import os
import re
import subprocess

import bpy

from vse_toolbox import bl_utils


def launch_split(movie_strip, threshold, frame_start=None, frame_end=None):
    """Launch ffmpeg command to detect changing frames from a movie strip.

    Args:
        movie_strip (bpy.types.Sequence): blender sequence strip to detect changes.
        threshold (float): value of the detection factor (from 0 to 1).
        frame_start (int, optional): first frame to detect.
            Defaults to None.
        frame_end (int, optional): last frame to detect.
            Defaults to None.

    Returns:
        str: ffmpeg command log.
    """

    path = bl_utils.abspath(movie_strip.filepath)
    fps = bpy.context.scene.render.fps

    if frame_start is None:
        frame_start = 0
    if frame_end is None:
        frame_end = movie_strip.frame_duration

    frame_start = frame_start - movie_strip.frame_start

    #frame_start += movie_strip.frame_offset_start
    #frame_end -= movie_strip.frame_offset_end

    # Launch ffmpeg command to split
    ffmpeg_cmd = get_command(str(path), threshold, frame_start, frame_end, fps)

    print(ffmpeg_cmd)
    process = subprocess.Popen(
        ffmpeg_cmd,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        universal_newlines=True)

    return process


def get_command(path, threshold, frame_start, frame_end, fps):
    """Generate the ffmpeg command which detect change from a movie. 

    Args:
        path (_type_): path to detect changes.
        threshold (_type_): value of the detection factor (from 0 to 1).
        frame_start (_type_): first frame to detect.
        frame_end (_type_): last frame to detect.
        fps (_type_): framerate of the movie.

    Returns:
        list: ffmpeg command as list for subprocess module.
    """

    start_time = frame_start/fps
    end_time = frame_end/fps

    return [
            'ffmpeg',
            '-i',
            str(path),
            '-vf',
            f"trim=start={start_time}:end={end_time}, select='gt(scene, {threshold})',showinfo",
            '-f',
            'null',
            '-'
            ]


def get_split_time(log, as_frame=True, fps=None):
    """Parse ffmpeg command lines to detect the timecode

    Args:
        log (str): log to parse.
        as_frame (bool, optional): if wanted the timecode as frame number.
            Defaults to True.
        fps (_type_, optional): framerate of the movie (mandatory if as_frame used).
            Defaults to None.

    Returns:
        _type_: _description_
    """
    timecodes = re.findall(r'pts_time:([\d.]+)', log)

    if not timecodes:
        return

    timecode = timecodes[0]

    if as_frame:
        # convert timecode to frame number
        return round(float(timecode) * fps)

    return timecode