/* jslint node: true */
'use strict';

//  ENiGMA½
const PluginModule          = require('./plugin_module.js').PluginModule;
const Config                = require('./config.js').get;
const Log                   = require('./logger.js').log;
const { Errors }            = require('./enig_error.js');

const _                     = require('lodash');
const later                 = require('@breejs/later');
const path                  = require('path');
const pty                   = require('node-pty');
const sane                  = require('sane');
const moment                = require('moment');
const paths                 = require('path');
const fse                   = require('fs-extra');

exports.getModule               = EventSchedulerModule;
exports.EventSchedulerModule    = EventSchedulerModule; //  allow for loadAndStart

exports.moduleInfo = {
    name    : 'Event Scheduler',
    desc    : 'Support for scheduling arbritary events',
    author  : 'NuSkooler',
};

const SCHEDULE_REGEXP   = /(?:^|or )?(@watch:)([^\0]+)?$/;
const ACTION_REGEXP     = /@(method|execute):([^\0]+)?$/;

class ScheduledEvent {
    constructor(events, name) {
        this.name       = name;
        this.schedule   = this.parseScheduleString(events[name].schedule);
        this.action     = this.parseActionSpec(events[name].action);
        if(this.action) {
            this.action.args = events[name].args || [];
        }
    }

    get isValid() {
        if((!this.schedule || (!this.schedule.sched && !this.schedule.watchFile)) || !this.action) {
            return false;
        }

        if('method' === this.action.type && !this.action.location) {
            return false;
        }

        return true;
    }

    parseScheduleString(schedStr) {
        if(!schedStr) {
            return false;
        }

        let schedule = {};

        const m = SCHEDULE_REGEXP.exec(schedStr);
        if(m) {
            schedStr = schedStr.substr(0, m.index).trim();

            if('@watch:' === m[1]) {
                schedule.watchFile = m[2];
            }
        }

        if(schedStr.length > 0) {
            const sched = later.parse.text(schedStr);
            if(-1 === sched.error) {
                schedule.sched = sched;
            }
        }

        //  return undefined if we couldn't parse out anything useful
        if(!_.isEmpty(schedule)) {
            return schedule;
        }
    }

    parseActionSpec(actionSpec) {
        if(actionSpec) {
            if('@' === actionSpec[0]) {
                const m = ACTION_REGEXP.exec(actionSpec);
                if(m) {
                    if(m[2].indexOf(':') > -1) {
                        const parts = m[2].split(':');
                        return {
                            type        : m[1],
                            location    : parts[0],
                            what        : parts[1],
                        };
                    } else {
                        return {
                            type    : m[1],
                            what    : m[2],
                        };
                    }
                }
            } else {
                return {
                    type    : 'execute',
                    what    : actionSpec,
                };
            }
        }
    }

    executeAction(reason, cb) {
        Log.info( { eventName : this.name, action : this.action, reason : reason }, 'Executing scheduled event action...');

        if('method' === this.action.type) {
            const modulePath = path.join(__dirname, '../', this.action.location);   //  enigma-bbs base + supplied location (path/file.js')
            try {
                const methodModule = require(modulePath);
                methodModule[this.action.what](this.action.args, err => {
                    if(err) {
                        Log.debug(
                            { error : err.message, eventName : this.name, action : this.action },
                            'Error performing scheduled event action');
                    }

                    return cb(err);
                });
            } catch(e) {
                Log.warn(
                    { error : e.message, eventName : this.name, action : this.action },
                    'Failed to perform scheduled event action');

                return cb(e);
            }
        } else if('execute' === this.action.type) {
            const opts = {
                //  :TODO: cwd
                name    : this.name,
                cols    : 80,
                rows    : 24,
                env     : process.env,
            };

