import argparse
import json
import math
import os
import sys
from pathlib import Path

import matplotlib.pyplot as plt
import numpy as np
import torch
import torch.nn.functional as tF
from tqdm import tqdm
from torchvision import transforms
from torchvision.transforms import InterpolationMode

try:
    import cv2
except ImportError:
    cv2 = None

try:
    import decord
    from decord import VideoReader, cpu
except ImportError:
    decord = None


VIDEOALIGN_ROOT = Path(__file__).resolve().parents[1] / "VideoAlign"
if str(VIDEOALIGN_ROOT) not in sys.path:
    sys.path.insert(0, str(VIDEOALIGN_ROOT))

from inference_flow_grpo import VideoVLMRewardInference  # noqa: E402
from prompt_template import build_prompt  # noqa: E402


def smart_resize(height, width, factor=28, min_pixels=56 * 56, max_pixels=14 * 14 * 4 * 1280):
    if max(height, width) / min(height, width) > 200:
        raise ValueError(f"absolute aspect ratio must be smaller than 200, got {max(height, width) / min(height, width)}")
    h_bar = round(height / factor) * factor
    w_bar = round(width / factor) * factor
    if h_bar * w_bar > max_pixels:
        beta = math.sqrt((height * width) / max_pixels)
        h_bar = max(factor, math.floor(height / beta / factor) * factor)
        w_bar = max(factor, math.floor(width / beta / factor) * factor)
    elif h_bar * w_bar < min_pixels:
        beta = math.sqrt(min_pixels / (height * width))
        h_bar = math.ceil(height * beta / factor) * factor
        w_bar = math.ceil(width * beta / factor) * factor
    return int(h_bar), int(w_bar)


def resize_frames(frames, max_frame_pixels, resize_factor=28, min_pixels=128 * 128):
    bsz, channels, t_num, height, width = frames.shape
    x = frames.permute(0, 2, 1, 3, 4)
    resized_height, resized_width = smart_resize(
        height,
        width,
        factor=resize_factor,
        min_pixels=min_pixels,
        max_pixels=max_frame_pixels,
    )
    frames_resized = []
    for v in x:
        v_r = transforms.functional.resize(
            v,
            [resized_height, resized_width],
            interpolation=InterpolationMode.BICUBIC,
            antialias=True,
        ).float()
        frames_resized.append(v_r)

    del bsz, channels, t_num
    return torch.stack(frames_resized)


def read_video(video_path, num_frames, resize_factor=28, min_pixels=128 * 128, max_pixels=256 * 256):
    if decord is None:
        raise ImportError("decord is required for reading videos. Please install decord.")

    decord.bridge.set_bridge("torch")
    vr = VideoReader(video_path, ctx=cpu(0))
    total_frames = len(vr)
    if total_frames == 0:
        raise ValueError(f"Empty video: {video_path}")

    idx = torch.linspace(0, total_frames - 1, num_frames).round().long().tolist()
    video = vr.get_batch(idx).permute(0, 3, 1, 2).float() / 255.0
    video = resize_frames(video.unsqueeze(0), max_pixels, resize_factor=resize_factor, min_pixels=min_pixels).permute(0, 2, 1, 3, 4)[0]
    return video


def plot_heatmap_from_token_grads(
    input_video,
    video_grid_thw,
    token_grads,
    save_path,
    merge_size=2,
    temporal_patch_size=2,
):
    if isinstance(video_grid_thw, torch.Tensor):
        grid = video_grid_thw.reshape(-1, 3)[0].tolist()
    else:
        grid = list(video_grid_thw)
        if len(grid) != 3 and len(grid) > 0 and hasattr(grid[0], "__len__"):
            grid = list(grid[0])
    grid_t, grid_h, grid_w = [int(x) for x in grid]

    grads = token_grads.detach().cpu().float()
    if grads.dim() > 1:
        grads = grads.norm(dim=-1)
    grads = grads.flatten()

    if grid_h % merge_size != 0 or grid_w % merge_size != 0:
        raise ValueError(f"grid_h/grid_w should be divisible by merge_size, got ({grid_h}, {grid_w}) vs {merge_size}")

    token_t, token_h, token_w = grid_t, grid_h // merge_size, grid_w // merge_size
    expected_tokens = token_t * token_h * token_w
    if grads.numel() != expected_tokens:
        raise ValueError(f"token count mismatch: grads={grads.numel()}, expected={expected_tokens}")

    grads = (grads - grads.min()) / (grads.max() - grads.min() + 1e-8)
    heatmap_small = grads.view(token_t, token_h, token_w)
    heatmap_small = heatmap_small.repeat_interleave(int(temporal_patch_size), dim=0)

