package task

import (
	"context"
	"errors"
	"fmt"
	"path/filepath"
	"strings"
	"time"

	"github.com/bytedance/sonic"
	"github.com/hibiken/asynq"
	"github.com/redis/go-redis/v9"
	"go.uber.org/zap"
	"gorm.io/gorm"

	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/internal/store/postgres"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/storage"
	"github.com/break/junhong_cmp_fiber/pkg/utils"
	"github.com/break/junhong_cmp_fiber/pkg/validator"
)

var (
	ErrStorageNotConfigured = errors.New("对象存储服务未配置")
	ErrStorageKeyEmpty      = errors.New("文件存储路径为空")
)

const batchSize = 1000

type IotCardImportPayload struct {
	TaskID uint `json:"task_id"`
}

// PollingCallback 轮询回调接口
// 用于在卡创建/删除/状态变化时通知轮询系统
type PollingCallback interface {
	// OnBatchCardsCreated 批量卡创建时的回调
	OnBatchCardsCreated(ctx context.Context, cards []*model.IotCard)
}

type IotCardImportHandler struct {
	db              *gorm.DB
	redis           *redis.Client
	importTaskStore *postgres.IotCardImportTaskStore
	iotCardStore    *postgres.IotCardStore
	storageService  *storage.Service
	pollingCallback PollingCallback
	logger          *zap.Logger
}

func NewIotCardImportHandler(
	db *gorm.DB,
	redis *redis.Client,
	importTaskStore *postgres.IotCardImportTaskStore,
	iotCardStore *postgres.IotCardStore,
	storageSvc *storage.Service,
	pollingCallback PollingCallback,
	logger *zap.Logger,
) *IotCardImportHandler {
	return &IotCardImportHandler{
		db:              db,
		redis:           redis,
		importTaskStore: importTaskStore,
		iotCardStore:    iotCardStore,
		storageService:  storageSvc,
		pollingCallback: pollingCallback,
		logger:          logger,
	}
}

func (h *IotCardImportHandler) HandleIotCardImport(ctx context.Context, task *asynq.Task) error {
	var payload IotCardImportPayload
	if err := sonic.Unmarshal(task.Payload(), &payload); err != nil {
		h.logger.Error("解析 IoT 卡导入任务载荷失败",
			zap.Error(err),
			zap.String("task_id", task.ResultWriter().TaskID()),
		)
		return asynq.SkipRetry
	}

	importTask, err := h.importTaskStore.GetByID(ctx, payload.TaskID)
	if err != nil {
		h.logger.Error("获取导入任务失败",
			zap.Uint("task_id", payload.TaskID),
			zap.Error(err),
		)
		return asynq.SkipRetry
	}

	if importTask.Status != model.ImportTaskStatusPending {
		h.logger.Info("导入任务已处理，跳过",
			zap.Uint("task_id", payload.TaskID),
			zap.Int("status", importTask.Status),
		)
		return nil
	}

	h.importTaskStore.UpdateStatus(ctx, importTask.ID, model.ImportTaskStatusProcessing, "")

	h.logger.Info("开始处理 IoT 卡导入任务",
		zap.Uint("task_id", importTask.ID),
		zap.String("task_no", importTask.TaskNo),
		zap.String("storage_key", importTask.StorageKey),
	)

	cards, totalCount, err := h.downloadAndParse(ctx, importTask)
	if err != nil {
		h.logger.Error("下载或解析 Excel 失败",
			zap.Uint("task_id", importTask.ID),
			zap.Error(err),
		)
		h.importTaskStore.UpdateStatus(ctx, importTask.ID, model.ImportTaskStatusFailed, err.Error())
		return asynq.SkipRetry
	}

	importTask.CardList = cards
	importTask.TotalCount = totalCount
	h.importTaskStore.UpdateCardList(ctx, importTask.ID, cards, totalCount)

	result := h.processImport(ctx, importTask)

	h.importTaskStore.UpdateResult(ctx, importTask.ID, result.successCount, result.skipCount, result.failCount, result.skippedItems, result.failedItems)

	if result.failCount > 0 && result.successCount == 0 {
		h.importTaskStore.UpdateStatus(ctx, importTask.ID, model.ImportTaskStatusFailed, "所有导入均失败")
	} else {
		h.importTaskStore.UpdateStatus(ctx, importTask.ID, model.ImportTaskStatusCompleted, "")
	}

	h.logger.Info("IoT 卡导入任务完成",
		zap.Uint("task_id", importTask.ID),
		zap.Int("success_count", result.successCount),
		zap.Int("skip_count", result.skipCount),
		zap.Int("fail_count", result.failCount),
	)

	return nil
}

func (h *IotCardImportHandler) downloadAndParse(ctx context.Context, task *model.IotCardImportTask) (model.CardListJSON, int, error) {
	if h.storageService == nil {
		return nil, 0, ErrStorageNotConfigured
	}

	if task.StorageKey == "" {
		return nil, 0, ErrStorageKeyEmpty
	}

	localPath, cleanup, err := h.storageService.DownloadToTemp(ctx, task.StorageKey)
	if err != nil {
		return nil, 0, err
	}
	defer cleanup()

	if !strings.HasSuffix(strings.ToLower(task.FileName), ".xlsx") {
		ext := filepath.Ext(task.FileName)
		return nil, 0, fmt.Errorf("不支持的文件格式 %s,请上传Excel文件(.xlsx)", ext)
	}

