// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc

import (
	"context"
	"regexp"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
	"golang.org/x/tools/internal/lsp/cache"
	"golang.org/x/tools/internal/lsp/debug"
	"golang.org/x/tools/internal/lsp/fake"
	"golang.org/x/tools/internal/lsp/protocol"
)

type fakeClient struct {
	protocol.Client

	logs chan string
}

func (c fakeClient) LogMessage(ctx context.Context, params *protocol.LogMessageParams) error {
	c.logs <- params.Message
	return nil
}

type pingServer struct{ protocol.Server }

func (s pingServer) DidOpen(ctx context.Context, params *protocol.DidOpenTextDocumentParams) error {
	event.Log(ctx, "ping")
	return nil
}

func (s pingServer) Shutdown(ctx context.Context) error {
	return nil
}

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

	server := pingServer{}
	client := fakeClient{logs: make(chan string, 10)}

	ctx = debug.WithInstance(ctx, "", "")
	ss := NewStreamServer(cache.New(ctx, nil))
	ss.serverForTest = server
	ts := servertest.NewPipeServer(ctx, ss, nil)
	defer checkClose(t, ts.Close)
	cc := ts.Connect(ctx)
	cc.Go(ctx, protocol.ClientHandler(client, jsonrpc2.MethodNotFound))

	protocol.ServerDispatcher(cc).DidOpen(ctx, &protocol.DidOpenTextDocumentParams{})

	select {
	case got := <-client.logs:
		want := "ping"
		matched, err := regexp.MatchString(want, got)
		if err != nil {
			t.Fatal(err)
		}
		if !matched {
			t.Errorf("got log %q, want a log containing %q", got, want)
		}
	case <-time.After(1 * time.Second):
		t.Error("timeout waiting for client log")
	}
}

// waitableServer instruments LSP request so that we can control their timing.
// The requests chosen are arbitrary: we simply needed one that blocks, and
// another that doesn't.
type waitableServer struct {
	protocol.Server

	started chan struct{}
}

func (s waitableServer) Hover(ctx context.Context, _ *protocol.HoverParams) (*protocol.Hover, error) {
	s.started <- struct{}{}
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	case <-time.After(200 * time.Millisecond):
	}
	return &protocol.Hover{}, nil
}

func (s waitableServer) Resolve(_ context.Context, item *protocol.CompletionItem) (*protocol.CompletionItem, error) {
	return item, nil
}

func (s waitableServer) Shutdown(ctx context.Context) error {
	return nil
}

func checkClose(t *testing.T, closer func() error) {
	t.Helper()
	if err := closer(); err != nil {
		t.Errorf("closing: %v", err)
	}
}

func TestRequestCancellation(t *testing.T) {
	server := waitableServer{
		started: make(chan struct{}),
	}
	baseCtx := context.Background()
	serveCtx := debug.WithInstance(baseCtx, "", "")
	ss := NewStreamServer(cache.New(serveCtx, nil))
	ss.serverForTest = server
	tsDirect := servertest.NewTCPServer(serveCtx, ss, nil)
	defer checkClose(t, tsDirect.Close)

	forwarderCtx := debug.WithInstance(baseCtx, "", "")
	forwarder := NewForwarder("tcp", tsDirect.Addr)
	tsForwarded := servertest.NewPipeServer(forwarderCtx, forwarder, nil)
	defer checkClose(t, tsForwarded.Close)

	tests := []struct {
		serverType string
		ts         servertest.Connector
	}{
		{"direct", tsDirect},
		{"forwarder", tsForwarded},
	}

	for _, test := range tests {
		t.Run(test.serverType, func(t *testing.T) {
			cc := test.ts.Connect(baseCtx)
			sd := protocol.ServerDispatcher(cc)
			cc.Go(baseCtx,
				protocol.Handlers(
					jsonrpc2.MethodNotFound))

