const express = require('express')
const fileUpload = require('express-fileupload')
const app = express()
const fs = require('fs');
const port = 3000

const uploadPath = process.env.UPLOAD_PATH || '/tmp';
const config = process.env.config || '{ "uploadGroups": [{ "matcher": "^test.*\.txt$", "groupSize": 3}] } ';

app.use(fileUpload())


const processGroups = () => {
    const files = [] = fs.readdirSync(uploadPath);

    // Sort files by modification time (mtime)
    files.sort((a, b) => {
        const statA = fs.statSync(uploadPath + "/" + a);
        const statB = fs.statSync(uploadPath + "/" + b);
        return statA.mtime - statB.mtime;
    });

    const groups = [];

    // collection files for defined groups
    JSON.parse(config).uploadGroups.forEach(group => {
        //const filesStartingWithPrefix = files.filter(file => new RegExp(group.mathcer).test(file));
        const filesStartingWithPrefix = files.filter(file => new RegExp(group.matcher).test(file));
        groups.push({ ...group, files: filesStartingWithPrefix })
    });
    return groups;
}

const cleanUp = () => {

    const groups = processGroups();

    groups.forEach(group => {
        if (group.files.length > group.groupSize) {
            const filesToDelete = group.files.slice(0, group.files.length - group.groupSize);
            filesToDelete.forEach(file => {
                console.log(new Date().toISOString() +" Deleting file: ", file);
                fs.unlinkSync(uploadPath + "/" + file);
            });
        }
    });

}


app.get('/state', (req, res) => {
    const groups = processGroups();

    res.setHeader('Content-Type', 'application/json');
    res.send(groups);
});

app.get('/', (req, res) => {
    const files = [];
    fs.readdirSync(uploadPath).forEach(file => {
        const stat = fs.statSync(uploadPath + "/" + file);
        files.push({
            name: file,
            "mtime": stat.mtime
        });
    });

    res.setHeader('Content-Type', 'application/json');
    res.send(files);
});

app.post('/*', function (req, res) {
    let sampleFile;

    const uploadedFileKeys = Object.keys(req.files);
    if (!req.files || uploadedFileKeys.length === 0) {
        return res.status(400).send('No files were uploaded.');
    }

    let messages = "";

    const uploadedFileObj = req.files[uploadedFileKeys[0]];
    let uploadFilePath = uploadPath + "/" + uploadedFileObj.name;

    uploadedFileObj.mv(uploadFilePath, function (err) {
        if (err) {
            return res.status(500).send(err);
        }
        console.log( new Date().toISOString() +" File uploaded to: ", uploadFilePath);
        cleanUp();
        res.send('File(s) uploaded!');
    });

});



app.listen(port, () => {
    console.log(`Example app listening on port ${port}`)
})