Support multiple prefixes for command-groups (#343)

4 files changed, 62 insertions, 28 deletions

diff --git a/src/framework/standard/command.rs b/src/framework/standard/command.rs
index 23f2f0c..d15b6b2 100644
--- a/src/framework/standard/command.rs
+++ b/src/framework/standard/command.rs
@@ -90,7 +90,7 @@ impl<D: fmt::Display> From<D> for Error {
 
 #[derive(Debug)]
 pub struct CommandGroup {
-    pub prefix: Option<String>,
+    pub prefixes: Option<Vec<String>>,
     pub commands: HashMap<String, CommandOrAlias>,
     /// Some fields taken from Command
     pub bucket: Option<String>,
@@ -109,7 +109,7 @@ pub struct CommandGroup {
 impl Default for CommandGroup {
     fn default() -> CommandGroup {
         CommandGroup {
-            prefix: None,
+            prefixes: None,
             commands: HashMap::new(),
             bucket: None,
             required_permissions: Permissions::empty(),
diff --git a/src/framework/standard/create_group.rs b/src/framework/standard/create_group.rs
index c99b829..91eef78 100644
--- a/src/framework/standard/create_group.rs
+++ b/src/framework/standard/create_group.rs
@@ -13,8 +13,10 @@ pub use super::{
 };
 
 use client::Context;
-use model::channel::Message;
-use model::Permissions;
+use model::{
+    channel::Message,
+    Permissions,
+};
 use std::sync::Arc;
 
 /// Used to create command groups
@@ -56,11 +58,15 @@ impl CreateGroup {
         let cmd = f(self.build_command()).finish();
 
         for n in &cmd.options().aliases {
-            if let Some(ref prefix) = self.0.prefix {
-                self.0.commands.insert(
-                    format!("{} {}", prefix, n.to_string()),
-                    CommandOrAlias::Alias(format!("{} {}", prefix, command_name.to_string())),
-                );
+
+            if let Some(ref prefixes) = self.0.prefixes {
+
+                for prefix in prefixes {
+                    self.0.commands.insert(
+                        format!("{} {}", prefix, n.to_string()),
+                        CommandOrAlias::Alias(format!("{} {}", prefix, command_name.to_string())),
+                    );
+                }
             } else {
                 self.0.commands.insert(
                     n.to_string(),
@@ -106,8 +112,20 @@ impl CreateGroup {
     /// **Note**: serenity automatically puts a space after group prefix.
     ///
     /// **Note**: It's suggested to call this first when making a group.
-    pub fn prefix(mut self, desc: &str) -> Self {
-        self.0.prefix = Some(desc.to_string());
+    pub fn prefix(mut self, prefix: &str) -> Self {
+        self.0.prefixes = Some(vec![prefix.to_string()]);
+
+        self
+    }
+
+    /// Sets prefixes to respond to. Each can be a string slice of any
+    /// non-zero length.
+    ///
+    /// **Note**: serenity automatically puts a space after group prefix.
+    ///
+    /// **Note**: It's suggested to call this first when making a group.
+    pub fn prefixes<T: ToString, I: IntoIterator<Item=T>>(mut self, prefixes: I) -> Self {
+        self.0.prefixes = Some(prefixes.into_iter().map(|prefix| prefix.to_string()).collect());
 
         self
     }
diff --git a/src/framework/standard/help_commands.rs b/src/framework/standard/help_commands.rs
index c01325e..a088ef1 100644
--- a/src/framework/standard/help_commands.rs
+++ b/src/framework/standard/help_commands.rs
@@ -159,8 +159,8 @@ pub fn with_embeds<H: BuildHasher>(
             let mut found: Option<(&String, &InternalCommand)> = None;
 
             for (command_name, command) in &group.commands {
-                let with_prefix = if let Some(ref prefix) = group.prefix {
-                    format!("{} {}", prefix, command_name)
+                let with_prefix = if let Some(ref prefixes) = group.prefixes {
+                    format!("{} {}", prefixes.join("`, `"), command_name)
                 } else {
                     command_name.to_string()
                 };
@@ -229,7 +229,7 @@ pub fn with_embeds<H: BuildHasher>(
                         }
 
