auth.py

"""
auth.py  –  JWT-based authentication blueprint
Routes: /register  /login  /refresh  /logout
"""

from datetime import datetime, timezone, timedelta
from flask import Blueprint, render_template, redirect, url_for, request, flash, make_response, jsonify
from flask_jwt_extended import (
    create_access_token, create_refresh_token,
    jwt_required, get_jwt_identity, get_jwt,
    set_access_cookies, set_refresh_cookies,
    unset_jwt_cookies
)
from flask_bcrypt import Bcrypt
from flask_limiter import Limiter
from flask_limiter.util import get_remote_address
from project.database import (
    create_user, find_user_by_email, find_user_by_id,
    add_token_to_blocklist
)
from project.config import BCRYPT_PEPPER

auth    = Blueprint('auth', __name__)
bcrypt  = Bcrypt()
limiter = Limiter(key_func=get_remote_address)


# ── Helpers ────────────────────────────────────────────────────────────────────
def _pepper(password: str) -> str:
    """Append server-side pepper before hashing. Means a leaked DB alone
    cannot crack passwords without also knowing this secret."""
    return password + BCRYPT_PEPPER


# ── Register ───────────────────────────────────────────────────────────────────
@auth.route('/register', methods=['GET', 'POST'])
@limiter.limit("3 per minute")
def register():
    if request.method == 'POST':
        username = request.form.get('username', '').strip()
        email    = request.form.get('email', '').strip().lower()
        password = request.form.get('password', '')
        confirm  = request.form.get('confirm_password', '')

        if not username or not email or not password:
            flash('All fields are required.', 'error')
            return render_template('register.html')
        if password != confirm:
            flash('Passwords do not match.', 'error')
            return render_template('register.html')
        if len(password) < 6:
            flash('Password must be at least 6 characters.', 'error')
            return render_template('register.html')
        if find_user_by_email(email):
            flash('An account with that email already exists.', 'error')
            return render_template('register.html')

        pw_hash = bcrypt.generate_password_hash(_pepper(password)).decode('utf-8')
        
        # First user is automatically an admin if none exist (Convenience/Bootstrap)
        from project.database import get_db
        is_admin = get_db().users.count_documents({}) == 0
        
        uid = create_user(username, email, pw_hash, is_admin=is_admin)
        if uid:
            return jsonify({"msg": "Account created! Please log in."}), 201
        return jsonify({"detail": "Registration failed. Please try again."}), 400

    return render_template('register.html')


# ── Login ──────────────────────────────────────────────────────────────────────
@auth.route('/login', methods=['GET', 'POST'])
@limiter.limit("5 per minute")
def login():
    if request.method == 'POST':
        email    = request.form.get('email', '').strip().lower()
        password = request.form.get('password', '')

        user_doc = find_user_by_email(email)
        if user_doc and bcrypt.check_password_hash(
                user_doc['password_hash'], _pepper(password)):

            user_id  = str(user_doc['_id'])
            username = user_doc['username']

            # Issue tokens — identity is the user_id string
            access_token  = create_access_token(
                identity=user_id,
                additional_claims={
                    "username": username,
                    "is_admin": user_doc.get("is_admin", False)
                }
            )
            refresh_token = create_refresh_token(identity=user_id)

            # Store in HttpOnly cookies — JS cannot read these
            resp = make_response(jsonify({"msg": "Login successful", "username": username, "is_admin": user_doc.get("is_admin", False)}))
            set_access_cookies(resp, access_token)
            set_refresh_cookies(resp, refresh_token)
            return resp

        # Return JSON error for the Next.js frontend
        return jsonify({"detail": "Invalid email or password."}), 401

    return render_template('login.html')


# ── Token Refresh ──────────────────────────────────────────────────────────────
@auth.route('/refresh', methods=['POST'])
@jwt_required(refresh=True)
def refresh():
    """Issue a new short-lived access token using the long-lived refresh token."""
    user_id      = get_jwt_identity()
    user_doc     = find_user_by_id(user_id)
    username     = user_doc['username'] if user_doc else ''
    access_token = create_access_token(
        identity=user_id,
        additional_claims={
            "username": username,
            "is_admin": user_doc.get("is_admin", False)
        }
    )
    resp = make_response(redirect(request.referrer or url_for('index')))
    set_access_cookies(resp, access_token)
    return resp


# ── Logout ─────────────────────────────────────────────────────────────────────
@auth.route('/logout', methods=['GET', 'POST'])
@jwt_required(optional=True)
def logout():
    """Revoke both tokens and clear cookies."""
    jwt_data = get_jwt()
    if jwt_data:
        jti = jwt_data.get('jti')
        exp = datetime.fromtimestamp(jwt_data.get('exp', 0), tz=timezone.utc)
        add_token_to_blocklist(jti, exp)

    resp = make_response(redirect(url_for('auth.login')))
    unset_jwt_cookies(resp)
    return resp


# ── Rate-limit error handler ───────────────────────────────────────────────────
@auth.errorhandler(429)
def rate_limit_hit(e):
    flash('Too many attempts. Please wait a moment and try again.', 'error')
    return render_template('login.html'), 429