'use strict';

exports = module.exports = {
    get,
    add,
    update,
    setCompleted,
    setCompletedByType,
    listByTypePaged,

    getLogs,

    startTask,
    stopTask,
    stopAllTasks,

    removePrivateFields,

    // task types. if you add a task here, fill up the function table in taskworker and dashboard client.js
    TASK_APP: 'app',
    TASK_BACKUP: 'backup',
    TASK_UPDATE: 'update',
    TASK_CHECK_CERTS: 'checkCerts',
    TASK_SETUP_DNS_AND_CERT: 'setupDnsAndCert',
    TASK_CLEAN_BACKUPS: 'cleanBackups',
    TASK_SYNC_EXTERNAL_LDAP: 'syncExternalLdap',
    TASK_CHANGE_MAIL_LOCATION: 'changeMailLocation',
    TASK_SYNC_DNS_RECORDS: 'syncDnsRecords',

    // error codes
    ESTOPPED: 'stopped',
    ECRASHED: 'crashed',
    ETIMEOUT: 'timeout',

    // testing
    _TASK_IDENTITY: '_identity',
    _TASK_CRASH: '_crash',
    _TASK_ERROR: '_error',
    _TASK_SLEEP: '_sleep'
};

const assert = require('assert'),
    BoxError = require('./boxerror.js'),
    debug = require('debug')('box:tasks'),
    path = require('path'),
    paths = require('./paths.js'),
    shell = require('./shell.js'),
    spawn = require('child_process').spawn,
    split = require('split'),
    taskdb = require('./taskdb.js'),
    _ = require('underscore');

let gTasks = {}; // indexed by task id

const NOOP_CALLBACK = function (error) { if (error) debug(error); };
const START_TASK_CMD = path.join(__dirname, 'scripts/starttask.sh');
const STOP_TASK_CMD = path.join(__dirname, 'scripts/stoptask.sh');

function postProcess(result) {
    assert.strictEqual(typeof result, 'object');

    result.active = !!gTasks[result.id];

    // we rely on 'percent' to determine success. maybe this can become a db field
    result.success = result.percent === 100 && !result.error;

    // we rely on 'percent' to determine pending. maybe this can become a db field
    result.pending = result.percent === 1;

    // the error in db will be empty if we didn't get a chance to handle task exit
    if (!result.active && result.percent !== 100 && !result.error) {
        result.error = { message: 'Cloudron crashed/stopped', code: exports.ECRASHED };
    }
}

function get(id, callback) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof callback, 'function');

    taskdb.get(id, function (error, task) {
        if (error) return callback(error);

        postProcess(task);

        callback(null, task);
    });
}

function update(id, task, callback) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof task, 'object');
    assert.strictEqual(typeof callback, 'function');

    debug(`${id}: ${JSON.stringify(task)}`);

    taskdb.update(id, task, function (error) {
        if (error) return callback(error);

        callback();
    });
}

function setCompleted(id, task, callback) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof task, 'object');
    assert.strictEqual(typeof callback, 'function');

    debug(`setCompleted - ${id}: ${JSON.stringify(task)}`);

    update(id, _.extend({ percent: 100 }, task), callback);
}

function setCompletedByType(type, task, callback) {
    assert.strictEqual(typeof type, 'string');
    assert.strictEqual(typeof task, 'object');
    assert.strictEqual(typeof callback, 'function');

    listByTypePaged(type, 1, 1, function (error, results) {
        if (error) return callback(error);
        if (results.length !== 1) return callback(new BoxError(BoxError.NOT_FOUND));

        setCompleted(results[0].id, task, function (error) {
            if (error) return callback(error);

            callback();
        });
    });
}

function add(type, args, callback) {
    assert.strictEqual(typeof type, 'string');
    assert(Array.isArray(args));
    assert.strictEqual(typeof callback, 'function');

    taskdb.add({ type: type, percent: 0, message: 'Queued', args: args }, function (error, taskId) {
        if (error) return callback(error);

        callback(null, taskId);
    });
}

function startTask(id, options, callback) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    const logFile = options.logFile || `${paths.TASKS_LOG_DIR}/${id}.log`;
    debug(`startTask - starting task ${id} with options ${JSON.stringify(options)}. logs at ${logFile}`);

    let killTimerId = null, timedOut = false;

    gTasks[id] = shell.sudo('startTask', [ START_TASK_CMD, id, logFile, options.nice || 0, options.memoryLimit || 400 ], { preserveEnv: true }, function (error) {
        if (!gTasks[id]) return; // ignore task exit since we are shutting down. see stopAllTasks

        const code = error ? error.code : 0;
        const signal = error ? error.signal : 0;

