package middleware

import (
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/opentracing/opentracing-go"
	"github.com/opentracing/opentracing-go/ext"
	"github.com/uber/jaeger-client-go/config"
	"io"
)

const (
	AppName        = "gateway"
	JaegerHostPort = "192.168.0.124:6831"
)

func OpenTracing() gin.HandlerFunc {
	return func(c *gin.Context) {
		var parentSpan opentracing.Span

		tracer, closer := NewJaegerTracer(AppName)
		defer closer.Close()

		spCtx, err := opentracing.GlobalTracer().Extract(opentracing.HTTPHeaders, opentracing.HTTPHeadersCarrier(c.Request.Header))

		if err != nil {
			parentSpan = tracer.StartSpan(c.Request.URL.Path)
			defer parentSpan.Finish()
		} else {
			parentSpan = opentracing.StartSpan(
				c.Request.URL.Path,
				opentracing.ChildOf(spCtx),
				opentracing.Tag{Key: string(ext.Component), Value: "HTTP"},
				ext.SpanKindRPCServer,
			)
			defer parentSpan.Finish()
		}

		c.Set("Tracer", tracer)
		asd := fmt.Sprintf("%v", parentSpan.Context())
		c.Set("UberTraceId", asd)
		c.Set("ParentSpanContext", parentSpan.Context())

		c.Next()

		ext.HTTPStatusCode.Set(parentSpan, uint16(c.Writer.Status()))

		if c.Writer.Status() > 299 {
			ext.Error.Set(parentSpan, true)
		}
	}
}

//var Tracer opentracing.Tracer

func NewJaegerTracer(serviceName string) (opentracing.Tracer, io.Closer) {
	cfg := &config.Configuration{
		Sampler: &config.SamplerConfig{
			Type:  "const", //固定采样
			Param: 1,       //1=全采样、0=不采样
		},

		Reporter: &config.ReporterConfig{
			LogSpans:           true,
			LocalAgentHostPort: JaegerHostPort,
		},

		ServiceName: serviceName,
	}

	tracer, closer, err := cfg.NewTracer()
	if err != nil {
		return nil, nil
	}
	opentracing.SetGlobalTracer(tracer)
	//Tracer = tracer
	return tracer, closer
}