package trace

import (
	"net/http"

	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/trace"
)

type recorder struct {
	http.ResponseWriter
	status int
}

func (r *recorder) WriteHeader(code int) {
	r.status = code
	r.ResponseWriter.WriteHeader(code)
}

func Middleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ctx := otel.GetTextMapPropagator().Extract(r.Context(), propagation.HeaderCarrier(r.Header))

		tracer := otel.Tracer("")
		spanName := r.Method + " " + r.URL.Path

		ctx, span := tracer.Start(ctx, spanName,
			trace.WithAttributes(
				attribute.String("http.method", r.Method),
				attribute.String("http.target", r.URL.String()),
				attribute.String("http.host", r.Host),
				attribute.String("http.scheme", scheme(r)),
			),
		)
		defer span.End()

		rec := &recorder{ResponseWriter: w, status: http.StatusOK}
		next.ServeHTTP(rec, r.WithContext(ctx))

		span.SetAttributes(
			attribute.Int("http.status_code", rec.status),
			attribute.String("http.status_text", http.StatusText(rec.status)),
		)
	})
}

func scheme(r *http.Request) string {
	if r.TLS != nil {
		return "https"
	}
	return "http"
}