package rext

import "regexp"

type Regex interface {
	IsMatch(haystack string) bool
	MatchFirst(haystack string) (RegexMatch, bool)
	MatchAll(haystack string) []RegexMatch
	ReplaceAll(haystack string, repl string, literal bool) string
	ReplaceAllFunc(haystack string, repl func(string) string) string
	RemoveAll(haystack string) string
	GroupCount() int
}

type regexWrapper struct {
	rex      *regexp.Regexp
	subnames []string
}

type RegexMatch struct {
	haystack        string
	submatchesIndex []int
	subnames        []string
}

type RegexMatchGroup struct {
	haystack string
	start    int
	end      int
}

func W(rex *regexp.Regexp) Regex {
	return &regexWrapper{rex: rex, subnames: rex.SubexpNames()}
}

// ---------------------------------------------------------------------------------------------------------------------

func (w *regexWrapper) IsMatch(haystack string) bool {
	return w.rex.MatchString(haystack)
}

func (w *regexWrapper) MatchFirst(haystack string) (RegexMatch, bool) {
	res := w.rex.FindStringSubmatchIndex(haystack)
	if res == nil {
		return RegexMatch{}, false
	}

	return RegexMatch{haystack: haystack, submatchesIndex: res, subnames: w.subnames}, true
}

func (w *regexWrapper) MatchAll(haystack string) []RegexMatch {
	resarr := w.rex.FindAllStringSubmatchIndex(haystack, -1)

	matches := make([]RegexMatch, 0, len(resarr))
	for _, res := range resarr {
		matches = append(matches, RegexMatch{haystack: haystack, submatchesIndex: res, subnames: w.subnames})
	}

	return matches
}

func (w *regexWrapper) ReplaceAll(haystack string, repl string, literal bool) string {
	if literal {
		// do not expand placeholder aka $1, $2, ...
		return w.rex.ReplaceAllLiteralString(haystack, repl)
	} else {
		return w.rex.ReplaceAllString(haystack, repl)
	}
}

func (w *regexWrapper) ReplaceAllFunc(haystack string, repl func(string) string) string {
	return w.rex.ReplaceAllStringFunc(haystack, repl)
}

func (w *regexWrapper) RemoveAll(haystack string) string {
	return w.rex.ReplaceAllLiteralString(haystack, "")
}

// GroupCount returns the amount of groups in this match, does not count group-0 (whole match)
func (w *regexWrapper) GroupCount() int {
	return len(w.subnames) - 1
}

// ---------------------------------------------------------------------------------------------------------------------

func (m RegexMatch) FullMatch() RegexMatchGroup {
	return RegexMatchGroup{haystack: m.haystack, start: m.submatchesIndex[0], end: m.submatchesIndex[1]}
}

// GroupCount returns the amount of groups in this match, does not count group-0 (whole match)
func (m RegexMatch) GroupCount() int {
	return len(m.subnames) - 1
}

// GroupByIndex returns the value of a matched group (group 0 == whole match)
func (m RegexMatch) GroupByIndex(idx int) RegexMatchGroup {
	return RegexMatchGroup{haystack: m.haystack, start: m.submatchesIndex[idx*2], end: m.submatchesIndex[idx*2+1]}
}

// GroupByName returns the value of a matched group (group 0 == whole match)
func (m RegexMatch) GroupByName(name string) RegexMatchGroup {
	for idx, subname := range m.subnames {
		if subname == name {
			return RegexMatchGroup{haystack: m.haystack, start: m.submatchesIndex[idx*2], end: m.submatchesIndex[idx*2+1]}
		}
	}
	panic("failed to find regex-group by name")
}

// ---------------------------------------------------------------------------------------------------------------------

func (g RegexMatchGroup) Value() string {
	return g.haystack[g.start:g.end]
}

func (g RegexMatchGroup) Start() int {
	return g.start
}

func (g RegexMatchGroup) End() int {
	return g.end
}

func (g RegexMatchGroup) Range() (int, int) {
	return g.start, g.end
}

func (g RegexMatchGroup) Length() int {
	return g.end - g.start
}