// Copyright (c) The EfficientGo Authors.
// Licensed under the Apache License 2.0.

package internal

import (
	"bytes"
	"fmt"
	"math"
	"reflect"
	"strings"
	"testing"
)

func assertAlmostEqual(t *testing.T, a, b float64, places int) {
	if math.Abs(a-b) > math.Pow10(-places) {
		t.Errorf("%.7f != %.7f", a, b)
	}
}

func assertEqual(t *testing.T, a, b interface{}) {
	if !reflect.DeepEqual(a, b) {
		t.Errorf("%v != %v", a, b)
	}
}

func splitChars(s string) []string {
	chars := make([]string, 0, len(s))
	// Assume ASCII inputs
	for i := 0; i != len(s); i++ {
		chars = append(chars, string(s[i]))
	}
	return chars
}

func TestSequenceMatcherRatio(t *testing.T) {
	s := NewMatcher(splitChars("abcd"), splitChars("bcde"))
	assertEqual(t, s.Ratio(), 0.75)
	assertEqual(t, s.QuickRatio(), 0.75)
	assertEqual(t, s.RealQuickRatio(), 1.0)
}

func TestGetOptCodes(t *testing.T) {
	a := "qabxcd"
	b := "abycdf"
	s := NewMatcher(splitChars(a), splitChars(b))
	w := &bytes.Buffer{}
	for _, op := range s.GetOpCodes() {
		fmt.Fprintf(w, "%s a[%d:%d], (%s) b[%d:%d] (%s)\n", string(op.Tag),
			op.I1, op.I2, a[op.I1:op.I2], op.J1, op.J2, b[op.J1:op.J2])
	}
	result := w.String()
	expected := `d a[0:1], (q) b[0:0] ()
e a[1:3], (ab) b[0:2] (ab)
r a[3:4], (x) b[2:3] (y)
e a[4:6], (cd) b[3:5] (cd)
i a[6:6], () b[5:6] (f)
`
	if expected != result {
		t.Errorf("unexpected op codes: \n%s", result)
	}
}

func TestGroupedOpCodes(t *testing.T) {
	a := []string{}
	for i := 0; i != 39; i++ {
		a = append(a, fmt.Sprintf("%02d", i))
	}
	b := []string{}
	b = append(b, a[:8]...)
	b = append(b, " i")
	b = append(b, a[8:19]...)
	b = append(b, " x")
	b = append(b, a[20:22]...)
	b = append(b, a[27:34]...)
	b = append(b, " y")
	b = append(b, a[35:]...)
	s := NewMatcher(a, b)
	w := &bytes.Buffer{}
	for _, g := range s.GetGroupedOpCodes(-1) {
		fmt.Fprintf(w, "group\n")
		for _, op := range g {
			fmt.Fprintf(w, "  %s, %d, %d, %d, %d\n", string(op.Tag),
				op.I1, op.I2, op.J1, op.J2)
		}
	}
	result := w.String()
	expected := `group
  e, 5, 8, 5, 8
  i, 8, 8, 8, 9
  e, 8, 11, 9, 12
group
  e, 16, 19, 17, 20
  r, 19, 20, 20, 21
  e, 20, 22, 21, 23
  d, 22, 27, 23, 23
  e, 27, 30, 23, 26
group
  e, 31, 34, 27, 30
  r, 34, 35, 30, 31
  e, 35, 38, 31, 34
`
	if expected != result {
		t.Errorf("unexpected op codes: \n%s", result)
	}
}

func rep(s string, count int) string {
	return strings.Repeat(s, count)
}

func TestWithAsciiOneInsert(t *testing.T) {
	sm := NewMatcher(splitChars(rep("b", 100)),
		splitChars("a"+rep("b", 100)))
	assertAlmostEqual(t, sm.Ratio(), 0.995, 3)
	assertEqual(t, sm.GetOpCodes(),
		[]OpCode{{'i', 0, 0, 0, 1}, {'e', 0, 100, 1, 101}})
	assertEqual(t, len(sm.bPopular), 0)

