app.py

from flask import Flask, request, jsonify
import json
import os

app = Flask(__name__)
app.config['DATA_FILE'] = "tasks.json"  # Χρησιμοποιούμε config αντί για global

# Βοηθητικές συναρτήσεις
def load_tasks():
    file = app.config['DATA_FILE']
    if not os.path.exists(file):
        return []
    with open(file, "r") as f:
        return json.load(f)

def save_tasks(tasks):
    file = app.config['DATA_FILE']
    with open(file, "w") as f:
        json.dump(tasks, f, indent=4)
        
def get_next_id(tasks):
    if not tasks:
        return 1
    # Παίρνουμε το μεγαλύτερο υπάρχον id και προσθέτουμε 1
    return max(task["id"] for task in tasks) + 1

# 1. Get all tasks
@app.route("/tasks", methods=["GET"])
def get_tasks():
    tasks = load_tasks()
    # Ταξινόμηση κατά id
    tasks_sorted = sorted(tasks, key=lambda x: x["id"])
    return jsonify(tasks_sorted), 200

# 2. Get task by id
@app.route("/tasks/<int:task_id>", methods=["GET"])
def get_task_by_id(task_id):
    tasks = load_tasks()
    for task in tasks:
        if task["id"] == task_id:
            return jsonify(task), 200
    return jsonify({"error": "Task not found"}), 404

# 3. Create task
@app.route("/tasks", methods=["POST"])
def create_task():
    tasks = load_tasks()
    data = request.get_json()
    new_task = {
        "id": get_next_id(tasks),
        "username": data["username"],
        "title": data["title"],
        "description": data["description"],
        "deadline": data["deadline"]
    }
    tasks.append(new_task)
    save_tasks(tasks)
    return jsonify(new_task), 201

# 4. Delete task
@app.route("/tasks/<int:task_id>", methods=["DELETE"])
def delete_task(task_id):
    tasks = load_tasks()
    for task in tasks:
        if task["id"] == task_id:
            tasks.remove(task)
            save_tasks(tasks)
            return jsonify({"message": "Task deleted"}), 200
    return jsonify({"error": "Task not found"}), 404

if __name__ == "__main__":
    app.run(debug=True)