import os
import spaces
import torch
import numpy as np
from PIL import Image
import pymeshlab
import pymeshlab as ml
from pymeshlab import PercentageValue
from pytorch3d.renderer import TexturesVertex
from pytorch3d.structures import Meshes
from rembg import new_session, remove
import torch.nn.functional as F
from typing import List, Tuple
import trimesh

# ZeroGPU 환경 감지
IS_ZEROGPU = os.environ.get('SPACE_ID') is not None or os.environ.get('ZEROGPU') is not None

# 전역 변수로 session 선언 (초기에는 None)
_session = None
_gpu_session = None

def get_providers():
    """환경에 따른 적절한 providers 반환"""
    if IS_ZEROGPU:
        # ZeroGPU 환경에서는 초기에 CPU만 사용
        return ['CPUExecutionProvider']
    else:
        # 일반 환경에서는 CUDA 우선 사용
        return [
            ('CUDAExecutionProvider', {
                'device_id': 0,
                'arena_extend_strategy': 'kSameAsRequested',
                'gpu_mem_limit': 8 * 1024 * 1024 * 1024,
                'cudnn_conv_algo_search': 'HEURISTIC',
            })
        ]

def get_session():
    """세션을 lazy loading으로 생성"""
    global _session
    if _session is None:
        _session = new_session(providers=get_providers())
    return _session

# 기존 코드와의 호환성을 위한 session 변수
session = None  # 초기에는 None, 필요시 get_session() 사용

NEG_PROMPT="sketch, sculpture, hand drawing, outline, single color, NSFW, lowres, bad anatomy,bad hands, text, error, missing fingers, yellow sleeves, extra digit, fewer digits, cropped, worst quality, low quality, normal quality, jpeg artifacts, signature, watermark, username, blurry,(worst quality:1.4),(low quality:1.4)"

def load_mesh_with_trimesh(file_name, file_type=None):
    import trimesh
    mesh: trimesh.Trimesh = trimesh.load(file_name, file_type=file_type)
    if isinstance(mesh, trimesh.Scene):
        assert len(mesh.geometry) > 0
        # save to obj first and load again to avoid offset issue
        from io import BytesIO
        with BytesIO() as f:
            mesh.export(f, file_type="obj")
            f.seek(0)
            mesh = trimesh.load(f, file_type="obj")
        if isinstance(mesh, trimesh.Scene):
            # we lose texture information here
            mesh = trimesh.util.concatenate(
                tuple(trimesh.Trimesh(vertices=g.vertices, faces=g.faces)
                    for g in mesh.geometry.values()))
    assert isinstance(mesh, trimesh.Trimesh)

    vertices = torch.from_numpy(mesh.vertices).T
    faces = torch.from_numpy(mesh.faces).T
    colors = None
    if mesh.visual is not None:
        if hasattr(mesh.visual, 'vertex_colors'):
            colors = torch.from_numpy(mesh.visual.vertex_colors)[..., :3].T / 255.
    if colors is None:
        # print("Warning: no vertex color found in mesh! Filling it with gray.")
        colors = torch.ones_like(vertices) * 0.5
    return vertices, faces, colors

def meshlab_mesh_to_py3dmesh(mesh: pymeshlab.Mesh) -> Meshes:
    verts = torch.from_numpy(mesh.vertex_matrix()).float()
    faces = torch.from_numpy(mesh.face_matrix()).long()
    colors = torch.from_numpy(mesh.vertex_color_matrix()[..., :3]).float()
    textures = TexturesVertex(verts_features=[colors])
    return Meshes(verts=[verts], faces=[faces], textures=textures)

def py3dmesh_to_meshlab_mesh(meshes: Meshes) -> pymeshlab.Mesh:
    colors_in = F.pad(meshes.textures.verts_features_packed().cpu().float(), [0,1], value=1).numpy().astype(np.float64)
    m1 = pymeshlab.Mesh(
        vertex_matrix=meshes.verts_packed().cpu().float().numpy().astype(np.float64),
        face_matrix=meshes.faces_packed().cpu().long().numpy().astype(np.int32),
        v_normals_matrix=meshes.verts_normals_packed().cpu().float().numpy().astype(np.float64),
        v_color_matrix=colors_in)
    return m1

def to_pyml_mesh(vertices,faces):
    m1 = pymeshlab.Mesh(
        vertex_matrix=vertices.cpu().float().numpy().astype(np.float64),
        face_matrix=faces.cpu().long().numpy().astype(np.int32),
    )
    return m1

