import os
import sqlite3
import uuid
import hashlib
import threading
import time
import secrets
import string
import argparse
from datetime import datetime, timedelta
from werkzeug.utils import secure_filename
from flask import Flask, request, jsonify, render_template, send_from_directory, abort, make_response
from werkzeug.security import generate_password_hash
import re

def generate_secret_key(length=32):
    """Generate a random secret key with specified length"""
    alphabet = string.ascii_letters + string.digits + string.punctuation
    return ''.join(secrets.choice(alphabet) for _ in range(length))

def parse_arguments():
    """Parse command line arguments"""
    parser = argparse.ArgumentParser(description='Flask Temporary File Upload Server')
    parser.add_argument('--host', default='127.0.0.1', help='Host to bind to (default: 127.0.0.1)')
    parser.add_argument('--port', type=int, default=5000, help='Port to bind to (default: 5000)')
    parser.add_argument('--debug', action='store_true', help='Enable debug mode')
    parser.add_argument('--base-url', default=None, help='Base URL for download links (e.g., https://mysite.com)')
    parser.add_argument('--network', action='store_true', help='Bind to all network interfaces (0.0.0.0)')
    parser.add_argument('--max-file-size', type=int, default=16, help='Maximum file size in MB (default: 16)')
    return parser.parse_args()

# Parse command line arguments
args = parse_arguments()

# Set host based on arguments
if args.network:
    HOST = '0.0.0.0'
else:
    HOST = args.host

# Set base URL for download links
BASE_URL = args.base_url or os.environ.get('BASE_URL', f'http://{HOST}:{args.port}')

# Validate max file size
if args.max_file_size <= 0:
    print("❌ Error: Maximum file size must be a positive integer")
    exit(1)

app = Flask(__name__)
app.config['SECRET_KEY'] = generate_secret_key(32)
app.config['UPLOAD_FOLDER'] = 'uploads'
app.config['MAX_CONTENT_LENGTH'] = args.max_file_size * 1024 * 1024  # Convert MB to bytes
app.config['BASE_URL'] = BASE_URL

# Ensure upload directory exists
os.makedirs(app.config['UPLOAD_FOLDER'], exist_ok=True)

# Database initialization
def init_db():
    conn = sqlite3.connect('files.db')
    cursor = conn.cursor()
    cursor.execute('''
        CREATE TABLE IF NOT EXISTS files (
            id TEXT PRIMARY KEY,
            original_filename TEXT NOT NULL,
            sanitized_filename TEXT NOT NULL,
            file_path TEXT NOT NULL,
            user_session TEXT NOT NULL,
            upload_date TEXT NOT NULL,
            expiration_date TEXT NOT NULL,
            duration_hours INTEGER NOT NULL,
            file_size INTEGER NOT NULL,
            mime_type TEXT
        )
    ''')
    conn.commit()
    conn.close()

def sanitize_filename(filename):
    """Sanitize filename for safe storage"""
    # Remove special characters and spaces
    name, ext = os.path.splitext(filename)
    sanitized = re.sub(r'[^a-zA-Z0-9_-]', '_', name)
    # Generate unique identifier
    unique_id = str(uuid.uuid4())[:8]
    return f"{sanitized}_{unique_id}{ext}"

def cleanup_expired_files():
    """Remove expired files from database and filesystem"""
    conn = sqlite3.connect('files.db')
    cursor = conn.cursor()
    
    # Get expired files
    cursor.execute('''
        SELECT file_path FROM files 
        WHERE expiration_date < ?
    ''', (datetime.now().isoformat(),))
    
    expired_files = cursor.fetchall()
    
    # Delete files from filesystem
    for (file_path,) in expired_files:
        full_path = os.path.join(app.config['UPLOAD_FOLDER'], file_path)
        try:
            if os.path.exists(full_path):
                os.remove(full_path)
                print(f"Deleted expired file: {file_path}")
        except Exception as e:
            print(f"Error deleting file {file_path}: {e}")
    
