h.base.requeueCard(ctx, cardID, constants.TaskTypePollingCarddata)
	}
	defer h.base.releaseConcurrency(ctx, constants.TaskTypePollingCarddata)

	card, err := h.base.getCardWithCache(ctx, cardID)
	if err != nil {
		if isNotFound(err) {
			return nil
		}
		h.base.logger.Error("获取卡信息失败", zap.Uint("card_id", cardID), zap.Error(err))
		h.base.updateStats(ctx, constants.TaskTypePollingCarddata, false, time.Since(startTime))
		return h.base.requeueCard(ctx, cardID, constants.TaskTypePollingCarddata)
	}

	var gatewayFlowMB float64
	if h.gateway != nil {
		result, gwErr := h.gateway.QueryFlow(ctx, &gateway.FlowQueryReq{CardNo: card.ICCID})
		if gwErr != nil {
			h.base.logger.Warn("查询流量失败",
				zap.Uint("card_id", cardID), zap.String("iccid", card.ICCID), zap.Error(gwErr))
			h.base.updateStats(ctx, constants.TaskTypePollingCarddata, false, time.Since(startTime))
			return h.base.requeueCard(ctx, cardID, constants.TaskTypePollingCarddata)
		}
		gatewayFlowMB = result.Used
	} else {
		gatewayFlowMB = card.CurrentMonthUsageMB
	}

	now := time.Now()
	resetDay := h.carrierStore.GetDataResetDay(ctx, card.CarrierID)
	updates, flowIncrementMB, isCrossMonth := h.calculateFlowUpdates(card, gatewayFlowMB, now, resetDay)
	updates["last_data_check_at"] = now

	if updateErr := h.iotCardStore.UpdateFields(ctx, cardID, updates); updateErr != nil {
		h.base.logger.Error("更新卡流量信息失败", zap.Uint("card_id", cardID), zap.Error(updateErr))
	}

	go h.base.insertDataUsageRecord(context.Background(), cardID, flowIncrementMB, now)

	cacheUpdates := map[string]any{"last_gateway_reading_mb": gatewayFlowMB}
	if isCrossMonth {
		// 跨月时同步更新缓存中的本月开始日期和本月用量，避免下次从缓存读取时再次误判跨月
		currentMonthStart := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
		cacheUpdates["current_month_start_date"] = currentMonthStart.Unix()
		if flowIncrementMB > 0 {
			cacheUpdates["current_month_usage_mb"] = flowIncrementMB
		} else {
			cacheUpdates["current_month_usage_mb"] = float64(0)
		}
	}
	h.base.updateCardCache(ctx, cardID, cacheUpdates)

	if flowIncrementMB > 0 && h.usageService != nil {
		if deductErr := h.usageService.DeductDataUsage(ctx, "iot_card", cardID, int64(flowIncrementMB)); deductErr != nil {
			h.base.logger.Warn("套餐流量扣减失败",
				zap.Uint("card_id", cardID), zap.Float64("increment_mb", flowIncrementMB), zap.Error(deductErr))
		}
	}

	if h.stopResumeSvc != nil {
		freshCard, loadErr := h.iotCardStore.GetByID(ctx, cardID)
		if loadErr == nil {
			if evalErr := h.stopResumeSvc.EvaluateAndAct(ctx, freshCard); evalErr != nil {
				h.base.logger.Warn("流量检查后停复机评估失败",
					zap.Uint("card_id", cardID), zap.Error(evalErr))
			}
		}
	}

	h.base.updateStats(ctx, constants.TaskTypePollingCarddata, true, time.Since(startTime))
	return h.base.requeueCard(ctx, cardID, constants.TaskTypePollingCarddata)
}

// calculateFlowUpdates 计算流量更新字段、增量和是否跨月
// 决策13：完整迁移跨月流量边界检测逻辑（月份切换检测、上月总量保存、当月计数器重置）
// 第三个返回值 isCrossMonth 供调用方同步更新 Redis 缓存，避免下次误判跨月
func (h *PollingCarddataHandler) calculateFlowUpdates(card *model.IotCard, gatewayFlowMB float64, now time.Time, resetDay int) (map[string]any, float64, bool) {
	updates := make(map[string]any)

	increment := gatewayFlowMB - card.LastGatewayReadingMB
	if increment < 0 {
		if isResetWindow(now, resetDay) {
			increment = gatewayFlowMB
			h.base.logger.Info("检测到上游运营商重置",
				zap.Uint("card_id", card.ID),
				zap.Float64("gateway_flow", gatewayFlowMB),
				zap.Float64("last_reading", card.LastGatewayReadingMB),
				zap.Int("reset_day", resetDay))
		} else {
			h.base.logger.Warn("流量异常：非重置日出现值下降",
				zap.Uint("card_id", card.ID),
				zap.Float64("gateway_flow", gatewayFlowMB),
				zap.Float64("last_reading", card.LastGatewayReadingMB))
			increment = 0
		}
	}

	updates["last_gateway_reading_mb"] = gatewayFlowMB

	currentMonthStart := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
	isCrossMonth := card.CurrentMonthStartDate == nil ||
		card.CurrentMonthStartDate.Before(currentMonthStart)

	if isCrossMonth {
		h.base.logger.Info("检测到跨月，重置流量计数",
			zap.Uint("card_id", card.ID),
			zap.Float64("last_month_total", card.CurrentMonthUsageMB))
		updates["last_month_total_mb"] = card.CurrentMonthUsageMB
		updates["current_month_start_date"] = currentMonthStart
		if increment > 0 {
			updates["current_month_usage_mb"] = increment
		} else {
			updates["current_month_usage_mb"] = float64(0)
		}
	} else if increment > 0 {
		updates["current_month_usage_mb"] = gorm.Expr("current_month_usage_mb + ?", increment)
	}

	if increment > 0 {
		updates["data_usage_mb"] = gorm.Expr("data_usage_mb + ?", int64(increment))
	}

	if card.CurrentMonthStartDate == nil {
		updates["current_month_start_date"] = currentMonthStart
	}

	return updates, increment, isCrossMonth
}
