feat: add UserVoiceState

[raa0121]

close: #1375

By getting the user's VoiceState from *Session, the bot can log into that channel.

example

package main

import (
    "context"
    "log"
    "os"
    "os/signal"
    "syscall"

    "github.com/bwmarrin/discordgo"
    "github.com/joho/godotenv"
)

var (
    ctx context.Context

    voiceConnections []*discordgo.VoiceConnection
    textChannels []string

    commands = []*discordgo.ApplicationCommand{
        {
            Name: "vs-connect",
            Description: "add channel to text2speach",
        },
        {
            Name: "vs-disconnect",
            Description: "stop text2speach",
        },
    }

    commandHandlers = map[string]func(s *discordgo.Session, i *discordgo.InteractionCreate) {
        "vs-connect": connect,
        "vs-disconnect": disconnect,
    }
)

func main() {
    botToken := os.Getenv("DISCORD_BOT_TOKEN")
    if botToken == "" {
        log.Fatal("DISCORD_BOT_TOKEN is not set.")
    }

    dg, err := discordgo.New("Bot " + botToken)
    if err != nil {
        log.Fatal(err)
    }
    defer dg.Close()
    dg.AddHandler(func(s *discordgo.Session, i *discordgo.InteractionCreate) {
        if h, ok := commandHandlers[i.ApplicationCommandData().Name]; ok {
            h(s, i)
        }
    })

    dg.Identify.Intents = discordgo.IntentsGuilds | discordgo.IntentsGuildMessages | discordgo.IntentsGuildVoiceStates
    err = dg.Open()
    if err != nil {
        log.Fatal(err)
    }

    log.Println("Adding commands...")
    registeredCommands := make([]*discordgo.ApplicationCommand, len(commands))
    for i, v := range commands {
        cmd, err := dg.ApplicationCommandCreate(dg.State.User.ID, "", v)
        if err != nil {
            log.Panicf("Cannot create '%v' command: %v", v.Name, err)
        }
        registeredCommands[i] = cmd
    }

    fmt.Println("Bot is now running.  Press CTRL-C to exit.")
    sc := make(chan os.Signal, 1)
    signal.Notify(sc, syscall.SIGINT, syscall.SIGTERM, os.Interrupt, os.Kill)
    <-sc
}

func connect(s *discordgo.Session, i *discordgo.InteractionCreate) {
    var channelId string
    voiceState, err := s.UserVoiceState(i.GuildID, i.Interaction.Member.User.ID)
    if err != nil {
        s.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
            Type: discordgo.InteractionResponseChannelMessageWithSource,
            Data: &discordgo.InteractionResponseData{
                Content: "Please Join VoiceChannel.",
            },
        })
        return
    }
    channelId = voiceState.ChannelID
    j, err := s.ChannelVoiceJoin(i.GuildID, channelId, false, false)
    if err != nil {
        s.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
            Type: discordgo.InteractionResponseChannelMessageWithSource,
            Data: &discordgo.InteractionResponseData{
                Content: "Failed to join VoiceChannel.",
            },
        })
        return
    }
    s.InteractionRespond(i.Interaction, &discordgo.InteractionResponse{
        Type: discordgo.InteractionResponseChannelMessageWithSource,
        Data: &discordgo.InteractionResponseData{
            Content: "Start Text2Speach.",
        },
    })
    voiceConnections = append(voiceConnections, j)
    textChannels = append(textChannels, i.ChannelID)
}