feat: add prefix slash command

interactions/commands/prefix.js

@@ -0,0 +1,49 @@
+module.exports = {
+  name: 'prefix',
+  async execute(client, interaction) {
+    const database = client.db.prepare('SELECT prefix FROM guilds WHERE id = ?').get(interaction.guildId);
+    const statement = database ? 'UPDATE guilds SET prefix = @prefix WHERE id = @id' : 'INSERT INTO guilds (id, prefix) VALUES (@id, @prefix)';
+    const badLetters = require('../../detector/detection.json').join('');
+    const detector = RegExp(`[${badLetters}]`, 'giu');
+
+    const prefix = interaction.options.getString('prefix');
+
+    if (!prefix) {
+      return interaction.reply({
+        embeds: [{
+          title: 'Prefix',
+          description: `The current prefix is \`${database?.prefix ?? client.config.prefix}\``,
+          color: client.config.color
+        }]
+      });
+    }
+
+    if (!interaction.member.permissions.has('MANAGE_MESSAGES')) {
+      return interaction.reply({
+        content: 'You need the `MANAGE_MESSAGES` permission to chanqe the prefix',
+        ephemeral: true
+      });
+    }
+
+    if (prefix.length >= 10 || detector.test(prefix)) {
+      return interaction.reply({
+        embeds: [{
+          title: 'Invalid Prefix',
+          description: 'It must be shorter than 10 characters and it can\'t contain the bad letter',
+          color: client.config.color
+        }],
+        ephemeral: true
+      });
+    }
+
+    const newPrefix = prefix === client.config.prefix ? null : prefix;
+    client.db.prepare(statement).run({ id: interaction.guildId, prefix: newPrefix });
+    interaction.reply({
+      embeds: [{
+        title: 'Prefix',
+        description: `Chanqed prefix to \`${prefix}\``,
+        color: client.config.color
+      }]
+    });
+  }
+};