Implement command aliases

- Add alias parsing to `Context.findCommand`.
- Add new function to `Subcommand`: `AddAliases` that add new alias(es) to command.
- Added `Aliases` property to `MethodContext`

bot/command.go

@@ -85,6 +85,9 @@ type MethodContext struct {
 	// Command is the Discord command used to call the method.
 	Command string // plumb if empty
 
+	// Aliases is alternative way to call command in Discord.
+	Aliases []string
+
 	// Hidden if true will not be shown by (*Subcommand).HelpGenerate().
 	Hidden bool
 

bot/ctx_call.go

@@ -322,6 +322,12 @@ func (ctx *Context) findCommand(parts []string) ([]string, *MethodContext, *Subc
 		if c.Command == parts[0] {
 			return parts[1:], c, ctx.Subcommand, nil
 		}
+		// Check for alias
+		for _, alias := range c.Aliases {
+			if alias == parts[0] {
+				return parts[1:], c, ctx.Subcommand, nil
+			}
+		}
 	}
 
 	// Can't find the command, look for subcommands if len(args) has a 2nd
@@ -343,6 +349,12 @@ func (ctx *Context) findCommand(parts []string) ([]string, *MethodContext, *Subc
 				if c.Command == parts[1] {
 					return parts[2:], c, s, nil
 				}
+				// Check for aliases
+				for _, alias := range c.Aliases {
+					if alias == parts[1] {
+						return parts[2:], c, s, nil
+					}
+				}
 			}
 		}
 

bot/subcommand.go

@@ -390,6 +390,30 @@ func (sub *Subcommand) SetPlumb(methodName string) {
 	sub.plumbed = sub.FindCommand(methodName)
 }
 
+// AddAliases add alias(es) to specific command (defined with MethodName).
+// This removes silently all duplicate aliases. Use this instead overwriting aliases
+// for safety reasons (duplicates).
+func (sub *Subcommand) AddAliases(commandName string, aliases ...string) {
+	// Get command
+	command := sub.FindCommand(commandName)
+
+	// Merge current aliases for duplicate removing
+	aliases = append(aliases, command.Aliases...)
+
+	// Remove all duplicate aliases
+	keys := make(map[string]bool)
+	var uniqueAliases []string
+	for _, alias := range aliases {
+		if _, value := keys[alias]; !value {
+			keys[alias] = true
+			uniqueAliases = append(uniqueAliases, alias)
+		}
+	}
+
+	// Write new listing of aliases
+	command.Aliases = uniqueAliases
+}
+
 func lowerFirstLetter(name string) string {
 	return strings.ToLower(string(name[0])) + name[1:]
 }