def to_py3d_mesh(vertices, faces, normals=None):
    from pytorch3d.structures import Meshes
    from pytorch3d.renderer.mesh.textures import TexturesVertex
    mesh = Meshes(verts=[vertices], faces=[faces], textures=None)
    if normals is None:
        normals = mesh.verts_normals_packed()
    # set normals as vertext colors
    mesh.textures = TexturesVertex(verts_features=[normals / 2 + 0.5])
    return mesh

def from_py3d_mesh(mesh):
    return mesh.verts_list()[0], mesh.faces_list()[0], mesh.textures.verts_features_packed()

def rotate_normalmap_by_angle(normal_map: np.ndarray, angle: float):
    """
    rotate along y-axis
    normal_map: np.array, shape=(H, W, 3) in [-1, 1]
    angle: float, in degree
    """
    angle = angle / 180 * np.pi
    R = np.array([[np.cos(angle), 0, np.sin(angle)], [0, 1, 0], [-np.sin(angle), 0, np.cos(angle)]])
    return np.dot(normal_map.reshape(-1, 3), R.T).reshape(normal_map.shape)

# from view coord to front view world coord
def rotate_normals(normal_pils, return_types='np', rotate_direction=1) -> np.ndarray:  # [0, 255]
    n_views = len(normal_pils)
    ret = []
    for idx, rgba_normal in enumerate(normal_pils):
        # rotate normal
        normal_np = np.array(rgba_normal)[:, :, :3] / 255           # in [-1, 1]
        alpha_np = np.array(rgba_normal)[:, :, 3] / 255             # in [0, 1]
        normal_np = normal_np * 2 - 1
        normal_np = rotate_normalmap_by_angle(normal_np, rotate_direction * idx * (360 / n_views))
        normal_np = (normal_np + 1) / 2
        normal_np = normal_np * alpha_np[..., None]                 # make bg black
        rgba_normal_np = np.concatenate([normal_np * 255, alpha_np[:, :, None] * 255] , axis=-1)
        if return_types == 'np':
            ret.append(rgba_normal_np)
        elif return_types == 'pil':
            ret.append(Image.fromarray(rgba_normal_np.astype(np.uint8)))
        else:
            raise ValueError(f"return_types should be 'np' or 'pil', but got {return_types}")
    return ret

def rotate_normalmap_by_angle_torch(normal_map, angle):
    """
    rotate along y-axis
    normal_map: torch.Tensor, shape=(H, W, 3) in [-1, 1], device='cuda'
    angle: float, in degree
    """
    angle = torch.tensor(angle / 180 * np.pi).to(normal_map)
    R = torch.tensor([[torch.cos(angle), 0, torch.sin(angle)], 
                      [0, 1, 0], 
                      [-torch.sin(angle), 0, torch.cos(angle)]]).to(normal_map)
    return torch.matmul(normal_map.view(-1, 3), R.T).view(normal_map.shape)

def do_rotate(rgba_normal, angle):
    # GPU 사용 가능 여부 확인
    device = 'cuda' if torch.cuda.is_available() else 'cpu'
    rgba_normal = torch.from_numpy(rgba_normal).float().to(device) / 255
    rotated_normal_tensor = rotate_normalmap_by_angle_torch(rgba_normal[..., :3] * 2 - 1, angle)
    rotated_normal_tensor = (rotated_normal_tensor + 1) / 2
    rotated_normal_tensor = rotated_normal_tensor * rgba_normal[:, :, [3]]    # make bg black
    rgba_normal_np = torch.cat([rotated_normal_tensor * 255, rgba_normal[:, :, [3]] * 255], dim=-1).cpu().numpy()
    return rgba_normal_np

def rotate_normals_torch(normal_pils, return_types='np', rotate_direction=1):
    n_views = len(normal_pils)
    ret = []
    for idx, rgba_normal in enumerate(normal_pils):
        # rotate normal
        angle = rotate_direction * idx * (360 / n_views)
        rgba_normal_np = do_rotate(np.array(rgba_normal), angle)
        if return_types == 'np':
            ret.append(rgba_normal_np)
        elif return_types == 'pil':
            ret.append(Image.fromarray(rgba_normal_np.astype(np.uint8)))
        else:
            raise ValueError(f"return_types should be 'np' or 'pil', but got {return_types}")
    return ret

def change_bkgd(img_pils, new_bkgd=(0., 0., 0.)):
    ret = []
    new_bkgd = np.array(new_bkgd).reshape(1, 1, 3)
    for rgba_img in img_pils:
        img_np = np.array(rgba_img)[:, :, :3] / 255
        alpha_np = np.array(rgba_img)[:, :, 3] / 255
        ori_bkgd = img_np[:1, :1]
        # color = ori_color * alpha + bkgd * (1-alpha)
        # ori_color = (color - bkgd * (1-alpha)) / alpha
        alpha_np_clamp = np.clip(alpha_np, 1e-6, 1) # avoid divide by zero
        ori_img_np = (img_np - ori_bkgd * (1 - alpha_np[..., None])) / alpha_np_clamp[..., None]
        img_np = np.where(alpha_np[..., None] > 0.05, ori_img_np * alpha_np[..., None] + new_bkgd * (1 - alpha_np[..., None]), new_bkgd)
        rgba_img_np = np.concatenate([img_np * 255, alpha_np[..., None] * 255], axis=-1)
        ret.append(Image.fromarray(rgba_img_np.astype(np.uint8)))
    return ret

