app.py

# app.py (With JSON Download Feature)

from flask import Flask, render_template, request, redirect, url_for, session, flash, abort, Response
from datetime import datetime
import copy
import json # Import the json library

# --- App Configuration ---
app = Flask(__name__)
app.config['SECRET_KEY'] = 'a-key-for-json-download-demo'

# --- In-Memory Data Store ---
chirps_data = {}
chirp_id_counter = 0

# --- Helper Function to Build the Comment Tree ---
def get_chirp_tree():
    nodes = copy.deepcopy(chirps_data)
    for chirp_id in nodes:
        nodes[chirp_id]['children'] = []
    nested_chirps = []
    for chirp_id, chirp in nodes.items():
        if chirp['parent_id'] is not None:
            parent = nodes.get(chirp['parent_id'])
            if parent:
                parent['children'].append(chirp)
        else:
            nested_chirps.append(chirp)
    for chirp_id in nodes:
        nodes[chirp_id]['children'].sort(key=lambda x: x['timestamp'])
    nested_chirps.sort(key=lambda x: x['timestamp'], reverse=True)
    return nested_chirps

# --- Routes ---

@app.route('/', methods=['GET', 'POST'])
def index():
    if 'username' not in session:
        return redirect(url_for('join'))
    if request.method == 'POST':
        global chirp_id_counter
        content = request.form.get('content')
        if content:
            chirp_id_counter += 1
            new_chirp = {
                'id': chirp_id_counter, 'parent_id': None, 'username': session['username'],
                'content': content, 'timestamp': datetime.utcnow()
            }
            chirps_data[new_chirp['id']] = new_chirp
            flash('Your new chirp has been posted!', 'success')
            return redirect(url_for('index'))
    top_level_posts = get_chirp_tree()
    return render_template('index.html', posts=top_level_posts)

@app.route('/chirp/<int:chirp_id>')
def view_chirp(chirp_id):
    if 'username' not in session:
        return redirect(url_for('join'))
    all_chirps_tree = get_chirp_tree()
    def find_chirp_in_tree(chirp_id, chirps):
        for chirp in chirps:
            if chirp['id'] == chirp_id: return chirp
            found = find_chirp_in_tree(chirp_id, chirp.get('children', []))
            if found: return found
        return None
    main_chirp = find_chirp_in_tree(chirp_id, all_chirps_tree)
    if not main_chirp:
        abort(404)
    return render_template('view_chirp.html', main_chirp=main_chirp)

@app.route('/reply/<int:parent_id>', methods=['POST'])
def reply(parent_id):
    if 'username' not in session:
        return redirect(url_for('join'))
    global chirp_id_counter
    content = request.form.get('content')
    if parent_id not in chirps_data:
        flash('Cannot reply to a non-existent chirp.', 'danger')
        return redirect(url_for('index'))
    if content:
        chirp_id_counter += 1
        new_comment = {
            'id': chirp_id_counter, 'parent_id': parent_id, 'username': session['username'],
            'content': content, 'timestamp': datetime.utcnow()
        }
        chirps_data[new_comment['id']] = new_comment
        flash('Your reply was posted!', 'success')
    else:
        flash('Reply cannot be empty.', 'danger')
    return redirect(url_for('view_chirp', chirp_id=parent_id))

# --- NEW DOWNLOAD ROUTE ---
@app.route('/download_data')
def download_data():
    """Filters user's chirps and provides them as a JSON file download."""
    if 'username' not in session:
        flash("You must be logged in to download your data.", "danger")
        return redirect(url_for('join'))

    current_username = session['username']
    
    # Filter the chirps_data dictionary to get only the user's posts and comments
    user_chirps = [
        chirp for chirp in chirps_data.values() 
        if chirp['username'] == current_username
    ]

    # Sort the user's data by time for consistency
    user_chirps.sort(key=lambda x: x['timestamp'])

    # Prepare the JSON data. `indent=2` makes it human-readable.
    # `default=str` is crucial to handle datetime objects, which are not JSON serializable by default.
    json_data = json.dumps(user_chirps, indent=2, default=str)

    # Create a dynamic filename
    filename = f"chirp_data_{current_username}.json"

    # Create a Flask Response object
    return Response(
        json_data,
        mimetype="application/json",
        headers={"Content-Disposition": f"attachment;filename={filename}"}
    )

# --- Standard User Routes ---
@app.route('/join', methods=['GET', 'POST'])
def join():
    if 'username' in session:
        return redirect(url_for('index'))
    if request.method == 'POST':
        username = request.form.get('username')
        if username:
            session['username'] = username
            flash(f'Welcome, {username}!', 'success')
            return redirect(url_for('index'))
        else:
            flash('Please enter a name to join.', 'danger')
    return render_template('join.html')

@app.route('/logout')
def logout():
    session.pop('username', None)
    flash('You have been logged out.', 'success')
    return redirect(url_for('join'))

if __name__ == '__main__':
    app.run(debug=True,host="0.0.0.0",port=7860)