Add support for command permissions to the framework

src/framework/commands/mod.rs

@@ -9,6 +9,7 @@ pub mod arguments;
 pub mod context;
 pub mod messages;
 pub mod runner;
+pub mod permissions;
 
 #[derive(Debug, Error)]
 pub enum CommandError {
@@ -37,6 +38,9 @@ pub trait Command<T>: Send + Sync + Debug {
     fn arguments(&self) -> &'static [Argument] {
         &[]
     }
+    fn permissions(&self) -> &'static [Box<dyn permissions::Permission<T> + Send + Sync>] {
+        &[]
+    }
 
     /// Returns the command name + all its aliases.
     ///

src/framework/commands/permissions.rs

@@ -0,0 +1,10 @@
+use std::fmt::Debug;
+
+use async_trait::async_trait;
+
+use crate::framework::commands::{CommandError, context::CommandContext};
+
+#[async_trait]
+pub trait Permission<S: Send + Sync + 'static>: Debug {
+    async fn check(&self, ctx: &CommandContext<S>) -> Result<bool, CommandError>;
+}

src/framework/commands/runner.rs

@@ -31,12 +31,21 @@ impl<T: Send + Sync + 'static> OnMessageHandler<T> for CommandRunner {
                 });
 
                 if let Some(command) = command {
-                    command
-                        .execute(
-                            CommandContext::new(event, rt.clone(), &prefixes[0]),
-                            parts.args,
-                        )
-                        .await?;
+                    let ctx = CommandContext::new(event, rt.clone(), &prefixes[0]);
+
+                    for permission in command.permissions() {
+                        if !permission
+                            .check(&ctx)
+                            .await
+                            .inspect_err(|e| log::error!("Permission check failed: {e}"))?
+                        {
+                            return Err(
+                                format!("The check for permission {permission:?} failed").into()
+                            );
+                        }
+                    }
+
+                    command.execute(ctx, parts.args).await?;
 
                     break;
                 }