// Copyright 2019 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 cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/lsp/protocol"
	"golang.org/x/tools/internal/tool"
)

// rename implements the rename verb for gopls.
type rename struct {
	EditFlags
	app *Application
}

func (r *rename) Name() string      { return "rename" }
func (r *rename) Parent() string    { return r.app.Name() }
func (r *rename) Usage() string     { return "[rename-flags] <position> <name>" }
func (r *rename) ShortHelp() string { return "rename selected identifier" }
func (r *rename) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-based location (:line:column or :#position) of the thing to change
	$ gopls rename helper/helper.go:8:6 Foo
	$ gopls rename helper/helper.go:#53 Foo

rename-flags:
`)
	printFlagDefaults(f)
}

// Run renames the specified identifier and either;
// - if -w is specified, updates the file(s) in place;
// - if -d is specified, prints out unified diffs of the changes; or
// - otherwise, prints the new versions to stdout.
func (r *rename) Run(ctx context.Context, args ...string) error {
	if len(args) != 2 {
		return tool.CommandLineErrorf("rename expects 2 arguments (position, new name)")
	}
	r.app.editFlags = &r.EditFlags
	conn, err := r.app.connect(ctx, nil)
	if err != nil {
		return err
	}
	defer conn.terminate(ctx)

	from := parseSpan(args[0])
	file, err := conn.openFile(ctx, from.URI())
	if err != nil {
		return err
	}
	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}
	p := protocol.RenameParams{
		TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
		Position:     loc.Range.Start,
		NewName:      args[1],
	}
	edit, err := conn.Rename(ctx, &p)
	if err != nil {
		return err
	}
	return conn.client.applyWorkspaceEdit(edit)
}