const logger = require('./logger.js');
const util = require('./util.js');
const Keyfilter = require('./keyfilter.js');
const cli = require('./cli.js');
const spawn = require('child_process').spawn;

const inputDevices = '/dev/input/';
const inputDevicesById = '/dev/input/by-id/';

class Watcher {
    constructor(config, callback) {
        if (config == undefined || config.device == undefined) {
            return;
        }
        for (var key in config) {
            this[key] = config[key];
        }
        this.keyfilter = new Keyfilter(config.keys);
        this.callback = callback;
    }
    start() {
        if (this.process != undefined) {
            return;
        }
        logger.debug('starting watcher \'' + this.device + '\'...');
        this.process = spawn("evtest", [this.device, "|", "grep", "EV_KEY"]);
        this.attachListeners();
        logger.info('watcher \'' + this.device + '\' initialized and capturing configured events');
    }
    stop() {
        if (this.process == undefined) {
            return;
        }
        logger.debug('stopping watcher \'' + this.device + '\'...');
        this.process.kill();
        logger.info('watcher \'' + this.device + '\' stopped');
    }
    attachListeners() {
        if (this.process == undefined) {
            return;
        }
        this.addStdOutListener();
        this.addStdErrListener();
        this.addCloseListener();
        this.addErrorListener();
    }
    addStdOutListener() {
        if (this.process == undefined) {
            return;
        }
        logger.debug('adding stdout listener to watcher \'' + this.device + '\'...');
        this.process.stdout.on('data', (data) => {
            if (this.keyfilter == undefined) {
                return;
            }
            var filtered = this.keyfilter.filter(data);
            if (filtered == undefined) {
                return;
            }
            var msg = 'watcher \'' + this.device + '\' captured event';
            if (filtered.delayed) {
                logger.debug('delaying captured \'' + filtered.type + '\' event for \'' + filtered.key + '\' from watcher \'' + this.device + '\'');
                return;
            }
            logger.info('executing command \'' + filtered.command + '\' (args: \'' + filtered.args + '\') registered for captured \'' + filtered.type + '\' event for \'' + filtered.key + '\' from watcher \'' + this.device + '\'');
            cli.execute(filtered.command, filtered.args)
                .then(logger.info)
                .catch(logger.error);
        });
    }
    addStdErrListener() {
        if (this.process == undefined) {
            return;
        }
        logger.debug('adding stderr listener to watcher \'' + this.device + '\'...');
        this.process.stderr.on('data', (data) => {
            logger.error(data);
        });
    }
    addCloseListener() {
        if (this.process == undefined) {
            return;
        }
        logger.debug('adding close listener to watcher \'' + this.device + '\'...');
        this.process.on('close', (code) => {
            if (code == undefined) {
                code = 0;
            }
            this.code = code;
            logger.info('watcher \'' + this.device + '\' finished with exit code ' + code);
            if (this.callback != undefined) {
                this.callback(this.device);
            }
        });
    }
    addErrorListener() {
        if (this.process == undefined) {
            return;
        }
        logger.debug('adding error listener to \'' + this.device + '\'...');
        this.process.on('error', (err) => {
            logger.error('watcher \'' + this.device + '\' encountered an error >>> ' + err);
        });
    }
    check() {
        return new Promise((resolve, reject) => {
            if (!this.keyfilter.isValid()) {
                reject('no key(s) defined for watcher \'' + this.device + '\'');
            }
            Promise.any([this.device, inputDevices + this.device, inputDevicesById + this.device].map(util.fileExists))
                .then((result) => {
                    if (result.path != this.device) {
                        logger.info('resolved watcher for device \'' + this.device + '\' to \'' + result.path + '\'')
                    }
                    this.device = result.path;
                    resolve(this);
                })
                .catch(reject);
        });
    }
}
module.exports = Watcher;