// Copyright 2011 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 syntax

import (
	"bytes"
	"fmt"
	"testing"
	"unicode"
)

var parseTests = []struct {
	Regexp string
	Dump   string
}{
	// Base cases
	{"a", "lit{a}"},
	{"a.", "cat{lit{a}dot{}}"},
	{"a.b", "cat{lit{a}dot{}lit{b}}"},
	//	{ "ab", "str{ab}" },
	{"ab", "cat{lit{a}lit{b}}"},
	{"a.b.c", "cat{lit{a}dot{}lit{b}dot{}lit{c}}"},
	//	{ "abc", "str{abc}" },
	{"abc", "cat{lit{a}lit{b}lit{c}}"},
	{"a|^", "alt{lit{a}bol{}}"},
	//	{ "a|b", "cc{0x61-0x62}" },
	{"a|b", "alt{lit{a}lit{b}}"},
	{"(a)", "cap{lit{a}}"},
	{"(a)|b", "alt{cap{lit{a}}lit{b}}"},
	{"a*", "star{lit{a}}"},
	{"a+", "plus{lit{a}}"},
	{"a?", "que{lit{a}}"},
	{"a{2}", "rep{2,2 lit{a}}"},
	{"a{2,3}", "rep{2,3 lit{a}}"},
	{"a{2,}", "rep{2,-1 lit{a}}"},
	{"a*?", "nstar{lit{a}}"},
	{"a+?", "nplus{lit{a}}"},
	{"a??", "nque{lit{a}}"},
	{"a{2}?", "nrep{2,2 lit{a}}"},
	{"a{2,3}?", "nrep{2,3 lit{a}}"},
	{"a{2,}?", "nrep{2,-1 lit{a}}"},
	{"", "emp{}"},
	//	{ "|", "emp{}" },  // alt{emp{}emp{}} but got factored
	{"|", "alt{emp{}emp{}}"},
	{"|x|", "alt{emp{}lit{x}emp{}}"},
	{".", "dot{}"},
	{"^", "bol{}"},
	{"$", "eol{}"},
	{"\\|", "lit{|}"},
	{"\\(", "lit{(}"},
	{"\\)", "lit{)}"},
	{"\\*", "lit{*}"},
	{"\\+", "lit{+}"},
	{"\\?", "lit{?}"},
	{"{", "lit{{}"},
	{"}", "lit{}}"},
	{"\\.", "lit{.}"},
	{"\\^", "lit{^}"},
	{"\\$", "lit{$}"},
	{"\\\\", "lit{\\}"},
	{"[ace]", "cc{0x61 0x63 0x65}"},
	{"[abc]", "cc{0x61-0x63}"},
	{"[a-z]", "cc{0x61-0x7a}"},
	//	{ "[a]", "lit{a}" },
	{"[a]", "cc{0x61}"},
	{"\\-", "lit{-}"},
	{"-", "lit{-}"},
	{"\\_", "lit{_}"},

	// Posix and Perl extensions
	{"[[:lower:]]", "cc{0x61-0x7a}"},
	{"[a-z]", "cc{0x61-0x7a}"},
	{"[^[:lower:]]", "cc{0x0-0x60 0x7b-0x10ffff}"},
	{"[[:^lower:]]", "cc{0x0-0x60 0x7b-0x10ffff}"},
	//	{ "(?i)[[:lower:]]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}" },
	//	{ "(?i)[a-z]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}" },
	//	{ "(?i)[^[:lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
	//	{ "(?i)[[:^lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
	{"\\d", "cc{0x30-0x39}"},
	{"\\D", "cc{0x0-0x2f 0x3a-0x10ffff}"},
	{"\\s", "cc{0x9-0xa 0xc-0xd 0x20}"},
	{"\\S", "cc{0x0-0x8 0xb 0xe-0x1f 0x21-0x10ffff}"},
	{"\\w", "cc{0x30-0x39 0x41-0x5a 0x5f 0x61-0x7a}"},
	{"\\W", "cc{0x0-0x2f 0x3a-0x40 0x5b-0x5e 0x60 0x7b-0x10ffff}"},
	//	{ "(?i)\\w", "cc{0x30-0x39 0x41-0x5a 0x5f 0x61-0x7a 0x17f 0x212a}" },
	//	{ "(?i)\\W", "cc{0x0-0x2f 0x3a-0x40 0x5b-0x5e 0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
	{"[^\\\\]", "cc{0x0-0x5b 0x5d-0x10ffff}"},
	//	{ "\\C", "byte{}" },

