#!/usr/bin/env python3

# SàT: an XMPP client
# Copyright (C) 2009-2020 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""Methods to manipulate images"""

import tempfile
import mimetypes
from PIL import Image
from pathlib import Path
from twisted.internet import threads


def check(host, path, max_size=None):
    """Analyze image and return a report

    report will indicate if image is too large, and the recommended new size if this is
    the case
    @param host: SàT instance
    @param path(str, pathlib.Path): image to open
    @param max_size(tuple[int, int]): maximum accepted size of image
        None to use value set in config
    @return dict: report on image, with following keys:
        - too_large: true if image is oversized
        - recommended_size: if too_large is True, recommended size to use
    """
    report = {}
    image = Image.open(path)
    if max_size is None:
        max_size = tuple(host.memory.getConfig(None, "image_max", (1200, 720)))
    if image.size > max_size:
        report['too_large'] = True
        if image.size[0] > max_size[0]:
            factor = max_size[0] / image.size[0]
            if image.size[1] * factor > max_size[1]:
                factor = max_size[1] / image.size[1]
        else:
            factor = max_size[1] / image.size[1]
        report['recommended_size'] = [int(image.width*factor), int(image.height*factor)]
    else:
        report['too_large'] = False

    return report


def _resizeBlocking(image_path, new_size, dest=None):
    im_path = Path(image_path)
    im = Image.open(im_path)
    resized = im.resize(new_size, Image.LANCZOS)

    if dest is None:
        dest = tempfile.NamedTemporaryFile(suffix=im_path.suffix, delete=False)
    elif isinstance(dest, Path):
        dest = dest.open('wb')

    with dest as f:
        resized.save(f, format=im.format)

    return Path(f.name)


def resize(image_path, new_size, dest=None):
    """Resize an image to a new file, and return its path

    @param image_path(str, Path): path of the original image
    @param new_size(tuple[int, int]): size to use for new image
    @param dest(None, Path, file): where the resized image must be stored, can be:
        - None: use a temporary file
        - Path: path to the file to create/overwrite
        - file: a file object which must be opened for writing in binary mode
    @return (Path): path of the resized file.
        The image at this path should be deleted after use
    """
    return threads.deferToThread(_resizeBlocking, image_path, new_size, dest)


def guess_type(source):
    """Guess image media type

    @param source(str, Path, file): image to guess type
    @return (str, None): media type, or None if we can't guess
    """
    if isinstance(source, str):
        source = Path(source)

    if isinstance(source, Path):
        # we first try to guess from file name
        media_type = mimetypes.guess_type(source, strict=False)[0]
        if media_type is not None:
            return media_type

    # file name is not enough, we try to open it
    img = Image.open(source)
    try:
        return Image.MIME[img.format]
    except KeyError:
        return None