    t_in, _, h_in, w_in = input_video.shape
    if heatmap_small.shape[0] < t_in:
        pad_t = t_in - heatmap_small.shape[0]
        heatmap_small = torch.cat([heatmap_small, heatmap_small[-1:].repeat(pad_t, 1, 1)], dim=0)
    elif heatmap_small.shape[0] > t_in:
        heatmap_small = heatmap_small[:t_in]

    heatmap_upsampled = tF.interpolate(
        heatmap_small.unsqueeze(1),
        size=(h_in, w_in),
        mode="bilinear",
        align_corners=False,
    ).squeeze(1)
    heatmap_upsampled = (heatmap_upsampled - heatmap_upsampled.min()) / (
        heatmap_upsampled.max() - heatmap_upsampled.min() + 1e-8
    )

    video_np = input_video.detach().cpu().permute(0, 2, 3, 1).numpy()
    video_np = (video_np - video_np.min()) / (video_np.max() - video_np.min() + 1e-8)
    heatmap_np = heatmap_upsampled.numpy()

    cols = min(10, t_in)
    rows = math.ceil(t_in / cols) * 2
    fig, axes = plt.subplots(rows, cols, figsize=(cols * 2.2, rows * 1.8))
    axes = np.array(axes).reshape(rows, cols)

    for t in range(t_in):
        r_top = t // cols
        c = t % cols
        r_bottom = r_top + (rows // 2)

        ax_top = axes[r_top, c]
        ax_top.imshow(video_np[t])
        ax_top.imshow(heatmap_np[t], cmap="jet", alpha=0.45, vmin=0, vmax=1)
        ax_top.axis("off")
        ax_top.set_title(f"F{t}", fontsize=8)

        ax_bot = axes[r_bottom, c]
        ax_bot.imshow(video_np[t])
        ax_bot.axis("off")

    used_rows_per_half = math.ceil(t_in / cols)
    for r in range(rows):
        for c in range(cols):
            if r < used_rows_per_half:
                idx = r * cols + c
            else:
                idx = (r - used_rows_per_half) * cols + c
            if idx >= t_in:
                axes[r, c].axis("off")

    plt.tight_layout()
    plt.savefig(save_path, dpi=150, bbox_inches="tight")
    plt.close()

    return heatmap_upsampled


def save_overlay_mp4(video_uint8, heatmap, out_mp4, fps=4):
    if cv2 is None:
        return False

    t_num, h, w, _ = video_uint8.shape
    writer = cv2.VideoWriter(out_mp4, cv2.VideoWriter_fourcc(*"mp4v"), fps, (w, h))
    for t in range(t_num):
        hm = plt.get_cmap("jet")(heatmap[t])[..., :3]
        frame = (0.5 * (video_uint8[t] / 255.0) + 0.5 * hm) * 255.0
        frame = frame.astype(np.uint8)
        writer.write(cv2.cvtColor(frame, cv2.COLOR_RGB2BGR))
    writer.release()
    return True


def save_frame_images(video_uint8, heatmap, out_dir):
    out_dir = Path(out_dir)
    overlay_dir = out_dir / "frames_overlay"
    original_dir = out_dir / "frames_original"
    overlay_dir.mkdir(parents=True, exist_ok=True)
    original_dir.mkdir(parents=True, exist_ok=True)

    heatmap_np = heatmap if isinstance(heatmap, np.ndarray) else np.asarray(heatmap)
    t_num = video_uint8.shape[0]
    for t in range(t_num):
        hm_rgb = plt.get_cmap("jet")(heatmap_np[t])[..., :3]
        overlay = (0.5 * (video_uint8[t].astype(np.float32) / 255.0) + 0.5 * hm_rgb) * 255.0
        overlay = np.clip(overlay, 0, 255).astype(np.uint8)

        if cv2 is not None:
            cv2.imwrite(str(overlay_dir / f"frame_{t:03d}.png"), cv2.cvtColor(overlay, cv2.COLOR_RGB2BGR))
            cv2.imwrite(str(original_dir / f"frame_{t:03d}.png"), cv2.cvtColor(video_uint8[t], cv2.COLOR_RGB2BGR))
        else:
            plt.imsave(str(overlay_dir / f"frame_{t:03d}.png"), overlay)
            plt.imsave(str(original_dir / f"frame_{t:03d}.png"), video_uint8[t])

    return str(overlay_dir), str(original_dir), t_num


def build_messages(question):
    return [
        {
            "role": "user",
            "content": [
                {"type": "video", "video": "<video>"},
                {"type": "text", "text": question},
            ],
        },
    ]


