package httpapi

import (
	"context"
	"errors"
	"io"
	"net"
	"net/http"
	"sync"
	"testing"
	"time"

	"git.5iot.com/iotlcm-public/iotlcm-worker-svr/internal/fullsync/contract"
)

func awaitServer(t *testing.T, done <-chan error) error {
	t.Helper()
	select {
	case err := <-done:
		return err
	case <-time.After(5 * time.Second):
		t.Fatal("server did not stop")
		return nil
	}
}

func startTestServer(t *testing.T, deps Dependencies, timeout time.Duration) (*Server, context.CancelFunc, <-chan error) {
	t.Helper()
	server, err := NewServer(Config{Addr: "127.0.0.1:0", BearerToken: testToken, ShutdownTimeout: timeout}, deps)
	if err != nil {
		t.Fatal(err)
	}
	if server.Addr() != nil {
		t.Fatal("address before Start")
	}
	ctx, cancel := context.WithCancel(context.Background())
	t.Cleanup(cancel)
	if err := server.Start(ctx); err != nil {
		t.Fatal(err)
	}
	done := make(chan error, 1)
	go func() { done <- server.Wait() }()
	return server, cancel, done
}

func serverRequest(server *Server) (*http.Response, error) {
	req, err := http.NewRequest(http.MethodGet, "http://"+server.Addr().String()+runPath, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", "Bearer "+testToken)
	client := &http.Client{Timeout: 4 * time.Second}
	return client.Do(req)
}

func TestServerStartServeAndCancel(t *testing.T) {
	server, cancel, done := startTestServer(t, testDependencies(), 0)
	response, err := serverRequest(server)
	if err != nil {
		t.Fatal(err)
	}
	_ = response.Body.Close()
	if response.StatusCode != 404 {
		t.Fatalf("status = %d", response.StatusCode)
	}
	if err := server.Start(context.Background()); err == nil {
		t.Fatal("duplicate Start succeeded")
	}
	cancel()
	if err := awaitServer(t, done); err != nil {
		t.Fatal(err)
	}
	if err := server.Wait(); err != nil {
		t.Fatal(err)
	}
	connection, err := net.DialTimeout("tcp", server.Addr().String(), time.Second)
	if err == nil {
		_ = connection.Close()
		t.Fatal("listener still accepts after shutdown")
	}
}

func TestServerGracefulShutdownDrainsActiveRequest(t *testing.T) {
	var (
		entered = make(chan struct{})
		release = make(chan struct{})
		once    sync.Once
	)
	t.Cleanup(func() { once.Do(func() { close(release) }) })
	deps := testDependencies()
	deps.Runs = runFunc(func(ctx context.Context, id string) (contract.RunView, error) {
		close(entered)
		select {
		case <-release:
			return contract.RunView{Source: contract.SourceLive, Run: contract.RunMeta{RunID: id}}, nil
		case <-ctx.Done():
			return contract.RunView{}, ctx.Err()
		}
	})
	server, cancel, done := startTestServer(t, deps, 2*time.Second)
	requestDone := make(chan error, 1)
	go func() {
		response, err := serverRequest(server)
		if err == nil {
			_, err = io.ReadAll(response.Body)
			_ = response.Body.Close()
			if response.StatusCode != 200 {
				err = errors.New("active request did not complete successfully")
			}
		}
		requestDone <- err
	}()
	select {
	case <-entered:
	case <-time.After(3 * time.Second):
		t.Fatal("request did not enter handler")
	}
	cancel()
	select {
	case err := <-done:
		t.Fatalf("shutdown returned before draining: %v", err)
	case <-time.After(50 * time.Millisecond):
	}
	once.Do(func() { close(release) })
	if err := awaitServer(t, requestDone); err != nil {
		t.Fatal(err)
	}
	if err := awaitServer(t, done); err != nil {
		t.Fatal(err)
	}
}

func TestServerShutdownDeadlineClosesActiveConnections(t *testing.T) {
	var (
		entered = make(chan struct{})
		exited  = make(chan struct{})
	)
	deps := testDependencies()
	deps.Runs = runFunc(func(ctx context.Context, _ string) (contract.RunView, error) {
		close(entered)
		<-ctx.Done()
		close(exited)
		return contract.RunView{}, ctx.Err()
	})
	server, cancel, done := startTestServer(t, deps, 50*time.Millisecond)
	requestDone := make(chan error, 1)
	go func() {
		response, err := serverRequest(server)
		if response != nil {
			_ = response.Body.Close()
		}
		requestDone <- err
	}()
	select {
	case <-entered:
	case <-time.After(3 * time.Second):
		t.Fatal("request did not enter handler")
	}
	cancel()
	if err := awaitServer(t, done); !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("shutdown error = %v", err)
	}
	select {
	case <-exited:
	case <-time.After(3 * time.Second):
		t.Fatal("forced close did not cancel request context")
	}
	_ = awaitServer(t, requestDone)
}

func TestServerStartupFailureIsSynchronous(t *testing.T) {
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = listener.Close() })
	server, err := NewServer(Config{Addr: listener.Addr().String(), BearerToken: testToken}, testDependencies())
	if err != nil {
		t.Fatal(err)
	}
	startErr := server.Start(context.Background())
	if startErr == nil {
		t.Fatal("Start did not report occupied port")
	}
	if server.Wait() != startErr || server.Addr() != nil {
		t.Fatal("failed startup state was lost")
	}
	var netErr *net.OpError
	if !errors.As(startErr, &netErr) {
		t.Fatalf("network error cause lost: %v", startErr)
	}
}

func TestServerCanceledBeforeStartAndImmediateCancellation(t *testing.T) {
	server, err := NewServer(Config{Addr: "127.0.0.1:0", BearerToken: testToken}, testDependencies())
	if err != nil {
		t.Fatal(err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	if err := server.Start(ctx); !errors.Is(err, context.Canceled) {
		t.Fatalf("Start = %v", err)
	}
	if err := server.Wait(); !errors.Is(err, context.Canceled) {
		t.Fatalf("Wait = %v", err)
	}
	// Cancellation can win the race before Serve starts accepting requests.
	for i := 0; i < 10; i++ {
		_, cancel, done := startTestServer(t, testDependencies(), time.Second)
		cancel()
		if err := awaitServer(t, done); err != nil {
			t.Fatal(err)
		}
	}
}

func TestNewServerRejectsInvalidConfiguration(t *testing.T) {
	for _, config := range []Config{
		{BearerToken: testToken},
		{Addr: "127.0.0.1:0", BearerToken: testToken, ShutdownTimeout: -time.Second},
	} {
		if _, err := NewServer(config, testDependencies()); err == nil {
			t.Fatalf("accepted config %+v", config)
		}
	}
}