    # Remove from database
    cursor.execute('DELETE FROM files WHERE expiration_date < ?', 
                  (datetime.now().isoformat(),))
    
    conn.commit()
    conn.close()
    print(f"Cleaned up {len(expired_files)} expired files")

def cleanup_worker():
    """Background worker to cleanup expired files every 10 minutes"""
    while True:
        time.sleep(600)  # 10 minutes
        cleanup_expired_files()

@app.route('/')
def index():
    max_file_size = app.config['MAX_CONTENT_LENGTH'] // (1024 * 1024)  # Convert bytes to MB
    return render_template('index.html', max_file_size=max_file_size)

@app.route('/upload', methods=['POST'])
def upload_file():
    if 'file' not in request.files:
        return jsonify({'error': 'No file provided'}), 400
    
    file = request.files['file']
    user_session = request.form.get('user_session')
    duration_hours = int(request.form.get('duration_hours', 24))
    
    if file.filename == '':
        return jsonify({'error': 'No file selected'}), 400
    
    if not user_session:
        return jsonify({'error': 'No user session provided'}), 400
    
    if file:
        # Generate file info
        file_id = str(uuid.uuid4())
        original_filename = file.filename
        sanitized_filename = sanitize_filename(original_filename)
        upload_date = datetime.now()
        expiration_date = upload_date + timedelta(hours=duration_hours)
        
        # Save file
        file_path = sanitized_filename
        full_path = os.path.join(app.config['UPLOAD_FOLDER'], file_path)
        file.save(full_path)
        
        # Get file info
        file_size = os.path.getsize(full_path)
        mime_type = file.content_type
        
        # Save to database
        conn = sqlite3.connect('files.db')
        cursor = conn.cursor()
        cursor.execute('''
            INSERT INTO files (id, original_filename, sanitized_filename, file_path, 
                             user_session, upload_date, expiration_date, duration_hours, 
                             file_size, mime_type)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
        ''', (file_id, original_filename, sanitized_filename, file_path, user_session,
              upload_date.isoformat(), expiration_date.isoformat(), duration_hours,
              file_size, mime_type))
        conn.commit()
        conn.close()
        
        return jsonify({
            'success': True,
            'file_id': file_id,
            'original_filename': original_filename,
            'download_url': f'{app.config["BASE_URL"]}/download/{file_id}',
            'expiration_date': expiration_date.isoformat(),
            'file_size': file_size
        })

@app.route('/files/<user_session>')
def get_user_files(user_session):
    conn = sqlite3.connect('files.db')
    cursor = conn.cursor()
    cursor.execute('''
        SELECT id, original_filename, upload_date, expiration_date, 
               duration_hours, file_size, mime_type
        FROM files 
        WHERE user_session = ? AND expiration_date > ?
        ORDER BY upload_date DESC
    ''', (user_session, datetime.now().isoformat()))
    
    files = cursor.fetchall()
    conn.close()
    
    file_list = []
    for file_data in files:
        file_list.append({
            'id': file_data[0],
            'original_filename': file_data[1],
            'upload_date': file_data[2],
            'expiration_date': file_data[3],
            'duration_hours': file_data[4],
            'file_size': file_data[5],
            'mime_type': file_data[6],
            'download_url': f'{app.config["BASE_URL"]}/download/{file_data[0]}'
        })
    
    return jsonify(file_list)

@app.route('/download/<file_id>')
def download_page(file_id):
    conn = sqlite3.connect('files.db')
    cursor = conn.cursor()
    cursor.execute('''
        SELECT original_filename, file_path, expiration_date, file_size, mime_type
        FROM files 
        WHERE id = ?
    ''', (file_id,))
    
    file_data = cursor.fetchone()
    conn.close()
    
    if not file_data:
        return make_response(render_template('file_not_found.html'), 404)
    
    original_filename, file_path, expiration_date, file_size, mime_type = file_data
    
    # Check if file has expired
    if datetime.fromisoformat(expiration_date) < datetime.now():
        return make_response(render_template('file_not_found.html'), 410)
    
