nikoksr/notify

package discord

import (
    "context"
    "fmt"

    "github.com/bwmarrin/discordgo"
)

//go:generate mockery --name=discordSession --output=. --case=underscore --inpackage
type discordSession interface {
    ChannelMessageSend(channelID string, content string, options ...discordgo.RequestOption) (*discordgo.Message, error)
}

// Compile-time check to ensure that discordgo.Session implements the discordSession interface.
var _ discordSession = new(discordgo.Session)

// Discord struct holds necessary data to communicate with the Discord API.
type Discord struct {
    client     discordSession
    channelIDs []string
}

// New returns a new instance of a Discord notification service.
func New() *Discord {
    return &Discord{
        client:     &discordgo.Session{},
        channelIDs: []string{},
    }
}

// authenticate will try and authenticate to discord.
func (d *Discord) authenticate(token string) error {
    client, err := discordgo.New(token)
    if err != nil {
        return err
    }

    client.Identify.Intents = discordgo.IntentsGuildMessageTyping

    d.client = client

    return nil
}

// AuthenticateWithBotToken authenticates you as a bot to Discord via the given access token.
// For more info, see here: https://pkg.go.dev/github.com/bwmarrin/discordgo@v0.22.1#New
func (d *Discord) AuthenticateWithBotToken(token string) error {
    token = parseBotToken(token)

    return d.authenticate(token)
}

// AuthenticateWithOAuth2Token authenticates you to Discord via the given OAUTH2 token.
// For more info, see here: https://pkg.go.dev/github.com/bwmarrin/discordgo@v0.22.1#New
func (d *Discord) AuthenticateWithOAuth2Token(token string) error {
    token = parseOAuthToken(token)

    return d.authenticate(token)
}

// parseBotToken parses a regular token to a bot token that is understandable for discord.
// For more info, see here: https://pkg.go.dev/github.com/bwmarrin/discordgo@v0.22.1#New
func parseBotToken(token string) string {
    return "Bot " + token
}

// parseBotToken parses a regular token to a OAUTH2 token that is understandable for discord.
// For more info, see here: https://pkg.go.dev/github.com/bwmarrin/discordgo@v0.22.1#New
func parseOAuthToken(token string) string {
    return "Bearer " + token
}

// AddReceivers takes Discord channel IDs and adds them to the internal channel ID list. The Send method will send
// a given message to all those channels.
func (d *Discord) AddReceivers(channelIDs ...string) {
    d.channelIDs = append(d.channelIDs, channelIDs...)
}

// Send takes a message subject and a message body and sends them to all previously set chats.
func (d Discord) Send(ctx context.Context, subject, message string) error {
    fullMessage := subject + "\n" + message // Treating subject as message title

    for _, channelID := range d.channelIDs {
        select {
        case <-ctx.Done():
            return ctx.Err()
        default:
            _, err := d.client.ChannelMessageSend(channelID, fullMessage)
            if err != nil {
                return fmt.Errorf("send message to Discord channel %q: %w", channelID, err)
            }
        }
    }

    return nil
}