const { EventEmitter } = require('events'); 
// eslint-disable-next-line no-unused-vars
const { inspect } = require('util');
const os = require('os');

const ShardManager = require('./middleware/ShardManager.js');
const Logger = require('./middleware/logger/Logger.js');

class Manager extends EventEmitter {

    constructor(options) {

        super();

        this.shardManager = new ShardManager('./structure/client/DiscordClient.js', options);
        this.logger = new Logger(this);

        this._built = false;
        this.readyAt = null;

        this.shardManager.on('message', this._handleMessage.bind(this));
        // this.on('built', () => {
        //     this.shardManager.broadcast({ _built: true });
        // });
        
    }

    _handleMessage(shard, message) {

        if (message._mEval) return this.eval(shard, message);
        // Messages coming from the API that have the _logger flag will be caught here, i.e. both flags should be on
        if (message._logger) return this.logger._handleMessage(shard, message);
        if (message._webhook) return undefined; //todo
        if (message._api) return this.apiRequest(shard, message);

    }

    async build() {

        this.info('Spawning shards...');
        await this.shardManager.spawn();
        // G:\Documents\My programs\GBot\New GBot\api\index.cjs
        this.info('Shards done, booting up API...');
        const API = await import('./api/index.js').catch((err) => this.error(`Import of API Manager failed.\n${err.stack}`));
        if (API) {
            const { default: APIManager } = API;
            this.apiManager = new APIManager(this);
            await this.apiManager.init();
            this.info('API done. Manager built.');
        } else this.info('Missing API source, skipping');

        this._built = true;
        this.emit('built');
        this.readyAt = Date.now();

    }

    /**
     *
     *
     * @param {*} shard The shard from which the eval came and to which it will be returned
     * @param {*} script The script to be executed
     * @memberof Manager
     * @private
     */
    async eval(shard, { script }) {

        this.info(`Incoming manager eval from shard ${shard.id}:\n${script}`);
        let result = null,
            error = null;
        
        try {
            // eslint-disable-next-line no-eval
            result = eval(script);
            if (result instanceof Promise) result = await result;
            //if(typeof result !== 'string') result = inspect(result);
        } catch (err) {
            error = err.stack || err;
        }

        return shard.send({
            _evalResult: true,
            script,
            result,
            error
        });

    }

    async apiRequest(shard, message) {

        const { type } = message;
        switch (type) {
            case 'statsQuery':
                break;
                // TODO: Figure out best strategy for stats querying - push/pull, prometheus, simple polling
                //return this.aggregateStatistics();
        }

    }

    async aggregateStatistics() {

        const managerData = {
            memory: process.memoryUsage().heapUsed, // Bytes
            uptime: Date.now() - this.readyAt,
            library: {
                name: 'Discord.js',
                versionersion: require('discord.js').version
            },
            managedShards: this.shardManager.shards.size
        };

        const CPU = os.cpus();
        const freeMemory = os.freemem();
        const totalMemory = os.totalmem();
        const systemData = {
            cpu: CPU[0].model,
            cores: CPU.length,
            memory: {
                used: totalMemory - freeMemory,
                total: totalMemory
            },
            osType: os.type(),
            uptime: os.uptime(),
            hostname: os.hostname()
        };

    }

    get uptime() {
        return this.readyAt !== null ? Date.now() - this.readyAt : 0;
    }

    info(message) {
        this.logger.write('info', message);
    }

    warn(message) {
        this.logger.write('warn', message);
    }

    error(message) {
        this.logger.write('error', message);
    }

}

module.exports = Manager;