#!/usr/bin/env python3

# Libervia: an XMPP client
# Copyright (C) 2009-2026 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 videos"""

from typing import Union
from pathlib import Path
from twisted.python.procutils import which
from libervia.backend.core.i18n import _
from libervia.backend.core import exceptions
from libervia.backend.core.log import getLogger
from .common import async_process

log = getLogger(__name__)

try:
    ffmpeg_path = which("ffmpeg")[0]
except IndexError:
    log.warning(_("ffmpeg executable not found, video thumbnails won't be available"))
    ffmpeg_path = None

try:
    ffprobe_path = which("ffprobe")[0]
except IndexError:
    log.warning(
        _("ffprobe executable not found, video thumbnails will use the first frame")
    )
    ffprobe_path = None


async def _get_duration(video_path: Path | str) -> float | None:
    """Get the duration of a video in seconds

    @return: duration in seconds, or None if ffprobe is unavailable or fails
    """
    if ffprobe_path is None:
        return None
    try:
        result = await async_process.run(
            ffprobe_path,
            "-v",
            "error",
            "-show_entries",
            "format=duration",
            "-of",
            "default=noprint_wrappers=1:nokey=1",
            str(video_path),
        )
    except exceptions.CommandException:
        return None
    try:
        return float(result)
    except ValueError:
        log.error(f"Can't parse ffprobe duration for {video_path}: {result!r}")
        return None


async def get_thumbnail(video_path: Union[Path, str], dest_path: Path) -> Path:
    """Extract thumbnail from video

    The frame is extracted at 25% of the video duration, falling back to the first frame
    if the duration is unknown or the extraction fails.

    @param video_path: source of the video
    @param dest_path: path where the file must be saved
    @return: path of the generated thumbnail
        image is created in temporary directory but is not delete automatically
        it should be deleted after use.
        Image will be in JPEG format.
    @raise exceptions.NotFound: ffmpeg is missing
    @raise exceptions.DataError: can't extract a frame from the video
    """
    if ffmpeg_path is None:
        raise exceptions.NotFound(
            _("ffmpeg executable is not available, can't generate video thumbnail")
        )
    ffmpeg = ffmpeg_path

    async def extract(seek_time: str) -> None:
        await async_process.run(
            ffmpeg,
            "-ss",
            seek_time,
            "-i",
            str(video_path),
            "-frames:v",
            "1",
            "-y",
            str(dest_path),
        )

    duration = await _get_duration(video_path)
    data_error = exceptions.DataError(
        _("Can't extract a frame from the video {video_path}").format(
            video_path=video_path
        )
    )
    seek_times = [f"{duration * 0.25:.2f}", "0"] if duration else ["0"]
    last_error = None
    for seek_time in seek_times:
        try:
            await extract(seek_time)
            break
        except exceptions.CommandException as e:
            last_error = e
    if not dest_path.exists() or dest_path.stat().st_size == 0:
        raise data_error from last_error
    return dest_path