server migration to TypeScript

server/src/core/Process.ts

@@ -0,0 +1,133 @@
+import { spawn } from 'child_process';
+import { join } from 'path';
+import { Readable } from 'stream';
+import { deleteDownloadByPID, insertDownload } from '../db/db';
+import Logger from '../utils/BetterLogger';
+
+const log = new Logger();
+
+/**
+ * Represents a download process that spawns yt-dlp.
+ * @constructor
+ * @param {string} url - The downlaod url.
+ * @param {Array<String>} params - The cli arguments passed by the frontend.
+ * @param {*} settings - The download settings passed by the frontend.
+ */
+
+class Process {
+    private url: string;
+    private params: Array<string>;
+    private settings: any;
+    private stdout: Readable;
+    private pid: number;
+    private info: any;
+    private lock: boolean;
+    private exePath = join(__dirname, 'yt-dlp');
+
+    constructor(url: string, params: Array<string>, settings: any) {
+        this.url = url;
+        this.params = params || [];
+        this.settings = settings
+        this.stdout = undefined;
+        this.pid = undefined;
+        this.info = null;
+    }
+
+    /**
+     * function that launch the download process, sets the stdout property and the pid
+     * @param {Function} callback not yet implemented
+     * @returns {Promise<this>} the process instance
+     */
+    async start(callback?: Function): Promise<this> {
+        await this.#__internalGetInfo();
+
+        const ytldp = spawn(this.exePath,
+            ['-o', `${this.settings?.download_path || 'downloads/'}%(title)s.%(ext)s`]
+                .concat(this.params)
+                .concat([this.url])
+        );
+
+        this.pid = ytldp.pid;
+        this.stdout = ytldp.stdout;
+
+        log.info('proc', `Spawned a new process, pid: ${this.pid}`)
+
+        await insertDownload(this.url, this.info?.title, this.info?.thumbnail, null, this.pid);
+
+        return this;
+    }
+
+    /**
+     * @private
+     * function used internally by the download process to fetch information, usually thumbnail and title
+     * @returns Promise to the lock
+     */
+    async #__internalGetInfo() {
+        let lock = true;
+        let stdoutChunks = [];
+        const ytdlpInfo = spawn(this.exePath, ['-s', '-j', this.url]);
+
+        ytdlpInfo.stdout.on('data', (data) => {
+            stdoutChunks.push(data);
+        });
+
+        ytdlpInfo.on('exit', () => {
+            try {
+                const buffer = Buffer.concat(stdoutChunks);
+                const json = JSON.parse(buffer.toString());
+                this.info = json;
+                this.lock = false;
+
+            } catch (e) {
+                this.info = {
+                    title: "",
+                    thumbnail: "",
+                };
+            }
+        });
+
+        if (!lock) {
+            return true;
+        }
+    }
+
+    /**
+     * function that kills the current process
+     */
+    async kill() {
+        spawn('kill', [String(this.pid)]).on('exit', () => {
+            deleteDownloadByPID(this.pid).then(() => {
+                log.info('db', `Deleted ${this.pid} because SIGKILL`)
+            })
+        });
+    }
+
+    /**
+     * pid getter function
+     * @returns {number} pid
+     */
+    getPid(): number {
+        if (!this.pid) {
+            throw "Process isn't started"
+        }
+        return this.pid;
+    }
+
+    /**
+     * stdout getter function
+     * @returns {Readable} stdout as stream
+     */
+    getStdout(): Readable {
+        return this.stdout
+    }
+
+    /**
+     * download info getter function
+     * @returns {object}
+     */
+    getInfo(): object {
+        return this.info
+    }
+}
+
+export default Process;