package middleware

import (
	"github.com/gin-gonic/gin"
	"github.com/opentracing/opentracing-go"
)

// Trace 链路追踪
func Trace() gin.HandlerFunc {
	return func(ctx *gin.Context) {
		var sp opentracing.Span
		opName := ctx.Request.URL.Path
		// Attempt to join a trace by getting trace context from the headers.
		wireContext, err := opentracing.GlobalTracer().Extract(
			opentracing.TextMap,
			opentracing.HTTPHeadersCarrier(ctx.Request.Header))
		if err != nil {
			// If for whatever reason we can't join, go ahead an start a new root span.
			sp = opentracing.StartSpan(opName)
		} else {
			sp = opentracing.StartSpan(opName, opentracing.ChildOf(wireContext))
		}
		ctx.Set("traceSpan", sp)
		ctx.Next()
		sp.Finish()
	}
}