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

//  ENiGMA½
const Log                   = require('../../logger.js').log;
const { ServerModule }      = require('../../server_module.js');
const Config                = require('../../config.js').get;
const {
    splitTextAtTerms,
    isAnsi,
    cleanControlCodes
}                           = require('../../string_util.js');
const {
    getMessageConferenceByTag,
    getMessageAreaByTag,
    getMessageListForArea,
}                           = require('../../message_area.js');
const { sortAreasOrConfs }  = require('../../conf_area_util.js');
const AnsiPrep              = require('../../ansi_prep.js');
const { wordWrapText }      = require('../../word_wrap.js');

//  deps
const net                   = require('net');
const _                     = require('lodash');
const fs                    = require('graceful-fs');
const paths                 = require('path');
const moment                = require('moment');

const ModuleInfo = exports.moduleInfo = {
    name        : 'Gopher',
    desc        : 'A RFC-1436-ish Gopher Server',
    author      : 'NuSkooler',
    packageName : 'codes.l33t.enigma.gopher.server',
    notes       : 'https://tools.ietf.org/html/rfc1436',
};

const Message               = require('../../message.js');

const ItemTypes = {
    Invalid             : '',   //  not really a type, of course!

    //  Canonical, RFC-1436
    TextFile            : '0',
    SubMenu             : '1',
    CCSONameserver      : '2',
    Error               : '3',
    BinHexFile          : '4',
    DOSFile             : '5',
    UuEncodedFile       : '6',
    FullTextSearch      : '7',
    Telnet              : '8',
    BinaryFile          : '9',
    AltServer           : '+',
    GIFFile             : 'g',
    ImageFile           : 'I',
    Telnet3270          : 'T',

    //  Non-canonical
    HtmlFile            : 'h',
    InfoMessage         : 'i',
    SoundFile           : 's',
};

exports.getModule = class GopherModule extends ServerModule {

    constructor() {
        super();

        this.routes = new Map();    //  selector->generator => gopher item
        this.log = Log.child( { server : 'Gopher' } );
    }

    createServer() {
        if(!this.enabled) {
            return;
        }

        const config = Config();
        this.publicHostname = config.contentServers.gopher.publicHostname;
        this.publicPort     = config.contentServers.gopher.publicPort;

        this.addRoute(/^\/?\r\n$/, this.defaultGenerator);
        this.addRoute(/^\/msgarea(\/[a-z0-9_-]+(\/[a-z0-9_-]+)?(\/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}(_raw)?)?)?\/?\r\n$/, this.messageAreaGenerator);

        this.server = net.createServer( socket => {
            socket.setEncoding('ascii');

            socket.on('data', data => {
                this.routeRequest(data, socket);
            });

            socket.on('error', err => {
                if('ECONNRESET' !== err.code) { //  normal
                    this.log.trace( { error : err.message }, 'Socket error');
                }
            });
        });
    }

    listen() {
        if(!this.enabled) {
            return true;    //  nothing to do, but not an error
        }

        const config = Config();
        const port = parseInt(config.contentServers.gopher.port);
        if(isNaN(port)) {
            this.log.warn( { port : config.contentServers.gopher.port, server : ModuleInfo.name }, 'Invalid port' );
            return false;
        }

        return this.server.listen(port);
    }

    get enabled() {
        return _.get(Config(), 'contentServers.gopher.enabled', false) && this.isConfigured();
    }

    isConfigured() {
        //  public hostname & port must be set; responses contain them!
        const config = Config();
        return _.isString(_.get(config, 'contentServers.gopher.publicHostname')) &&
            _.isNumber(_.get(config, 'contentServers.gopher.publicPort'));
    }

    addRoute(selectorRegExp, generatorHandler) {
        if(_.isString(selectorRegExp)) {
            try {
                selectorRegExp = new RegExp(`${selectorRegExp}\r\n`);
            } catch(e) {
                this.log.warn( { pattern : selectorRegExp }, 'Invalid RegExp for selector' );
                return false;
            }
        }
        this.routes.set(selectorRegExp, generatorHandler.bind(this));
    }

    routeRequest(selector, socket) {
        let match;
        for(let [regex, gen] of this.routes) {
            match = selector.match(regex);
            if(match) {
                return gen(match, res => {
                    return socket.end(`${res}`);
                });
            }
        }
        this.notFoundGenerator(selector, res => {
            return socket.end(`${res}`);
        });
    }

    makeItem(itemType, text, selector, hostname, port) {
        selector = selector || '';  //  e.g. for info
        hostname = hostname || this.publicHostname;
        port = port || this.publicPort;
        return `${itemType}${text}\t${selector}\t${hostname}\t${port}\r\n`;
    }