	// Unicode, negatives, and a double negative.
	{"\\p{Braille}", "cc{0x2800-0x28ff}"},
	{"\\P{Braille}", "cc{0x0-0x27ff 0x2900-0x10ffff}"},
	{"\\p{^Braille}", "cc{0x0-0x27ff 0x2900-0x10ffff}"},
	{"\\P{^Braille}", "cc{0x2800-0x28ff}"},
	{"\\pZ", "cc{0x20 0xa0 0x1680 0x180e 0x2000-0x200a 0x2028-0x2029 0x202f 0x205f 0x3000}"},
	{"[\\p{Braille}]", "cc{0x2800-0x28ff}"},
	{"[\\P{Braille}]", "cc{0x0-0x27ff 0x2900-0x10ffff}"},
	{"[\\p{^Braille}]", "cc{0x0-0x27ff 0x2900-0x10ffff}"},
	{"[\\P{^Braille}]", "cc{0x2800-0x28ff}"},
	{"[\\pZ]", "cc{0x20 0xa0 0x1680 0x180e 0x2000-0x200a 0x2028-0x2029 0x202f 0x205f 0x3000}"},

	// More interesting regular expressions.
	//	{ "a{,2}", "str{a{,2}}" },
	//	{ "\\.\\^\\$\\\\", "str{.^$\\}" },
	{"[a-zABC]", "cc{0x41-0x43 0x61-0x7a}"},
	{"[^a]", "cc{0x0-0x60 0x62-0x10ffff}"},
	{"[\xce\xb1-\xce\xb5\xe2\x98\xba]", "cc{0x3b1-0x3b5 0x263a}"}, // utf-8
	{"a*{", "cat{star{lit{a}}lit{{}}"},

	// Test precedences
	//	{ "(?:ab)*", "star{str{ab}}" },
	//	{ "(ab)*", "star{cap{str{ab}}}" },
	//	{ "ab|cd", "alt{str{ab}str{cd}}" },
	//	{ "a(b|c)d", "cat{lit{a}cap{cc{0x62-0x63}}lit{d}}" },
	{"(?:ab)*", "star{cat{lit{a}lit{b}}}"},
	{"(ab)*", "star{cap{cat{lit{a}lit{b}}}}"},
	{"ab|cd", "alt{cat{lit{a}lit{b}}cat{lit{c}lit{d}}}"},
	{"a(b|c)d", "cat{lit{a}cap{alt{lit{b}lit{c}}}lit{d}}"},

	// Test flattening.
	{"(?:a)", "lit{a}"},
	//	{ "(?:ab)(?:cd)", "str{abcd}" },
	//	{ "(?:a|b)|(?:c|d)", "cc{0x61-0x64}" },
	//	{ "a|.", "dot{}" },
	//	{ ".|a", "dot{}" },

	// Test Perl quoted literals
	{"\\Q+|*?{[\\E", "str{+|*?{[}"},
	{"\\Q+\\E+", "plus{lit{+}}"},
	{"\\Q\\\\E", "lit{\\}"},
	{"\\Q\\\\\\E", "str{\\\\}"},

	// Test Perl \A and \z
	{"(?m)^", "bol{}"},
	{"(?m)$", "eol{}"},
	{"(?-m)^", "bot{}"},
	{"(?-m)$", "eot{}"},
	{"(?m)\\A", "bot{}"},
	{"(?m)\\z", "eot{\\z}"},
	{"(?-m)\\A", "bot{}"},
	{"(?-m)\\z", "eot{\\z}"},

