package core

import (
	"regexp"
	"strings"
)

// source on www.socketloop.com
func removeCharacters(input string, characters string) string {
	filter := func(r rune) rune {
		if strings.IndexRune(characters, r) < 0 {
			return r
		}
		return -1
	}
	return strings.Map(filter, input)
}

// https://stackoverflow.com/questions/34839659/how-can-i-easily-get-a-substring-in-go-while-guarding-against-slice-bounds-out
func maxString(s string, max int) string {
	if len(s) > max {
		r := 0
		for i := range s {
			r++
			if r > max {
				return s[:i]
			}
		}
	}
	return s
}

// this only strip custom emoji, not default unicode ones
func stripEmoji(msg string) string {
	re := regexp.MustCompile(`:\w+:`)
	match := re.FindAll([]byte(msg), -1)
	if len(match) > 0 {
		s := msg
		for i := range match {
			s = strings.Replace(s, string(match[i]), "", -1)
		}
		return s
	} else {
		return msg
	}
}

func prepareTTSMessage(msg string) string {
	t1 := maxString(msg, 300)
	t2 := stripEmoji(t1)
	t3 := removeCharacters(t2, "-\"'`$();:.\\")
	return strings.Trim(t3, " ")
}