#!/usr/bin/env python3
"""
Auth-related Flask routes (login, logout, change-password, etc).

The Blueprint expects ``auth_manager`` (an instance of
``auth_manager.AuthManager``) to be assigned at module level by app.py
after instantiation. A ``require_auth(role=None)`` decorator is also
exported so individual routes can opt-in to specific role requirements.
"""

import secrets
from functools import wraps

from flask import Blueprint, request, jsonify, session


# Set by app.py after AuthManager is constructed.
auth_manager = None  # type: ignore

auth_bp = Blueprint('auth', __name__, url_prefix='/api/auth')


def require_auth(role=None):
    """Decorator that enforces session authentication and an optional role."""
    def deco(fn):
        @wraps(fn)
        def wrapper(*args, **kwargs):
            username = session.get('username')
            if not username:
                return jsonify({'error': 'Not authenticated'}), 401
            if role == 'admin' and session.get('role') != 'admin':
                return jsonify({'error': 'Forbidden'}), 403
            if role == 'peer' and session.get('role') != 'peer':
                return jsonify({'error': 'Forbidden'}), 403
            request.auth_user = {
                'username': username,
                'role': session.get('role'),
                'peer_name': session.get('peer_name'),
            }
            return fn(*args, **kwargs)
        return wrapper
    return deco


@auth_bp.route('/login', methods=['POST'])
def login():
    if auth_manager is None:
        return jsonify({'error': 'Auth not initialised'}), 500
    data = request.get_json(silent=True) or {}
    username = (data.get('username') or '').strip()
    password = data.get('password') or ''
    if not username or not password:
        return jsonify({'error': 'username and password required'}), 400

    # Detect lockout up-front so we can return 423 instead of generic 401.
    pre = auth_manager.get_user(username)
    if pre and pre.get('locked_until'):
        try:
            from datetime import datetime
            until = datetime.strptime(pre['locked_until'], '%Y-%m-%dT%H:%M:%SZ')
            if datetime.utcnow() < until:
                return jsonify({'error': 'Account locked', 'locked_until': pre['locked_until']}), 423
        except Exception:
            pass

    user = auth_manager.verify_password(username, password)
    if not user:
        # Re-check lockout after the attempt (this attempt may have triggered it).
        post = auth_manager.get_user(username)
        if post and post.get('locked_until'):
            try:
                from datetime import datetime
                until = datetime.strptime(post['locked_until'], '%Y-%m-%dT%H:%M:%SZ')
                if datetime.utcnow() < until:
                    return jsonify({'error': 'Account locked', 'locked_until': post['locked_until']}), 423
            except Exception:
                pass
        return jsonify({'error': 'Invalid credentials'}), 401

    session.permanent = True
    session['username'] = user['username']
    session['role'] = user.get('role')
    session['peer_name'] = user.get('peer_name')
    session['csrf_token'] = secrets.token_hex(32)
    return jsonify({
        'username': user['username'],
        'role': user.get('role'),
        'peer_name': user.get('peer_name'),
        'must_change_password': bool(user.get('must_change_password', False)),
        'csrf_token': session['csrf_token'],
    })


@auth_bp.route('/logout', methods=['POST'])
def logout():
    session.clear()
    return jsonify({'ok': True})


@auth_bp.route('/me', methods=['GET'])
def me():
    username = session.get('username')
    if not username:
        return jsonify({'error': 'Not authenticated'}), 401
    return jsonify({
        'username': username,
        'role': session.get('role'),
        'peer_name': session.get('peer_name'),
    })


@auth_bp.route('/change-password', methods=['POST'])
@require_auth()
def change_password():
    if auth_manager is None:
        return jsonify({'error': 'Auth not initialised'}), 500
    data = request.get_json(silent=True) or {}
    old_pw = data.get('old_password') or ''
    new_pw = data.get('new_password') or ''
    if not old_pw or not new_pw:
        return jsonify({'error': 'old_password and new_password required'}), 400
    if len(new_pw) < 10:
        return jsonify({'error': 'new_password must be at least 10 characters'}), 400
    username = session.get('username')
    ok = auth_manager.change_password(username, old_pw, new_pw)
    if not ok:
        return jsonify({'error': 'Password change failed'}), 400
    return jsonify({'ok': True})


@auth_bp.route('/admin/reset-password', methods=['POST'])
@require_auth('admin')
def admin_reset_password():
    if auth_manager is None:
        return jsonify({'error': 'Auth not initialised'}), 500
    data = request.get_json(silent=True) or {}
    username = (data.get('username') or '').strip()
    new_pw = data.get('new_password') or ''
    if not username or not new_pw:
        return jsonify({'error': 'username and new_password required'}), 400
    if len(new_pw) < 10:
        return jsonify({'error': 'new_password must be at least 10 characters'}), 400
    ok = auth_manager.set_password_admin(username, new_pw)
    if not ok:
        return jsonify({'error': 'Reset failed (user not found?)'}), 400
    return jsonify({'ok': True})


@auth_bp.route('/csrf-token', methods=['GET'])
def get_csrf_token():
    """Return the current session's CSRF token, generating one if absent."""
    token = session.get('csrf_token')
    if not token:
        token = secrets.token_hex(32)
        session['csrf_token'] = token
    return jsonify({'csrf_token': token})


@auth_bp.route('/users', methods=['GET'])
@require_auth('admin')
def list_users():
    if auth_manager is None:
        return jsonify({'error': 'Auth not initialised'}), 500
    return jsonify(auth_manager.list_users())