import torch
import io
import numpy as np
from pathlib import Path
import re
import trimesh
import imageio


def to_numpy(*args):
    def convert(a):
        if isinstance(a, torch.Tensor):
            return a.detach().cpu().numpy()
        assert a is None or isinstance(a, np.ndarray)
        return a

    return convert(args[0]) if len(args) == 1 else tuple(convert(a) for a in args)


def save_obj(vertices: torch.Tensor, faces: torch.Tensor, filename: Path):
    filename = Path(filename)

    bytes_io = io.BytesIO()
    np.savetxt(bytes_io, vertices.detach().cpu().numpy(), "v %.4f %.4f %.4f")
    np.savetxt(bytes_io, faces.cpu().numpy() + 1, "f %d %d %d")  # 1-based indexing

    obj_path = filename.with_suffix(".obj")
    with open(obj_path, "w") as file:
        file.write(bytes_io.getvalue().decode("UTF-8"))


def load_obj(filename: Path, device="cuda") -> tuple[torch.Tensor, torch.Tensor]:
    filename = Path(filename)
    obj_path = filename.with_suffix(".obj")
    with open(obj_path) as file:
        obj_text = file.read()
    num = r"([0-9\.\-eE]+)"
    v = re.findall(f"(v {num} {num} {num})", obj_text)
    vertices = np.array(v)[:, 1:].astype(np.float32)
    all_faces = []
    f = re.findall(f"(f {num} {num} {num})", obj_text)
    if f:
        all_faces.append(np.array(f)[:, 1:].astype(np.long).reshape(-1, 3, 1)[..., :1])
    f = re.findall(f"(f {num}/{num} {num}/{num} {num}/{num})", obj_text)
    if f:
        all_faces.append(np.array(f)[:, 1:].astype(np.long).reshape(-1, 3, 2)[..., :2])
    f = re.findall(
        f"(f {num}/{num}/{num} {num}/{num}/{num} {num}/{num}/{num})", obj_text
    )
    if f:
        all_faces.append(np.array(f)[:, 1:].astype(np.long).reshape(-1, 3, 3)[..., :2])
    f = re.findall(f"(f {num}//{num} {num}//{num} {num}//{num})", obj_text)
    if f:
        all_faces.append(np.array(f)[:, 1:].astype(np.long).reshape(-1, 3, 2)[..., :1])
    all_faces = np.concatenate(all_faces, axis=0)
    all_faces -= 1  # 1-based indexing
    faces = all_faces[:, :, 0]

    vertices = torch.tensor(vertices, dtype=torch.float32, device=device)
    faces = torch.tensor(faces, dtype=torch.long, device=device)

    return vertices, faces


def save_ply(
    filename: Path,
    vertices: torch.Tensor,  # V,3
    faces: torch.Tensor,  # F,3
    vertex_colors: torch.Tensor = None,  # V,3
    vertex_normals: torch.Tensor = None,  # V,3
):

    filename = Path(filename).with_suffix(".ply")
    vertices, faces, vertex_colors = to_numpy(vertices, faces, vertex_colors)
    assert (
        np.all(np.isfinite(vertices))
        and faces.min() == 0
        and faces.max() == vertices.shape[0] - 1
    )

    header = "ply\nformat ascii 1.0\n"

    header += "element vertex " + str(vertices.shape[0]) + "\n"
    header += "property double x\n"
    header += "property double y\n"
    header += "property double z\n"

    if vertex_normals is not None:
        header += "property double nx\n"
        header += "property double ny\n"
        header += "property double nz\n"

    if vertex_colors is not None:
        assert vertex_colors.shape[0] == vertices.shape[0]
        color = (vertex_colors * 255).astype(np.uint8)
        header += "property uchar red\n"
        header += "property uchar green\n"
        header += "property uchar blue\n"

    header += "element face " + str(faces.shape[0]) + "\n"
    header += "property list int int vertex_indices\n"
    header += "end_header\n"

    with open(filename, "w") as file:
        file.write(header)

        for i in range(vertices.shape[0]):
            s = f"{vertices[i,0]} {vertices[i,1]} {vertices[i,2]}"
            if vertex_normals is not None:
                s += f" {vertex_normals[i,0]} {vertex_normals[i,1]} {vertex_normals[i,2]}"
            if vertex_colors is not None:
                s += f" {color[i,0]:03d} {color[i,1]:03d} {color[i,2]:03d}"
            file.write(s + "\n")