            let proc;
            try {
                proc = pty.spawn(this.action.what, this.action.args, opts);
            } catch(e) {
                Log.warn(
                    {
                        error       : 'Failed to spawn @execute process',
                        reason      : e.message,
                        eventName   : this.name,
                        action      : this.action,
                        what        : this.action.what,
                        args        : this.action.args
                    }
                );
                return cb(e);
            }

            proc.once('exit', exitCode => {
                if(exitCode) {
                    Log.warn(
                        { eventName : this.name, action : this.action, exitCode : exitCode },
                        'Bad exit code while performing scheduled event action');
                }
                return cb(exitCode ? Errors.ExternalProcess(`Bad exit code while performing scheduled event action: ${exitCode}`) : null);
            });
        }
    }
}

function EventSchedulerModule(options) {
    PluginModule.call(this, options);

    const config = Config();
    if(_.has(config, 'eventScheduler')) {
        this.moduleConfig = config.eventScheduler;
    }

    const self = this;
    this.runningActions = new Set();

    this.performAction = function(schedEvent, reason) {
        if(self.runningActions.has(schedEvent.name)) {
            return; //  already running
        }

        self.runningActions.add(schedEvent.name);

        schedEvent.executeAction(reason, () => {
            self.runningActions.delete(schedEvent.name);
        });
    };
}

//  convienence static method for direct load + start
EventSchedulerModule.loadAndStart = function(cb) {
    const loadModuleEx = require('./module_util.js').loadModuleEx;

    const loadOpts = {
        name        : path.basename(__filename, '.js'),
        path        : __dirname,
    };

    loadModuleEx(loadOpts, (err, mod) => {
        if(err) {
            return cb(err);
        }

        const modInst = new mod.getModule();
        modInst.startup( err => {
            return cb(err, modInst);
        });
    });
};

EventSchedulerModule.prototype.startup = function(cb) {

    this.eventTimers    = [];
    const self = this;

    if(this.moduleConfig && _.has(this.moduleConfig, 'events')) {
        const events = Object.keys(this.moduleConfig.events).map( name => {
            return new ScheduledEvent(this.moduleConfig.events, name);
        });

        events.forEach( schedEvent => {
            if(!schedEvent.isValid) {
                Log.warn( { eventName : schedEvent.name }, 'Invalid scheduled event entry');
                return;
            }

            Log.debug(
                {
                    eventName   : schedEvent.name,
                    schedule    : this.moduleConfig.events[schedEvent.name].schedule,
                    action      : schedEvent.action,
                    next        : schedEvent.schedule.sched ? moment(later.schedule(schedEvent.schedule.sched).next(1)).format('ddd, MMM Do, YYYY @ h:m:ss a') : 'N/A',
                },
                'Scheduled event loaded'
            );

            if(schedEvent.schedule.sched) {
                this.eventTimers.push(later.setInterval( () => {
                    self.performAction(schedEvent, 'Schedule');
                }, schedEvent.schedule.sched));
            }

            if(schedEvent.schedule.watchFile) {
                const watcher = sane(
                    paths.dirname(schedEvent.schedule.watchFile),
                    {
                        glob : `**/${paths.basename(schedEvent.schedule.watchFile)}`
                    }
                );

                //  :TODO: should track watched files & stop watching @ shutdown?

                [ 'change', 'add', 'delete' ].forEach(event => {
                    watcher.on(event, (fileName, fileRoot) => {
                        const eventPath = paths.join(fileRoot, fileName);
                        if(schedEvent.schedule.watchFile === eventPath) {
                            self.performAction(schedEvent, `Watch file: ${eventPath}`);
                        }
                    });
                });

                fse.exists(schedEvent.schedule.watchFile, exists => {
                    if(exists) {
                        self.performAction(schedEvent, `Watch file: ${schedEvent.schedule.watchFile}`);
                    }
                });
            }
        });
    }

    cb(null);
};

EventSchedulerModule.prototype.shutdown = function(cb) {
    if(this.eventTimers) {
        this.eventTimers.forEach( et => et.clear() );
    }

    cb(null);
};