// Copyright (c) 2026, Pim van Pelt <pim@ipng.ch>

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.Config{
		HealthChecker: config.HealthCheckerConfig{TransitionHistory: 5},
		HealthChecks: map[string]config.HealthCheck{
			"icmp": {
				Type:     "icmp",
				Interval: time.Hour, // long interval: probes won't fire during tests
				Timeout:  time.Second,
				Fall:     3,
				Rise:     2,
			},
		},
		Backends: map[string]config.Backend{
			"be0": {
				Address:     net.ParseIP("10.0.0.2"),
				HealthCheck: "icmp",
				Enabled:     true,
				Weight:      100,
			},
		},
		Frontends: map[string]config.Frontend{
			"web": {
				Address:  net.ParseIP("192.0.2.1"),
				Protocol: "tcp",
				Port:     80,
				Backends: []string{"be0"},
			},
		},
	}
	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, ctx context.Context, c *checker.Checker) (MaglevClient, func()) {
	t.Helper()
	lis, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen: %v", err)
	}
	srv := grpc.NewServer()
	RegisterMaglevServer(srv, NewServer(ctx, 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 NewMaglevClient(conn), func() {
		conn.Close()
		srv.Stop()
	}
}

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

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

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

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

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

	info, err := client.GetFrontend(ctx, &GetFrontendRequest{Name: "web"})
	if err != nil {
		t.Fatalf("GetFrontend: %v", err)
	}
	if info.Address != "192.0.2.1" {
		t.Errorf("GetFrontend address: got %q, want 192.0.2.1", info.Address)
	}
	if info.Port != 80 {
		t.Errorf("GetFrontend port: got %d, want 80", info.Port)
	}
	if len(info.BackendNames) != 1 || info.BackendNames[0] != "be0" {
		t.Errorf("GetFrontend backend_names: got %v, want [be0]", info.BackendNames)
	}
}

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

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

	_, err := client.GetFrontend(ctx, &GetFrontendRequest{Name: "nope"})
	if err == nil {
		t.Error("expected error for unknown frontend")
	}
}

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

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

	resp, err := client.ListBackends(ctx, &ListBackendsRequest{})
	if err != nil {
		t.Fatalf("ListBackends: %v", err)
	}
	if len(resp.BackendNames) != 1 || resp.BackendNames[0] != "be0" {
		t.Errorf("ListBackends: got %v, want [be0]", resp.BackendNames)
	}
}

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

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

	info, err := client.GetBackend(ctx, &GetBackendRequest{Name: "be0"})
	if err != nil {
		t.Fatalf("GetBackend: %v", err)
	}
	if info.State != health.StateUnknown.String() {
		t.Errorf("initial state: got %q, want unknown", info.State)
	}
	if !info.Enabled {
		t.Error("expected enabled=true")
	}
	if info.Weight != 100 {
		t.Errorf("weight: got %d, want 100", info.Weight)
	}
	if info.Healthcheck != "icmp" {
		t.Errorf("healthcheck: got %q, want icmp", info.Healthcheck)
	}
}

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

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

	_, err := client.GetBackend(ctx, &GetBackendRequest{Name: "nope"})
	if err == nil {
		t.Error("expected error for unknown backend")
	}
}

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

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

	info, err := client.PauseBackend(ctx, &PauseResumeRequest{Name: "be0"})
	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{Name: "be0"})
	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 TestListHealthChecks(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

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

	resp, err := client.ListHealthChecks(ctx, &ListHealthChecksRequest{})
	if err != nil {
		t.Fatalf("ListHealthChecks: %v", err)
	}
	if len(resp.Names) != 1 || resp.Names[0] != "icmp" {
		t.Errorf("ListHealthChecks: got %v, want [icmp]", resp.Names)
	}
}

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

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

	info, err := client.GetHealthCheck(ctx, &GetHealthCheckRequest{Name: "icmp"})
	if err != nil {
		t.Fatalf("GetHealthCheck: %v", err)
	}
	if info.Type != "icmp" {
		t.Errorf("type: got %q, want icmp", info.Type)
	}
	if info.Fall != 3 || info.Rise != 2 {
		t.Errorf("fall/rise: got %d/%d, want 3/2", info.Fall, info.Rise)
	}
}

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

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

	_, err := client.GetHealthCheck(ctx, &GetHealthCheckRequest{Name: "nope"})
	if err == nil {
		t.Error("expected error for unknown healthcheck")
	}
}

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

	c := makeTestChecker(ctx)

	// Use a separate server context so we can cancel it independently.
	srvCtx, srvCancel := context.WithCancel(ctx)
	client, cleanup := startTestServer(t, srvCtx, c)
	defer cleanup()

	stream, err := client.WatchBackendEvents(ctx, &WatchRequest{})
	if err != nil {
		t.Fatalf("WatchBackendEvents: %v", err)
	}
	// Drain the initial synthetic event.
	if _, err := stream.Recv(); err != nil {
		t.Fatalf("initial Recv: %v", err)
	}

	// Cancel the server context; the stream must terminate.
	srvCancel()
	_, err = stream.Recv()
	if err == nil {
		t.Fatal("expected stream to close after server shutdown, got nil error")
	}
}

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

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

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

	// Should receive the current state for be0 immediately.
	ev, err := stream.Recv()
	if err != nil {
		t.Fatalf("Recv: %v", err)
	}
	if ev.BackendName != "be0" {
		t.Errorf("initial event: backend=%q, want be0", ev.BackendName)
	}
}