package grpcapi

import (
	"context"
	"net"
	"testing"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"

	"git.ipng.ch/ipng/vpp-maglev/internal/checker"
	"git.ipng.ch/ipng/vpp-maglev/internal/config"
	"git.ipng.ch/ipng/vpp-maglev/internal/health"
)

func makeTestChecker(ctx context.Context) *checker.Checker {
	cfg := &config.Frontend{
		HealthCheckNetns: "test",
		HealthChecker:    config.HealthCheckerConfig{TransitionHistory: 5},
		VIPs: map[string]config.VIP{
			"web": {
				Address:  net.ParseIP("192.0.2.1"),
				Protocol: "tcp",
				Port:     80,
				Backends: []net.IP{net.ParseIP("10.0.0.2")},
				HealthCheck: config.HealthCheck{
					Type:     "icmp",
					Interval: time.Hour, // long interval: probes won't fire during tests
					Timeout:  time.Second,
					Fall:     3,
					Rise:     2,
				},
			},
		},
	}
	c := checker.New(cfg)
	go c.Run(ctx) //nolint:errcheck
	// Allow the Run goroutine to initialize workers.
	time.Sleep(10 * time.Millisecond)
	return c
}

func startTestServer(t *testing.T, c *checker.Checker) (HealthCheckerClient, func()) {
	t.Helper()
	lis, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen: %v", err)
	}
	srv := grpc.NewServer()
	RegisterHealthCheckerServer(srv, NewServer(c))
	go srv.Serve(lis) //nolint:errcheck

	conn, err := grpc.NewClient(lis.Addr().String(),
		grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		t.Fatalf("dial: %v", err)
	}
	return NewHealthCheckerClient(conn), func() {
		conn.Close()
		srv.Stop()
	}
}

func TestListVIPs(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := makeTestChecker(ctx)
	client, cleanup := startTestServer(t, c)
	defer cleanup()

	resp, err := client.ListVIPs(ctx, &ListVIPsRequest{})
	if err != nil {
		t.Fatalf("ListVIPs: %v", err)
	}
	if len(resp.VipNames) != 1 || resp.VipNames[0] != "web" {
		t.Errorf("ListVIPs: got %v, want [web]", resp.VipNames)
	}
}

func TestGetVIP(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := makeTestChecker(ctx)
	client, cleanup := startTestServer(t, c)
	defer cleanup()

	info, err := client.GetVIP(ctx, &GetVIPRequest{VipName: "web"})
	if err != nil {
		t.Fatalf("GetVIP: %v", err)
	}
	if info.Address != "192.0.2.1" {
		t.Errorf("GetVIP address: got %q, want 192.0.2.1", info.Address)
	}
	if info.Port != 80 {
		t.Errorf("GetVIP port: got %d, want 80", info.Port)
	}
}

func TestGetVIPNotFound(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := makeTestChecker(ctx)
	client, cleanup := startTestServer(t, c)
	defer cleanup()

	_, err := client.GetVIP(ctx, &GetVIPRequest{VipName: "nope"})
	if err == nil {
		t.Error("expected error for unknown VIP")
	}
}

func TestGetBackend(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := makeTestChecker(ctx)
	client, cleanup := startTestServer(t, c)
	defer cleanup()

	info, err := client.GetBackend(ctx, &GetBackendRequest{
		VipName:        "web",
		BackendAddress: "10.0.0.2",
	})
	if err != nil {
		t.Fatalf("GetBackend: %v", err)
	}
	if info.State != health.StateUnknown.String() {
		t.Errorf("initial state: got %q, want unknown", info.State)
	}
}

func TestPauseResumeBackend(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := makeTestChecker(ctx)
	client, cleanup := startTestServer(t, c)
	defer cleanup()

	info, err := client.PauseBackend(ctx, &PauseResumeRequest{
		VipName:        "web",
		BackendAddress: "10.0.0.2",
	})
	if err != nil {
		t.Fatalf("PauseBackend: %v", err)
	}
	if info.State != health.StatePaused.String() {
		t.Errorf("after pause: got %q, want paused", info.State)
	}

	info, err = client.ResumeBackend(ctx, &PauseResumeRequest{
		VipName:        "web",
		BackendAddress: "10.0.0.2",
	})
	if err != nil {
		t.Fatalf("ResumeBackend: %v", err)
	}
	if info.State != health.StateUnknown.String() {
		t.Errorf("after resume: got %q, want unknown", info.State)
	}
}

func TestWatchTransitions(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	c := makeTestChecker(ctx)
	client, cleanup := startTestServer(t, c)
	defer cleanup()

	stream, err := client.WatchTransitions(ctx, &WatchRequest{})
	if err != nil {
		t.Fatalf("WatchTransitions: %v", err)
	}

	// Should receive the current state for web:10.0.0.2 immediately.
	ev, err := stream.Recv()
	if err != nil {
		t.Fatalf("Recv: %v", err)
	}
	if ev.VipName != "web" || ev.BackendAddress != "10.0.0.2" {
		t.Errorf("initial event: vip=%q backend=%q", ev.VipName, ev.BackendAddress)
	}
}