import os
import argparse
import datetime
import PIL.Image
import numpy as np

import torch
import torch.distributed as dist

from transformers import AutoTokenizer, UMT5EncoderModel
from torchvision.io import write_video
from diffusers.utils import load_image

from longcat_video.pipeline_longcat_video import LongCatVideoPipeline
from longcat_video.modules.scheduling_flow_match_euler_discrete import FlowMatchEulerDiscreteScheduler
from longcat_video.modules.autoencoder_kl_wan import AutoencoderKLWan
from longcat_video.modules.longcat_video_dit import LongCatVideoTransformer3DModel
from longcat_video.context_parallel import context_parallel_util
from longcat_video.context_parallel.context_parallel_util import init_context_parallel


def torch_gc():
    torch.cuda.empty_cache()
    torch.cuda.ipc_collect()


def generate(args):
    # case setup
    image_path = "assets/girl.png"
    image = load_image(image_path)
    prompt = "A woman sits at a wooden table by the window in a cozy café. She reaches out with her right hand, picks up the white coffee cup from the saucer, and gently brings it to her lips to take a sip. After drinking, she places the cup back on the table and looks out the window, enjoying the peaceful atmosphere."
    negative_prompt = "Bright tones, overexposed, static, blurred details, subtitles, style, works, paintings, images, static, overall gray, worst quality, low quality, JPEG compression residue, ugly, incomplete, extra fingers, poorly drawn hands, poorly drawn faces, deformed, disfigured, misshapen limbs, fused fingers, still picture, messy background, three legs, many people in the background, walking backwards"

    # load parsed args
    checkpoint_dir = args.checkpoint_dir
    context_parallel_size = args.context_parallel_size
    enable_compile = args.enable_compile

    # prepare distributed environment
    rank = int(os.environ['RANK'])
    num_gpus = torch.cuda.device_count()
    local_rank = rank % num_gpus
    torch.cuda.set_device(local_rank)
    dist.init_process_group(backend="nccl", timeout=datetime.timedelta(seconds=3600*24))
    global_rank    = dist.get_rank()
    num_processes  = dist.get_world_size()

    # initialize context parallel before loading models
    init_context_parallel(context_parallel_size=context_parallel_size, global_rank=global_rank, world_size=num_processes)
    cp_size = context_parallel_util.get_cp_size()
    cp_split_hw = context_parallel_util.get_optimal_split(cp_size)

    tokenizer = AutoTokenizer.from_pretrained(checkpoint_dir, subfolder="tokenizer", torch_dtype=torch.bfloat16)
    text_encoder = UMT5EncoderModel.from_pretrained(checkpoint_dir, subfolder="text_encoder", torch_dtype=torch.bfloat16)
    vae = AutoencoderKLWan.from_pretrained(checkpoint_dir, subfolder="vae", torch_dtype=torch.bfloat16)
    scheduler = FlowMatchEulerDiscreteScheduler.from_pretrained(checkpoint_dir, subfolder="scheduler", torch_dtype=torch.bfloat16)
    dit = LongCatVideoTransformer3DModel.from_pretrained(checkpoint_dir, subfolder="dit", cp_split_hw=cp_split_hw, torch_dtype=torch.bfloat16)

    if enable_compile:
        dit = torch.compile(dit)

    pipe = LongCatVideoPipeline(
        tokenizer = tokenizer,
        text_encoder = text_encoder,
        vae = vae,
        scheduler = scheduler,
        dit = dit,
    )
    pipe.to(local_rank)

    global_seed = 42
    seed = global_seed + global_rank

    generator = torch.Generator(device=local_rank)
    generator.manual_seed(seed)

    target_size = image.size  # (width, height)

    ### i2v (480p)
    output = pipe.generate_i2v(
        image=image,
        prompt=prompt,
        negative_prompt=negative_prompt,
        resolution='480p', # 480p / 720p
        num_frames=93,
        num_inference_steps=50,
        guidance_scale=4.0,
        generator=generator
    )[0]

    if local_rank == 0:
        output = [(output[i] * 255).astype(np.uint8) for i in range(output.shape[0])]
        output = [PIL.Image.fromarray(img) for img in output]
        output = [frame.resize(target_size, PIL.Image.BICUBIC) for frame in output]

        output_tensor = torch.from_numpy(np.array(output))
        write_video("output_i2v.mp4", output_tensor, fps=15, video_codec="libx264", options={"crf": f"{18}"})
    del output
    torch_gc()

    ### i2v distill (480p)
    cfg_step_lora_path = os.path.join(checkpoint_dir, 'lora/cfg_step_lora.safetensors')
    pipe.dit.load_lora(cfg_step_lora_path, 'cfg_step_lora')
    pipe.dit.enable_loras(['cfg_step_lora'])

    if enable_compile:
        dit = torch.compile(dit)

    output_distill = pipe.generate_i2v(
        image=image,
        prompt=prompt,
        resolution='480p', # 480p / 720p
        num_frames=93,
        num_inference_steps=16,
        use_distill=True,
        guidance_scale=1.0,
        generator=generator,
    )[0]
    pipe.dit.disable_all_loras()

    if local_rank == 0:
        output_processed = [(output_distill[i] * 255).astype(np.uint8) for i in range(output_distill.shape[0])]
        output_processed = [PIL.Image.fromarray(img) for img in output_processed]
        output_processed = [frame.resize(target_size, PIL.Image.BICUBIC) for frame in output_processed]

        output_processed_tensor = torch.from_numpy(np.array(output_processed))
        write_video("output_i2v_distill.mp4", output_processed_tensor, fps=15, video_codec="libx264", options={"crf": f"{18}"})

    ### i2v refinement (720p)
    refinement_lora_path = os.path.join(checkpoint_dir, 'lora/refinement_lora.safetensors')
    pipe.dit.load_lora(refinement_lora_path, 'refinement_lora')
    pipe.dit.enable_loras(['refinement_lora'])
    pipe.dit.enable_bsa()

    if enable_compile:
        dit = torch.compile(dit)
    
    stage1_video = [(output_distill[i] * 255).astype(np.uint8) for i in range(output_distill.shape[0])]
    stage1_video = [PIL.Image.fromarray(img) for img in stage1_video]
    del output_distill 
    torch_gc()

    output_refine = pipe.generate_refine(
        image=image,
        prompt=prompt,
        stage1_video=stage1_video,
        num_cond_frames=1,
        num_inference_steps=50,
        generator=generator,
    )[0]

    pipe.dit.disable_all_loras()
    pipe.dit.disable_bsa()

    if local_rank == 0:
        output_refine = [(output_refine[i] * 255).astype(np.uint8) for i in range(output_refine.shape[0])]
        output_refine = [PIL.Image.fromarray(img) for img in output_refine]
        output_refine = [frame.resize(target_size, PIL.Image.BICUBIC) for frame in output_refine]

        output_tensor = torch.from_numpy(np.array(output_refine))
        write_video("output_i2v_refine.mp4", output_tensor, fps=30, video_codec="libx264", options={"crf": f"{10}"})


def _parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--context_parallel_size",
        type=int,
        default=1,
    )
    parser.add_argument(
        "--checkpoint_dir",
        type=str,
        default=None,
    )
    parser.add_argument(
        '--enable_compile',
        action='store_true',
    )

    args = parser.parse_args()

    return args


if __name__ == "__main__":
    args = _parse_args()
    generate(args)