from __future__ import annotations

from pathlib import Path
from typing import Any

import numpy as np
import open3d as o3d
import trimesh


class IOHandler:
    """Centralized input validation and file loading."""

    def resolve_path(self, path: str | Path) -> Path:
        return Path(path).expanduser()

    def require_file(self, path: str | Path, label: str = "file") -> Path:
        resolved = self.resolve_path(path)
        if not resolved.exists():
            raise FileNotFoundError(f"{label} not found: {resolved}")
        if not resolved.is_file():
            raise ValueError(f"{label} is not a file: {resolved}")
        return resolved

    def ensure_parent_dir(self, path: str | Path) -> Path:
        resolved = self.resolve_path(path)
        resolved.parent.mkdir(parents=True, exist_ok=True)
        return resolved

    def load_point_cloud(self, pointcloud_path: str | Path) -> o3d.geometry.PointCloud:
        path = self.require_file(pointcloud_path, "Point cloud")
        pcd = o3d.io.read_point_cloud(str(path))
        if len(pcd.points) == 0:
            raise ValueError(f"Point cloud is empty or unreadable: {path}")
        return pcd

    def load_mesh(self, mesh_path: str | Path) -> trimesh.Trimesh:
        path = self.require_file(mesh_path, "Mesh")
        mesh = trimesh.load(str(path), force="mesh")
        if mesh.is_empty:
            raise ValueError(f"Mesh is empty or unreadable: {path}")
        return mesh

    def require_cad(self, cad_path: str | Path) -> Path:
        return self.require_file(cad_path, "CAD")

    def save_point_cloud(self, pointcloud: o3d.geometry.PointCloud, output_path: str | Path) -> Path:
        path = self.ensure_parent_dir(output_path)
        ok = o3d.io.write_point_cloud(str(path), pointcloud)
        if not ok:
            raise IOError(f"Failed to save point cloud: {path}")
        return path

    def point_cloud_to_numpy(self, pointcloud: o3d.geometry.PointCloud) -> np.ndarray:
        points = np.asarray(pointcloud.points, dtype=np.float64)
        if points.size == 0:
            raise ValueError("Point cloud has no points.")
        return points

    def mesh_triangles_to_numpy(self, mesh: trimesh.Trimesh) -> tuple[np.ndarray, np.ndarray]:
        vertices = np.asarray(mesh.vertices, dtype=np.float64)
        faces = np.asarray(mesh.faces, dtype=np.int64)
        if len(vertices) == 0 or len(faces) == 0:
            raise ValueError("Mesh must contain vertices and faces.")
        return vertices, faces

    def print_mapping(self, data: dict[str, Any]) -> None:
        for key, value in data.items():
            print(f"{key}: {value}")