import re
import time

from flask import Blueprint, request, jsonify, g
from app import db, limiter
from app.models.user import User
from app.models.audit_log import AuditLog
from app.services.auth_service import (
    hash_auth_token,
    verify_auth_token,
    generate_tokens,
    generate_mfa_token,
    decode_token,
    blacklist_token,
    require_jwt,
    encrypt_totp_secret,
    decrypt_totp_secret,
)

auth_bp = Blueprint('auth', __name__)

EMAIL_RE = re.compile(r'^[^@\s]+@[^@\s]+\.[^@\s]+$')


def _client_ip():
    """Return the best-effort client IP from the request context."""
    return request.headers.get('X-Forwarded-For', request.remote_addr or '').split(',')[0].strip()


@auth_bp.route('/register', methods=['POST'])
@limiter.limit('10 per minute')
def register():
    data = request.get_json(silent=True) or {}
    email = (data.get('email') or '').strip().lower()
    auth_hash = data.get('auth_hash', '')
    enc_key_salt = data.get('enc_key_salt', '')

    if not email or not EMAIL_RE.match(email):
        return jsonify({'error': 'Invalid email address'}), 400
    if not auth_hash:
        return jsonify({'error': 'auth_hash is required'}), 400
    if not enc_key_salt:
        return jsonify({'error': 'enc_key_salt is required'}), 400

    if User.query.filter_by(email=email).first():
        return jsonify({'error': 'Email already registered'}), 409

    master_hash = hash_auth_token(auth_hash)
    user = User(email=email, master_hash=master_hash, enc_key_salt=enc_key_salt)
    db.session.add(user)
    db.session.flush()  # populate user.id before logging

    AuditLog.log(
        user_id=user.id,
        action='auth.register',
        resource_type='user',
        resource_id=user.id,
        detail=f'New account registered: {email}',
        ip_address=_client_ip(),
    )
    db.session.commit()

    return jsonify({'message': 'Account created successfully'}), 201


@auth_bp.route('/login', methods=['POST'])
@limiter.limit('10 per minute')
def login():
    data = request.get_json(silent=True) or {}
    email = (data.get('email') or '').strip().lower()
    auth_hash = data.get('auth_hash', '')

    time.sleep(0.1)  # mitigate timing-based user enumeration

    if not email or not auth_hash:
        return jsonify({'error': 'Email and auth_hash are required'}), 400

    user = User.query.filter_by(email=email).first()
    if not user or not verify_auth_token(auth_hash, user.master_hash):
        if user:
            AuditLog.log(
                user_id=user.id,
                action='auth.login_failed',
                resource_type='user',
                resource_id=user.id,
                detail='Failed login attempt — invalid password',
                ip_address=_client_ip(),
            )
            db.session.commit()
        return jsonify({'error': 'Invalid email or password'}), 401

    from datetime import datetime
    user.last_login = datetime.utcnow()

    AuditLog.log(
        user_id=user.id,
        action='auth.login',
        resource_type='user',
        resource_id=user.id,
        detail=f'Successful login{" (MFA pending)" if user.totp_enabled else ""}',
        ip_address=_client_ip(),
    )
    db.session.commit()

    # MFA gate: if enabled, issue a short-lived mfa_token instead of full tokens
    if user.totp_enabled:
        mfa_token = generate_mfa_token(user.id)
        return jsonify({
            'mfa_required': True,
            'mfa_token': mfa_token,
            'enc_key_salt': user.enc_key_salt,
        }), 200

    tokens = generate_tokens(user.id)
    return jsonify({
        'access_token': tokens['access_token'],
        'refresh_token': tokens['refresh_token'],
        'enc_key_salt': user.enc_key_salt,
    }), 200


@auth_bp.route('/logout', methods=['POST'])
def logout():
    """Blacklist both the access token (from header) and refresh token (from body)."""
    auth_header = request.headers.get('Authorization', '')
    if auth_header.startswith('Bearer '):
        blacklist_token(auth_header[7:], 'access')

    data = request.get_json(silent=True) or {}
    refresh_token = data.get('refresh_token', '')
    if refresh_token:
        blacklist_token(refresh_token, 'refresh')

    return jsonify({'message': 'Logged out'}), 200


@auth_bp.route('/refresh', methods=['POST'])
@limiter.limit('30 per minute')
def refresh():
    data = request.get_json(silent=True) or {}
    refresh_token = data.get('refresh_token', '')
    if not refresh_token:
        return jsonify({'error': 'refresh_token is required'}), 400

    try:
        payload = decode_token(refresh_token, expected_type='refresh')
    except Exception:
        return jsonify({'error': 'Invalid or expired refresh token'}), 401

    # Rotate: blacklist old refresh token and issue fresh pair
    blacklist_token(refresh_token, 'refresh')
    tokens = generate_tokens(int(payload['sub']))
    return jsonify({
        'access_token': tokens['access_token'],
        'refresh_token': tokens['refresh_token'],
    }), 200