	sm = NewMatcher(splitChars(rep("b", 100)),
		splitChars(rep("b", 50)+"a"+rep("b", 50)))
	assertAlmostEqual(t, sm.Ratio(), 0.995, 3)
	assertEqual(t, sm.GetOpCodes(),
		[]OpCode{{'e', 0, 50, 0, 50}, {'i', 50, 50, 50, 51}, {'e', 50, 100, 51, 101}})
	assertEqual(t, len(sm.bPopular), 0)
}

func TestWithAsciiOnDelete(t *testing.T) {
	sm := NewMatcher(splitChars(rep("a", 40)+"c"+rep("b", 40)),
		splitChars(rep("a", 40)+rep("b", 40)))
	assertAlmostEqual(t, sm.Ratio(), 0.994, 3)
	assertEqual(t, sm.GetOpCodes(),
		[]OpCode{{'e', 0, 40, 0, 40}, {'d', 40, 41, 40, 40}, {'e', 41, 81, 40, 80}})
}

func TestWithAsciiBJunk(t *testing.T) {
	isJunk := func(s string) bool {
		return s == " "
	}
	sm := NewMatcherWithJunk(splitChars(rep("a", 40)+rep("b", 40)),
		splitChars(rep("a", 44)+rep("b", 40)), true, isJunk)
	assertEqual(t, sm.bJunk, map[string]struct{}{})

	sm = NewMatcherWithJunk(splitChars(rep("a", 40)+rep("b", 40)),
		splitChars(rep("a", 44)+rep("b", 40)+rep(" ", 20)), false, isJunk)
	assertEqual(t, sm.bJunk, map[string]struct{}{" ": {}})

	isJunk = func(s string) bool {
		return s == " " || s == "b"
	}
	sm = NewMatcherWithJunk(splitChars(rep("a", 40)+rep("b", 40)),
		splitChars(rep("a", 44)+rep("b", 40)+rep(" ", 20)), false, isJunk)
	assertEqual(t, sm.bJunk, map[string]struct{}{" ": {}, "b": {}})
}

func TestSFBugsRatioForNullSeqn(t *testing.T) {
	sm := NewMatcher(nil, nil)
	assertEqual(t, sm.Ratio(), 1.0)
	assertEqual(t, sm.QuickRatio(), 1.0)
	assertEqual(t, sm.RealQuickRatio(), 1.0)
}

func TestSFBugsComparingEmptyLists(t *testing.T) {
	groups := NewMatcher(nil, nil).GetGroupedOpCodes(-1)
	assertEqual(t, len(groups), 0)
	diff := UnifiedDiff{
		FromFile: "Original",
		ToFile:   "Current",
		Context:  3,
	}
	result, err := GetUnifiedDiffString(diff)
	assertEqual(t, err, nil)
	assertEqual(t, result, "")
}

func TestOutputFormatRangeFormatUnified(t *testing.T) {
	// Per the diff spec at http://www.unix.org/single_unix_specification/
	//
	// Each <range> field shall be of the form:
	//   %1d", <beginning line number>  if the range contains exactly one line,
	// and:
	//  "%1d,%1d", <beginning line number>, <number of lines> otherwise.
	// If a range is empty, its beginning line number shall be the number of
	// the line just before the range, or 0 if the empty range starts the file.
	fm := formatRangeUnified
	assertEqual(t, fm(3, 3), "3,0")
	assertEqual(t, fm(3, 4), "4")
	assertEqual(t, fm(3, 5), "4,2")
	assertEqual(t, fm(3, 6), "4,3")
	assertEqual(t, fm(0, 0), "0,0")
}

func TestSplitLines(t *testing.T) {
	allTests := []struct {
		input string
		want  []string
	}{
		{"foo", []string{"foo\n"}},
		{"foo\nbar", []string{"foo\n", "bar\n"}},
		{"foo\nbar\n", []string{"foo\n", "bar\n", "\n"}},
	}
	for _, test := range allTests {
		assertEqual(t, SplitLines(test.input), test.want)
	}
}

func benchmarkSplitLines(b *testing.B, count int) {
	str := strings.Repeat("foo\n", count)

	b.ResetTimer()

	n := 0
	for i := 0; i < b.N; i++ {
		n += len(SplitLines(str))
	}
}

func BenchmarkSplitLines100(b *testing.B) {
	benchmarkSplitLines(b, 100)
}

func BenchmarkSplitLines10000(b *testing.B) {
	benchmarkSplitLines(b, 10000)
}