import os
import uuid
import sqlite3
from flask import Flask, request, jsonify, session, send_from_directory
from werkzeug.utils import secure_filename
from werkzeug.security import generate_password_hash, check_password_hash
from flask_cors import CORS
import PyPDF2
import pandas as pd

app = Flask(__name__)
CORS(app)
app.secret_key = 'your_secret_key_here'
UPLOAD_FOLDER = 'uploads'
ALLOWED_EXTENSIONS = {'pdf', 'csv', 'txt'}
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER

# Ensure upload folder exists
os.makedirs(UPLOAD_FOLDER, exist_ok=True)

# === DATABASE SETUP ===
def init_db():
    with sqlite3.connect('users.db') as conn:
        conn.execute('''CREATE TABLE IF NOT EXISTS users (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            email TEXT UNIQUE NOT NULL,
            username TEXT UNIQUE NOT NULL,
            password TEXT NOT NULL
        )''')

init_db()

# === HELPERS ===
def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

def extract_text_from_pdf(file_path):
    text = ""
    with open(file_path, 'rb') as f:
        reader = PyPDF2.PdfReader(f)
        for page in reader.pages:
            text += page.extract_text() or ""
    return text

def extract_text_from_csv(file_path):
    df = pd.read_csv(file_path)
    return df.to_string(index=False)

# === ROUTES ===
@app.route('/')
def index():
    return send_from_directory('.', 'index.html')

@app.route('/<path:path>')
def static_proxy(path):
    return send_from_directory('.', path)

@app.route('/register', methods=['POST'])
def register():
    data = request.json
    email = data.get('email')
    username = data.get('username')
    password = generate_password_hash(data.get('password'))

    with sqlite3.connect('users.db') as conn:
        try:
            conn.execute("INSERT INTO users (email, username, password) VALUES (?, ?, ?)",
                         (email, username, password))
            return jsonify({'message': 'User registered successfully'}), 201
        except sqlite3.IntegrityError:
            return jsonify({'error': 'Email or username already exists'}), 409

@app.route('/login', methods=['POST'])
def login():
    data = request.json
    username = data.get('username')
    password = data.get('password')

    with sqlite3.connect('users.db') as conn:
        user = conn.execute("SELECT * FROM users WHERE username=?", (username,)).fetchone()
        if user and check_password_hash(user[3], password):
            session['user_id'] = user[0]
            return jsonify({'message': 'Login successful'})
        return jsonify({'error': 'Invalid credentials'}), 401

@app.route('/upload', methods=['POST'])
def upload_file():
    if 'file' not in request.files:
        return jsonify({'error': 'No file part'}), 400
    file = request.files['file']
    if file and allowed_file(file.filename):
        filename = secure_filename(file.filename)
        file_id = str(uuid.uuid4()) + "_" + filename
        file_path = os.path.join(app.config['UPLOAD_FOLDER'], file_id)
        file.save(file_path)

        if filename.endswith('.pdf'):
            text = extract_text_from_pdf(file_path)
        elif filename.endswith('.csv'):
            text = extract_text_from_csv(file_path)
        else:
            text = file.read().decode('utf-8')

        return jsonify({'extracted_text': text})
    return jsonify({'error': 'Invalid file type'}), 400

@app.route('/logout', methods=['GET'])
def logout():
    session.clear()
    return jsonify({'message': 'Logged out successfully'})

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