# -*- coding: utf-8 -*-

from __future__ import unicode_literals, absolute_import

import logging

import mimetypes

import kitchen.text.converters as ktc

import six

import pagure.lib.encoding_utils

_log = logging.getLogger(__name__)

def guess_type(filename, data):

    """

    Guess the type of a file based on its filename and data.

    Return value is a tuple (type, encoding) where type or encoding is None

    if it can't be guessed.

    :param filename: file name string

    :param data: file data string

    """

    mimetype = None

    encoding = None

    if filename:

        mimetype, encoding = mimetypes.guess_type(filename)

    if data:

        if not mimetype:

            if not isinstance(data, six.text_type) and b"\0" in data:

                mimetype = "application/octet-stream"

            else:

                mimetype = "text/plain"

        if mimetype.startswith("text/") and not encoding:

            try:

                encoding = pagure.lib.encoding_utils.guess_encoding(

                    ktc.to_bytes(data)

                )

            except pagure.exceptions.PagureException:  # pragma: no cover

                # We cannot decode the file, so bail but warn the admins

                _log.exception("File could not be decoded")

    return mimetype, encoding

def get_type_headers(filename, data):

    """

    Get the HTTP headers used for downloading or previewing the file.

    If the file is html, it will return headers which make browser start

    downloading.

    :param filename: file name string

    :param data: file data string

    """

    mimetype, encoding = guess_type(filename, data)

    if not mimetype:

        return None

    headers = {str("X-Content-Type-Options"): "nosniff"}

    if "html" in mimetype or "javascript" in mimetype or "svg" in mimetype:

        mimetype = "application/octet-stream"

        headers[str("Content-Disposition")] = "attachment"

    if encoding:

        mimetype += "; charset={encoding}".format(encoding=encoding)

    headers[str("Content-Type")] = mimetype

    return headers