	// Test named captures
	{"(?P<name>a)", "cap{name:lit{a}}"},

	// Case-folded literals
	//	{ "[Aa]", "litfold{a}" },

	// Strings
	//	{ "abcde", "str{abcde}" },
	//	{ "[Aa][Bb]cd", "cat{strfold{ab}str{cd}}" },
}

const testFlags = MatchNL | PerlX | UnicodeGroups

// Test Parse -> Dump.
func TestParseDump(t *testing.T) {
	for _, tt := range parseTests {
		re, err := Parse(tt.Regexp, testFlags)
		if err != nil {
			t.Errorf("Parse(%#q): %v", tt.Regexp, err)
			continue
		}
		d := dump(re)
		if d != tt.Dump {
			t.Errorf("Parse(%#q).Dump() = %#q want %#q", tt.Regexp, d, tt.Dump)
		}
	}
}

// dump prints a string representation of the regexp showing
// the structure explicitly.
func dump(re *Regexp) string {
	var b bytes.Buffer
	dumpRegexp(&b, re)
	return b.String()
}

var opNames = []string{
	OpNoMatch:        "no",
	OpEmptyMatch:     "emp",
	OpLiteral:        "lit",
	OpCharClass:      "cc",
	OpAnyCharNotNL:   "dnl",
	OpAnyChar:        "dot",
	OpBeginLine:      "bol",
	OpEndLine:        "eol",
	OpBeginText:      "bot",
	OpEndText:        "eot",
	OpWordBoundary:   "wb",
	OpNoWordBoundary: "nwb",
	OpCapture:        "cap",
	OpStar:           "star",
	OpPlus:           "plus",
	OpQuest:          "que",
	OpRepeat:         "rep",
	OpConcat:         "cat",
	OpAlternate:      "alt",
}

// dumpRegexp writes an encoding of the syntax tree for the regexp re to b.
// It is used during testing to distinguish between parses that might print
// the same using re's String method.
func dumpRegexp(b *bytes.Buffer, re *Regexp) {
	if int(re.Op) >= len(opNames) || opNames[re.Op] == "" {
		fmt.Fprintf(b, "op%d", re.Op)
	} else {
		switch re.Op {
		default:
			b.WriteString(opNames[re.Op])
		case OpStar, OpPlus, OpQuest, OpRepeat:
			if re.Flags&NonGreedy != 0 {
				b.WriteByte('n')
			}
			b.WriteString(opNames[re.Op])
		case OpLiteral:
			if len(re.Rune) > 1 {
				b.WriteString("str")
			} else {
				b.WriteString("lit")
			}
			if re.Flags&FoldCase != 0 {
				for _, r := range re.Rune {
					if unicode.ToUpper(r) != r {
						b.WriteString("fold")
					}
				}
			}
		}
	}
	b.WriteByte('{')
	switch re.Op {
	case OpEndText:
		if re.Flags&WasDollar == 0 {
			b.WriteString(`\z`)
		}
	case OpLiteral:
		for _, r := range re.Rune {
			b.WriteRune(r)
		}
	case OpConcat, OpAlternate:
		for _, sub := range re.Sub {
			dumpRegexp(b, sub)
		}
	case OpStar, OpPlus, OpQuest:
		dumpRegexp(b, re.Sub[0])
	case OpRepeat:
		fmt.Fprintf(b, "%d,%d ", re.Min, re.Max)
		dumpRegexp(b, re.Sub[0])
	case OpCapture:
		if re.Name != "" {
			b.WriteString(re.Name)
			b.WriteByte(':')
		}
		dumpRegexp(b, re.Sub[0])
	case OpCharClass:
		sep := ""
		for i := 0; i < len(re.Rune); i += 2 {
			b.WriteString(sep)
			sep = " "
			lo, hi := re.Rune[i], re.Rune[i+1]
			if lo == hi {
				fmt.Fprintf(b, "%#x", lo)
			} else {
				fmt.Fprintf(b, "%#x-%#x", lo, hi)
			}
		}
	}
	b.WriteByte('}')
}