package main

import (
	//"fmt"
	"path"
	"strings"
	"unicode/utf8"
	"regexp"
)

var ErrBadPattern = path.ErrBadPattern

func main(){
	
	match, _ := ExpMatch("linux*","linux1")
	println(match)
	
	match, _ = regexp.MatchString("linux.*?","linux1")
	println("regexp ==>", match)
	
	match, _ = ExpMatch("linux?","linux1")
	println(match)
	
	match, _ = regexp.MatchString("linux.","linux1")
	println("regexp ==>", match)
	
	match, _ = ExpMatch("linux[1-2]","linux1")
	println(match)
	
	match, _ = regexp.MatchString("linux[1-2]","linux1")
	println("regexp ==>", match)
	
	match, _ = ExpMatch("linux[12]","linux1")
	println(match)
	
	match, _ = regexp.MatchString("linux[12]","linux1")
	println("regexp ==>", match)
	
	match, _ = ExpMatch("linux[^2345]","linux1")
	println(match)
	
	match, _ = regexp.MatchString("linux[^2345]","linux1")
	println("regexp ==>", match)
	println("----------------------")
	
	match, _ = ExpMatch("linux[^12345]","linux1")
	println(match)
	
	match, _ = regexp.MatchString("linux[^12345]","linux1")
	println("regexp ==>", match)
	
	match, _ = ExpMatch("linux*[^12345]","linux1")
	println(match)
	
	match, _ = regexp.MatchString("linux.*?[^12345]","linux1")
	println("regexp ==>", match)
	
	match, _ = ExpMatch("中文*","中文测试")
	println(match)
	
	match, _ = regexp.MatchString("中文*","中文测试")
	println("regexp ==>", match)
	
	match, _ = ExpMatch("中文??","中文测试")
	println(match)
	
	match, _ = regexp.MatchString("中文..","中文测试")
	println("regexp ==>", match)
	
	srp := strings.NewReplacer("?", ".", "*", ".*?")
	s := "linux*?"
	print( "replace ==>", srp.Replace(s) )
	
}

func ExpMatch(pattern, name string) (bool, error) {
	// check some base cases
	patternLen, nameLen := len(pattern), len(name)
	if patternLen == 0 && nameLen == 0 {
		return true, nil
	}
	if patternLen == 0 {
		return false, nil
	}
	if nameLen == 0 && pattern != "*" {
		return false, nil
	}

	// check for matches one rune at a time
	patIdx, nameIdx := 0, 0
	for patIdx < patternLen && nameIdx < nameLen {
		patRune, patAdj := utf8.DecodeRuneInString(pattern[patIdx:])
		nameRune, nameAdj := utf8.DecodeRuneInString(name[nameIdx:])
		if patRune == '\\' {
			// handle escaped runes
			patIdx += patAdj
			patRune, patAdj = utf8.DecodeRuneInString(pattern[patIdx:])
			if patRune == utf8.RuneError {
				return false, ErrBadPattern
			} else if patRune == nameRune {
				patIdx += patAdj
				nameIdx += nameAdj
			} else {
				return false, nil
			}
		} else if patRune == '*' {
			// handle stars
			if patIdx += patAdj; patIdx >= patternLen {
				// a star at the end of a pattern will always
				// match the rest of the path
				return true, nil
			}

			// check if we can make any matches
			for ; nameIdx < nameLen; nameIdx += nameAdj {
				if m, _ := ExpMatch(pattern[patIdx:], name[nameIdx:]); m {
					return true, nil
				}
			}
			return false, nil
		} else if patRune == '[' {
			// handle character sets
			patIdx += patAdj
			endClass := indexRuneWithEscaping(pattern[patIdx:], ']')
			if endClass == -1 {
				return false, ErrBadPattern
			}
			endClass += patIdx
			classRunes := []rune(pattern[patIdx:endClass])
			classRunesLen := len(classRunes)
			if classRunesLen > 0 {
				classIdx := 0
				matchClass := false
				if classRunes[0] == '^' {
					classIdx++
				}
				for classIdx < classRunesLen {
					low := classRunes[classIdx]
					if low == '-' {
						return false, ErrBadPattern
					}
					classIdx++
					if low == '\\' {
						if classIdx < classRunesLen {
							low = classRunes[classIdx]
							classIdx++
						} else {
							return false, ErrBadPattern
						}
					}
					high := low
					if classIdx < classRunesLen && classRunes[classIdx] == '-' {
						// we have a range of runes
						if classIdx++; classIdx >= classRunesLen {
							return false, ErrBadPattern
						}
						high = classRunes[classIdx]
						if high == '-' {
							return false, ErrBadPattern
						}
						classIdx++
						if high == '\\' {
							if classIdx < classRunesLen {
								high = classRunes[classIdx]
								classIdx++
							} else {
								return false, ErrBadPattern
							}
						}
					}
					if low <= nameRune && nameRune <= high {
						matchClass = true
					}
				}
				if matchClass == (classRunes[0] == '^') {
					return false, nil
				}
			} else {
				return false, ErrBadPattern
			}
			patIdx = endClass + 1
			nameIdx += nameAdj
		}else if patRune == '?' || patRune == nameRune {
			// handle single-rune wildcard
			patIdx += patAdj
			nameIdx += nameAdj
		} else {
			return false, nil
		}
	}
	if patIdx >= patternLen && nameIdx >= nameLen {
		return true, nil
	}
	if nameIdx >= nameLen && pattern[patIdx:] == "*" || pattern[patIdx:] == "**" {
		return true, nil
	}
	return false, nil
}

// Find the first index of a rune in a string,
// ignoring any times the rune is escaped using "\".
func indexRuneWithEscaping(s string, r rune) int {
	end := strings.IndexRune(s, r)
	if end == -1 {
		return -1
	}
	if end > 0 && s[end-1] == '\\' {
		start := end + utf8.RuneLen(r)
		end = indexRuneWithEscaping(s[start:], r)
		if end != -1 {
			end += start
		}
	}
	return end
}