package util

import "regexp"

// RegexpSplit split slices s into substrings separated by the expression and
// returns a slice of the substrings between those expression matches.
// If capturing parentheses are used in expression, then the text of all groups
// in the expression are also returned as part of the resulting slice.
//
// This function acts consistent with Python's re.split function.
func RegexpSplit(re *regexp.Regexp, s string, n int) []string {
	if n == 0 {
		return nil
	}

	if len(re.String()) > 0 && len(s) == 0 {
		return []string{""}
	}

	var matches [][]int
	if len(re.SubexpNames()) > 1 {
		matches = re.FindAllStringSubmatchIndex(s, n)
	} else {
		matches = re.FindAllStringIndex(s, n)
	}
	strings := make([]string, 0, len(matches))

	beg := 0
	end := 0
	for _, match := range matches {
		if n > 0 && len(strings) >= n-1 {
			break
		}

		end = match[0]
		if match[1] != 0 {
			strings = append(strings, s[beg:end])
		}
		beg = match[1]
		if len(re.SubexpNames()) > 1 {
			strings = append(strings, s[match[0]:match[1]])
		}
	}

	if end != len(s) {
		strings = append(strings, s[beg:])
	}

	return strings
}