                         if !command.aliases.is_empty() {
-                            let aliases = command.aliases.join(", ");
+                            let aliases = command.aliases.join("`, `");
 
                             embed = embed.field(&help_options.aliases_label, aliases, true);
                         }
@@ -283,8 +283,8 @@ pub fn with_embeds<H: BuildHasher>(
                 let group = &groups[group_name];
                 let mut desc = String::new();
 
-                if let Some(ref x) = group.prefix {
-                    let _ = write!(desc, "{}: `{}`\n", &help_options.group_prefix, x);
+                if let Some(ref prefixes) = group.prefixes {
+                    let _ = write!(desc, "{}: `{}`\n", &help_options.group_prefix, prefixes.join("`, `"));
                 }
 
                 let mut has_commands = false;
@@ -408,8 +408,8 @@ pub fn plain<H: BuildHasher>(
             let mut found: Option<(&String, &InternalCommand)> = None;
 
             for (command_name, command) in &group.commands {
-                let with_prefix = if let Some(ref prefix) = group.prefix {
-                    format!("{} {}", prefix, command_name)
+                let with_prefix = if let Some(ref prefixes) = group.prefixes {
+                    format!("{} {}", prefixes.join("`, `"), command_name)
                 } else {
                     command_name.to_string()
                 };
@@ -592,8 +592,8 @@ pub fn plain<H: BuildHasher>(
         if !group_help.is_empty() {
             let _ = write!(result, "**{}:** ", group_name);
 
-            if let Some(ref x) = group.prefix {
-                let _ = write!(result, "({}: `{}`): ", help_options.group_prefix, x);
+            if let Some(ref prefixes) = group.prefixes {
+                let _ = write!(result, "({}: `{}`): ", help_options.group_prefix, prefixes.join("`, `"));
             }
 
             result.push_str(&group_help);
diff --git a/src/framework/standard/mod.rs b/src/framework/standard/mod.rs
index 6eaa83e..42da699 100644
--- a/src/framework/standard/mod.rs
+++ b/src/framework/standard/mod.rs
@@ -718,12 +718,16 @@ impl StandardFramework {
                 let cmd = f(CreateCommand::default()).finish();
                 let name = command_name.to_string();
 
-                if let Some(ref prefix) = group.prefix {
+                if let Some(ref prefixes) = group.prefixes {
+
                     for v in &cmd.options().aliases {
-                        group.commands.insert(
-                            format!("{} {}", prefix, v),
-                            CommandOrAlias::Alias(format!("{} {}", prefix, name)),
-                        );
+
+                        for prefix in prefixes {
+                            group.commands.insert(
+                                format!("{} {}", prefix, v),
+                                CommandOrAlias::Alias(format!("{} {}", prefix, name)),
+                            );
+                        }
                     }
                 } else {
                     for v in &cmd.options().aliases {
@@ -1019,9 +1023,21 @@ impl Framework for StandardFramework {
                         built = points_to.to_string();
                     }
 
-                    let to_check = if let Some(ref prefix) = group.prefix {
-                        if built.starts_with(prefix) && command_length > prefix.len() + 1 {
-                            built[(prefix.len() + 1)..].to_string()
+                    let to_check = if let Some(ref prefixes) = group.prefixes {
+                        // Once `built` starts with a set prefix,
+                        // we want to make sure that all following matching prefixes are longer
+                        // than the last matching one, this prevents picking a wrong prefix,
+                        // e.g. "f" instead of "ferris" due to "f" having a lower index in the `Vec`.
+                        let longest_matching_prefix_len = prefixes.iter().fold(0, |longest_prefix_len, prefix|
+                            if prefix.len() > longest_prefix_len && built.starts_with(prefix) && command_length > prefix.len() + 1 {
+                                prefix.len()
+                            } else {
+                                longest_prefix_len
+                            }
+                        );
+
+                        if longest_matching_prefix_len > 0 {
+                            built[(longest_matching_prefix_len + 1)..].to_string()
                         } else {
                             continue;
                         }