# Copyright (c) 2024 Bytedance Ltd. and/or its affiliates
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import os
import imageio
import numpy as np
import json
from typing import Union
import matplotlib.pyplot as plt

import torch
import torch.nn as nn
import torch.nn.functional as F
import torchvision
import torch.distributed as dist
from torchvision import transforms

from tqdm import tqdm
from einops import rearrange
import cv2
from decord import AudioReader, VideoReader
import shutil
import subprocess


# Machine epsilon for a float32 (single precision)
eps = np.finfo(np.float32).eps


def read_json(filepath: str):
    with open(filepath) as f:
        json_dict = json.load(f)
    return json_dict


def read_video(video_path: str, change_fps=True, use_decord=True):
    if change_fps:
        temp_dir = "temp"
        if os.path.exists(temp_dir):
            shutil.rmtree(temp_dir)
        os.makedirs(temp_dir, exist_ok=True)
        command = (
            f"ffmpeg -loglevel error -y -nostdin -i {video_path} -r 25 -crf 18 {os.path.join(temp_dir, 'video.mp4')}"
        )
        subprocess.run(command, shell=True)
        target_video_path = os.path.join(temp_dir, "video.mp4")
    else:
        target_video_path = video_path

    if use_decord:
        return read_video_decord(target_video_path)
    else:
        return read_video_cv2(target_video_path)


def read_video_decord(video_path: str):
    vr = VideoReader(video_path)
    video_frames = vr[:].asnumpy()
    vr.seek(0)
    return video_frames


def read_video_cv2(video_path: str):
    # Open the video file
    cap = cv2.VideoCapture(video_path)

    # Check if the video was opened successfully
    if not cap.isOpened():
        print("Error: Could not open video.")
        return np.array([])

    frames = []

    while True:
        # Read a frame
        ret, frame = cap.read()

        # If frame is read correctly ret is True
        if not ret:
            break

        # Convert BGR to RGB
        frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)

        frames.append(frame_rgb)

    # Release the video capture object
    cap.release()

    return np.array(frames)


def read_audio(audio_path: str, audio_sample_rate: int = 16000):
    if audio_path is None:
        raise ValueError("Audio path is required.")
    ar = AudioReader(audio_path, sample_rate=audio_sample_rate, mono=True)

    # To access the audio samples
    audio_samples = torch.from_numpy(ar[:].asnumpy())
    audio_samples = audio_samples.squeeze(0)

    return audio_samples


def write_video(video_output_path: str, video_frames: np.ndarray, fps: int):
    height, width = video_frames[0].shape[:2]
    out = cv2.VideoWriter(video_output_path, cv2.VideoWriter_fourcc(*"mp4v"), fps, (width, height))
    # out = cv2.VideoWriter(video_output_path, cv2.VideoWriter_fourcc(*"vp09"), fps, (width, height))
    for frame in video_frames:
        frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR)
        out.write(frame)
    out.release()


def init_dist(backend="nccl", **kwargs):
    """Initializes distributed environment."""
    rank = int(os.environ["RANK"])
    num_gpus = torch.cuda.device_count()
    if num_gpus == 0:
        raise RuntimeError("No GPUs available for training.")
    local_rank = rank % num_gpus
    torch.cuda.set_device(local_rank)
    dist.init_process_group(backend=backend, **kwargs)

    return local_rank


def zero_rank_print(s):
    if dist.is_initialized() and dist.get_rank() == 0:
        print("### " + s)


def zero_rank_log(logger, message: str):
    if dist.is_initialized() and dist.get_rank() == 0:
        logger.info(message)


def make_audio_window(audio_embeddings: torch.Tensor, window_size: int):
    audio_window = []
    end_idx = audio_embeddings.shape[1] - window_size + 1
    for i in range(end_idx):
        audio_window.append(audio_embeddings[:, i : i + window_size, :])
    audio_window = torch.stack(audio_window)
    audio_window = rearrange(audio_window, "f b w d -> b f w d")
    return audio_window


def check_video_fps(video_path: str):
    cam = cv2.VideoCapture(video_path)
    fps = cam.get(cv2.CAP_PROP_FPS)
    if fps != 25:
        raise ValueError(f"Video FPS is not 25, it is {fps}. Please convert the video to 25 FPS.")


