import os
import imageio
import numpy as np
from typing import Union

import torch
import torchvision
import torch.distributed as dist

from safetensors import safe_open
from tqdm import tqdm
from einops import rearrange
from fancyvideo.utils.convert_from_ckpt import convert_ldm_unet_checkpoint, convert_ldm_clip_checkpoint, convert_ldm_vae_checkpoint
from fancyvideo.utils.convert_lora_safetensor_to_diffusers import convert_lora, convert_motion_lora_ckpt_to_diffusers


def zero_rank_print(s):
    if (not dist.is_initialized()) and (dist.is_initialized() and dist.get_rank() == 0): print("### " + s)


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")
    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)


# 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 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 load_weights(
    animation_pipeline,
    # motion module
    motion_module_path         = "",
    motion_module_lora_configs = [],
    # image layers
    dreambooth_model_path = "",
    lora_model_path       = "",
    lora_alpha            = 0.8,
):
    # 1.1 motion module
    unet_state_dict = {}
    if motion_module_path != "":
        print(f"load motion module from {motion_module_path}")
        motion_module_state_dict = torch.load(motion_module_path, map_location="cpu")
        motion_module_state_dict = motion_module_state_dict["state_dict"] if "state_dict" in motion_module_state_dict else motion_module_state_dict
        unet_state_dict.update({name: param for name, param in motion_module_state_dict.items() if "motion_modules." in name})
    
    missing, unexpected = animation_pipeline.unet.load_state_dict(unet_state_dict, strict=False)
    assert len(unexpected) == 0
    del unet_state_dict

    if dreambooth_model_path != "":
        print(f"load dreambooth model from {dreambooth_model_path}")
        if dreambooth_model_path.endswith(".safetensors"):
            dreambooth_state_dict = {}
            with safe_open(dreambooth_model_path, framework="pt", device="cpu") as f:
                for key in f.keys():
                    dreambooth_state_dict[key] = f.get_tensor(key)
        elif dreambooth_model_path.endswith(".ckpt"):
            dreambooth_state_dict = torch.load(dreambooth_model_path, map_location="cpu")
            
        # 1. vae
        converted_vae_checkpoint = convert_ldm_vae_checkpoint(dreambooth_state_dict, animation_pipeline.vae.config)
        animation_pipeline.vae.load_state_dict(converted_vae_checkpoint)
        # 2. unet
        converted_unet_checkpoint = convert_ldm_unet_checkpoint(dreambooth_state_dict, animation_pipeline.unet.config)
        animation_pipeline.unet.load_state_dict(converted_unet_checkpoint, strict=False)
        # 3. text_model
        animation_pipeline.text_encoder = convert_ldm_clip_checkpoint(dreambooth_state_dict)
        del dreambooth_state_dict
        
    if lora_model_path != "":
        print(f"load lora model from {lora_model_path}")
        assert lora_model_path.endswith(".safetensors")
        lora_state_dict = {}
        with safe_open(lora_model_path, framework="pt", device="cpu") as f:
            for key in f.keys():
                lora_state_dict[key] = f.get_tensor(key)
                
        animation_pipeline = convert_lora(animation_pipeline, lora_state_dict, alpha=lora_alpha)
        del lora_state_dict


    for motion_module_lora_config in motion_module_lora_configs:
        path, alpha = motion_module_lora_config["path"], motion_module_lora_config["alpha"]
        print(f"load motion LoRA from {path}")

        motion_lora_state_dict = torch.load(path, map_location="cpu")
        motion_lora_state_dict = motion_lora_state_dict["state_dict"] if "state_dict" in motion_lora_state_dict else motion_lora_state_dict

        animation_pipeline = convert_motion_lora_ckpt_to_diffusers(animation_pipeline, motion_lora_state_dict, alpha)

    return animation_pipeline