			ctx := context.Background()
			ctx1, cancel1 := context.WithCancel(ctx)
			var (
				err1, err2 error
				wg         sync.WaitGroup
			)
			wg.Add(2)
			go func() {
				defer wg.Done()
				_, err1 = sd.Hover(ctx1, &protocol.HoverParams{})
			}()
			go func() {
				defer wg.Done()
				_, err2 = sd.Resolve(ctx, &protocol.CompletionItem{})
			}()
			// Wait for the Hover request to start.
			<-server.started
			cancel1()
			wg.Wait()
			if err1 == nil {
				t.Errorf("cancelled Hover(): got nil err")
			}
			if err2 != nil {
				t.Errorf("uncancelled Hover(): err: %v", err2)
			}
			if _, err := sd.Resolve(ctx, &protocol.CompletionItem{}); err != nil {
				t.Errorf("subsequent Hover(): %v", err)
			}
		})
	}
}

const exampleProgram = `
-- go.mod --
module mod

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("Hello World.")
}`

func TestDebugInfoLifecycle(t *testing.T) {
	sb, err := fake.NewSandbox("gopls-lsprpc-test", exampleProgram, "", false)
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := sb.Close(); err != nil {
			// TODO(golang/go#38490): we can't currently make this an error because
			// it fails on Windows: the workspace directory is still locked by a
			// separate Go process.
			// Once we have a reliable way to wait for proper shutdown, make this an
			// error.
			t.Logf("closing workspace failed: %v", err)
		}
	}()

	baseCtx, cancel := context.WithCancel(context.Background())
	defer cancel()
	clientCtx := debug.WithInstance(baseCtx, "", "")
	serverCtx := debug.WithInstance(baseCtx, "", "")

	cache := cache.New(serverCtx, nil)
	ss := NewStreamServer(cache)
	tsBackend := servertest.NewTCPServer(serverCtx, ss, nil)

	forwarder := NewForwarder("tcp", tsBackend.Addr)
	tsForwarder := servertest.NewPipeServer(clientCtx, forwarder, nil)

	conn1 := tsForwarder.Connect(clientCtx)
	ed1, err := fake.NewEditor(sb, fake.EditorConfig{}).Connect(clientCtx, conn1, fake.ClientHooks{})
	if err != nil {
		t.Fatal(err)
	}
	defer ed1.Close(clientCtx)
	conn2 := tsBackend.Connect(baseCtx)
	ed2, err := fake.NewEditor(sb, fake.EditorConfig{}).Connect(baseCtx, conn2, fake.ClientHooks{})
	if err != nil {
		t.Fatal(err)
	}
	defer ed2.Close(baseCtx)

	serverDebug := debug.GetInstance(serverCtx)
	if got, want := len(serverDebug.State.Clients()), 2; got != want {
		t.Errorf("len(server:Clients) = %d, want %d", got, want)
	}
	if got, want := len(serverDebug.State.Sessions()), 2; got != want {
		t.Errorf("len(server:Sessions) = %d, want %d", got, want)
	}
	clientDebug := debug.GetInstance(clientCtx)
	if got, want := len(clientDebug.State.Servers()), 1; got != want {
		t.Errorf("len(client:Servers) = %d, want %d", got, want)
	}
	// Close one of the connections to verify that the client and session were
	// dropped.
	if err := ed1.Close(clientCtx); err != nil {
		t.Fatal(err)
	}
	/*TODO: at this point we have verified the editor is closed
	However there is no way currently to wait for all associated go routines to
	go away, and we need to wait for those to trigger the client drop
	for now we just give it a little bit of time, but we need to fix this
	in a principled way
	*/
	start := time.Now()
	delay := time.Millisecond
	const maxWait = time.Second
	for len(serverDebug.State.Clients()) > 1 {
		if time.Since(start) > maxWait {
			break
		}
		time.Sleep(delay)
		delay *= 2
	}
	if got, want := len(serverDebug.State.Clients()), 1; got != want {
		t.Errorf("len(server:Clients) = %d, want %d", got, want)
	}
	if got, want := len(serverDebug.State.Sessions()), 1; got != want {
		t.Errorf("len(server:Sessions()) = %d, want %d", got, want)
	}
}