# ── MFA / TOTP endpoints ─────────────────────────────────────────────────────

@auth_bp.route('/mfa/setup', methods=['GET'])
@require_jwt
def mfa_setup():
    """Generate a new TOTP secret and return QR code (as base64 PNG data URI)."""
    user = db.session.get(User, g.current_user_id)
    if user.totp_enabled:
        return jsonify({'error': 'MFA is already enabled'}), 400

    import pyotp
    import qrcode
    import io
    import base64

    secret = pyotp.random_base32()
    uri = pyotp.TOTP(secret).provisioning_uri(
        name=user.email,
        issuer_name='PassKeeper',
    )

    img = qrcode.make(uri)
    buf = io.BytesIO()
    img.save(buf, format='PNG')
    qr_b64 = base64.b64encode(buf.getvalue()).decode()

    return jsonify({
        'secret': secret,
        'qr_code': f'data:image/png;base64,{qr_b64}',
        'uri': uri,
    }), 200


@auth_bp.route('/mfa/enable', methods=['POST'])
@require_jwt
def mfa_enable():
    """Enable MFA after verifying the first TOTP code."""
    user = db.session.get(User, g.current_user_id)
    if user.totp_enabled:
        return jsonify({'error': 'MFA is already enabled'}), 400

    data = request.get_json(silent=True) or {}
    secret = (data.get('secret') or '').strip()
    totp_code = (data.get('totp_code') or '').strip()

    if not secret or not totp_code:
        return jsonify({'error': 'secret and totp_code are required'}), 400

    import pyotp
    if not pyotp.TOTP(secret).verify(totp_code, valid_window=1):
        return jsonify({'error': 'Invalid verification code'}), 400

    totp_secret_enc, totp_iv = encrypt_totp_secret(secret)
    user.totp_secret = totp_secret_enc
    user.totp_iv = totp_iv
    user.totp_enabled = True

    AuditLog.log(
        user_id=user.id,
        action='auth.mfa_enable',
        resource_type='user',
        resource_id=user.id,
        detail='TOTP two-factor authentication enabled',
        ip_address=_client_ip(),
    )
    db.session.commit()

    return jsonify({'message': 'MFA enabled successfully'}), 200


@auth_bp.route('/mfa/disable', methods=['POST'])
@require_jwt
def mfa_disable():
    """Disable MFA after verifying the current TOTP code."""
    user = db.session.get(User, g.current_user_id)
    if not user.totp_enabled:
        return jsonify({'error': 'MFA is not enabled'}), 400

    data = request.get_json(silent=True) or {}
    totp_code = (data.get('totp_code') or '').strip()

    import pyotp
    plaintext_secret = decrypt_totp_secret(user.totp_secret, user.totp_iv)
    if not pyotp.TOTP(plaintext_secret).verify(totp_code, valid_window=1):
        return jsonify({'error': 'Invalid verification code'}), 400

    user.totp_secret = None
    user.totp_iv = None
    user.totp_enabled = False

    AuditLog.log(
        user_id=user.id,
        action='auth.mfa_disable',
        resource_type='user',
        resource_id=user.id,
        detail='TOTP two-factor authentication disabled',
        ip_address=_client_ip(),
    )
    db.session.commit()

    return jsonify({'message': 'MFA disabled'}), 200


@auth_bp.route('/mfa/verify', methods=['POST'])
@limiter.limit('10 per minute')
def mfa_verify():
    """Complete MFA login: verify TOTP code and exchange mfa_token for real tokens."""
    data = request.get_json(silent=True) or {}
    mfa_token = data.get('mfa_token', '')
    totp_code = (data.get('totp_code') or '').strip()

    if not mfa_token or not totp_code:
        return jsonify({'error': 'mfa_token and totp_code are required'}), 400

    try:
        payload = decode_token(mfa_token, expected_type='mfa', check_blacklist=True)
    except Exception:
        return jsonify({'error': 'Invalid or expired MFA token'}), 401

    user = db.session.get(User, int(payload['sub']))
    if not user or not user.totp_enabled:
        return jsonify({'error': 'MFA not configured for this account'}), 400

    import pyotp
    plaintext_secret = decrypt_totp_secret(user.totp_secret, user.totp_iv)
    if not pyotp.TOTP(plaintext_secret).verify(totp_code, valid_window=1):
        return jsonify({'error': 'Invalid verification code'}), 400

    # One-time use: blacklist the mfa_token
    blacklist_token(mfa_token, 'mfa')

    AuditLog.log(
        user_id=user.id,
        action='auth.mfa_verify',
        resource_type='user',
        resource_id=user.id,
        detail='MFA verification successful — session tokens issued',
        ip_address=_client_ip(),
    )
    db.session.commit()

    tokens = generate_tokens(user.id)
    return jsonify({
        'access_token': tokens['access_token'],
        'refresh_token': tokens['refresh_token'],
    }), 200


@auth_bp.route('/mfa/status', methods=['GET'])
@require_jwt
def mfa_status():
    user = db.session.get(User, g.current_user_id)
    return jsonify({'totp_enabled': user.totp_enabled}), 200