    defaultGenerator(selectorMatch, cb) {
        this.log.debug( { selector : selectorMatch[0] }, 'Serving default content');

        let bannerFile = _.get(Config(), 'contentServers.gopher.bannerFile', 'gopher_banner.asc');
        bannerFile = paths.isAbsolute(bannerFile) ? bannerFile : paths.join(__dirname, '../../../misc', bannerFile);
        fs.readFile(bannerFile, 'utf8', (err, banner) => {
            if(err) {
                return cb('You have reached an ENiGMA½ Gopher server!');
            }

            banner = splitTextAtTerms(banner).map(l => this.makeItem(ItemTypes.InfoMessage, l)).join('');
            banner += this.makeItem(ItemTypes.SubMenu, 'Public Message Area', '/msgarea');
            return cb(banner);
        });
    }

    notFoundGenerator(selector, cb) {
        this.log.debug( { selector }, 'Serving not found content');
        return cb('Not found');
    }

    isAreaAndConfExposed(confTag, areaTag) {
        const conf = _.get(Config(), [ 'contentServers', 'gopher', 'messageConferences', confTag ]);
        return Array.isArray(conf) && conf.includes(areaTag);
    }

    prepareMessageBody(body, cb) {
        //
        //  From RFC-1436:
        //  "User display strings are intended to be displayed on a line on a
        //   typical screen for a user's viewing pleasure.  While many screens can
        //   accommodate 80 character lines, some space is needed to display a tag
        //   of some sort to tell the user what sort of item this is.  Because of
        //   this, the user display string should be kept under 70 characters in
        //   length.  Clients may truncate to a length convenient to them."
        //
        //  Messages on BBSes however, have generally been <= 79 characters. If we
        //  start wrapping earlier, things will generally be OK except:
        //  * When we're doing with FTN-style quoted lines
        //  * When dealing with ANSI/ASCII art
        //
        //  Anyway, the spec says "should" and not MUST or even SHOULD! ...so, to
        //  to follow the KISS principle: Wrap at 79.
        //
        const WordWrapColumn = 79;
        if(isAnsi(body)) {
            AnsiPrep(
                body,
                {
                    cols            : WordWrapColumn,   //  See notes above
                    forceLineTerm   : true,             //  Ensure each line is term'd
                    asciiMode       : true,             //  Export to ASCII
                    fillLines       : false,            //  Don't fill up to |cols|
                },
                (err, prepped) => {
                    return cb(prepped || body);
                }
            );
        } else {
            const prepped = splitTextAtTerms(cleanControlCodes(body, { all : true } ) )
                .map(l => (wordWrapText(l, { width : WordWrapColumn } ).wrapped || []).join('\n'))
                .join('\n');

            return cb(prepped);
        }
    }

    shortenSubject(subject) {
        return _.truncate(subject, { length : 30 } );
    }

    messageAreaGenerator(selectorMatch, cb) {
        this.log.debug( { selector : selectorMatch[0] }, 'Serving message area content');
        //
        //  Selector should be:
        //  /msgarea - list confs
        //  /msgarea/conftag - list areas in conf
        //  /msgarea/conftag/areatag - list messages in area
        //  /msgarea/conftag/areatag/<UUID> - message as text
        //  /msgarea/conftag/areatag/<UUID>_raw - full message as text + headers
        //
        if(selectorMatch[3] || selectorMatch[4]) {
            //  message
            //const raw = selectorMatch[4] ? true : false;
            //  :TODO: support 'raw'
            const msgUuid   = selectorMatch[3].replace(/\r\n|\//g, '');
            const confTag   = selectorMatch[1].substr(1).split('/')[0];
            const areaTag   = selectorMatch[2].replace(/\r\n|\//g, '');
            const message   = new Message();

            return message.load( { uuid : msgUuid }, err => {
                if(err) {
                    this.log.debug( { uuid : msgUuid }, 'Attempted access to non-existent message UUID!');
                    return this.notFoundGenerator(selectorMatch, cb);
                }

                if(message.areaTag !== areaTag || !this.isAreaAndConfExposed(confTag, areaTag)) {
                    this.log.warn( { areaTag }, 'Attempted access to non-exposed conference and/or area!');
                    return this.notFoundGenerator(selectorMatch, cb);
                }

                if(Message.isPrivateAreaTag(areaTag)) {
                    this.log.warn( { areaTag }, 'Attempted access to message in private area!');
                    return this.notFoundGenerator(selectorMatch, cb);
                }