def compute_videoalign_grad_heatmap(inferencer, video_tensor, question, target_dim="TA"):
    model = inferencer.model
    processor = inferencer.processor
    tokenizer = processor.tokenizer

    messages = build_messages(question)
    text = processor.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
    batch = processor(
        text=[text],
        images=None,
        videos=[video_tensor],
        return_tensors="pt",
        do_rescale=False,
        do_resize=False,
        # do_sample_frames=False,
    )
    batch = inferencer._prepare_inputs(batch)

    target_dim = target_dim.upper()
    dim2idx = {"VQ": 0, "MQ": 1, "TA": 2}
    if target_dim not in dim2idx:
        raise ValueError(f"Unsupported target_dim: {target_dim}. Choose from VQ/MQ/TA.")

    with torch.enable_grad():
        model.zero_grad(set_to_none=True)
        outputs = model(
            return_dict=True,
            output_hidden_states=True,
            enable_input_grads=True,
            **batch,
        )
        logits = outputs["logits"]
        import pdb
        # pdb.set_trace()
        target_score = logits[0, dim2idx[target_dim]]
        loss = -target_score

        embeddings = outputs.get("inputs_embeds", None)
        if embeddings is None:
            if outputs.get("hidden_states", None) is None:
                raise RuntimeError("Model forward did not return hidden_states with output_hidden_states=True.")
            embeddings = outputs["hidden_states"][0]
        if not embeddings.requires_grad:
            raise RuntimeError("Differentiation target does not require grad. Check enable_input_grads path.")
        grads = torch.autograd.grad(loss, embeddings, retain_graph=False)[0]

    vid_pad_id = tokenizer.convert_tokens_to_ids("<|video_pad|>")
    if vid_pad_id is None:
        raise RuntimeError("Tokenizer has no <|video_pad|> token id.")

    video_mask = batch["input_ids"][0] == vid_pad_id
    video_grads = grads[0, video_mask]
    saliency = video_grads.norm(dim=-1)
    saliency = (saliency - saliency.min()) / (saliency.max() - saliency.min() + 1e-8)

    score = {
        "VQ": float(logits[0, 0].detach().cpu().item()),
        "MQ": float(logits[0, 1].detach().cpu().item()),
        "TA": float(logits[0, 2].detach().cpu().item()),
        "target_dim": target_dim,
        "target_score": float(target_score.detach().cpu().item()),
    }

    return (
        saliency.detach().cpu(),
        score,
        batch["video_grid_thw"].detach().cpu(),
        video_mask.detach().cpu(),
        grads.detach().cpu(),
    )


def load_json(path):
    with open(path, "r", encoding="utf-8") as f:
        return json.load(f)


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--input_dir",
        type=str,
        default="/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative",
        help="Directory containing paired *.json and *.mp4.",
    )
    parser.add_argument(
        "--output_dir",
        type=str,
        default="/nfs/ywang29/Reward_finetuning/VideoX-Fun/visualization/chunk/videoalign_objects_grad_heatmap_sel",
        help="Output directory for heatmaps.",
    )
    parser.add_argument(
        "--videoalign_ckpt",
        type=str,
        default="/nfs/ywang29/Reward_finetuning/VideoX-Fun/VideoAlign/checkpoints",
        help="VideoAlign checkpoint directory (contains model_config.json).",
    )
    parser.add_argument("--num_frames", type=int, default=10)
    parser.add_argument("--resize_factor", type=int, default=28)
    parser.add_argument("--min_pixels", type=int, default=128 * 128)
    parser.add_argument("--max_pixels", type=int, default=256 * 256)
    parser.add_argument("--target_dim", type=str, default="TA", choices=["VQ", "MQ", "TA", "vq", "mq", "ta"])
    parser.add_argument("--save_pt", action="store_true", help="Save raw grads/video_mask/video_grid to grad_data.pt")
    parser.add_argument("--max_samples", type=int, default=None)
    args = parser.parse_args()

    input_dir = Path(args.input_dir)
    output_dir = Path(args.output_dir)
    output_dir.mkdir(parents=True, exist_ok=True)

    if not input_dir.exists():
        raise FileNotFoundError(f"Input dir not found: {input_dir}")

    device = "cuda:0" if torch.cuda.is_available() else "cpu"
    dtype = torch.bfloat16 if torch.cuda.is_available() else torch.float32
    inferencer = VideoVLMRewardInference(args.videoalign_ckpt, device=device, dtype=dtype)

    image_processor = getattr(inferencer.processor, "image_processor", None)
    merge_size = int(getattr(image_processor, "merge_size", 2))
    temporal_patch_size = int(getattr(image_processor, "temporal_patch_size", 2))
    patch_size = int(getattr(image_processor, "patch_size", 14))
    args.resize_factor = patch_size * merge_size

    json_files = sorted(input_dir.glob("*.json"))
    
