'use strict';

exports = module.exports = {
    sync,
    deleteJobs,

    suspendAppJobs,
    resumeAppJobs
};

const apps = require('./apps.js'),
    assert = require('assert'),
    BoxError = require('./boxerror.js'),
    cloudron = require('./cloudron.js'),
    constants = require('./constants.js'),
    { CronJob } = require('cron'),
    debug = require('debug')('box:scheduler'),
    docker = require('./docker.js'),
    safe = require('safetydance'),
    _ = require('underscore');

const gState = {}; // appId -> { containerId, schedulerConfig (manifest+crontab), cronjobs }
const gSuspendedAppIds = new Set(); // suspended because some apptask is running

// TODO: this should probably also stop existing jobs to completely prevent race but the code is not re-entrant
function suspendAppJobs(appId) {
    debug(`suspendAppJobs: ${appId}`);
    gSuspendedAppIds.add(appId);
}

function resumeAppJobs(appId) {
    debug(`resumeAppJobs: ${appId}`);
    gSuspendedAppIds.delete(appId);
}

async function runTask(appId, taskName) {
    assert.strictEqual(typeof appId, 'string');
    assert.strictEqual(typeof taskName, 'string');

    const JOB_MAX_TIME = 30 * 60 * 1000; // 30 minutes
    const containerName = `${appId}-${taskName}`;

    if (gSuspendedAppIds.has(appId)) return;

    const app = await apps.get(appId);
    if (!app) throw new BoxError(BoxError.NOT_FOUND, 'App not found');

    if (app.installationState !== apps.ISTATE_INSTALLED || app.runState !== apps.RSTATE_RUNNING || app.health !== apps.HEALTH_HEALTHY) return;

    const [error, data] = await safe(docker.inspect(containerName));
    if (!error && data?.State?.Running === true) {
        const jobStartTime = new Date(data.State.StartedAt); // iso 8601
        if ((new Date() - jobStartTime) < JOB_MAX_TIME) return;
        debug(`runTask: ${containerName} is running too long, restarting`);
    }

    await docker.restartContainer(containerName);
}

async function createJobs(app, schedulerConfig) {
    assert.strictEqual(typeof app, 'object');
    assert(schedulerConfig && typeof schedulerConfig === 'object');

    const appId = app.id;
    const jobs = {};
    const tz = await cloudron.getTimeZone();

    for (const taskName of Object.keys(schedulerConfig)) {
        const { schedule, command } = schedulerConfig[taskName];
        const containerName = `${app.id}-${taskName}`;

        // stopJobs only deletes jobs since previous sync. This means that when box code restarts, none of the containers
        // are removed. The deleteContainer here ensures we re-create the cron containers with the latest config
        await safe(docker.deleteContainer(containerName)); // ignore error
        const [error] = await safe(docker.createSubcontainer(app, containerName, [ '/bin/sh', '-c', command ], {} /* options */), { debug });
        if (error && error.reason !== BoxError.ALREADY_EXISTS) continue;

        debug(`createJobs: ${taskName} (${app.fqdn}) will run in container ${containerName}`);

        let cronTime;
        if (schedule === '@service') {
            cronTime = new Date(Date.now() + 2*1000); // 2 seconds from now
        } else {
            // random is so that all crons start at once to decrease memory pressure
            cronTime = (constants.TEST ? '*/5 ' : `${Math.floor(60*Math.random())} `) + schedule; // time ticks faster in tests
        }

        const cronJob = CronJob.from({
            cronTime,
            onTick: async () => {
                const [error] = await safe(runTask(appId, taskName)); //  put the app id in closure, so we don't use the outdated app object by mistake
                if (error) debug(`could not run task ${taskName} : ${error.message}`);
            },
            start: true,
            timeZone: tz
        });

        jobs[taskName] = cronJob;
    }

    return jobs;
}

async function deleteAppJobs(appId, appState) {
    assert.strictEqual(typeof appId, 'string');
    assert.strictEqual(typeof appState, 'object');

    if (!appState) return;

    for (const taskName of Object.keys(appState.schedulerConfig)) {
        if (appState.cronJobs && appState.cronJobs[taskName]) appState.cronJobs[taskName].stop();

        const containerName = `${appId}-${taskName}`;
        const [error] = await safe(docker.deleteContainer(containerName));
        if (error) debug(`deleteAppJobs: failed to delete task container with name ${containerName} : ${error.message}`);
    }
}

async function deleteJobs() {
    for (const appId of Object.keys(gState)) {
        debug(`deleteJobs: removing jobs of ${appId}`);
        const [error] = await safe(deleteAppJobs(appId, gState[appId]));
        if (error) debug(`deleteJobs: error stopping jobs of removed app ${appId}: ${error.message}`);
        delete gState[appId];
    }
}

async function sync() {
    if (constants.TEST) return;

    const allApps = await apps.list();

    const allAppIds = allApps.map(app => app.id);
    const removedAppIds = _.difference(Object.keys(gState), allAppIds);
    if (removedAppIds.length !== 0) debug(`sync: stopping jobs of removed apps ${JSON.stringify(removedAppIds)}`);

    for (const appId of removedAppIds) {
        debug(`sync: removing jobs of ${appId}`);
        const [error] = await safe(deleteAppJobs(appId, gState[appId]));
        if (error) debug(`sync: error stopping jobs of removed app ${appId}: ${error.message}`);
        delete gState[appId];
    }

    for (const app of allApps) {
        const appState = gState[app.id] || null;
        const schedulerConfig = apps.getSchedulerConfig(app);

        if (!appState && !schedulerConfig) continue; // nothing to do
        if (appState && appState.cronJobs) { // we had created jobs for this app previously
            if (_.isEqual(appState.schedulerConfig, schedulerConfig) && appState.containerId === app.containerId) continue; // nothing changed
        }

        debug(`sync: clearing jobs of ${app.id} (${app.fqdn})`);

        const [error] = await safe(deleteAppJobs(app.id, appState));
        if (error) debug(`sync: error stopping jobs of ${app.id} : ${error.message}`);

        if (!schedulerConfig) { // updated app version removed scheduler addon
            delete gState[app.id];
            continue;
        }

        if (gSuspendedAppIds.has(app.id)) continue; // do not create jobs of suspended apps

        const cronJobs = await createJobs(app, schedulerConfig); //  if docker is down, the next sync() will recreate everything for this app
        gState[app.id] = {  containerId: app.containerId, schedulerConfig, cronJobs };
    }
}