import cv2
import numpy as np


def write_video(file_path, frames, fps, reversed=True, start_frame_dupe_amount=15, last_frame_dupe_amount=30):
    """
    Writes frames to an mp4 video file
    :param file_path: Path to output video, must end with .mp4
    :param frames: List of PIL.Image objects
    :param fps: Desired frame rate
    :param reversed: if order of images to be reversed (default = True)
    """
    if reversed == True:
        frames.reverse()

    w, h = frames[0].size
    fourcc = cv2.VideoWriter_fourcc('m', 'p', '4', 'v')
    # fourcc = cv2.VideoWriter_fourcc('h', '2', '6', '4')
    # fourcc = cv2.VideoWriter_fourcc(*'avc1')
    writer = cv2.VideoWriter(file_path, fourcc, fps, (w, h))

# start frame duplicated
    for x in range(start_frame_dupe_amount):
        np_frame = np.array(frames[0].convert('RGB'))
        cv_frame = cv2.cvtColor(np_frame, cv2.COLOR_RGB2BGR)
        writer.write(cv_frame)

    for frame in frames:
        np_frame = np.array(frame.convert('RGB'))
        cv_frame = cv2.cvtColor(np_frame, cv2.COLOR_RGB2BGR)
        writer.write(cv_frame)

# last frame duplicated
    for x in range(last_frame_dupe_amount):
        np_frame = np.array(frames[len(frames) - 1].convert('RGB'))
        cv_frame = cv2.cvtColor(np_frame, cv2.COLOR_RGB2BGR)
        writer.write(cv_frame)

    writer.release()