"""
For examples:

>>> python visualize_2d.py \
        --seq_dir synbody_v1_0/20230113/Downtown/LS_0114_004551_088_CAM002 \
        --body_model {path_to_body_model} \
        --save_path vis/LS_0114_004551_088_CAM002.mp4
"""

from pathlib import Path

import cv2
import numpy as np
import pyrender
import smplx
import torch
import tqdm
import trimesh
from pyrender.viewer import DirectionalLight, Node

# some constants
num_betas = 10
num_pca_comps = 45
flat_hand_mean = False

w = 1280
h = 720
fx = fy = max(w, h) / 2


def load_data(seq_dir):
    seq_dir = Path(seq_dir)
    # load images
    frame_paths = sorted(seq_dir.glob('rgb/*.jpeg'))
    images = [cv2.imread(str(p)) for p in frame_paths]

    # load parameters
    person_paths = sorted(seq_dir.glob('smplx/*.npz'))
    persons = {}
    for p in person_paths:
        person_id = p.stem
        person = dict(np.load(p, allow_pickle=True))
        for annot in person.keys():
            if isinstance(person[annot], np.ndarray) and person[annot].ndim == 0:
                person[annot] = person[annot].item()
        persons[person_id] = person

    return images, persons


def compute_camera_pose(camera_pose):
    # Convert OpenCV cam pose to OpenGL cam pose

    # x,-y,-z -> x,y,z
    R_convention = np.array([[1.0, 0.0, 0.0, 0.0], [0.0, -1.0, 0.0, 0.0], [0.0, 0.0, -1.0, 0.0], [0.0, 0.0, 0.0, 1.0]])
    camera_pose = R_convention @ camera_pose

    return camera_pose


def create_raymond_lights():
    # set directional light at axis origin, with -z direction align with +z direction of camera/world frame
    matrix = np.array([[1, 0, 0, 0], [0, -1, 0, 0], [0, 0, -1, 0], [0, 0, 0, 1]])
    return [Node(light=DirectionalLight(color=np.ones(3), intensity=2.0), matrix=matrix)]


def draw_overlay(img, camera, camera_pose, meshes):
    scene = pyrender.Scene(bg_color=[0.0, 0.0, 0.0, 0.0], ambient_light=(0.3, 0.3, 0.3))

    for i, mesh in enumerate(meshes):
        scene.add(mesh, f'mesh_{i}')

    # Defination of cam_pose: transformation from cam coord to world coord
    scene.add(camera, pose=camera_pose)

    light_nodes = create_raymond_lights()
    for node in light_nodes:
        scene.add_node(node)

    r = pyrender.OffscreenRenderer(viewport_width=w, viewport_height=h, point_size=1)
    color, _ = r.render(scene, flags=pyrender.RenderFlags.RGBA)
    color = color.astype(np.float32) / 255.0

    valid_mask = color > 0
    img = img / 255
    output_img = color * valid_mask + (1 - valid_mask) * img
    img = (output_img * 255).astype(np.uint8)

    return img


def draw_bboxes(img, bboxes):
    for person_id, bbox in bboxes.items():
        x, y, w, h = bbox
        x, y, w, h = int(x), int(y), int(w), int(h)
        img = cv2.rectangle(img, (x, y), (x + w, y + h), (0, 0, 255), 2)
        img = cv2.putText(img, person_id, (x, y - 10), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 0, 255), 2)

    return img


def visualize_2d(seq_dir, body_model_path, save_path):
    # Set device
    device = torch.device('cuda') if torch.cuda.is_available() else torch.device('cpu')

    # Initialize body model
    body_model = smplx.create(
        body_model_path,
        model_type='smplx',
        flat_hand_mean=flat_hand_mean,
        use_face_contour=True,
        use_pca=True,
        num_betas=num_betas,
        num_pca_comps=num_pca_comps,
    ).to(device)

    # Initialize components for rendering
    camera = pyrender.camera.IntrinsicsCamera(fx=fx, fy=fy, cx=w / 2, cy=h / 2)
    camera_pose = compute_camera_pose(np.eye(4))  # visualize in camera coord
    material = pyrender.MetallicRoughnessMaterial(
        metallicFactor=0.0, alphaMode='OPAQUE', baseColorFactor=(1.0, 1.0, 0.9, 1.0)
    )

    # Load data
    images, persons = load_data(seq_dir)

    # Draw overlay
    save_images = []
    for frame_idx, image in enumerate(tqdm.tqdm(images)):
        # Prepare meshes to visualize
        meshes = []
        for person in persons.values():
            person = person['smplx']
            model_output = body_model(
                global_orient=torch.tensor(person['global_orient'][[frame_idx]], device=device),
                body_pose=torch.tensor(person['body_pose'][[frame_idx]], device=device),
                transl=torch.tensor(person['transl'][[frame_idx]], device=device),
                betas=torch.tensor(person['betas'][[frame_idx]], device=device),
                left_hand_pose=torch.tensor(person['left_hand_pose'][[frame_idx]], device=device),
                right_hand_pose=torch.tensor(person['right_hand_pose'][[frame_idx]], device=device),
                return_verts=True,
            )
            vertices = model_output.vertices.detach().cpu().numpy().squeeze()
            faces = body_model.faces

            out_mesh = trimesh.Trimesh(vertices, faces, process=False)
            mesh = pyrender.Mesh.from_trimesh(out_mesh, material=material)
            meshes.append(mesh)

        image = draw_overlay(image, camera, camera_pose, meshes)

        # Visualize bounding boxes
        # bboxes = {person_id: person['keypoints2d'][frame_idx] for person_id, person in persons.items()}
        # image = draw_bboxes(image, bboxes)

        save_images.append(image)

    # Save visualization video
    Path(save_path).parent.mkdir(parents=True, exist_ok=True)
    fourcc = cv2.VideoWriter_fourcc(*'mp4v')
    video = cv2.VideoWriter(save_path, fourcc, fps=15, frameSize=(w, h))
    for image in save_images:
        video.write(image)
    video.release()

    print(f'Visualization video saved at {save_path}')


if __name__ == '__main__':
    import argparse

    parser = argparse.ArgumentParser()
    parser.add_argument('--seq_dir', type=str, required=True, help='directory containing the sequence data.')
    parser.add_argument(
        '--body_model_path', type=str, required=True, help='directory in which SMPL body models are stored.'
    )
    parser.add_argument('--save_path', type=str, required=True, help='path to save the visualization video.')
    args = parser.parse_args()

    visualize_2d(args.seq_dir, args.body_model_path, args.save_path)