import numpy as np
from scipy.spatial import ConvexHull
from stl import mesh


def generate_mesh(points, depth):
    """
    Generate a mesh by extruding a 2D shape along the Z-axis.

    :param points: List of (x, y) tuples representing the 2D shape.
    :param depth: Extrusion depth along the Z-axis.
    :return: Tuple of vertices and faces.
    """
    # Convert points to a numpy array
    points_2d = np.array(points)

    # Get the convex hull of the points to ensure they form a proper polygon
    hull = ConvexHull(points_2d)
    hull_points = points_2d[hull.vertices]

    # Generate the top and bottom faces
    bottom_face = np.hstack((hull_points, np.zeros((hull_points.shape[0], 1))))
    top_face = np.hstack((hull_points, np.ones((hull_points.shape[0], 1)) * depth))

    # Combine top and bottom vertices
    vertices_array = np.vstack((bottom_face, top_face))

    # Create faces
    faces = []

    # Bottom face triangulation (counter-clockwise)
    for i in range(len(hull_points) - 2):
        faces.append([0, i + 2, i + 1])

    # Top face triangulation (counter-clockwise, with an offset)
    top_offset = len(hull_points)
    for i in range(len(hull_points) - 2):
        faces.append([top_offset, top_offset + i + 1, top_offset + i + 2])

    # Side faces (ensure counter-clockwise order)
    for i in range(len(hull_points)):
        next_i = (i + 1) % len(hull_points)
        faces.append([i, top_offset + i, top_offset + next_i])
        faces.append([i, top_offset + next_i, next_i])

    # Convert vertices to the desired format: list of tuples
    vertices = [tuple(vertex) for vertex in vertices_array]

    return vertices, faces