import os
import re
import subprocess

import bpy

from vse_toolbox import bl_utils


def detect_scene_change(strip, movie_type="ANIMATED", threshold=0.5, frame_start=None, frame_end=None, crop=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(strip.filepath)
    fps = bpy.context.scene.render.fps

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

    frame_start = frame_start - strip.frame_start

    start_time = frame_start/fps
    end_time = frame_end/fps

    #frame_start += strip.frame_offset_start
    #frame_end -= strip.frame_offset_end
    
    if movie_type == 'ANIMATED':
        return select_generator(path, start_time=start_time, end_time=end_time, threshold=threshold, crop=crop)
    
    elif movie_type == 'STILL':
        return freeze_detect_generator(path, start_time=start_time, end_time=end_time, threshold=threshold, crop=crop)
    
    else:
        raise Exception(f'movie_type: {movie_type} not implemented')


def freeze_detect_generator(path, start_time, end_time, threshold=0.005, crop=None):
    """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.
    """

    if crop is None:
        crop = [0, 0, 0, 0]

    crop_expr = f"crop=iw-{crop[0]}-{crop[1]}:ih-{crop[2]}-{crop[3]}:{crop[0]}:{crop[-1]}"

    command = [
            'ffmpeg',
            '-nostats',
            '-i',
            str(path),
            '-ss', str(start_time),
            '-t', str(end_time),
            '-vf',
            f"{crop_expr}, freezedetect=n={threshold}:d=0.01,metadata=print", #,
            '-f',
            'null',
            '-'
            ]
    
    print(command)

    process = subprocess.Popen(
        command,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        universal_newlines=True)
    
    def parse_split_time(log):
        print(log)
        timecodes = re.findall(r'freeze_end: ([\d.]+)', log)
        if timecodes:
            return round(float(timecodes[0]) * bpy.context.scene.render.fps)

    return filter(None, (parse_split_time(x) for x in process.stdout))

def select_generator(path, start_time, end_time, threshold, crop=None):
    """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.
    """

    if crop is None:
        crop = [0, 0, 0, 0]

    crop_expr = f"crop=iw-{crop[0]}-{crop[1]}:ih-{crop[2]}-{crop[3]}:{crop[0]}:{crop[-1]}"

    command = [
            'ffmpeg',
            '-nostats',
            '-i',
            str(path),
            '-ss', str(start_time),
            '-t', str(end_time),
            '-vf',
            f"{crop_expr}, select='gt(scene, {threshold})', showinfo",
            '-f',
            'null',
            '-'
            ]

    print(command)

    process = subprocess.Popen(
        command,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        universal_newlines=True)
        
    def parse_split_time(log):
        print(log)
        timecodes = re.findall(r'pts_time:([\d.]+)', log)
        if timecodes:
            return round(float(timecodes[0]) * bpy.context.scene.render.fps)

    return filter(None, (parse_split_time(x) for x in process.stdout))