import fs from 'fs'
import https from 'https'
import initLog from '../utils/log.js'
import { exec } from 'child_process'

const log = initLog("Downloader")


/**
 * This function can download and save data to files, or simply return the data.
 * @param {string} url The URL of which to download from...
 * @param {string} target This is the file path you want to save to. Alterntively use "_RETURN_VALUE_" to get value returned instead of saved to a file.
 * 
 * @returns {Promise}
 * 
 * @author BurnyLlama
 */
export function download(url, target) {
    return new Promise(
        (resolve, reject) => {
            log(`Starting a download >> ${url}`)

            https.get(
                url,
                data => {
                    if (target === "_RETURN_VALUE_") {
                        let result = ""

                        data.on(
                            'data',
                            chunk => result += chunk
                        )
                                
                        data.on(
                            'end',
                            () => resolve(result)
                        )
                    } else {
                        fs.unlink(target, () => {
                            const file = fs.createWriteStream(target)
                            data.pipe(file)
                        })
                    }

                    data.on(
                        'end',
                        () => {
                            log(`Done with a download >> ${url}`)

                            if (!target === "_RETURN_VALUE_")
                                file.close()
            
                            resolve()
                        }
                    )
                }
            )
        }
    )
}

export function downloadEssentialData() {
    return new Promise(
        (resolve, reject) => {
            log("Downloading 'ddnet.sqlite.zip' and 'players.msgpack'...")
            Promise.all([
                download("https://ddnet.tw/stats/ddnet.sqlite.zip", process.env.DATA_DIR ? `${process.env.DATA_DIR}/ddnet.sqlite.zip` : 'data/ddnet.sqlite.zip'),
                download("https://ddnet.tw/players.msgpack", process.env.DATA_DIR ? `${process.env.DATA_DIR}/players.msgpack` : 'data/players.msgpack')
            ]).then(() => {
                log("All downloads done! Going to unzip 'ddnet.sqlite.zip'...")

                exec(
                    `unzip -o ${process.env.DATA_DIR ? `${process.env.DATA_DIR}/ddnet.sqlite.zip` : 'data/ddnet.sqlite.zip'} \
                           -d ${process.env.DATA_DIR ? process.env.DATA_DIR : 'data'}`,
                    err => {
                        if (err) {
                            log("Error while unzipping!")
                            reject()
                        }

                        log("Done unzipping!")
                        resolve()
                    }
                )
            })
        }
    )
}