package task

import (
	"bytes"
	"context"
	"encoding/csv"
	"io"
	"os"
	"strings"

	"github.com/hibiken/asynq"

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

type deviceBatchAllocationRow struct {
	line       int
	identifier string
}

func (h *DeviceImportHandler) handleDeviceBatchAllocation(ctx context.Context, task *model.DeviceImportTask) error {
	if h.allocationExecutor == nil || task.TargetID == nil || *task.TargetID == 0 {
		_ = h.importTaskStore.UpdateStatus(ctx, task.ID, model.ImportTaskStatusFailed, "设备批量分配执行器或目标未配置")
		return asynq.SkipRetry
	}
	rows, err := h.downloadDeviceBatchAllocationCSV(ctx, task)
	if err != nil {
		_ = h.importTaskStore.UpdateStatus(ctx, task.ID, model.ImportTaskStatusFailed, err.Error())
		return asynq.SkipRetry
	}
	workerCtx := middleware.SetUserContext(ctx, &middleware.UserContextInfo{
		UserID: task.Creator, UserType: task.OperatorType, Username: task.CreatorName,
		ShopID: valueOrZero(task.OperatorShopID), SubordinateShopIDs: operatorDeviceShopScope(task.OperatorShopID),
	})
	result, err := h.executeDeviceBatchAllocation(workerCtx, task, rows)
	if err != nil {
		_ = h.importTaskStore.UpdateStatus(ctx, task.ID, model.ImportTaskStatusFailed, err.Error())
		return asynq.SkipRetry
	}
	_ = h.importTaskStore.UpdateResult(ctx, task.ID, len(rows), result.successCount, result.skipCount, result.failCount, 0, result.skippedItems, result.failedItems, nil)
	if result.successCount == 0 && result.failCount > 0 {
		_ = h.importTaskStore.UpdateStatus(ctx, task.ID, model.ImportTaskStatusFailed, "所有设备分配均失败")
	} else {
		_ = h.importTaskStore.UpdateStatus(ctx, task.ID, model.ImportTaskStatusCompleted, "")
	}
	return nil
}

func (h *DeviceImportHandler) downloadDeviceBatchAllocationCSV(ctx context.Context, task *model.DeviceImportTask) ([]deviceBatchAllocationRow, error) {
	if h.storageService == nil || task.StorageKey == "" {
		return nil, errors.New(errors.CodeServiceUnavailable, "设备批量分配对象存储未配置")
	}
	path, cleanup, err := h.storageService.DownloadToTemp(ctx, task.StorageKey)
	if err != nil {
		return nil, errors.Wrap(errors.CodeInternalError, err, "下载设备批量分配CSV失败")
	}
	defer cleanup()
	info, err := os.Stat(path)
	if err != nil || info.Size() > constants.DeviceBatchAllocationMaxFileSize {
		return nil, errors.New(errors.CodeInvalidParam, "设备批量分配CSV不存在或超过10MB")
	}
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, errors.Wrap(errors.CodeInternalError, err, "读取设备批量分配CSV失败")
	}
	return parseDeviceBatchAllocationCSV(data)
}

func parseDeviceBatchAllocationCSV(data []byte) ([]deviceBatchAllocationRow, error) {
	data = bytes.TrimPrefix(data, []byte{0xEF, 0xBB, 0xBF})
	reader := csv.NewReader(bytes.NewReader(data))
	reader.FieldsPerRecord = -1
	rows := make([]deviceBatchAllocationRow, 0)
	for line := 1; ; line++ {
		record, err := reader.Read()
		if err == io.EOF {
			break
		}
		if err != nil || len(record) != 1 {
			return nil, errors.New(errors.CodeInvalidParam, "设备批量分配CSV必须只有一列设备标识")
		}
		identifier := strings.TrimSpace(record[0])
		if line == 1 && (identifier == "device_identifier" || identifier == "设备标识") {
			continue
		}
		if identifier == "" {
			return nil, errors.New(errors.CodeInvalidParam, "设备批量分配CSV存在空设备标识")
		}
		rows = append(rows, deviceBatchAllocationRow{line: line, identifier: identifier})
		if len(rows) > constants.DeviceBatchAllocationMaxRows {
			return nil, errors.New(errors.CodeInvalidParam, "设备批量分配CSV最多包含1000行设备")
		}
	}
	if len(rows) == 0 {
		return nil, errors.New(errors.CodeInvalidParam, "设备批量分配CSV没有有效数据行")
	}
	return rows, nil
}

