External Chat Linking (!4)

This PR adds the functionality for plugins to send and recieve messages linked to a specific channel.

Co-authored-by: Layla <layla@layla.gg>
Reviewed-on: https://gitea.sumulayla.synology.me/layla/birdbot/pulls/4

discord/message.go

@@ -0,0 +1,45 @@
+package discord
+
+import (
+	"log"
+
+	"github.com/bwmarrin/discordgo"
+	"github.com/yeslayla/birdbot/core"
+	"github.com/yeslayla/birdbot/persistence"
+)
+
+func (discord *Discord) WebhookSendMessage(channel *core.Channel, displayName string, message string) {
+
+	webhookData, err := discord.db.GetDiscordWebhook(channel.ID)
+	if err != nil {
+		log.Printf("Error getting webhook from DB: %s", err)
+		return
+	}
+
+	if webhookData == nil {
+		webhook, err := discord.session.WebhookCreate(channel.ID, "BirdBot", "")
+		if err != nil {
+			log.Printf("Error creating webhook: %s", err)
+			return
+		}
+
+		webhookData = &persistence.DBDiscordWebhook{
+			ID:    webhook.ID,
+			Token: webhook.Token,
+		}
+
+		if err := discord.db.SetDiscordWebhook(channel.ID, webhookData); err != nil {
+			log.Fatalf("Error failed to store webhook in DB: %s", err)
+			return
+		}
+
+	}
+
+	if _, err = discord.session.WebhookExecute(webhookData.ID, webhookData.Token, false, &discordgo.WebhookParams{
+		Content:  message,
+		Username: displayName,
+	}); err != nil {
+		log.Printf("Failed to send message over webhook: %s", err)
+	}
+
+}