                this.prepareMessageBody(message.message, msgBody => {
                    const response = `${'-'.repeat(70)}
To     : ${message.toUserName}
From   : ${message.fromUserName}
When   : ${moment(message.modTimestamp).format('dddd, MMMM Do YYYY, h:mm:ss a (UTCZ)')}
Subject: ${message.subject}
ID     : ${message.messageUuid} (${message.messageId})
${'-'.repeat(70)}
${msgBody}
    `;
                    return cb(response);
                });
            });
        } else if(selectorMatch[2]) {
            //  list messages in area
            const confTag   = selectorMatch[1].substr(1).split('/')[0];
            const areaTag   = selectorMatch[2].replace(/\r\n|\//g, '');
            const area      = getMessageAreaByTag(areaTag);

            if(Message.isPrivateAreaTag(areaTag)) {
                this.log.warn( { areaTag }, 'Attempted access to private area!');
                return cb(this.makeItem(ItemTypes.InfoMessage, 'Area is private'));
            }

            if(!area || !this.isAreaAndConfExposed(confTag, areaTag)) {
                this.log.warn( { confTag, areaTag }, 'Attempted access to non-exposed conference and/or area!');
                return this.notFoundGenerator(selectorMatch, cb);
            }

            const filter = {
                resultType  : 'messageList',
                sort        : 'messageId',
                order       : 'descending',  //  we want newest messages first for Gopher
            };

            return getMessageListForArea(null, areaTag, filter, (err, msgList) => {
                const response = [
                    this.makeItem(ItemTypes.InfoMessage, '-'.repeat(70)),
                    this.makeItem(ItemTypes.InfoMessage, `Messages in ${area.name}`),
                    this.makeItem(ItemTypes.InfoMessage, '(newest first)'),
                    this.makeItem(ItemTypes.InfoMessage, '-'.repeat(70)),
                    ...msgList.map(msg => this.makeItem(
                        ItemTypes.TextFile,
                        `${moment(msg.modTimestamp).format('YYYY-MM-DD hh:mma')}: ${this.shortenSubject(msg.subject)}  (${msg.fromUserName} to ${msg.toUserName})`,
                        `/msgarea/${confTag}/${areaTag}/${msg.messageUuid}`
                    ))
                ].join('');

                return cb(response);
            });
        } else if(selectorMatch[1]) {
            //  list areas in conf
            const sysConfig = Config();
            const confTag   = selectorMatch[1].replace(/\r\n|\//g, '');
            const conf      = _.get(sysConfig, [ 'contentServers', 'gopher', 'messageConferences', confTag ]) && getMessageConferenceByTag(confTag);
            if(!conf) {
                return this.notFoundGenerator(selectorMatch, cb);
            }

            const areas = _.get(sysConfig, [ 'contentServers', 'gopher', 'messageConferences', confTag ], {})
                .map(areaTag => Object.assign( { areaTag }, getMessageAreaByTag(areaTag)))
                .filter(area => area && !Message.isPrivateAreaTag(area.areaTag));

            if(0 === areas.length) {
                return cb(this.makeItem(ItemTypes.InfoMessage, 'No message areas available'));
            }

            sortAreasOrConfs(areas);

            const response = [
                this.makeItem(ItemTypes.InfoMessage, '-'.repeat(70)),
                this.makeItem(ItemTypes.InfoMessage, `Message areas in ${conf.name}`),
                this.makeItem(ItemTypes.InfoMessage, '-'.repeat(70)),
                ...areas.map(area => this.makeItem(ItemTypes.SubMenu, area.name, `/msgarea/${confTag}/${area.areaTag}`))
            ].join('');

            return cb(response);
        } else {
            //  message area base (list confs)
            const confs = Object.keys(_.get(Config(), 'contentServers.gopher.messageConferences', {}))
                .map(confTag => Object.assign( { confTag }, getMessageConferenceByTag(confTag)))
                .filter(conf => conf);  //  remove any baddies

            if(0 === confs.length) {
                return cb(this.makeItem(ItemTypes.InfoMessage, 'No message conferences available'));
            }

            sortAreasOrConfs(confs);

            const response = [
                this.makeItem(ItemTypes.InfoMessage, '-'.repeat(70)),
                this.makeItem(ItemTypes.InfoMessage, 'Available Message Conferences'),
                this.makeItem(ItemTypes.InfoMessage, '-'.repeat(70)),
                this.makeItem(ItemTypes.InfoMessage, ''),
                ...confs.map(conf => this.makeItem(ItemTypes.SubMenu, conf.name, `/msgarea/${conf.confTag}`))
            ].join('');

            return cb(response);
        }
    }
};