package httptransport

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

	amr "git.sendico.io/tech/sxchnge/bff/pkg/api/routers"
	"git.sendico.io/tech/sxchnge/bff/pkg/api/routers/health"
	"github.com/go-chi/chi/v5"
	chimetrics "github.com/go-chi/metrics"
	"github.com/prometheus/client_golang/prometheus"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"go.uber.org/zap/zaptest/observer"
	"moul.io/chizap"
)

func TestHTTPCollectorDoesNotGatherHealthOrMetricsRequests(t *testing.T) {
	router := chi.NewRouter()
	router.Use(chimetrics.Collector(chimetrics.CollectorOpts{
		Proto: true,
		Skip: func(r *http.Request) bool {
			return isObservabilityRequest("/api/v1", r.URL.Path)
		},
	}))
	router.Get("/api/v1/health", func(w http.ResponseWriter, _ *http.Request) { w.WriteHeader(http.StatusOK) })
	router.Handle("/metrics", chimetrics.Handler())
	router.Handle("/api/v1/metrics", chimetrics.Handler())
	router.Get("/api/v1/accounts", func(w http.ResponseWriter, _ *http.Request) { w.WriteHeader(http.StatusOK) })

	beforeHealth := gatheredHTTPRequestCount(t, "GET /api/v1/health")
	beforeMetrics := gatheredHTTPRequestCount(t, "GET /metrics")
	beforeAPIMetrics := gatheredHTTPRequestCount(t, "GET /api/v1/metrics")
	beforeApplication := gatheredHTTPRequestCount(t, "GET /api/v1/accounts")

	for _, requestPath := range []string{"/api/v1/health", "/metrics", "/api/v1/metrics", "/api/v1/accounts"} {
		request := httptest.NewRequestWithContext(context.Background(), http.MethodGet, requestPath, nil)
		response := httptest.NewRecorder()
		router.ServeHTTP(response, request)
		if response.Code != http.StatusOK {
			t.Fatalf("GET %s returned %d", requestPath, response.Code)
		}
	}

	if got := gatheredHTTPRequestCount(t, "GET /api/v1/health") - beforeHealth; got != 0 {
		t.Fatalf("health probe changed http_requests_total by %v", got)
	}
	if got := gatheredHTTPRequestCount(t, "GET /metrics") - beforeMetrics; got != 0 {
		t.Fatalf("metrics scrape changed http_requests_total by %v", got)
	}
	if got := gatheredHTTPRequestCount(t, "GET /api/v1/metrics") - beforeAPIMetrics; got != 0 {
		t.Fatalf("API metrics scrape changed http_requests_total by %v", got)
	}
	if got := gatheredHTTPRequestCount(t, "GET /api/v1/accounts") - beforeApplication; got != 1 {
		t.Fatalf("application request changed http_requests_total by %v, want 1", got)
	}
}

func gatheredHTTPRequestCount(t *testing.T, endpoint string) float64 {
	t.Helper()

	families, err := prometheus.DefaultGatherer.Gather()
	if err != nil {
		t.Fatalf("gather metrics: %v", err)
	}
	for _, family := range families {
		if family.GetName() != "http_requests_total" {
			continue
		}

		var total float64
		for _, metric := range family.GetMetric() {
			for _, label := range metric.GetLabel() {
				if label.GetName() == "endpoint" && label.GetValue() == endpoint {
					total += metric.GetCounter().GetValue()
				}
			}
		}
		return total
	}

	return 0
}

func TestObservabilityRequestsAreExcludedFromHTTPMetrics(t *testing.T) {
	tests := []struct {
		name        string
		apiEndpoint string
		requestPath string
		want        bool
	}{
		{name: "health under API endpoint", apiEndpoint: "/api/v1", requestPath: "/api/v1/health", want: true},
		{name: "metrics at root", apiEndpoint: "/api/v1", requestPath: "/metrics", want: true},
		{name: "metrics under API endpoint", apiEndpoint: "/api/v1", requestPath: "/api/v1/metrics", want: true},
		{name: "trailing endpoint slash", apiEndpoint: "/api/v1/", requestPath: "/api/v1/health", want: true},
		{name: "application endpoint", apiEndpoint: "/api/v1", requestPath: "/api/v1/accounts", want: false},
		{name: "health suffix is not a probe", apiEndpoint: "/api/v1", requestPath: "/api/v1/health/history", want: false},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := isObservabilityRequest(tt.apiEndpoint, tt.requestPath); got != tt.want {
				t.Fatalf("isObservabilityRequest(%q, %q) = %t, want %t", tt.apiEndpoint, tt.requestPath, got, tt.want)
			}
		})
	}
}

func TestHealthMountedOutsideTraceMiddleware(t *testing.T) {
	core, observed := observer.New(zapcore.InfoLevel)
	logger := zap.New(core)

	rootRouter := chi.NewRouter()
	apiRouter := chi.NewRouter()

	apiRouter.Use(chizap.New(logger.Named("middleware").Named("http_trace"), &chizap.Opts{}))
	apiRouter.Get("/api/v1/accounts", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	})

	healthRouter, err := amr.NewHealthRouter(logger.Named("middleware"), rootRouter, "/api/v1")
	if err != nil {
		t.Fatalf("failed to create health router: %v", err)
	}
	healthRouter.SetStatus(health.SSRunning)

	rootRouter.Mount("/", apiRouter)

	healthReq := httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/api/v1/health", nil)
	healthRes := httptest.NewRecorder()
	rootRouter.ServeHTTP(healthRes, healthReq)
	if healthRes.Code != http.StatusOK {
		t.Fatalf("expected health status %d, got %d", http.StatusOK, healthRes.Code)
	}
	if got := observed.FilterMessage("Served").Len(); got != 0 {
		t.Fatalf("expected no trace logs for /health, got %d", got)
	}

	apiReq := httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/api/v1/accounts", nil)
	apiRes := httptest.NewRecorder()
	rootRouter.ServeHTTP(apiRes, apiReq)
	if apiRes.Code != http.StatusOK {
		t.Fatalf("expected api status %d, got %d", http.StatusOK, apiRes.Code)
	}

	entries := observed.FilterMessage("Served").All()
	if len(entries) != 1 {
		t.Fatalf("expected one trace log for non-health request, got %d", len(entries))
	}
	if got := entries[0].ContextMap()["path"]; got != "/api/v1/accounts" {
		t.Fatalf("expected logged path %q, got %#v", "/api/v1/accounts", got)
	}
}