const config = require('./config');

const express = require('express');
const fileUpload = require('express-fileupload');
const path = require('path');
const fs = require('fs');
const mime = require('mime-types')
const cors = require('cors');

const app = express();

app.use(fileUpload());
app.set('view engine', 'ejs')
app.use(express.urlencoded({ extended: false }));
app.use(express.json());


const isPathValid = (filename, filePath) => {
    if (!filename) {
        return false;
    }

    if (filename.indexOf('\0') !== -1 || filename.indexOf('%') !== -1 || filename.indexOf('/') !== -1 || filename.indexOf('..') !== -1) {
        return false;
    }

    if (!/[A-Za-z1-9.]+/g.test(filename)) {
        return false;
    }

    if (filePath.indexOf(config.storagePath) !== 0) {
        return false;
    }

    return true;
};

const isFilenameValid = (filename) => {
    if (!filename) {
        return false;
    }

    if (filename.indexOf('\0') !== -1 || filename.indexOf('%') !== -1 || filename.indexOf('..') !== -1 || filename.indexOf('&') !== -1) {
        return false;
    }

    if (!/[A-Za-z1-9.]+/g.test(filename)) {
        return false;
    }

    return true;
};

const getFileType = (filename) => {
    const extension = path.extname(filename).substring(1);
    let type = config.files.embed[extension];

    if (!type) {
        type = config.files.other;
    }

    return type;
};

const allowlist = ['https://hippoz.xyz/', 'https://hippoz.xyz']
const corsOptions = {
    origin: function (origin, callback) {
        if (allowlist.indexOf(origin) !== -1) {
            callback(null, true)
        } else {
            callback(new Error('Not allowed by CORS'))
        }
    }
}

app.get('/', (req, res) => {
    if (!config.rootRedirect) {
        res.render('upload');
    } else {
        res.redirect(301, config.rootRedirect);
    }
});

app.get('/file/:filename', (req, res) => {
    const filename = req.params.filename;
    const filePath = path.join(config.storagePath, filename);
    const isValid = isPathValid(filename, filePath);

    if (!isValid) {
        res.status(400).send('invalid input.');
        return;
    }

    fs.access(filePath, fs.F_OK, (err) => {
        if (err) {
            res.status(404).send('file not found or is invalid.');
            return;
        }

        const type = getFileType(filePath);
        const mimeType = mime.lookup(filePath);

        if (type === config.files.other) {
            res.contentType('text/plain');
        } else {
            res.contentType(mimeType);
        }
        
        res.sendFile(filePath);
    });
});

// TODO: add cors for all endpoints
app.post('/api/upload', [ cors(corsOptions) ], (req, res) => {
    const password = req.body.password;
    const chosenFileName = req.body.filename;

    if (config.passwords.indexOf(password) === -1) {
        return res.status(401).render('uploadfailed', { message: 'the password you entered is not correct.' });
    }

    if (!req.files || Object.keys(req.files).length === 0) {
        return res.status(400).render('uploadfailed', { message: 'you forgot to upload a file.' });
    }

    const file = req.files.file;

    if (!isFilenameValid(chosenFileName)) {
        return res.status(400).render('uploadfailed', { message: 'invalid name.' });
    }

    const filepath = path.join(config.storagePath, chosenFileName);

    if (!isFilenameValid(file.name) || !isPathValid(chosenFileName, filepath)) {
        return res.status(400).render('uploadfailed', { message: 'invalid name.' });
    }

    fs.stat(filepath, (err) => {
        if(err == null) {
            return res.status(400).render('uploadfailed', { message: 'a file with that name already exists.' });
        } else if(err.code === 'ENOENT') {
            file.mv(filepath, (err) => {
                if (err) return res.status(500).render('uploadfailed', { message: 'something went wrong while uploading the file.' });
                res.render('uploaded', { baseurl: config.url, file: { name: chosenFileName } });
            });
        } else {
            return res.status(500).render('uploadfailed', { message: 'something went wrong.' });;
        }
    });
});

app.use(function (err, req, res, next) {
    console.error(err.stack);
    res.status(500).send('internal server error: something went wrong');
});

app.listen(config.server.port, () => {
    console.log(`started server on port ${config.server.port}`);
});