package checks

import (
	"crypto/tls"
	"flag"
	"fmt"
	"log"
	"net"
	"os"
	"testing"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/health"
	hv1 "google.golang.org/grpc/health/grpc_health_v1"
)

var (
	port         int
	server       string
	svcHealthy   string
	svcUnhealthy string
	svcMissing   string
)

func startServer() (*health.Server, *grpc.Server) {
	listener, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	grpcServer := grpc.NewServer()
	server := health.NewServer()
	hv1.RegisterHealthServer(grpcServer, server)
	go grpcServer.Serve(listener)
	return server, grpcServer
}

func init() {
	flag.IntVar(&port, "grpc-stub-port", 54321, "port for the gRPC stub server")
}

func TestMain(m *testing.M) {
	flag.Parse()

	healthy := "healthy"
	unhealthy := "unhealthy"
	missing := "missing"

	srv, grpcStubApp := startServer()
	srv.SetServingStatus(healthy, hv1.HealthCheckResponse_SERVING)
	srv.SetServingStatus(unhealthy, hv1.HealthCheckResponse_NOT_SERVING)

	server = fmt.Sprintf("%s:%d", "localhost", port)
	svcHealthy = fmt.Sprintf("%s/%s", server, healthy)
	svcUnhealthy = fmt.Sprintf("%s/%s", server, unhealthy)
	svcMissing = fmt.Sprintf("%s/%s", server, missing)

	result := 1
	defer func() {
		grpcStubApp.Stop()
		os.Exit(result)
	}()

	result = m.Run()
}

func TestCheck(t *testing.T) {
	type args struct {
		target    string
		timeout   time.Duration
		tlsConfig *tls.Config
	}
	tests := []struct {
		name    string
		args    args
		healthy bool
	}{
		// successes
		{"should pass for healthy server", args{server, time.Second, nil}, true},
		{"should pass for healthy service", args{svcHealthy, time.Second, nil}, true},

		// failures
		{"should fail for unhealthy service", args{svcUnhealthy, time.Second, nil}, false},
		{"should fail for missing service", args{svcMissing, time.Second, nil}, false},
		{"should timeout for healthy service", args{server, time.Nanosecond, nil}, false},
		{"should fail if probe is secure, but server is not", args{server, time.Second, &tls.Config{}}, false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			probe := NewGrpcHealthProbe(tt.args.target, tt.args.timeout, tt.args.tlsConfig)
			actualError := probe.Check()
			actuallyHealthy := actualError == nil
			if tt.healthy != actuallyHealthy {
				t.Errorf("FAIL: %s. Expected healthy %t, but err == %v", tt.name, tt.healthy, actualError)
			}
		})
	}
}