package core

import (
	"bytes"
	"fmt"
	"os/exec"
	"regexp"
	"strings"
	"time"

	"github.com/bwmarrin/discordgo"
)

// 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, " ")
}

func createAudio(msg string) (filename string, file *bytes.Reader) {
	curr_time := time.Now().Unix()
	filename = fmt.Sprintf("/tmp/%d.mp3", curr_time)
	var cmd_args string = fmt.Sprintf("espeak-ng -s 120 -v mb-fr2 -p 30 '%s' --stdout",
		maxString(msg, 300))
	cmd := exec.Command("sh", "-c", cmd_args)
	out, err := cmd.CombinedOutput()
	if err != nil {
		fmt.Println(fmt.Sprint(err))
	}
	file = bytes.NewReader(out)
	return
}

func MessagePing(s *discordgo.Session, m *discordgo.MessageCreate) {
	// Ignore all messages created by the bot itself
	// This isn't required in this specific example but it's a good practice.
	if m.Author.ID == s.State.User.ID {
		return
	}

	if m.Content == "ping" {
		s.ChannelMessageSend(m.ChannelID, "Pong!")
	}

	if m.Content == "pong" {
		s.ChannelMessageSend(m.ChannelID, "Ping!")
	}
}

func MessageAudio(s *discordgo.Session, m *discordgo.MessageCreate) {
	if m.Author.ID == s.State.User.ID {
		return
	}
	var prefix string = "/gogodisco audio"
	if strings.HasPrefix(m.Content, prefix) {
		var message string = strings.TrimPrefix(m.Content, prefix)
		var cleanMessage string = prepareTTSMessage(message)
		filename, file := createAudio(cleanMessage)
		s.ChannelFileSend(m.ChannelID, filename, file)
	}
}