framework/commands.go

package framework

import (
	"github.com/QPixel/orderedmap"
	"github.com/bwmarrin/discordgo"
	"runtime"
	"runtime/debug"
	"strings"
	"time"
)

// commands.go
// This file contains everything required to add core commands to the bot, and parse commands from a message

// Group
// Defines different "groups" of commands for ordering in a help command
type Group string

var (
	Moderation Group = "moderation"
	Utility    Group = "utility"
)

// CommandInfo
// The definition of a command's info. This is everything about the command, besides the function it will run
type CommandInfo struct {
	Aliases     []string               // Aliases for the normal trigger
	Arguments   *orderedmap.OrderedMap // Arguments for the command
	Description string                 // A short description of what the command does
	Group       Group                  // The group this command belongs to
	ParentID    string                 // The ID of the parent command
	Public      bool                   // Whether non-admins and non-mods can use this command
	IsTyping    bool                   // Whether the command will show a typing thing when ran.
	IsParent    bool                   // If the command is the parent of a subcommand tree
	IsChild     bool                   // If the command is the child
	Trigger     string                 // The string that will trigger the command
}

// Context
// This is a context of a single command invocation
// This gives the command function access to all the information it might need
type Context struct {
	Guild       *Guild // NOTE: Guild is a pointer, since we want to use the SAME instance of the guild across the program!
	Cmd         CommandInfo
	Args        Arguments
	Message     *discordgo.Message
	Interaction *discordgo.Interaction
}

// BotFunction
// This type defines the functions that are called when commands are triggered
// Contexts are also passed as pointers, so they are not re-allocated when passed through
type BotFunction func(ctx *Context)

// Command
// The definition of a command, which is that command's information, along with the function it will run
type Command struct {
	Info     CommandInfo
	Function BotFunction
}

// ChildCommand
// Defines how child commands are stored
type ChildCommand map[string]map[string]Command

// commands
// All the registered core commands (not custom commands)
// This is private so that other commands cannot modify it
var commands = make(map[string]Command)

// childCommands
// All the registered ChildCommands (SubCmdGrps)
// This is private so other commands cannot modify it
var childCommands = make(ChildCommand)

// Command Aliases
// A map of aliases to command triggers
var commandAliases = make(map[string]string)

// slashCommands
// All the registered core commands that are also slash commands
// This is also private so other commands cannot modify it
var slashCommands = make(map[string]discordgo.ApplicationCommand)

// commandsGC
var commandsGC = 0

// AddCommand
// Add a command to the bot
func AddCommand(info *CommandInfo, function BotFunction) {
	// Add Trigger to the alias
	info.Aliases = append(info.Aliases, info.Trigger)
	// Build a Command object for this command
	command := Command{
		Info:     *info,
		Function: function,
	}
	// adds a alias to a map; command aliases are case-sensitive
	for _, alias := range info.Aliases {
		if _, ok := commandAliases[alias]; ok {
			log.Errorf("Alias was already registered %s for command %s", alias, info.Trigger)
			continue
		}
		alias = strings.ToLower(alias)
		commandAliases[alias] = info.Trigger
	}
	// Add the command to the map; command triggers are case-insensitive
	commands[strings.ToLower(info.Trigger)] = command
}

// AddChildCommand
// Adds a child command to the bot.
func AddChildCommand(info *CommandInfo, function BotFunction) {
	// Build a Command object for this command
	command := Command{
		Info:     *info,
		Function: function,
	}
	parentID := strings.ToLower(info.ParentID)
	if childCommands[parentID] == nil {
		childCommands[parentID] = make(map[string]Command)
	}
	// Add the command to the map; command triggers are case-insensitive
	childCommands[parentID][command.Info.Trigger] = command
}

// AddSlashCommand
// Adds a slash command to the bot
// Allows for separation between normal commands and slash commands
func AddSlashCommand(info *CommandInfo) {
	if !info.IsParent || !info.IsChild {
		s := createSlashCommandStruct(info)
		slashCommands[strings.ToLower(info.Trigger)] = *s
		return
	}
	if info.IsParent {
		s := createSlashSubCmdStruct(info, childCommands[info.Trigger])
		slashCommands[strings.ToLower(info.Trigger)] = *s
		return
	}
}

// AddSlashCommands
// Defaults to adding Global slash commands
// Currently hard coded to guild commands for testing
func AddSlashCommands(guildId string, c chan string) {
	for _, v := range slashCommands {
		_, err := Session.ApplicationCommandCreate(Session.State.User.ID, guildId, &v)
		if err != nil {
			c <- "Unable to register slash commands :/"
			log.Errorf("Cannot create '%v' command: %v", v.Name, err)
			log.Errorf("%v", v.Options)
			return
		}
	}
	c <- "Finished registering slash commands"
	return
}

