import re
from datetime import timedelta
from functools import wraps

import humanize
from flask import current_app, jsonify, request

from .models import User


def is_admin(user_id):
    user = User.query.filter_by(id=user_id).first()
    return user.admin


def is_valid_email(email):
    mail_pattern = r"(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)"
    return re.match(mail_pattern, email) is not None


def check_passwords(password, password_conf):
    ret = ''
    if password_conf != password:
        ret = 'Password and password confirmation don\'t match.\n'
    if len(password) < 8:
        ret += 'Password: 8 characters required.\n'
    return ret


def register_controls(username, email, password, password_conf):
    ret = ''
    if not 2 < len(username) < 13:
        ret += 'Username: 3 to 12 characters required.\n'
    if not is_valid_email(email):
        ret += 'Valid email must be provided.\n'
    ret += check_passwords(password, password_conf)
    return ret


def verify_extension_and_size(file_type, req):
    response_object = {'status': 'success'}
    code = 400

    if 'file' not in req.files:
        response_object = {'status': 'fail', 'message': 'No file part.'}
        return response_object, code

    file = req.files['file']
    if file.filename == '':
        response_object = {'status': 'fail', 'message': 'No selected file.'}
        return response_object, code

    allowed_extensions = (
        'ACTIVITY_ALLOWED_EXTENSIONS'
        if file_type == 'activity'
        else 'PICTURE_ALLOWED_EXTENSIONS'
    )

    file_extension = (
        file.filename.rsplit('.', 1)[1].lower()
        if '.' in file.filename
        else None
    )
    max_file_size = current_app.config['max_single_file_size']

    if not (
        file_extension
        and file_extension in current_app.config.get(allowed_extensions)
    ):
        response_object = {
            'status': 'fail',
            'message': 'File extension not allowed.',
        }
    elif file_extension != 'zip' and req.content_length > max_file_size:
        response_object = {
            'status': 'fail',
            'message': 'Error during picture update, file size exceeds '
            f'{display_readable_file_size(max_file_size)}.',
        }
        code = 413

    return response_object, code


def verify_user(current_request, verify_admin):
    response_object = {
        'status': 'error',
        'message': 'Something went wrong. Please contact us.',
    }
    code = 401
    auth_header = current_request.headers.get('Authorization')
    if not auth_header:
        response_object['message'] = 'Provide a valid auth token.'
        return response_object, code, None
    auth_token = auth_header.split(" ")[1]
    resp = User.decode_auth_token(auth_token)
    if isinstance(resp, str):
        response_object['message'] = resp
        return response_object, code, None
    user = User.query.filter_by(id=resp).first()
    if not user:
        return response_object, code, None
    if verify_admin and not is_admin(resp):
        response_object['message'] = 'You do not have permissions.'
        return response_object, 403, None
    return None, None, resp


def authenticate(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        verify_admin = False
        response_object, code, resp = verify_user(request, verify_admin)
        if response_object:
            return jsonify(response_object), code
        return f(resp, *args, **kwargs)

    return decorated_function


def authenticate_as_admin(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        verify_admin = True
        response_object, code, resp = verify_user(request, verify_admin)
        if response_object:
            return jsonify(response_object), code
        return f(resp, *args, **kwargs)

    return decorated_function


def can_view_activity(auth_user_id, activity_user_id):
    if auth_user_id != activity_user_id:
        response_object = {
            'status': 'error',
            'message': 'You do not have permissions.',
        }
        return response_object, 403
    return None, None


def display_readable_file_size(size_in_bytes):
    if size_in_bytes == 0:
        return '0 bytes'
    if size_in_bytes == 1:
        return '1 byte'
    for unit in [' bytes', 'KB', 'MB', 'GB', 'TB']:
        if abs(size_in_bytes) < 1024.0:
            return f"{size_in_bytes:3.1f}{unit}"
        size_in_bytes /= 1024.0
    return f"{size_in_bytes} bytes"


def get_readable_duration(duration, locale='en'):
    if locale is not None and locale != 'en':
        _t = humanize.i18n.activate(locale)  # noqa
    readable_duration = humanize.naturaldelta(timedelta(seconds=duration))
    if locale is not None and locale != 'en':
        humanize.i18n.deactivate()
    return readable_duration