// 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 span_test

import (
	"testing"

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

// TestUTF16 tests the conversion of column information between the native
// byte offset and the utf16 form.
func TestUTF16(t *testing.T) {
	var input = []byte(`
𐐀23456789
1𐐀3456789
12𐐀456789
123𐐀56789
1234𐐀6789
12345𐐀789
123456𐐀89
1234567𐐀9
12345678𐐀
`[1:])
	c := span.NewContentConverter("test", input)
	for line := 1; line <= 9; line++ {
		runeColumn, runeChr := 0, 0
		for chr := 1; chr <= 10; chr++ {
			switch {
			case chr <= line:
				runeChr = chr
				runeColumn = chr
			case chr == line+1:
				runeChr = chr - 1
				runeColumn = chr - 1
			default:
				runeChr = chr
				runeColumn = chr + 2
			}
			p := span.NewPoint(line, runeColumn, (line-1)*13+(runeColumn-1))
			// check conversion to utf16 format
			gotChr, err := span.ToUTF16Column(p, input)
			if err != nil {
				t.Error(err)
			}
			if runeChr != gotChr {
				t.Errorf("ToUTF16Column(%v): expected %v, got %v", p, runeChr, gotChr)
			}
			offset, err := c.ToOffset(p.Line(), p.Column())
			if err != nil {
				t.Error(err)
			}
			if p.Offset() != offset {
				t.Errorf("ToOffset(%v,%v): expected %v, got %v", p.Line(), p.Column(), p.Offset(), offset)
			}
			// and check the conversion back
			lineStart := span.NewPoint(p.Line(), 1, p.Offset()-(p.Column()-1))
			gotPoint, err := span.FromUTF16Column(lineStart, chr, input)
			if err != nil {
				t.Error(err)
			}
			if p != gotPoint {
				t.Errorf("FromUTF16Column(%v,%v): expected %v, got %v", p.Line(), chr, p, gotPoint)
			}
		}
	}
}

func TestUTF16Errors(t *testing.T) {
	var input = []byte(`
hello
world
`)[1:]
	for _, test := range []struct {
		line, col, offset int
		want              string
	}{
		{
			1, 6, 12,
			"ToUTF16Column: length of line (5) is less than column (6)",
		},
		{
			1, 6, 13,
			"ToUTF16Column: offsets 8-13 outside file contents (12)",
		},
	} {
		p := span.NewPoint(test.line, test.col, test.offset)
		if _, err := span.ToUTF16Column(p, input); err == nil || err.Error() != test.want {
			t.Errorf("expected %v, got %v", test.want, err)
		}
	}
}