1// Copyright 2019 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package cmd
6
7import (
8	"context"
9	"flag"
10	"fmt"
11	"io/ioutil"
12	"time"
13
14	"golang.org/x/tools/internal/lsp/diff"
15	"golang.org/x/tools/internal/lsp/protocol"
16	"golang.org/x/tools/internal/lsp/source"
17	"golang.org/x/tools/internal/span"
18	"golang.org/x/tools/internal/tool"
19	errors "golang.org/x/xerrors"
20)
21
22// suggestedfix implements the fix verb for gopls.
23type suggestedfix struct {
24	Diff  bool `flag:"d" help:"display diffs instead of rewriting files"`
25	Write bool `flag:"w" help:"write result to (source) file instead of stdout"`
26	All   bool `flag:"a" help:"apply all fixes, not just preferred fixes"`
27
28	app *Application
29}
30
31func (s *suggestedfix) Name() string      { return "fix" }
32func (s *suggestedfix) Usage() string     { return "<filename>" }
33func (s *suggestedfix) ShortHelp() string { return "apply suggested fixes" }
34func (s *suggestedfix) DetailedHelp(f *flag.FlagSet) {
35	fmt.Fprintf(f.Output(), `
36Example: apply suggested fixes for this file:
37
38  $ gopls fix -w internal/lsp/cmd/check.go
39
40gopls fix flags are:
41`)
42	f.PrintDefaults()
43}
44
45// Run performs diagnostic checks on the file specified and either;
46// - if -w is specified, updates the file in place;
47// - if -d is specified, prints out unified diffs of the changes; or
48// - otherwise, prints the new versions to stdout.
49func (s *suggestedfix) Run(ctx context.Context, args ...string) error {
50	if len(args) != 1 {
51		return tool.CommandLineErrorf("fix expects 1 argument")
52	}
53	conn, err := s.app.connect(ctx)
54	if err != nil {
55		return err
56	}
57	defer conn.terminate(ctx)
58
59	from := span.Parse(args[0])
60	uri := from.URI()
61	file := conn.AddFile(ctx, uri)
62	if file.err != nil {
63		return file.err
64	}
65
66	// Wait for diagnostics results
67	select {
68	case <-file.hasDiagnostics:
69	case <-time.After(30 * time.Second):
70		return errors.Errorf("timed out waiting for results from %v", file.uri)
71	}
72
73	file.diagnosticsMu.Lock()
74	defer file.diagnosticsMu.Unlock()
75
76	p := protocol.CodeActionParams{
77		TextDocument: protocol.TextDocumentIdentifier{
78			URI: protocol.NewURI(uri),
79		},
80		Context: protocol.CodeActionContext{
81			Only:        []protocol.CodeActionKind{protocol.QuickFix},
82			Diagnostics: file.diagnostics,
83		},
84	}
85	actions, err := conn.CodeAction(ctx, &p)
86	if err != nil {
87		return errors.Errorf("%v: %v", from, err)
88	}
89	var edits []protocol.TextEdit
90	for _, a := range actions {
91		if !a.IsPreferred && !s.All {
92			continue
93		}
94		for _, c := range a.Edit.DocumentChanges {
95			if c.TextDocument.URI == string(uri) {
96				edits = append(edits, c.Edits...)
97			}
98		}
99	}
100
101	sedits, err := source.FromProtocolEdits(file.mapper, edits)
102	if err != nil {
103		return errors.Errorf("%v: %v", edits, err)
104	}
105	newContent := diff.ApplyEdits(string(file.mapper.Content), sedits)
106
107	filename := file.uri.Filename()
108	switch {
109	case s.Write:
110		if len(edits) > 0 {
111			ioutil.WriteFile(filename, []byte(newContent), 0644)
112		}
113	case s.Diff:
114		diffs := diff.ToUnified(filename+".orig", filename, string(file.mapper.Content), sedits)
115		fmt.Print(diffs)
116	default:
117		fmt.Print(string(newContent))
118	}
119	return nil
120}
121