def tailor_tensor_to_length(tensor: torch.Tensor, length: int):
    if len(tensor) == length:
        return tensor
    elif len(tensor) > length:
        return tensor[:length]
    else:
        return torch.cat([tensor, tensor[-1].repeat(length - len(tensor))])


def save_videos_grid(videos: torch.Tensor, path: str, rescale=False, n_rows=6, fps=8):
    videos = rearrange(videos, "b c f h w -> f b c h w")
    outputs = []
    for x in videos:
        x = torchvision.utils.make_grid(x, nrow=n_rows)
        x = x.transpose(0, 1).transpose(1, 2).squeeze(-1)
        if rescale:
            x = (x + 1.0) / 2.0  # -1,1 -> 0,1
        x = (x * 255).numpy().astype(np.uint8)
        outputs.append(x)

    os.makedirs(os.path.dirname(path), exist_ok=True)
    imageio.mimsave(path, outputs, fps=fps)


def interpolate_features(features: torch.Tensor, output_len: int) -> torch.Tensor:
    features = features.cpu().numpy()
    input_len, num_features = features.shape

    input_timesteps = np.linspace(0, 10, input_len)
    output_timesteps = np.linspace(0, 10, output_len)
    output_features = np.zeros((output_len, num_features))
    for feat in range(num_features):
        output_features[:, feat] = np.interp(output_timesteps, input_timesteps, features[:, feat])
    return torch.from_numpy(output_features)


# DDIM Inversion
@torch.no_grad()
def init_prompt(prompt, pipeline):
    uncond_input = pipeline.tokenizer(
        [""], padding="max_length", max_length=pipeline.tokenizer.model_max_length, return_tensors="pt"
    )
    uncond_embeddings = pipeline.text_encoder(uncond_input.input_ids.to(pipeline.device))[0]
    text_input = pipeline.tokenizer(
        [prompt],
        padding="max_length",
        max_length=pipeline.tokenizer.model_max_length,
        truncation=True,
        return_tensors="pt",
    )
    text_embeddings = pipeline.text_encoder(text_input.input_ids.to(pipeline.device))[0]
    context = torch.cat([uncond_embeddings, text_embeddings])

    return context


def reversed_forward(ddim_scheduler, pred_noise, timesteps, x_t):
    # Compute alphas, betas
    alpha_prod_t = ddim_scheduler.alphas_cumprod[timesteps]
    beta_prod_t = 1 - alpha_prod_t

    # 3. compute predicted original sample from predicted noise also called
    # "predicted x_0" of formula (12) from https://arxiv.org/pdf/2010.02502.pdf
    if ddim_scheduler.config.prediction_type == "epsilon":
        beta_prod_t = beta_prod_t[:, None, None, None, None]
        alpha_prod_t = alpha_prod_t[:, None, None, None, None]
        pred_original_sample = (x_t - beta_prod_t ** (0.5) * pred_noise) / alpha_prod_t ** (0.5)
    else:
        raise NotImplementedError("This prediction type is not implemented yet")

    # Clip "predicted x_0"
    if ddim_scheduler.config.clip_sample:
        pred_original_sample = torch.clamp(pred_original_sample, -1, 1)
    return pred_original_sample


def next_step(
    model_output: Union[torch.FloatTensor, np.ndarray],
    timestep: int,
    sample: Union[torch.FloatTensor, np.ndarray],
    ddim_scheduler,
):
    timestep, next_timestep = (
        min(timestep - ddim_scheduler.config.num_train_timesteps // ddim_scheduler.num_inference_steps, 999),
        timestep,
    )
    alpha_prod_t = ddim_scheduler.alphas_cumprod[timestep] if timestep >= 0 else ddim_scheduler.final_alpha_cumprod
    alpha_prod_t_next = ddim_scheduler.alphas_cumprod[next_timestep]
    beta_prod_t = 1 - alpha_prod_t
    next_original_sample = (sample - beta_prod_t**0.5 * model_output) / alpha_prod_t**0.5
    next_sample_direction = (1 - alpha_prod_t_next) ** 0.5 * model_output
    next_sample = alpha_prod_t_next**0.5 * next_original_sample + next_sample_direction
    return next_sample