func (h *DeviceImportHandler) executeDeviceBatchAllocation(ctx context.Context, task *model.DeviceImportTask, rows []deviceBatchAllocationRow) (*deviceImportResult, error) {
	result := &deviceImportResult{skippedItems: model.ImportResultItems{}, failedItems: model.ImportResultItems{}}
	identifiers := make([]string, 0, len(rows))
	for _, row := range rows {
		identifiers = append(identifiers, row.identifier)
	}
	devices, err := h.deviceStore.GetByIdentifiers(ctx, identifiers)
	if err != nil {
		return nil, errors.Wrap(errors.CodeDatabaseError, err, "批量查询设备失败")
	}
	lookup := make(map[string]*model.Device, len(devices)*3)
	for _, device := range devices {
		for _, key := range []string{device.VirtualNo, device.IMEI, device.SN} {
			if key != "" {
				lookup[key] = device
			}
		}
	}
	seen := make(map[uint]struct{})
	pending := make([]uint, 0, len(rows))
	lineByID := make(map[uint]deviceBatchAllocationRow)
	for _, row := range rows {
		device := lookup[row.identifier]
		if device == nil {
			result.failedItems = append(result.failedItems, deviceAllocationResultItem(row, "设备不存在或无权限"))
			result.failCount++
			continue
		}
		if _, exists := seen[device.ID]; exists {
			result.skippedItems = append(result.skippedItems, deviceAllocationResultItem(row, "同一文件重复设备"))
			result.skipCount++
			continue
		}
		seen[device.ID] = struct{}{}
		if deviceAlreadyAtAllocationTarget(device, task.OperationType, *task.TargetID) {
			result.successCount++
			continue
		}
		pending = append(pending, device.ID)
		lineByID[device.ID] = row
	}
	if len(pending) == 0 {
		return result, nil
	}
	failed, err := h.applyDeviceBatchAllocation(ctx, task, pending)
	if err != nil {
		return nil, err
	}
	for _, id := range pending {
		if reason, exists := failed[id]; exists {
			result.failedItems = append(result.failedItems, deviceAllocationResultItem(lineByID[id], reason))
			result.failCount++
		} else {
			result.successCount++
		}
	}
	return result, nil
}

func (h *DeviceImportHandler) applyDeviceBatchAllocation(ctx context.Context, task *model.DeviceImportTask, deviceIDs []uint) (map[uint]string, error) {
	failed := make(map[uint]string)
	switch task.OperationType {
	case constants.DeviceImportOperationAssignShop:
		response, err := h.allocationExecutor.AllocateDevices(ctx, &dto.AllocateDevicesRequest{TargetShopID: *task.TargetID, DeviceIDs: deviceIDs, Remark: "CSV批量分配任务 " + task.TaskNo}, task.Creator, task.OperatorShopID)
		if err != nil {
			return nil, err
		}
		for _, item := range response.FailedItems {
			failed[item.DeviceID] = item.Reason
		}
	case constants.DeviceImportOperationAssignSeries:
		response, err := h.allocationExecutor.BatchSetSeriesBinding(ctx, &dto.BatchSetDeviceSeriesBindngRequest{SelectionType: dto.SelectionTypeList, DeviceIDs: deviceIDs, SeriesID: *task.TargetID}, task.OperatorShopID)
		if err != nil {
			return nil, err
		}
		for _, item := range response.FailedItems {
			failed[item.DeviceID] = item.Reason
		}
	default:
		return nil, errors.New(errors.CodeInvalidParam, "设备批量分配任务类型不支持")
	}
	return failed, nil
}

func deviceAlreadyAtAllocationTarget(device *model.Device, operation string, targetID uint) bool {
	if operation == constants.DeviceImportOperationAssignShop {
		return device.ShopID != nil && *device.ShopID == targetID
	}
	return operation == constants.DeviceImportOperationAssignSeries && device.SeriesID != nil && *device.SeriesID == targetID
}

func deviceAllocationResultItem(row deviceBatchAllocationRow, reason string) model.ImportResultItem {
	return model.ImportResultItem{Line: row.line, ICCID: row.identifier, Reason: reason}
}

func valueOrZero(value *uint) uint {
	if value == nil {
		return 0
	}
	return *value
}

func operatorDeviceShopScope(shopID *uint) []uint {
	if shopID == nil {
		return nil
	}
	return []uint{*shopID}
}