package discord

// Dispatcher is designed specifically to ease handling of text commands
// of the form "/command options"
// For other event types, you'll need the full Discord session,
// exported as the variable `Session`.

import (
	"fmt"
	"strings"

	"github.com/bwmarrin/discordgo"
)

type DiscordMessage func(*discordgo.Session, *discordgo.MessageCreate)

var handlers map[string]DiscordMessage
var helpHandlers map[string]DiscordMessage

// TODO: is this load-order dependent?
func init() {
	handlers = make(map[string]DiscordMessage)
	helpHandlers = make(map[string]DiscordMessage)
	handlers["/help"] = helpDispatcher
}

func RegisterHandler(command string, handler DiscordMessage, helpHandler DiscordMessage) {
	handlers[command] = handler
	helpHandlers[command[1:]] = helpHandler
}

func dispatcher(session *discordgo.Session, msg *discordgo.MessageCreate) {
	command := strings.Split(msg.Content, " ")[0]

	if msg.Author.ID == session.State.User.ID {
		return
	}

	if handler, ok := handlers[command]; ok {
		handler(session, msg)
	}
}

func helpDispatcher(session *discordgo.Session, msg *discordgo.MessageCreate) {
	data := strings.Split(msg.Content, " ")[1:]

	if len(data) == 0 {
		printCommandList(session, msg)
		return
	}

	command := data[0]
	if handler, ok := helpHandlers[command]; ok {
		handler(session, msg)
	}
}

func printCommandList(session *discordgo.Session, msg *discordgo.MessageCreate) {
	var output strings.Builder

	output.WriteString("Here are all the commands I know about:\n\n")
	for command, _ := range helpHandlers {
		output.WriteString(fmt.Sprintf("     %s\n", command))
	}
	output.WriteString("\nType `/help <command>` For more information about a particular command.")

	session.ChannelMessageSend(msg.ChannelID, output.String())
}