def get_noise_pred_single(latents, t, context, unet):
    noise_pred = unet(latents, t, encoder_hidden_states=context)["sample"]
    return noise_pred


@torch.no_grad()
def ddim_loop(pipeline, ddim_scheduler, latent, num_inv_steps, prompt):
    context = init_prompt(prompt, pipeline)
    uncond_embeddings, cond_embeddings = context.chunk(2)
    all_latent = [latent]
    latent = latent.clone().detach()
    for i in tqdm(range(num_inv_steps)):
        t = ddim_scheduler.timesteps[len(ddim_scheduler.timesteps) - i - 1]
        noise_pred = get_noise_pred_single(latent, t, cond_embeddings, pipeline.unet)
        latent = next_step(noise_pred, t, latent, ddim_scheduler)
        all_latent.append(latent)
    return all_latent


@torch.no_grad()
def ddim_inversion(pipeline, ddim_scheduler, video_latent, num_inv_steps, prompt=""):
    ddim_latents = ddim_loop(pipeline, ddim_scheduler, video_latent, num_inv_steps, prompt)
    return ddim_latents


def plot_loss_chart(save_path: str, *args):
    # Creating the plot
    plt.figure()
    for loss_line in args:
        plt.plot(loss_line[1], loss_line[2], label=loss_line[0])
    plt.xlabel("Step")
    plt.ylabel("Loss")
    plt.legend()

    # Save the figure to a file
    plt.savefig(save_path)

    # Close the figure to free memory
    plt.close()


CRED = "\033[91m"
CEND = "\033[0m"


def red_text(text: str):
    return f"{CRED}{text}{CEND}"


log_loss = nn.BCELoss(reduction="none")


def cosine_loss(vision_embeds, audio_embeds, y):
    sims = nn.functional.cosine_similarity(vision_embeds, audio_embeds)
    # sims[sims!=sims] = 0 # remove nan
    # sims = sims.clamp(0, 1)
    loss = log_loss(sims.unsqueeze(1), y).squeeze()
    return loss


def save_image(image, save_path):
    # input size (C, H, W)
    image = (image / 2 + 0.5).clamp(0, 1)
    image = (image * 255).to(torch.uint8)
    image = transforms.ToPILImage()(image)
    # Save the image copy
    image.save(save_path)

    # Close the image file
    image.close()


def gather_loss(loss, device):
    # Sum the local loss across all processes
    local_loss = loss.item()
    global_loss = torch.tensor(local_loss, dtype=torch.float32).to(device)
    dist.all_reduce(global_loss, op=dist.ReduceOp.SUM)

    # Calculate the average loss across all processes
    global_average_loss = global_loss.item() / dist.get_world_size()
    return global_average_loss


def gather_video_paths_recursively(input_dir):
    print(f"Recursively gathering video paths of {input_dir} ...")
    paths = []
    gather_video_paths(input_dir, paths)
    return paths


def gather_video_paths(input_dir, paths):
    for file in sorted(os.listdir(input_dir)):
        if file.endswith(".mp4"):
            filepath = os.path.join(input_dir, file)
            paths.append(filepath)
        elif os.path.isdir(os.path.join(input_dir, file)):
            gather_video_paths(os.path.join(input_dir, file), paths)


def count_video_time(video_path):
    video = cv2.VideoCapture(video_path)

    frame_count = video.get(cv2.CAP_PROP_FRAME_COUNT)
    fps = video.get(cv2.CAP_PROP_FPS)
    return frame_count / fps
