package statistic

import (
	"context"
	"sync"
	"time"

	dubboclient "dubbo.apache.org/dubbo-go/v3/client"
	"github.com/google/uuid"
	pb "github.com/topfans/backend/pkg/proto/event"
	statisticPb "github.com/topfans/backend/pkg/proto/statistic"
)

var (
	instance *Client
	once     sync.Once
)

// Client 业务侧统一 SDK（fire-and-forget 调用 statisticService）
type Client struct {
	service statisticPb.StatisticService
}

// Init 用 Dubbo client 初始化 SDK（在业务服务 main.go 启动时调用一次）
func Init(dubboClient *dubboclient.Client) error {
	var err error
	once.Do(func() {
		svc, e := statisticPb.NewStatisticService(dubboClient)
		if e != nil {
			err = e
			return
		}
		instance = &Client{service: svc}
	})
	return err
}

// Get 返回全局 SDK 实例（Init 之后才能用）
func Get() *Client { return instance }

// TrackEvent fire-and-forget 上报单个事件
//  - 自动填充 event_id（若为空）和 occurred_at
//  - 不阻塞业务方（独立 goroutine + background context）
func (c *Client) TrackEvent(ctx context.Context, e *pb.Event) {
	if c == nil || c.service == nil {
		return
	}
	if e.EventId == "" {
		e.EventId = uuid.New().String()
	}
	if e.OccurredAt == 0 {
		e.OccurredAt = time.Now().UnixMilli()
	}
	bgCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	go func() {
		defer cancel()
		_, _ = c.service.TrackEvent(bgCtx, e)
	}()
}

// SetMockForTest 测试钩子：注入 mock 客户端
var mockForTest Capturer

// Capturer 测试用 capture 接口
type Capturer interface {
	Capture(e *pb.Event)
}

// SetMockForTest 注入测试 mock
func SetMockForTest(c Capturer) { mockForTest = c }

// ResetMockForTest 重置 mock
func ResetMockForTest() { mockForTest = nil }

// TrackEventSync 同步版本（测试用）
func (c *Client) TrackEventSync(ctx context.Context, e *pb.Event) (*statisticPb.TrackEventResponse, error) {
	if e.EventId == "" {
		e.EventId = uuid.New().String()
	}
	if e.OccurredAt == 0 {
		e.OccurredAt = time.Now().UnixMilli()
	}
	if mockForTest != nil {
		mockForTest.Capture(e)
		return &statisticPb.TrackEventResponse{Accepted: 1, Rejected: 0}, nil
	}
	if c == nil || c.service == nil {
		return &statisticPb.TrackEventResponse{Accepted: 0, Rejected: 1}, nil
	}
	return c.service.TrackEvent(ctx, e)
}