import importlib
import os
import os.path as osp
import shutil
import sys
from pathlib import Path

import av
import numpy as np
import torch
import torchvision
from einops import rearrange
from PIL import Image


def seed_everything(seed):
    import random

    import numpy as np

    torch.manual_seed(seed)
    torch.cuda.manual_seed_all(seed)
    np.random.seed(seed % (2**32))
    random.seed(seed)


def import_filename(filename):
    spec = importlib.util.spec_from_file_location("mymodule", filename)
    module = importlib.util.module_from_spec(spec)
    sys.modules[spec.name] = module
    spec.loader.exec_module(module)
    return module


def delete_additional_ckpt(base_path, num_keep):
    dirs = []
    for d in os.listdir(base_path):
        if d.startswith("checkpoint-"):
            dirs.append(d)
    num_tot = len(dirs)
    if num_tot <= num_keep:
        return
    # ensure ckpt is sorted and delete the ealier!
    del_dirs = sorted(dirs, key=lambda x: int(x.split("-")[-1]))[: num_tot - num_keep]
    for d in del_dirs:
        path_to_dir = osp.join(base_path, d)
        if osp.exists(path_to_dir):
            shutil.rmtree(path_to_dir)


def save_videos_from_pil(pil_images, path, fps):

    save_fmt = Path(path).suffix
    os.makedirs(os.path.dirname(path), exist_ok=True)
    width, height = pil_images[0].size

    if save_fmt == ".mp4":
        codec = "libx264"
        container = av.open(path, "w")
        stream = container.add_stream(codec, rate=fps)

        stream.width = width
        stream.height = height
        stream.pix_fmt = 'yuv420p'
        stream.bit_rate = 10000000   
        stream.options["crf"] = "18"

        for pil_image in pil_images:
            # pil_image = Image.fromarray(image_arr).convert("RGB")
            av_frame = av.VideoFrame.from_image(pil_image)
            container.mux(stream.encode(av_frame))
        container.mux(stream.encode())
        container.close()

    elif save_fmt == ".gif":
        pil_images[0].save(
            fp=path,
            format="GIF",
            append_images=pil_images[1:],
            save_all=True,
            duration=(1 / fps * 1000),
            loop=0,
        )
    else:
        raise ValueError("Unsupported file type. Use .mp4 or .gif.")


def save_videos_grid(videos: torch.Tensor, path: str, rescale=False, n_rows=6, fps=8):
    videos = rearrange(videos, "b c t h w -> t b c h w")
    height, width = videos.shape[-2:]
    outputs = []

    for x in videos:
        x = torchvision.utils.make_grid(x, nrow=n_rows)  # (c h w)
        x = x.transpose(0, 1).transpose(1, 2).squeeze(-1)  # (h w c)
        if rescale:
            x = (x + 1.0) / 2.0  # -1,1 -> 0,1
        x = (x * 255).numpy().astype(np.uint8)
        x = Image.fromarray(x)

        outputs.append(x)

    os.makedirs(os.path.dirname(path), exist_ok=True)

    save_videos_from_pil(outputs, path, fps)


def read_frames(video_path):
    container = av.open(video_path)

    video_stream = next(s for s in container.streams if s.type == "video")
    frames = []
    for packet in container.demux(video_stream):
        for frame in packet.decode():
            image = Image.frombytes(
                "RGB",
                (frame.width, frame.height),
                frame.to_rgb().to_ndarray(),
            )
            frames.append(image)

    return frames


def get_fps(video_path):
    container = av.open(video_path)
    video_stream = next(s for s in container.streams if s.type == "video")
    fps = video_stream.average_rate
    container.close()
    return fps