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 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
    prompt = "In a realistic photography style, a white boy around seven or eight years old sits on a park bench, wearing a light blue T-shirt, denim shorts, and white sneakers. He holds an ice cream cone with vanilla and chocolate flavors, and beside him is a medium-sized golden Labrador. Smiling, the boy offers the ice cream to the dog, who eagerly licks it with its tongue. The sun is shining brightly, and the background features a green lawn and several tall trees, creating a warm and loving scene."
    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)

    ### t2v (480p)
    output = pipe.generate_t2v(
        prompt=prompt,
        negative_prompt=negative_prompt,
        height=512,
        width=832,
        num_frames=93,
        num_inference_steps=50,
        guidance_scale=4.0,
        generator=generator,
    )[0]

    if local_rank == 0:
        output_tensor = torch.from_numpy(np.array(output))
        output_tensor = (output_tensor * 255).clamp(0, 255).to(torch.uint8)
        write_video("output_t2v.mp4", output_tensor, fps=15, video_codec="libx264", options={"crf": f"{18}"})
    del output
    torch_gc()

    ### t2v 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_t2v(
        prompt=prompt,
        height=512,
        width=832,
        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_tensor = torch.from_numpy(np.array(output_distill))
        output_processed_tensor = (output_processed_tensor * 255).clamp(0, 255).to(torch.uint8)
        write_video("output_t2v_distill.mp4", output_processed_tensor, fps=15, video_codec="libx264", options={"crf": f"{18}"})

    ### t2v 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(
        prompt=prompt,
        stage1_video=stage1_video,
        num_inference_steps=50,
        generator=generator,
    )[0]

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

    if local_rank == 0:
        output_tensor = torch.from_numpy(output_refine)
        output_tensor = (output_tensor * 255).clamp(0, 255).to(torch.uint8)
        write_video("output_t2v_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)
