#  Tencent is pleased to support the open source community by making GNES available.
#
#  Copyright (C) 2019 THL A29 Limited, a Tencent company. All rights reserved.
#  Licensed under the Apache License, Version 2.0 (the 'License');
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#  http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an 'AS IS' BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

import io
import numpy as np

from typing import List

from .ffmpeg import get_media_meta, compile_args
from .helper import _check_input, run_command, run_command_async


def scale_video(input_fn: str = 'pipe:',
                output_fn: str = 'pipe:',
                input_data: bytes = None,
                start_time: float = None,
                end_time: float = None,
                scale: str = None,
                frame_rate: int = 15,
                crf: int = 16,
                vcodec: str = 'libx264',
                format: str = 'mp4',
                pix_fmt: str = 'yuv420p',
                **kwargs):

    _check_input(input_fn, input_data)

    capture_stdout = (output_fn == 'pipe:')

    input_kwargs = {}
    if start_time is not None:
        input_kwargs['ss'] = start_time
    else:
        start_time = 0.
    if end_time is not None:
        input_kwargs['t'] = end_time - start_time

    out_kwargs = {
        'vcodec': vcodec,
        'pix_fmt': pix_fmt,
        'crf': crf,
        'framerate': frame_rate,
        'acodec': 'aac',
        'strict': 'experimental',  # AAC audio encoder is experimental
    }

    if scale:
        out_kwargs['s'] = scale

    if capture_stdout:
        out_kwargs['format'] = format
        # an empty moov means it doesn't need to seek and thus works with a pipe.
        out_kwargs['movflags'] = 'frag_keyframe+empty_moov'

    cmd_args = compile_args(
        input_fn=input_fn,
        output_fn=output_fn,
        input_options=input_kwargs,
        output_options=out_kwargs,
        overwrite_output=True)
    stdout, _ = run_command(
        cmd_args, input=input_data, pipe_stdout=True, pipe_stderr=True)

    if capture_stdout:
        return stdout
    return None


def encode_video(images: 'np.ndarray',
                 pix_fmt: str = 'rgb24',
                 frame_rate: int = 15,
                 output_fn: str = 'pipe:',
                 vcodec: str = 'libx264',
                 format: str = 'mp4',
                 **kwargs):
    packet_size = 4096

    n = len(images)
    height, width, channels = images[0].shape

    capture_stdout = (output_fn == 'pipe:')

    input_kwargs = {
        'format': 'rawvideo',
        'pix_fmt': pix_fmt,
        'framerate': frame_rate,
        's': '{}x{}'.format(width, height),
    }

    output_kwargs = {
        'vcodec': vcodec,
        'r': frame_rate,
        'pix_fmt': 'yuv420p',
        'format': format,
        'movflags': 'frag_keyframe+empty_moov',
    }

    cmd_args = compile_args(
        input_fn='pipe:',
        output_fn=output_fn,
        input_options=input_kwargs,
        output_options=output_kwargs)

    with run_command_async(
            cmd_args,
            pipe_stdin=True,
            pipe_stdout=capture_stdout,
            pipe_stderr=True) as proc:

        input_stream = io.BytesIO(b'')
        for frame in images:
            input_stream.write(frame.astype(np.uint8).tobytes())

        output, err = proc.communicate(input_stream.getvalue())

        if proc.returncode:
            err = '\n'.join([' '.join(cmd_args), err.decode('utf8')])
            raise IOError(err)

        return output


def capture_frames(input_fn: str = 'pipe:',
                   input_data: bytes = None,
                   pix_fmt: str = 'rgb24',
                   fps: int = -1,
                   scale: str = None,
                   start_time: float = None,
                   end_time: float = None,
                   **kwargs) -> List['np.ndarray']:
    _check_input(input_fn, input_data)

    video_meta = get_media_meta(input_fn=input_fn, input_data=input_data)
    width = video_meta['frame_width']
    height = video_meta['frame_height']

    if scale is not None:
        _width, _height = map(int, scale.split(':'))
        if _width * _height < 0:
            if _width > 0:
                ratio = _width / width
                height = int(ratio * height)
                if _height == -2:
                    height += height % 2
                width = _width
            else:
                ratio = _height / height
                width = int(ratio * width)
                if _width == -2:
                    width += width % 2

                height = _height

            scale = '%d:%d' % (width, height)
        else:
            width = _width
            height = _height

    input_kwargs = {
        'err_detect': 'aggressive',
        'fflags': 'discardcorrupt'    # discard corrupted frames
    }
    if start_time is not None:
        input_kwargs['ss'] = str(start_time)
    else:
        start_time = 0.
    if end_time is not None:
        input_kwargs['t'] = str(end_time - start_time)

    video_filters = []
    if fps:
        video_filters += ['fps=%d' % fps]
    if scale:
        video_filters += ['scale=%s' % scale]

    output_kwargs = {
        'format': 'image2pipe',
        'pix_fmt': pix_fmt,
        'vcodec': 'rawvideo'
    }

    cmd_args = compile_args(
        input_fn=input_fn,
        input_options=input_kwargs,
        video_filters=video_filters,
        output_options=output_kwargs)

    out, _ = run_command(
        cmd_args, input=input_data, pipe_stdout=True, pipe_stderr=True)

    depth = 3
    if pix_fmt == 'rgba':
        depth = 4

    frames = np.frombuffer(out, np.uint8).reshape([-1, height, width, depth])
    return frames


# def read_frame_as_jpg(in_filename, frame_num):
#     out, err = (
#         ffmpeg
#         .input(in_filename)
#         .filter_('select', 'gte(n,{})'.format(frame_num))
#         .output('pipe:', vframes=1, format='image2', vcodec='mjpeg')
#         .run(capture_stdout=True)
#     )
#     return out