        debug(`startTask: ${id} completed with code ${code} and signal ${signal}`);

        if (options.timeout) clearTimeout(killTimerId);

        get(id, function (getError, task) {
            let taskError;
            if (!getError && task.percent !== 100) { // taskworker crashed or was killed by us
                if (code === 0) {
                    taskError = {
                        message: `Task ${id} ${timedOut ? 'timed out' : 'stopped'}` ,
                        code: timedOut ? exports.ETIMEOUT : exports.ESTOPPED
                    };
                } else { // task crashed
                    taskError = {
                        message: signal === 9 ? `Task ${id} crashed as it ran out of memory` : `Task ${id} crashed with code ${code} and signal ${signal}`,
                        code: exports.ECRASHED
                    };
                }

                // note that despite the update() here, we should handle the case where the box code was restarted and never got taskworker exit
                setCompleted(id, { error: taskError }, NOOP_CALLBACK);
            } else if (!getError && task.error) {
                taskError = task.error;
            } else if (!task) { // db got cleared in tests
                taskError = new BoxError(BoxError.NOT_FOUND, `No such task ${id}`);
            }

            delete gTasks[id];

            callback(taskError, task ? task.result : null);

            debug(`startTask: ${id} done`);
        });
    });

    if (options.timeout) {
        killTimerId = setTimeout(function () {
            debug(`startTask: task ${id} took too long. killing`);
            timedOut = true;
            stopTask(id, NOOP_CALLBACK);
        }, options.timeout);
    }
}

function stopTask(id, callback) {
    assert.strictEqual(typeof id, 'string');
    assert.strictEqual(typeof callback, 'function');

    if (!gTasks[id]) return callback(new BoxError(BoxError.BAD_STATE, 'task is not active'));

    debug(`stopTask: stopping task ${id}`);

    shell.sudo('stopTask', [ STOP_TASK_CMD, id, ], {}, NOOP_CALLBACK);

    callback(null);
}

function stopAllTasks(callback) {
    assert.strictEqual(typeof callback, 'function');

    debug('stopTask: stopping all tasks');

    gTasks = {}; // this signals startTask() to not set completion status as "crashed"
    shell.sudo('stopTask', [ STOP_TASK_CMD, 'all' ], { cwd: paths.baseDir() }, callback);
}

function listByTypePaged(type, page, perPage, callback) {
    assert(typeof type === 'string' || type === null);
    assert.strictEqual(typeof page, 'number');
    assert.strictEqual(typeof perPage, 'number');
    assert.strictEqual(typeof callback, 'function');

    taskdb.listByTypePaged(type, page, perPage, function (error, tasks) {
        if (error) return callback(error);

        tasks.forEach(postProcess);

        callback(null, tasks);
    });
}

function getLogs(taskId, options, callback) {
    assert.strictEqual(typeof taskId, 'string');
    assert(options && typeof options === 'object');
    assert.strictEqual(typeof callback, 'function');

    assert.strictEqual(typeof options.lines, 'number');
    assert.strictEqual(typeof options.format, 'string');
    assert.strictEqual(typeof options.follow, 'boolean');

    debug(`Getting logs for ${taskId}`);

    var lines = options.lines === -1 ? '+1' : options.lines,
        format = options.format || 'json',
        follow = options.follow;

    let cmd = '/usr/bin/tail';
    var args = [ '--lines=' + lines ];

    if (follow) args.push('--follow', '--retry', '--quiet'); // same as -F. to make it work if file doesn't exist, --quiet to not output file headers, which are no logs
    args.push(`${paths.TASKS_LOG_DIR}/${taskId}.log`);

    var cp = spawn(cmd, args);

    var transformStream = split(function mapper(line) {
        if (format !== 'json') return line + '\n';

        var data = line.split(' '); // logs are <ISOtimestamp> <msg>
        var timestamp = (new Date(data[0])).getTime();
        if (isNaN(timestamp)) timestamp = 0;
        var message = line.slice(data[0].length+1);

        // ignore faulty empty logs
        if (!timestamp && !message) return;

        return JSON.stringify({
            realtimeTimestamp: timestamp * 1000,
            message: message,
            source: taskId
        }) + '\n';
    });

    transformStream.close = cp.kill.bind(cp, 'SIGKILL'); // closing stream kills the child process

    cp.stdout.pipe(transformStream);

    callback(null, transformStream);
}

// removes all fields that are strictly private and should never be returned by API calls
function removePrivateFields(task) {
    var result = _.pick(task, 'id', 'type', 'percent', 'message', 'error', 'active', 'pending', 'creationTime', 'result', 'ts', 'success');
    return result;
}