def change_bkgd_to_normal(normal_pils) -> List[Image.Image]:
    n_views = len(normal_pils)
    ret = []
    for idx, rgba_normal in enumerate(normal_pils):
        # calcuate background normal
        target_bkgd = rotate_normalmap_by_angle(np.array([[[0., 0., 1.]]]), idx * (360 / n_views))
        normal_np = np.array(rgba_normal)[:, :, :3] / 255           # in [-1, 1]
        alpha_np = np.array(rgba_normal)[:, :, 3] / 255             # in [0, 1]
        normal_np = normal_np * 2 - 1
        old_bkgd = normal_np[:1,:1]
        normal_np[alpha_np > 0.05] = (normal_np[alpha_np > 0.05] - old_bkgd * (1 - alpha_np[alpha_np > 0.05][..., None])) / alpha_np[alpha_np > 0.05][..., None]
        normal_np = normal_np * alpha_np[..., None] + target_bkgd * (1 - alpha_np[..., None])
        normal_np = (normal_np + 1) / 2
        rgba_normal_np = np.concatenate([normal_np * 255, alpha_np[..., None] * 255] , axis=-1)
        ret.append(Image.fromarray(rgba_normal_np.astype(np.uint8)))
    return ret

def fix_vert_color_glb(mesh_path):
    from pygltflib import GLTF2, Material, PbrMetallicRoughness
    obj1 = GLTF2().load(mesh_path)
    obj1.meshes[0].primitives[0].material = 0
    obj1.materials.append(Material(
        pbrMetallicRoughness = PbrMetallicRoughness(
            baseColorFactor = [1.0, 1.0, 1.0, 1.0],
            metallicFactor = 0.,
            roughnessFactor = 1.0,
        ),
        emissiveFactor = [0.0, 0.0, 0.0],
        doubleSided = True,
    ))
    obj1.save(mesh_path)

def srgb_to_linear(c_srgb):
    c_linear = np.where(c_srgb <= 0.04045, c_srgb / 12.92, ((c_srgb + 0.055) / 1.055) ** 2.4)
    return c_linear.clip(0, 1.)

def save_py3dmesh_with_trimesh_fast(meshes: Meshes, save_glb_path, apply_sRGB_to_LinearRGB=True):
    # convert from pytorch3d meshes to trimesh mesh
    vertices = meshes.verts_packed().cpu().float().numpy()
    triangles = meshes.faces_packed().cpu().long().numpy()
    np_color = meshes.textures.verts_features_packed().cpu().float().numpy()
    if save_glb_path.endswith(".glb"):
        # rotate 180 along +Y
        vertices[:, [0, 2]] = -vertices[:, [0, 2]]

    if apply_sRGB_to_LinearRGB:
        np_color = srgb_to_linear(np_color)
    assert vertices.shape[0] == np_color.shape[0]
    assert np_color.shape[1] == 3
    assert 0 <= np_color.min() and np_color.max() <= 1, f"min={np_color.min()}, max={np_color.max()}"
    mesh = trimesh.Trimesh(vertices=vertices, faces=triangles, vertex_colors=np_color)
    mesh.remove_unreferenced_vertices()
    # save mesh
    mesh.export(save_glb_path)
    if save_glb_path.endswith(".glb"):
        fix_vert_color_glb(save_glb_path)
    print(f"saving to {save_glb_path}")

def save_glb_and_video(save_mesh_prefix: str, meshes: Meshes, with_timestamp=True, dist=3.5, azim_offset=180, resolution=512, fov_in_degrees=1 / 1.15, cam_type="ortho", view_padding=60, export_video=True) -> Tuple[str, str]:
    import time
    if '.' in save_mesh_prefix:
        save_mesh_prefix = ".".join(save_mesh_prefix.split('.')[:-1])
    if with_timestamp:
        save_mesh_prefix = save_mesh_prefix + f"_{int(time.time())}"
    ret_mesh = save_mesh_prefix + ".glb"
    # optimizied version
    save_py3dmesh_with_trimesh_fast(meshes, ret_mesh)
    return ret_mesh, None