        for i in range(faces.shape[0]):
            file.write(f"3 {faces[i,0]} {faces[i,1]} {faces[i,2]}\n")
    full_verts = vertices[faces]  # F,3,3


def save_images(
    images: torch.Tensor,  # B,H,W,CH
    dir: Path,
):
    dir = Path(dir)
    dir.mkdir(parents=True, exist_ok=True)
    for i in range(images.shape[0]):
        imageio.imwrite(
            dir / f"{i:02d}.png",
            (images.detach()[i, :, :, :3] * 255)
            .clamp(max=255)
            .type(torch.uint8)
            .cpu()
            .numpy(),
        )


def normalize_vertices(
    vertices: torch.Tensor,  # V,3
):
    """shift and resize mesh to fit into a unit sphere"""
    vertices -= (vertices.min(dim=0)[0] + vertices.max(dim=0)[0]) / 2
    vertices /= torch.norm(vertices, dim=-1).max()
    return vertices


def laplacian(num_verts: int, edges: torch.Tensor) -> torch.Tensor:  # E,2  # sparse V,V
    """create sparse Laplacian matrix"""
    V = num_verts
    E = edges.shape[0]

    # adjacency matrix,
    idx = torch.cat([edges, edges.fliplr()], dim=0).type(torch.long).T  # (2, 2*E)
    ones = torch.ones(2 * E, dtype=torch.float32, device=edges.device)
    A = torch.sparse.FloatTensor(idx, ones, (V, V))

    # degree matrix
    deg = torch.sparse.sum(A, dim=1).to_dense()
    idx = torch.arange(V, device=edges.device)
    idx = torch.stack([idx, idx], dim=0)
    D = torch.sparse.FloatTensor(idx, deg, (V, V))

    return D - A


def _translation(x, y, z, device):
    return torch.tensor(
        [[1.0, 0, 0, x], [0, 1, 0, y], [0, 0, 1, z], [0, 0, 0, 1]], device=device
    )  # 4,4


def _projection(r, device, l=None, t=None, b=None, n=1.0, f=50.0, flip_y=True):
    if l is None:
        l = -r
    if t is None:
        t = r
    if b is None:
        b = -t
    p = torch.zeros([4, 4], device=device)
    p[0, 0] = 2 * n / (r - l)
    p[0, 2] = (r + l) / (r - l)
    p[1, 1] = 2 * n / (t - b) * (-1 if flip_y else 1)
    p[1, 2] = (t + b) / (t - b)
    p[2, 2] = -(f + n) / (f - n)
    p[2, 3] = -(2 * f * n) / (f - n)
    p[3, 2] = -1
    return p  # 4,4


def make_star_cameras(
    az_count,
    pol_count,
    distance: float = 10.0,
    r=None,
    image_size=[512, 512],
    device="cuda",
):
    if r is None:
        r = 1 / distance
    A = az_count
    P = pol_count
    C = A * P

    phi = torch.arange(0, A) * (2 * torch.pi / A)
    phi_rot = torch.eye(3, device=device)[None, None].expand(A, 1, 3, 3).clone()
    phi_rot[:, 0, 2, 2] = phi.cos()
    phi_rot[:, 0, 2, 0] = -phi.sin()
    phi_rot[:, 0, 0, 2] = phi.sin()
    phi_rot[:, 0, 0, 0] = phi.cos()

    theta = torch.arange(1, P + 1) * (torch.pi / (P + 1)) - torch.pi / 2
    theta_rot = torch.eye(3, device=device)[None, None].expand(1, P, 3, 3).clone()
    theta_rot[0, :, 1, 1] = theta.cos()
    theta_rot[0, :, 1, 2] = -theta.sin()
    theta_rot[0, :, 2, 1] = theta.sin()
    theta_rot[0, :, 2, 2] = theta.cos()

    mv = torch.empty((C, 4, 4), device=device)
    mv[:] = torch.eye(4, device=device)
    mv[:, :3, :3] = (theta_rot @ phi_rot).reshape(C, 3, 3)
    mv = _translation(0, 0, -distance, device) @ mv

    return mv, _projection(r, device)


def make_sphere(
    level: int = 2, radius=1.0, device="cuda"
) -> tuple[torch.Tensor, torch.Tensor]:
    sphere = trimesh.creation.icosphere(subdivisions=level, radius=1.0, color=None)
    vertices = (
        torch.tensor(sphere.vertices, device=device, dtype=torch.float32) * radius
    )
    faces = torch.tensor(sphere.faces, device=device, dtype=torch.long)
    return vertices, faces