// GetCommands
// Provide a way to read commands without making it possible to modify their functions
func GetCommands() map[string]CommandInfo {
	list := make(map[string]CommandInfo)
	for x, y := range commands {
		list[x] = y.Info
	}
	return list
}

// commandHandler
// This handler will be added to a *discordgo.Session, and will scan an incoming messages for commands to run
func commandHandler(session *discordgo.Session, message *discordgo.MessageCreate) {
	// Try getting an object for the current channel, with a fallback in case session.state is not ready or is nil
	channel, err := session.State.Channel(message.ChannelID)
	if err != nil {
		if channel, err = session.Channel(message.ChannelID); err != nil {
			return
		}
	}

	// Ignore messages sent by the bot
	if message.Author.ID == session.State.User.ID {
		return
	}

	g := getGuild(message.GuildID)

	trigger, argString := ExtractCommand(&g.Info, message.Content)
	if trigger == nil {
		return
	}
	// Only do further checks if the user is not a bot admin
	if !IsAdmin(message.Author.ID) {
		// Ignore the command if it is globally disabled
		if g.IsGloballyDisabled(*trigger) {
			return
		}

		// Ignore the command if this channel has blocked the command
		if g.CommandIsDisabledInChannel(*trigger, message.ChannelID) {
			return
		}

		// Ignore any message if the user is banned from using the bot
		if !g.MemberOrRoleIsWhitelisted(message.Author.ID) || g.MemberOrRoleIsIgnored(message.Author.ID) {
			return
		}

		// Ignore the message if this channel is not whitelisted, or if it is ignored
		if !g.ChannelIsWhitelisted(message.ChannelID) || g.ChannelIsIgnored(message.ChannelID) {
			return
		}
	}

	//Get the command to run
	// Error Checking
	command, ok := commands[commandAliases[*trigger]]
	if !ok {
		log.Errorf("Command was not found")
		return
	}
	// Check if the command is public, or if the current user is a bot moderator
	// Bot admins supercede both checks
	if IsAdmin(message.Author.ID) || command.Info.Public || g.IsMod(message.Author.ID) {
		// Run the command with the necessary context
		if command.Info.IsTyping && g.Info.ResponseChannelId == "" {
			_ = Session.ChannelTyping(message.ChannelID)
		}
		// The command is valid, so now we need to delete the invoking message if that is configured
		if g.Info.DeletePolicy {
			err := Session.ChannelMessageDelete(message.ChannelID, message.ID)
			if err != nil {
				SendErrorReport(message.GuildID, message.ChannelID, message.Author.ID, "Failed to delete message: "+message.ID, err)
			}
		}

		defer handleCommandError(g.ID, channel.ID, message.Author.ID)
		if command.Info.IsParent {
			handleChildCommand(*argString, command, message.Message, g)
			return
		}
		command.Function(&Context{
			Guild:   g,
			Cmd:     command.Info,
			Args:    *ParseArguments(*argString, command.Info.Arguments),
			Message: message.Message,
		})
		// Makes sure that variables ran in ParseArguments are gone.
		if commandsGC == 25 && commandsGC > 25 {
			debug.FreeOSMemory()
			commandsGC = 0
		} else {
			commandsGC++
		}
		return
	}

}

// -- Helper Methods
func handleChildCommand(argString string, command Command, message *discordgo.Message, g *Guild) {
	split := strings.SplitN(argString, " ", 2)

	childCmd, ok := childCommands[command.Info.Trigger][split[0]]
	if !ok {
		command.Function(&Context{
			Guild:   g,
			Cmd:     command.Info,
			Args:    nil,
			Message: message,
		})
		return
	}
	if len(split) < 2 {
		childCmd.Function(&Context{
			Guild:   g,
			Cmd:     childCmd.Info,
			Args:    *ParseArguments("", childCmd.Info.Arguments),
			Message: message,
		})
		return
	}
	childCmd.Function(&Context{
		Guild:   g,
		Cmd:     childCmd.Info,
		Args:    *ParseArguments(split[1], childCmd.Info.Arguments),
		Message: message,
	})
	return
}

func handleCommandError(gID string, cId string, uId string) {
	if r := recover(); r != nil {
		log.Warningf("Recovering from panic: %s", r)
		log.Warningf("Sending Error report to admins")
		SendErrorReport(gID, cId, uId, "Error!", r.(runtime.Error))
		message, err := Session.ChannelMessageSend(cId, "Error!")
		if err != nil {
			log.Errorf("err sending message %s", err)
		}
		time.Sleep(5 * time.Second)
		_ = Session.ChannelMessageDelete(cId, message.ID)
		return
	}
	return
}