BACKEND DONE FOR ALL APPS

2024-10-21 18:34:45 +03:00
parent 4157ca9e7d
commit ab1eaec413
349 changed files with 17199 additions and 14015 deletions
@@ -0,0 +1,137 @@
+import fs from 'fs';
+import path from 'path';
+
+export class QueueManager<T> {
+    private readonly filePath: string;
+    private readonly lockFilePath: string;
+    private queue: T[];
+    private readonly compareFn: (a: T, b: T) => boolean; // Comparison function
+
+    constructor(filePath: string, compareFn: (a: T, b: T) => boolean) {
+        this.filePath = filePath;
+        this.lockFilePath = `${filePath}.lock`; // Define the lock file path
+        this.queue = [];
+        this.compareFn = compareFn;
+
+        const dir = path.dirname(filePath);
+
+        // Check if the directory exists, throw error if it doesn't
+        if (!fs.existsSync(dir)) {
+            throw new Error(`The directory does not exist: ${dir}`);
+        }
+
+        // If the file doesn't exist, create it
+        if (!fs.existsSync(filePath)) {
+            fs.writeFileSync(filePath, JSON.stringify([], null, 2), 'utf8');
+        }
+    }
+
+    // Method to acquire a lock (create .lock file)
+    private acquireLock(): void {
+        while (fs.existsSync(this.lockFilePath)) {
+            // Wait until the lock file is released
+            this.sleepSync(100); // 100ms delay before retrying
+        }
+        // Create the lock file
+        fs.writeFileSync(this.lockFilePath, '');
+    }
+
+    // Sleep function to simulate delay for locking mechanism
+    private sleepSync(ms: number): void {
+        const start = Date.now();
+        while (Date.now() - start < ms) {
+            // busy wait
+        }
+    }
+
+    // Method to release the lock (delete .lock file)
+    private releaseLock(): void {
+        if (fs.existsSync(this.lockFilePath)) {
+            fs.unlinkSync(this.lockFilePath);
+        }
+    }
+
+    // Load the queue from the JSON file
+    loadQueue(): void {
+        this.acquireLock(); // Acquire the lock
+
+        try {
+            const fileData = fs.readFileSync(this.filePath, 'utf8');
+            this.queue = JSON.parse(fileData) || [];
+        } catch (err) {
+            // If the file doesn't exist or is invalid, start with an empty queue
+            this.queue = [];
+        } finally {
+            this.releaseLock(); // Release the lock
+        }
+    }
+
+    // Save the queue back to the JSON file
+    saveQueue(): void {
+        this.acquireLock(); // Acquire the lock
+
+        try {
+            fs.writeFileSync(this.filePath, JSON.stringify(this.queue, null, 2), 'utf8');
+        } finally {
+            this.releaseLock(); // Release the lock
+        }
+    }
+
+    // Enqueue: Add an item to the end of the queue if it doesn't already exist
+    enqueue(item: T): void {
+        this.loadQueue();  // Ensure we load the latest queue
+
+        // Check if the item already exists in the queue
+        const exists = this.queue.some(existingItem => this.compareFn(existingItem, item));
+
+        console.log(this.queue);
+
+        if (!exists) {
+            this.queue.push(item);
+            this.saveQueue();  // Save the updated queue
+        } else {
+            console.log('Item already exists in the queue. Skipping enqueue.');
+        }
+    }
+
+    // Dequeue: Remove an item from the front of the queue
+    dequeue(): T | null {
+        this.loadQueue();  // Ensure we load the latest queue
+        if (this.queue.length === 0) {
+            return null;  // Queue is empty
+        }
+        const item = this.queue.shift() as T;  // Remove the first item
+        this.saveQueue();  // Save the updated queue
+        return item;
+    }
+
+    // Peek: Get the item at the front of the queue without removing it
+    peek(): T | null {
+        this.loadQueue();  // Ensure we load the latest queue
+        return this.queue.length > 0 ? this.queue[0] : null;
+    }
+
+    // Check if the queue is empty
+    isEmpty(): boolean {
+        this.loadQueue();  // Ensure we load the latest queue
+        return this.queue.length === 0;
+    }
+
+    // Get the length of the queue
+    length(): number {
+        this.loadQueue();  // Ensure we load the latest queue
+        return this.queue.length;
+    }
+
+    // Clear the entire queue
+    clearQueue(): void {
+        this.acquireLock(); // Acquire the lock
+
+        try {
+            this.queue = [];  // Clear the queue
+            fs.writeFileSync(this.filePath, JSON.stringify(this.queue, null, 2), 'utf8');
+        } finally {
+            this.releaseLock(); // Release the lock
+        }
+    }
+}