// 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 diff supports a pluggable diff algorithm.
package diff

import (
	"sort"

	"golang.org/x/tools/internal/span"
)

// TextEdit represents a change to a section of a document.
// The text within the specified span should be replaced by the supplied new text.
type TextEdit struct {
	Span    span.Span
	NewText string
}

type ComputeEdits func(uri span.URI, before, after string) []TextEdit

type OpKind int

const (
	Delete OpKind = iota
	Insert
	Equal
)

func (k OpKind) String() string {
	switch k {
	case Delete:
		return "delete"
	case Insert:
		return "insert"
	case Equal:
		return "equal"
	default:
		panic("unknown operation kind")
	}
}

// SortTextEdits attempts to order all edits by their starting points.
// The sort is stable so that edits with the same starting point will not
// be reordered.
func SortTextEdits(d []TextEdit) {
	// Use a stable sort to maintain the order of edits inserted at the same position.
	sort.SliceStable(d, func(i int, j int) bool {
		return span.Compare(d[i].Span, d[j].Span) < 0
	})
}