#!/usr/bin/env node
const minimist = require('minimist')
const loggerModule = require('./lib/logger')
const config = require('./lib/config')
const db = require('./lib/db')
const {uniq} = require('lodash')
const {createCallablePromise} = require('./lib/util')
const {validateObjectSchema, validateTargetsListFormat} = require('./lib/data-validator')
const RequestHandler = require('./lib/request-handler')
const {
    Server,
    Connection,
    RequestMessage,
    ResponseMessage
} = require('./lib/server')
const {
    Worker,
    STATUS_MANUAL,
    JOB_NOTFOUND,
    JOB_ACCEPTED,
    JOB_IGNORED
} = require('./lib/worker')
const package_json = require('../package.json')

/**
 * @type {Worker}
 */
let worker

/**
 * @type {Logger}
 */
let logger

/**
 * @type {Server}
 */
let server

/**
 * @type {RequestHandler}
 */
let requestHandler

/**
 * @type {object.<string, Promise>}
 */
let jobPromises = {}


main().catch(e => {
    console.error(e)
    process.exit(1)
})


async function main() {
    await initApp('jobd')
    await initDatabase()
    initWorker()
    initRequestHandler()
    initServer()
    connectToMaster()
}

async function initApp(appName) {
    if (process.argv.length < 3) {
        usage()
        process.exit(0)
    }

    process.on('SIGINT', term)
    process.on('SIGTERM', term)

    const argv = minimist(process.argv.slice(2))

    if (argv.help) {
        usage()
        process.exit(0)
    }

    if (argv.version) {
        console.log(package_json.version)
        process.exit(0)
    }

    if (!argv.config)
        throw new Error('--config option is required')

    // read config
    try {
        config.parseWorkerConfig(argv.config)
    } catch (e) {
        console.error(`config parsing error: ${e.message}`)
        process.exit(1)
    }

    await loggerModule.init({
        file: config.get('log_file'),
        levelFile: config.get('log_level_file'),
        levelConsole: config.get('log_level_console'),
    })
    logger = loggerModule.getLogger(appName)

    process.title = appName
}

function initWorker() {
    worker = new Worker()

    const targets = config.get('targets')
    for (const target in targets) {
        let limit = targets[target]
        worker.addTarget(target, limit)
    }

    worker.on('job-done', (data) => {
        if (jobPromises[data.id] !== undefined) {
            const P = jobPromises[data.id]
            delete jobPromises[data.id]

            logger.trace(`job-done: resolving promise of job ${data.id}`)
            P.resolve(data)
        } else {
            // this is not an error, as there will be no promise unless it's a manual job
            // so this is totally normal situation, thus debug() and not warn() or error()
            logger.debug(`job-done: jobPromises[${data.id}] is undefined`)
        }
    })
}

function initRequestHandler() {
    requestHandler = new RequestHandler()
    requestHandler.set('poll', onPollRequest)
    requestHandler.set('status', onStatus)
    requestHandler.set('run-manual', onRunManual)
    requestHandler.set('pause', onPause)
    requestHandler.set('continue', onContinue)
    requestHandler.set('set-target-concurrency', onSetTargetConcurrency)
}

function initServer() {
    server = new Server()
    server.on('new-connection', (connection) => {
        connection.on('request-message', (message, connection) => {
            requestHandler.process(message, connection)
        })
    })
    server.start(config.get('port'), config.get('host'))
}

async function initDatabase() {
    try {
        await db.init()
    } catch (error) {
        logger.error('failed to connect to MySQL', error)
        process.exit(1)
    }
    logger.info('db initialized')
}

/**
 * @param {object} data
 * @param {number} requestNo
 * @param {Connection} connection
 */
function onPollRequest(data, requestNo, connection) {
    let targets
    if ((targets = validateInputTargets(data, requestNo, connection)) === false)
        return

    worker.setPollTargets(targets)
    worker.poll()

    connection.send(
        new ResponseMessage(requestNo)
            .setData('ok')
    )
}

/**
 * @param {object} data
 * @param {number} requestNo
 * @param {Connection} connection
 */
function onStatus(data, requestNo, connection) {
    connection.send(
        new ResponseMessage(requestNo)
            .setData({
                targets: worker.getStatus(),
                jobPromisesCount: Object.keys(jobPromises).length,
                memoryUsage: process.memoryUsage()
            })
    )
}

/**
 * @param {object} data
 * @param {number} requestNo
 * @param {Connection} connection
 * @return {Promise<void>}
 */
async function onRunManual(data, requestNo, connection) {
    let {ids: jobIds} = data
    jobIds = uniq(jobIds)

    // if at least one of the jobs is already being run, reject
    // if at least one item is not a number, reject
    for (const id of jobIds) {
        if (typeof id !== 'number') {
            connection.send(
                new ResponseMessage(requestNo)
                    .setError(`all ids must be numbers, got ${typeof id}`)
            )
            return
        }

        if (id in jobPromises) {
            connection.send(
                new ResponseMessage(requestNo)
                    .setError(`another client is already waiting for job ${id}`)
            )
            return
        }
    }

