import tensorflow as tf
import numpy as np
from einops import rearrange
from decord import VideoReader

num_frames = 16
input_size = 224
patch_size = (16, 16)
IMAGENET_MEAN = np.array([0.485, 0.456, 0.406])
IMAGENET_STD = np.array([0.229, 0.224, 0.225])

def format_frames(frame, output_size):
    frame = tf.image.convert_image_dtype(frame, tf.uint8)
    frame = tf.image.resize(frame, size=output_size)
    frame = frame / 255.
    frame = frame - IMAGENET_MEAN
    frame = frame / IMAGENET_STD
    return frame

def read_video(file_path):
    container = VideoReader(file_path)
    return container

def frame_sampling(container, num_frames):
    interval = len(container) // num_frames
    bids = np.arange(num_frames) * interval
    offset = np.random.randint(interval, size=bids.shape)
    frame_index = bids + offset
    frames = container.get_batch(frame_index).asnumpy()
    frames = np.stack(frames)
    frames = format_frames(frames, [input_size] * 2)
    return frames

def denormalize(z):
    mean = np.array([0.485, 0.456, 0.406])
    std = np.array([0.225, 0.225, 0.225])
    x = (z * std) + mean
    x = x * 255
    return x.clip(0, 255)