package tracing

import (
	"context"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	"go.opentelemetry.io/otel/sdk/trace/tracetest"
	logf "sigs.k8s.io/controller-runtime/pkg/log"
)

const sampleTraceparent = "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01"

func TestHTTPMiddleware(t *testing.T) {
	t.Parallel()

	newServer := func(lines *[]string, tp *sdktrace.TracerProvider) http.Handler {
		mux := http.NewServeMux()
		handler := func(w http.ResponseWriter, r *http.Request) {
			logf.FromContext(r.Context()).Info("handling")
			w.WriteHeader(http.StatusOK)
		}
		mux.HandleFunc("GET /healthz", handler)
		mux.HandleFunc("GET /v1/things/{id}", handler)
		return HTTPMiddleware("discovery", captureLogger(lines), WithTracerProvider(tp))(mux)
	}

	t.Run("route span, enriched handler logs, traceparent continuation", func(t *testing.T) {
		t.Parallel()
		sr := tracetest.NewSpanRecorder()
		tp := sdktrace.NewTracerProvider(sdktrace.WithSpanProcessor(sr))
		t.Cleanup(func() { _ = tp.Shutdown(context.Background()) })

		var lines []string
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/v1/things/42", nil)
		req.Header.Set("traceparent", sampleTraceparent)
		newServer(&lines, tp).ServeHTTP(rec, req)

		ended := sr.Ended()
		if len(ended) != 1 {
			t.Fatalf("got %d spans, want 1", len(ended))
		}
		if got := ended[0].Name(); got != "GET /v1/things/{id}" {
			t.Errorf("span name = %q, want route pattern", got)
		}
		wantTrace := "4bf92f3577b34da6a3ce929d0e0e4736"
		if got := ended[0].SpanContext().TraceID().String(); got != wantTrace {
			t.Errorf("span traceID = %s, want continuation of client trace %s", got, wantTrace)
		}
		if len(lines) != 1 {
			t.Fatalf("got %d log lines, want 1: %v", len(lines), lines)
		}
		if n := strings.Count(lines[0], `"traceID"`); n != 1 {
			t.Errorf("traceID appears %d times, want 1: %s", n, lines[0])
		}
		if !strings.Contains(lines[0], wantTrace) {
			t.Errorf("handler log missing traceID %s: %s", wantTrace, lines[0])
		}
	})

	t.Run("healthz is not traced but still gets a logger", func(t *testing.T) {
		t.Parallel()
		sr := tracetest.NewSpanRecorder()
		tp := sdktrace.NewTracerProvider(sdktrace.WithSpanProcessor(sr))
		t.Cleanup(func() { _ = tp.Shutdown(context.Background()) })

		var lines []string
		rec := httptest.NewRecorder()
		newServer(&lines, tp).ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/healthz", nil))

		if len(sr.Ended()) != 0 {
			t.Fatalf("healthz produced %d spans, want 0", len(sr.Ended()))
		}
		if len(lines) != 1 || strings.Contains(lines[0], "traceID") {
			t.Fatalf("want one unenriched log line, got %v", lines)
		}
	})
}