def simple_clean_mesh(pyml_mesh: ml.Mesh, apply_smooth=True, stepsmoothnum=1, apply_sub_divide=False, sub_divide_threshold=0.25):
    ms = ml.MeshSet()
    ms.add_mesh(pyml_mesh, "cube_mesh")
    
    if apply_smooth:
        ms.apply_filter("apply_coord_laplacian_smoothing", stepsmoothnum=stepsmoothnum, cotangentweight=False)
    if apply_sub_divide:    # 5s, slow
        ms.apply_filter("meshing_repair_non_manifold_vertices")
        ms.apply_filter("meshing_repair_non_manifold_edges", method='Remove Faces')
        ms.apply_filter("meshing_surface_subdivision_loop", iterations=2, threshold=PercentageValue(sub_divide_threshold))
    return meshlab_mesh_to_py3dmesh(ms.current_mesh())

def expand2square(pil_img, background_color):
    width, height = pil_img.size
    if width == height:
        return pil_img
    elif width > height:
        result = Image.new(pil_img.mode, (width, width), background_color)
        result.paste(pil_img, (0, (width - height) // 2))
        return result
    else:
        result = Image.new(pil_img.mode, (height, height), background_color)
        result.paste(pil_img, ((height - width) // 2, 0))
        return result

# ZeroGPU용 배경 제거 함수
@spaces.GPU(duration=30)
def remove_background_gpu(input_image, alpha_matting=False):
    """GPU에서 배경 제거 실행"""
    global _gpu_session
    if _gpu_session is None:
        # GPU가 할당되면 CUDA 프로바이더로 새 세션 생성
        gpu_providers = [
            ('CUDAExecutionProvider', {
                'device_id': 0,
                'arena_extend_strategy': 'kSameAsRequested',
                'gpu_mem_limit': 8 * 1024 * 1024 * 1024,
                'cudnn_conv_algo_search': 'HEURISTIC',
            })
        ]
        _gpu_session = new_session(providers=gpu_providers)
    return remove(input_image, alpha_matting=alpha_matting, session=_gpu_session)

def simple_preprocess(input_image, rembg_session=None, background_color=255):
    RES = 2048
    input_image.thumbnail([RES, RES], Image.Resampling.LANCZOS)
    if input_image.mode != 'RGBA':
        image_rem = input_image.convert('RGBA')
        # ZeroGPU 환경에서는 GPU 함수 사용
        if IS_ZEROGPU:
            input_image = remove_background_gpu(image_rem, alpha_matting=False)
        else:
            # 일반 환경에서는 세션 사용
            if rembg_session is None:
                rembg_session = get_session()
            input_image = remove(image_rem, alpha_matting=False, session=rembg_session)

    arr = np.asarray(input_image)
    alpha = np.asarray(input_image)[:, :, -1]
    x_nonzero = np.nonzero((alpha > 60).sum(axis=1))
    y_nonzero = np.nonzero((alpha > 60).sum(axis=0))
    x_min = int(x_nonzero[0].min())
    y_min = int(y_nonzero[0].min())
    x_max = int(x_nonzero[0].max())
    y_max = int(y_nonzero[0].max())
    arr = arr[x_min: x_max, y_min: y_max]
    input_image = Image.fromarray(arr)
    input_image = expand2square(input_image, (background_color, background_color, background_color, 0))
    return input_image

def init_target(img_pils, new_bkgd=(0., 0., 0.), device=None):
    if device is None:
        device = "cuda" if torch.cuda.is_available() else "cpu"
    
    # Convert the background color to a PyTorch tensor
    new_bkgd = torch.tensor(new_bkgd, dtype=torch.float32).view(1, 1, 3).to(device)
    
    # Convert all images to PyTorch tensors and process them
    imgs = torch.stack([torch.from_numpy(np.array(img, dtype=np.float32)) for img in img_pils]).to(device) / 255
    img_nps = imgs[..., :3]
    alpha_nps = imgs[..., 3]
    ori_bkgds = img_nps[:, :1, :1]
    
    # Avoid divide by zero and calculate the original image
    alpha_nps_clamp = torch.clamp(alpha_nps, 1e-6, 1)
    ori_img_nps = (img_nps - ori_bkgds * (1 - alpha_nps.unsqueeze(-1))) / alpha_nps_clamp.unsqueeze(-1)
    ori_img_nps = torch.clamp(ori_img_nps, 0, 1)
    img_nps = torch.where(alpha_nps.unsqueeze(-1) > 0.05, ori_img_nps * alpha_nps.unsqueeze(-1) + new_bkgd * (1 - alpha_nps.unsqueeze(-1)), new_bkgd)

    rgba_img_np = torch.cat([img_nps, alpha_nps.unsqueeze(-1)], dim=-1)
    return rgba_img_np