    // create a bunch of promises, one per job
    let promises = []
    for (const id of jobIds) {
        const P = createCallablePromise()
        jobPromises[id] = P
        promises.push(P)
    }

    // get jobs from database and enqueue for execution
    const {results} = await worker.getTasks(null, STATUS_MANUAL, {ids: jobIds})

    // wait till all jobs are done (or failed), then send a response
    Promise.allSettled(promises).then(results => {
        const response = {}

        for (let i = 0; i < results.length; i++) {
            let jobId = jobIds[i]
            let result = results[i]

            if (result.status === 'fulfilled') {
                if (!('jobs' in response))
                    response.jobs = {}

                if (result.value?.id !== undefined)
                    delete result.value.id

                response.jobs[jobId] = result.value
            } else if (result.status === 'rejected') {
                if (!('errors' in response))
                    response.errors = {}

                response.errors[jobId] = result.reason?.message
            }
        }

        connection.send(
            new ResponseMessage(requestNo)
                .setData(response)
        )
    })

    // reject all ignored / non-found jobs
    for (const [id, value] of results.entries()) {
        if (!(id in jobPromises)) {
            this.logger.error(`run-manual: ${id} not found in jobPromises`)
            continue
        }

        if (value.result === JOB_IGNORED || value.result === JOB_NOTFOUND) {
            const P = jobPromises[id]
            delete jobPromises[id]

            if (value.result === JOB_IGNORED)
                P.reject(new Error(value.reason))

            else if (value.result === JOB_NOTFOUND)
                P.reject(new Error(`job ${id} not found`))
        }
    }
}

/**
 * @param {object} data
 * @param {number} requestNo
 * @param {Connection} connection
 */
function onPause(data, requestNo, connection) {
    let targets
    if ((targets = validateInputTargets(data, requestNo, connection)) === false)
        return

    worker.pauseTargets(targets)
    connection.send(
        new ResponseMessage(requestNo)
            .setData('ok')
    )
}

/**
 * @param {object} data
 * @param {number} requestNo
 * @param {Connection} connection
 */
function onContinue(data, requestNo, connection) {
    let targets
    if ((targets = validateInputTargets(data, requestNo, connection)) === false)
        return

    // continue queues
    worker.continueTargets(targets)

    // poll just in case
    worker.poll()

    // ok
    connection.send(
        new ResponseMessage(requestNo)
            .setData('ok')
    )
}

/**
 * @param {object} data
 * @param {number} requestNo
 * @param {Connection} connection
 */
function onSetTargetConcurrency(data, requestNo, connection) {
    try {
        validateObjectSchema(data, [
            // name         // type  // required
            ['concurrency', 'i',     true],
            ['target',      's',     true],
        ])
    } catch (e) {
        connection.send(
            new ResponseMessage(requestNo)
                .setError(e.message)
        )
        return
    }

    worker.setTargetConcurrency(data.target, data.concurrency)
    connection.send(
        new ResponseMessage(requestNo)
            .setData('ok')
    )
}

/**
 * @private
 * @param data
 * @param requestNo
 * @param connection
 * @return {null|boolean|string[]}
 */
function validateInputTargets(data, requestNo, connection) {
    // null means all targets
    let targets = null

    if (data.targets !== undefined) {
        targets = data.targets

        // validate data
        try {
            validateTargetsListFormat(targets)

            for (const t of targets) {
                if (!worker.hasTarget(t))
                    throw new Error(`invalid target '${t}'`)
            }
        } catch (e) {
            connection.send(
                new ResponseMessage(requestNo)
                    .setError(e.message)
            )
            return false
        }
    }

    return targets
}

function connectToMaster() {
    const port = config.get('master_port')
    const host = config.get('master_host')

    if (!host || !port) {
        logger.debug('connectToMaster: master host or port is not defined')
        return
    }

    const connection = new Connection()
    connection.connect(host, port)

    connection.on('connect', function() {
        connection.sendRequest(
            new RequestMessage('register-worker', {
                targets: worker.getTargets()
            })
        )
        .then(response => {
            logger.debug('connectToMaster: response:', response)
        })
        .catch(error => {
            logger.error('connectToMaster: error while awaiting response:', error)
        })
    })

    connection.on('close', () => {
        logger.warn(`connectToMaster: connection closed`)
        setTimeout(() => {
            connectToMaster()
        }, config.get('master_reconnect_timeout') * 1000)
    })

    connection.on('request-message', (message, connection) => {
        requestHandler.process(message, connection)
    })
}

function usage() {
    let s = `${process.argv[1]} OPTIONS

Options:
    --config <path>
    --help
    --version`

    console.log(s)
}

function term() {
    if (logger)
        logger.info('shutdown')

    loggerModule.shutdown(function() {
        process.exit()
    })
}