var express = require('express');
var view = require('./view');
var storage = require('./storage');
var md5 = require('md5');
var LRU = require('lru-cache');
var bodyParser = require('body-parser');
var fs = require('fs');
var blackList;

var app = express();

app.use(bodyParser.urlencoded({ extended: true, limit: '200kb' }));
app.use(express.static(__dirname + '/resources/public'));
app.use(function (error, req, res, next) {
    if (error) {
        sendResponse(res, 400, 'Bad request', error.message);
        log('REQUEST ERROR:', error);
    } else {
        next();
    }
});

var MODELS = {};
var CACHE = new LRU({
    max: 50,
    dispose: key => {
        log('disposing', key, 'from cache');
        var model = MODELS[key];
        if (model) model.save();
        delete MODELS[key];
    }
});

var log = function() {
    var date = new Date();
    var timestamp = date.getDate() + '/' + date.getMonth() + ' ' + date.getHours() + ':' +
        date.getMinutes() + ':' + date.getSeconds() + '.' + date.getMilliseconds();
    var message = Array.prototype.slice.call(arguments);
    message.unshift('--');
    message.unshift(timestamp);
    console.log.apply(console, message);
};

app.get('/TOS', (req, res) => res.send(view.renderTOS()));

app.get('/new', (req, res) => {
    log(req.ip, 'opens /new');
    res.send(view.newNotePage(md5('new')));
});

app.post('/note', (req, res) => {
    var body = req.body,
        session = body.session,
        note = body.note,
        password = body.password,
        action = body.action,
        id = body.id;
    log(req.ip, 'calls /note to', action, id);
    var goToNote = note => res.redirect('/' + note.id);
    if (!note || !session || session.indexOf(md5('edit/' + id)) !== 0 && session.indexOf(md5('new')) !== 0)
        return sendResponse(res, 400, 'Bad request');
    if (body.signature != md5(session + note.replace(/[\n\r]/g, '')))
        return sendResponse(res, 400, 'Signature mismatch');
    if (action == 'POST')
        storage.addNote(note, password).then(goToNote);
    else {
        if (!id) return sendResponse(res, 400, 'Wrong note ID');
        CACHE.del(id);
        if (body.button == 'Delete') {
            log('deleting note', id);
            storage.deleteNote(id, password).then(
                () => sendResponse(res, 200, 'Note deleted'),
                error => sendResponse(res, 400, 'Bad request', error.message));
        } else {
            log('updating note', id);
            storage.updateNote(id, password, note).then(goToNote,
                error => sendResponse(res, 400, 'Bad request', error.message));
        }
    }
});

app.get('/:year/:month/:day/:title', (req, res) => {
    var P = req.params, url = P.year + '/' + P.month + '/' + P.day + '/' + P.title;
    log(req.ip, 'resolves deprecated id', url);
    if (CACHE.has(url)) {
        log(url, 'is cached!');
        var id = CACHE.get(url);
        if (id) res.redirect('/' + id);
        else notFound(res);
    } else storage.getNoteId(url).then(note => {
        log(url, 'is not cached, resolving...');
        if (note) {
            CACHE.set(url, note.id);
            res.redirect('/' + note.id);
        } else {
            CACHE.set(url, null);
            notFound(res);
        }
    });
});

app.get(/\/([a-z0-9]+)\/edit/, (req, res) => {
    var id = req.params['0'];
    log(req.ip, 'calls /edit on', id);
    storage.getNote(id).then(note => res.send(note ? 
        view.editNotePage(md5('edit/' + id), note) : 
        notFound(res)));
});

app.get(/\/([a-z0-9]+)\/export/, (req, res) => {
    var id = req.params['0'];
    log(req.ip, 'calls /export on', id);
    res.set({ 'Content-Type': 'text/plain', 'Charset': 'utf-8' });
    storage.getNote(id).then(note => note ? 
        res.send(note.text) : 
        notFound(res));
});

app.get(/\/([a-z0-9]+)\/stats/, (req, res) => {
    var id = req.params['0'];
    log(req.ip, 'calls /stats on', id);
    var promise = id in MODELS ? 
        new Promise(resolve => resolve(MODELS[id])) : 
        storage.getNote(id);
    promise.then(note => note ? 
        res.send(view.renderStats(note)) : 
        notFound(res));
});

app.get(/\/([a-z0-9]+)/, (req, res) => {
    var id = req.params['0'];
    log(req.ip, 'open note', id, 'from', req.get('Referer'));
    if (CACHE.has(id)) {
        log(id, 'is cached!');
        var obj = MODELS[id];
        if (!obj) return notFound(res);
        obj.views++;
        res.send(CACHE.get(id));
    } else storage.getNote(id).then(note => {
        log(id, 'is not cached, resolving...');
        if (!note) {
            CACHE.set(id, null);
            return notFound(res);
        }
        var content = view.renderNote(note, blackList);
        CACHE.set(id, content);
        MODELS[id] = note;
        note.views++;
        res.send(content);
    });
});

var sendResponse = (res, code, message, details) => {
    log('sending response', code, message);
    res.status(code).send(view.renderPage(null, message, 
        `<h1>${message}</h1><br/>` +
        `<center>${details || '¯\\_(ツ)_/¯'}</center>`, ''));
};

var notFound = res => sendResponse(res, 404, 'Not found');

var server = app.listen(process.env.PORT || 3000, 
    () => log('NoteHub server listening on port', server.address().port));

setInterval(() => {
    var keys = Object.keys(MODELS);
    log('saving stats for', keys.length, 'models...');
    keys.forEach(id => MODELS[id].save());
}, 5 * 60 * 1000);

var updateBlackList = () => {
    var ids = fs.readFileSync(process.env.BLACK_LIST || '/dev/null', 'utf-8').split(/\n+/).filter(Boolean);
    ids.forEach(id => CACHE.del(id));
    blackList = new Set(ids);
    log('black list updated, entries:', blackList.size);
};

setInterval(updateBlackList, 60 * 60 * 1000);

updateBlackList();