    # json_files = [Path('/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-107-3.json')]
    json_files = [Path('/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-106-7.json')]
    json_files = [
        # Path('/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-233-2.json'),
        # Path('/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-172-7.json'),
        Path('/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-141-5.json'),

    ]
    json_files = [
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-30-2.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-36-1.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-40-2.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-42-0.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-43-1.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-47-1.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-54-7.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-82-2.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-80-2.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-83-7.json',
    ]
    json_files = [
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-112-4.json',
        '/nfs/ywang29/Reward_finetuning/VideoX-Fun/output_objects/negative/sample-125-1.json',
    ]
    json_files = [Path(json_file) for json_file in json_files]

    if args.max_samples is not None:
        json_files = json_files[: args.max_samples]

    for json_path in tqdm(json_files, desc="Processing"):
        stem = json_path.stem
        video_path = input_dir / f"{stem}.mp4"
        if not video_path.exists():
            continue

        data = load_json(json_path)
        questions = data.get("question", [])
        gt_answers = data.get("gt_answer", [])
        if not isinstance(questions, list) or not isinstance(gt_answers, list):
            continue
        if len(questions) == 0:
            continue

        video_tensor = read_video(
            str(video_path),
            args.num_frames,
            resize_factor=args.resize_factor,
            min_pixels=args.min_pixels,
            max_pixels=args.max_pixels,
        )
        video_uint8 = (video_tensor.permute(0, 2, 3, 1).detach().cpu().numpy().clip(0, 1) * 255).astype(np.uint8)

        for i, raw_question in enumerate(questions):
            gt = gt_answers[i] if i < len(gt_answers) else ""
            sample_out = output_dir / stem / f"q{i}"
            sample_out.mkdir(parents=True, exist_ok=True)
            question = build_prompt(
                raw_question,
                inferencer.data_config.eval_dim,
                inferencer.data_config.prompt_template_type,
            )

            try:
                saliency, score, video_grid_thw, video_mask, grads = compute_videoalign_grad_heatmap(
                    inferencer=inferencer,
                    video_tensor=video_tensor,
                    question=question,
                    target_dim=args.target_dim,
                )
            except Exception as e:
                with open(sample_out / "error.txt", "w", encoding="utf-8") as ef:
                    ef.write(str(e))
                continue

            try:
                heatmap = plot_heatmap_from_token_grads(
                    input_video=video_tensor.detach().cpu(),
                    video_grid_thw=video_grid_thw,
                    token_grads=saliency,
                    save_path=str(sample_out / "heatmap.png"),
                    merge_size=merge_size,
                    temporal_patch_size=temporal_patch_size,
                )
                saved_mp4 = save_overlay_mp4(video_uint8, heatmap.numpy(), str(sample_out / "heatmap.mp4"), fps=4)
                overlay_frames_dir, original_frames_dir, saved_frames = save_frame_images(
                    video_uint8, heatmap.numpy(), sample_out
                )
            except Exception as e:
                with open(sample_out / "plot_error.txt", "w", encoding="utf-8") as ef:
                    ef.write(str(e))
                saved_mp4 = False
                saved_frames = 0
                overlay_frames_dir = str(sample_out / "frames_overlay")
                original_frames_dir = str(sample_out / "frames_original")

            if args.save_pt:
                torch.save(
                    {
                        "video_grid_thw": video_grid_thw,
                        "video_mask": video_mask,
                        "grads": grads,
                        "video_token_saliency": saliency,
                    },
                    sample_out / "grad_data.pt",
                )

            meta = {
                "json_path": str(json_path),
                "video_path": str(video_path),
                "raw_question": raw_question,
                "question": question,
                "gt_answer": gt,
                "videoalign_scores": score,
                "video_grid_thw": video_grid_thw.reshape(-1, 3)[0].tolist(),
                "num_video_tokens": int(saliency.numel()),
                "merge_size": merge_size,
                "temporal_patch_size": temporal_patch_size,
                "saved_mp4": bool(saved_mp4),
                "saved_frames": int(saved_frames),
                "overlay_frames_dir": overlay_frames_dir,
                "original_frames_dir": original_frames_dir,
            }
            with open(sample_out / "metadata.json", "w", encoding="utf-8") as f:
                json.dump(meta, f, ensure_ascii=False, indent=2)


if __name__ == "__main__":
    main()