require('dotenv').config()
const express = require('express');
const fileUpload = require('express-fileupload');
const fs = require('fs');
const mime = require('mime');
const app = express();
const port = 3000;

const uploadPath = process.env.UPLOAD_PATH || '/tmp';
const config = process.env.CONFIG || "{ \"uploadGroups\": [] }";
//const config = process.env.CONFIG || "{ \"uploadGroups\": [{ \"matcher\": \"^mmkb-android-.*-test\\.apk$\", \"groupSize\": 3},{ \"matcher\": \"^mmkb-android-.*-int\\.apk$\", \"groupSize\": 3},{ \"matcher\": \"^mmkb-android-.*-prod\\.apk$\", \"groupSize\": 3}] }";

console.info("Upload path: ", uploadPath);  
console.info("Config: ", config);   


app.use(fileUpload());

app.use((req, res, next) => {
    if (process.env.API_KEY) {
        const authenticated = req.get('Authorization') === 'Bearer ' + process.env.API_KEY;
        if (!authenticated) {
            return res.status(401).send('Unauthorized');
        }
    }
    next();
});

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.matcher).test(file));
        groups.push({ ...group, files: filesStartingWithPrefix });
    });
    return groups;
};

/**
 *
 * clean up files based on the group size
 */
const cleanUp = () => {
    console.info("Cleaning up files...");
    const groups = processGroups();
    console.info("Groups: ", groups);   

    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);
            });
        }
    });
};

/**  
 *  
 * upload a file
 * throws 400 if no file was uploaded
 * throws 409 if file already exists and overwrite is false
 * throws 500 if file upload failed
 */
const uploadFile = (req, res, overwrite) => {
    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;

    if (fs.existsSync(uploadFilePath) && !overwrite) {
        console.log(new Date().toISOString() + " File already exists: ", uploadFilePath);
        return res.status(409).send('File already exists.');
    }

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

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

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

app.get('/clean', (req, res) => {
    cleanUp();

    res.setHeader('Content-Type', 'application/json');
    res.send('Clean up done!');
});

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);
});

/**
 * 
 * upload a file
 * throws 409 if file already exists
 */
app.post('/', function (req, res) {
    uploadFile(req, res, false);
});

/**
 * 
 * upload or replace a file
 */
app.put('/', function (req, res) {
    uploadFile(req, res, true);
});

/**
 * 
 * delete a file with the given filename
 * throws 404 if file not found
 */
app.delete('/:filename', (req, res) => {
    const filename = req.params.filename;
    const filePath = uploadPath + "/" + filename;

    if (fs.existsSync(filePath)) {
        fs.unlinkSync(filePath);
        res.send(`File ${filename} deleted!`);
    } else {
        res.status(404).send('File not found.');
    }
});

/**
 * 
 * get a file with the given filename
 * returns the file content with the appropriate Content-Type
 */
app.get('/:filename', (req, res) => {
    const filename = req.params.filename;
    const filePath = uploadPath + "/" + filename;

    if (fs.existsSync(filePath)) {
        // todo: mime.getType is not a function
        //const mimeType = mime.getType(filePath);
        //res.setHeader('Content-Type', mimeType);
        fs.createReadStream(filePath).pipe(res);
    } else {
        res.status(404).send('File not found.');
    }
});

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