const { stripIndents } = require('common-tags');
const { escapeRegex } = require('escape-string-regexp');

const { Observer } = require('../../interfaces');

class CommandHandler extends Observer {

    constructor(manager) {

        super(manager, {
            name: 'commandHandler',
            priority: 5,
            guarded: true
        });

        this.manager = manager;

        this.hooks = [
            ['message', this.handleMessage.bind(this)]
        ];

        this.commandPatterns = new Map();


    }

    async handleMessage(message) {

        const client = message.client;

        if(!this.manager._built
            || !client._built
            || message.webhookID
            || message.author.bot
            || (message.guild && !message.guild.available)) return undefined;

        if(message.guild && !message.member) {
            await message.guild.members.fetch(message.author.id);
        }

        const content = message.cleanContent;
        const args = content.split(' ');
        const command = await this._getCommand(message, args);
        if(!command) return undefined;

        return await this.handleCommand(message, command, args);

    }

    async handleCommand(message, command, args) {
        
    }

    async _getCommand(message, args = []) {

        const pattern = await this._getCommandPattern(message.guild);

        let command = await this._matchCommand(message, args, pattern, 2);
        if(!command && !message.guild) command = await this._matchCommand(message, args, /^([^\s]+)/i);

        return command || null;

    }

    async _getCommandPattern(guild) {

        const createCommandPattern = (guild = null) => {

            const prefix = this.client._options.discord.prefix;

            const escapedPrefix = escapeRegex(prefix);
            const pattern = new RegExp(`^(${escapedPrefix}\\s*|<@!?${this.client.user.id}>\\s+(?:${escapedPrefix})?)([^\\s]+)`, 'i');

            const obj = { pattern, prefix };
            if(guild) {
                this.client.logger.debug(`Created command pattern ${guild.name}: ${pattern}`);
                this.commandPatterns.set(guild.id, obj);
            }

            return obj;
        };

        if(!guild) return createCommandPattern().pattern;
        let commandPattern = this.commandPatterns.get(guild.id);

        return commandPattern.pattern;

    }

    async _matchCommand(message, args, pattern, index = 1) {

        const matches = pattern.exec(message.cleanContent);
        if(!matches) return null;

        const command = message.client.resolver.components(matches[index], 'command', true)[0];
        if(!command) return null;

        const indice = message.content.startsWith('<@') ? 2 : 1;
        args.splice(0, indice);

        return command;

    }


}

module.exports = CommandHandler;