    # Check if file exists
    full_path = os.path.join(app.config['UPLOAD_FOLDER'], file_path)
    if not os.path.exists(full_path):
        return make_response(render_template('file_not_found.html'), 404)
    
    # Check if it's a text file for preview
    is_text_file = mime_type and (mime_type.startswith('text/') or mime_type == 'application/json')
    file_content = None
    
    if is_text_file:
        try:
            with open(full_path, 'r', encoding='utf-8') as f:
                file_content = f.read()
        except (UnicodeDecodeError, Exception):
            # If can't read as text, treat as binary
            is_text_file = False
    
    return render_template('download.html', 
                         file_id=file_id,
                         filename=original_filename,
                         file_size=file_size,
                         mime_type=mime_type,
                         expiration_date=expiration_date,
                         is_text_file=is_text_file,
                         file_content=file_content)

@app.route('/download/<file_id>/direct')
def download_file_direct(file_id):
    conn = sqlite3.connect('files.db')
    cursor = conn.cursor()
    cursor.execute('''
        SELECT original_filename, file_path, expiration_date
        FROM files 
        WHERE id = ?
    ''', (file_id,))
    
    file_data = cursor.fetchone()
    conn.close()
    
    if not file_data:
        return make_response(render_template('file_not_found.html'), 404)
    
    original_filename, file_path, expiration_date = file_data
    
    # Check if file has expired
    if datetime.fromisoformat(expiration_date) < datetime.now():
        return make_response(render_template('file_not_found.html'), 410)
    
    # Check if file exists
    full_path = os.path.join(app.config['UPLOAD_FOLDER'], file_path)
    if not os.path.exists(full_path):
        return make_response(render_template('file_not_found.html'), 404)
    
    return send_from_directory(app.config['UPLOAD_FOLDER'], file_path, 
                              as_attachment=True, download_name=original_filename)

@app.route('/delete/<file_id>', methods=['DELETE'])
def delete_file(file_id):
    user_session = request.json.get('user_session')
    
    if not user_session:
        return jsonify({'error': 'No user session provided'}), 400
    
    conn = sqlite3.connect('files.db')
    cursor = conn.cursor()
    
    # Get file info and verify ownership
    cursor.execute('''
        SELECT file_path FROM files 
        WHERE id = ? AND user_session = ?
    ''', (file_id, user_session))
    
    file_data = cursor.fetchone()
    
    if not file_data:
        conn.close()
        return jsonify({'error': 'File not found or unauthorized'}), 404
    
    file_path = file_data[0]
    
    # Delete from filesystem
    full_path = os.path.join(app.config['UPLOAD_FOLDER'], file_path)
    try:
        if os.path.exists(full_path):
            os.remove(full_path)
    except Exception as e:
        print(f"Error deleting file {file_path}: {e}")
    
    # Delete from database
    cursor.execute('DELETE FROM files WHERE id = ? AND user_session = ?', 
                  (file_id, user_session))
    
    conn.commit()
    conn.close()
    
    return jsonify({'success': True})

if __name__ == '__main__':
    # Print configuration info
    print(f"🚀 Starting Flask Temporary File Upload Server")
    print(f"📁 Upload folder: {app.config['UPLOAD_FOLDER']}")
    print(f"🔑 Secret key: {app.config['SECRET_KEY'][:8]}... (32 chars)")
    print(f"🌐 Base URL: {app.config['BASE_URL']}")
    print(f"🖥️  Server: http://{HOST}:{args.port}")
    print(f"🔒 Max file size: {args.max_file_size}MB")
    print(f"⏰ Cleanup interval: 10 minutes")
    print(f"🐛 Debug mode: {'ON' if args.debug else 'OFF'}")
    print("-" * 50)
    
    init_db()
    
    # Start cleanup worker in background
    cleanup_thread = threading.Thread(target=cleanup_worker, daemon=True)
    cleanup_thread.start()
    
    # Initial cleanup
    cleanup_expired_files()
    
    app.run(debug=args.debug, host=HOST, port=args.port)