package service

import (
	"context"
	"encoding/json"
	"errors"

	"silk-server-go/internal/model"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// DetectionTaskCreatePayload 创建待确认检测任务的 outbox 载荷。
type DetectionTaskCreatePayload struct {
	SourceKey    string `json:"sourceKey"`
	SourceType   string `json:"sourceType"`
	SourceID     string `json:"sourceId"`
	RoomID       string `json:"roomId"`
	BatchID      string `json:"batchId"`
	InspectionID string `json:"inspectionId"`
	Disease      string `json:"disease"`
	Priority     string `json:"priority"`
}

// NewDetectionTaskOutboxHandler 创建检测任务事件处理器。
func NewDetectionTaskOutboxHandler(db *gorm.DB) EventHandler {
	return func(ctx context.Context, event model.OutboxEvent) error {
		if event.EventType != OutboxEventDetectionTaskCreate {
			return nil
		}
		var payload DetectionTaskCreatePayload
		if err := json.Unmarshal(event.Payload, &payload); err != nil {
			return err
		}
		if payload.SourceKey == "" {
			return errors.New("detection task sourceKey is required")
		}
		disease := payload.Disease
		if disease == "" {
			disease = "待确认"
		}
		priority := payload.Priority
		if priority == "" {
			priority = "routine"
		}
		task := model.DetectionTask{
			SourceKey:    payload.SourceKey,
			SourceType:   payload.SourceType,
			SourceID:     payload.SourceID,
			RoomID:       strPtrOrNil(payload.RoomID),
			BatchID:      strPtrOrNil(payload.BatchID),
			InspectionID: strPtrOrNil(payload.InspectionID),
			Disease:      disease,
			Priority:     priority,
			Status:       "pending",
		}
		return db.WithContext(ctx).
			Session(&gorm.Session{SkipDefaultTransaction: true}).
			Clauses(clause.OnConflict{
				Columns:   []clause.Column{{Name: "source_key"}},
				DoNothing: true,
			}).
			Create(&task).Error
	}
}

// NewOutboxHandler 分发当前已支持的业务事件。
func NewOutboxHandler(db *gorm.DB, wechat *WechatService) EventHandler {
	wechatHandler := NewWechatOutboxHandler(db, wechat)
	detectionHandler := NewDetectionTaskOutboxHandler(db)
	return func(ctx context.Context, event model.OutboxEvent) error {
		switch event.EventType {
		case OutboxEventWechatSubscribe:
			return wechatHandler(ctx, event)
		case OutboxEventDetectionTaskCreate:
			return detectionHandler(ctx, event)
		default:
			return nil
		}
	}
}