package handiebot.command;

import handiebot.utils.DisappearingMessage;
import handiebot.utils.FileUtil;
import handiebot.view.BotLog;
import sx.blah.discord.handle.impl.events.guild.channel.message.MessageReceivedEvent;
import sx.blah.discord.handle.obj.IChannel;
import sx.blah.discord.handle.obj.IGuild;
import sx.blah.discord.handle.obj.IMessage;
import sx.blah.discord.handle.obj.IUser;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import static handiebot.HandieBot.client;
import static handiebot.HandieBot.log;

/**
 * @author Andrew Lalis
 * Class to process commands.
 */
public class CommandHandler {

    public static final String DEFAULT_PREFIX = "!";
    public static Map<IGuild, String> PREFIXES = loadGuildPrefixes();
    /**
     * Main method to handle user messages.
     * @param event The event generated by the message.
     */
    public static void handleCommand(MessageReceivedEvent event){
        IMessage message = event.getMessage();
        IUser user = event.getAuthor();
        //Exit immediately if the user is a bot; avoids bot spam chat.
        if (user.isBot()){
            return;
        }
        IChannel channel = event.getChannel();
        IGuild guild = event.getGuild();
        //Check if the guild already has a prefix assigned, and if not, give it the default.
        if (!PREFIXES.containsKey(guild)){
            PREFIXES.put(guild, DEFAULT_PREFIX);
        }
        String command = extractCommand(message);
        String[] args = extractArgs(message);
        //Create a context to give to each command's execution, so it knows what channel to reply on, etc.
        CommandContext context = new CommandContext(user, channel, guild, args);
        if (guild != null && command != null){
            DisappearingMessage.deleteMessageAfter(1000, message);
            Commands.executeCommand(command, context);
        }
    }

    /**
     * Returns a command word, if one exists, from a given message.
     * @param message The message to get a command from.
     * @return The command word, minus the prefix, or null.
     */
    private static String extractCommand(IMessage message){
        String[] words = message.getContent().split(" ");
        if (words[0].startsWith(PREFIXES.get(message.getGuild()))){
            return words[0].replaceFirst(PREFIXES.get(message.getGuild()), "").toLowerCase();
        }
        return null;
    }

    /**
     * Extracts a list of arguments from a message, assuming a command exists.
     * @param message The message to parse.
     * @return A list of strings representing args.
     */
    private static String[] extractArgs(IMessage message){
        String[] words = message.getContent().split(" ");
        if (words[0].startsWith(PREFIXES.get(message.getGuild()))){
            String[] args = new String[words.length-1];
            for (int i = 0; i < words.length-1; i++){
                args[i] = words[i+1];
            }
            return args;
        }
        return new String[0];
    }

    /**
     * Loads a persistent list of prefixes for guilds from a file called guildPrefixes.txt
     * @return The mapping of guild to prefix.
     */
    private static Map<IGuild, String> loadGuildPrefixes(){
        File prefixFile = new File(FileUtil.getDataDirectory()+"guildPrefixes.txt");
        Map<IGuild, String> prefixes = new HashMap<>();
        if (prefixFile.exists()){
            List<String> lines = FileUtil.getLinesFromFile(prefixFile);
            for (String line : lines){
                String[] words = line.split(" / ");
                prefixes.put(client.getGuildByID(Long.parseLong(words[0])), words[1]);
            }
        }
        log.log(BotLog.TYPE.INFO, "Loaded prefixes.");
        return prefixes;
    }

    /**
     * Saves the list of prefixes to a file.
     */
    public static void saveGuildPrefixes(){
        File prefixFile = new File(FileUtil.getDataDirectory()+"guildPrefixes.txt");
        List<String> lines = new ArrayList<>();
        for (Map.Entry<IGuild, String> entry : PREFIXES.entrySet()){
            lines.add(Long.toString(entry.getKey().getLongID())+" / "+entry.getValue());
        }
        FileUtil.writeLinesToFile(lines, prefixFile);
        log.log(BotLog.TYPE.INFO, "Saved prefixes.");
    }

}