	parseResult, err := utils.ParseCardExcel(localPath)
	if err != nil {
		return nil, 0, err
	}

	cards := make(model.CardListJSON, 0, len(parseResult.Cards))
	for _, card := range parseResult.Cards {
		cards = append(cards, model.CardItem{
			ICCID:  card.ICCID,
			MSISDN: card.MSISDN,
		})
	}

	return cards, parseResult.TotalCount, nil
}

type importResult struct {
	successCount int
	skipCount    int
	failCount    int
	skippedItems model.ImportResultItems
	failedItems  model.ImportResultItems
}

func (h *IotCardImportHandler) processImport(ctx context.Context, task *model.IotCardImportTask) *importResult {
	result := &importResult{
		skippedItems: make(model.ImportResultItems, 0),
		failedItems:  make(model.ImportResultItems, 0),
	}

	cards := h.getCardsFromTask(task)
	if len(cards) == 0 {
		return result
	}

	for i := 0; i < len(cards); i += batchSize {
		end := min(i+batchSize, len(cards))
		batch := cards[i:end]
		h.processBatch(ctx, task, batch, i+1, result)
	}

	return result
}

// getCardsFromTask 从任务中获取待导入的卡列表
func (h *IotCardImportHandler) getCardsFromTask(task *model.IotCardImportTask) []model.CardItem {
	return []model.CardItem(task.CardList)
}

func (h *IotCardImportHandler) processBatch(ctx context.Context, task *model.IotCardImportTask, batch []model.CardItem, startLine int, result *importResult) {
	type cardMeta struct {
		line   int
		msisdn string
	}
	validCards := make([]model.CardItem, 0)
	cardMetaMap := make(map[string]cardMeta)

	for i, card := range batch {
		line := startLine + i
		cardMetaMap[card.ICCID] = cardMeta{line: line, msisdn: card.MSISDN}

		validationResult := validator.ValidateICCID(card.ICCID, task.CarrierType)
		if !validationResult.Valid {
			result.failedItems = append(result.failedItems, model.ImportResultItem{
				Line:   line,
				ICCID:  card.ICCID,
				MSISDN: card.MSISDN,
				Reason: validationResult.Message,
			})
			result.failCount++
			continue
		}
		validCards = append(validCards, card)
	}

	if len(validCards) == 0 {
		return
	}

	validICCIDs := make([]string, len(validCards))
	for i, card := range validCards {
		validICCIDs[i] = card.ICCID
	}

	existingMap, err := h.iotCardStore.ExistsByICCIDBatch(ctx, validICCIDs)
	if err != nil {
		h.logger.Error("批量检查 ICCID 是否存在失败",
			zap.Error(err),
			zap.Int("batch_size", len(validICCIDs)),
		)
		for _, card := range validCards {
			meta := cardMetaMap[card.ICCID]
			result.failedItems = append(result.failedItems, model.ImportResultItem{
				Line:   meta.line,
				ICCID:  card.ICCID,
				MSISDN: meta.msisdn,
				Reason: "数据库查询失败",
			})
			result.failCount++
		}
		return
	}

	newCards := make([]model.CardItem, 0)
	for _, card := range validCards {
		meta := cardMetaMap[card.ICCID]
		if existingMap[card.ICCID] {
			result.skippedItems = append(result.skippedItems, model.ImportResultItem{
				Line:   meta.line,
				ICCID:  card.ICCID,
				MSISDN: meta.msisdn,
				Reason: "ICCID 已存在",
			})
			result.skipCount++
		} else {
			newCards = append(newCards, card)
		}
	}

	if len(newCards) == 0 {
		return
	}

	iotCards := make([]*model.IotCard, 0, len(newCards))
	now := time.Now()
	for _, card := range newCards {
		iotCard := &model.IotCard{
			ICCID:            card.ICCID,
			MSISDN:           card.MSISDN,
			CarrierID:        task.CarrierID,
			BatchNo:          task.BatchNo,
			Status:           constants.IotCardStatusInStock,
			CardCategory:     constants.CardCategoryNormal,
			ActivationStatus: constants.ActivationStatusInactive,
			RealNameStatus:   constants.RealNameStatusNotVerified,
			NetworkStatus:    constants.NetworkStatusOffline,
		}
		iotCard.BaseModel.Creator = task.Creator
		iotCard.BaseModel.Updater = task.Creator
		iotCard.CreatedAt = now
		iotCard.UpdatedAt = now
		iotCards = append(iotCards, iotCard)
	}

	if err := h.iotCardStore.CreateBatch(ctx, iotCards); err != nil {
		h.logger.Error("批量创建 IoT 卡失败",
			zap.Error(err),
			zap.Int("batch_size", len(iotCards)),
		)
		for _, card := range newCards {
			meta := cardMetaMap[card.ICCID]
			result.failedItems = append(result.failedItems, model.ImportResultItem{
				Line:   meta.line,
				ICCID:  card.ICCID,
				MSISDN: meta.msisdn,
				Reason: "数据库写入失败",
			})
			result.failCount++
		}
		return
	}

	result.successCount += len(newCards)

	// 通知轮询系统：批量卡已创建
	if h.pollingCallback != nil {
		h.pollingCallback.OnBatchCardsCreated(ctx, iotCards)
	}
}