import numpy as np
import string
import struct

class Mesh(object):
    def __init__(self, vertices, triangles):
        vertices = np.asarray(vertices, dtype=float)
        triangles = np.asarray(triangles, dtype=int)

        if len(vertices.shape) != 2 or vertices.shape[1] != 3:
            raise ValueError('shape mismatch')

        if len(triangles.shape) != 2 or triangles.shape[1] != 3:
            raise ValueError('shape mismatch')

        if (triangles < 0).any():
            raise ValueError('indices in `triangles` must be positive.')

        if (triangles >= len(vertices)).any():
            raise ValueError('indices in `triangles` must be less than the '
                             'length of the vertex array.')

        self.vertices = vertices
        self.triangles = triangles

    def build(self):
        return self.vertices[self.triangles]

    def __getitem__(self, key):
        return self.vertices[self.triangles[key]]

    def __len__(self):
        return len(self.triangles)

def mesh_from_stl(filename):
    f = open(filename)
    buf = f.read(200)
    f.close()

    for char in buf:
        if char not in string.printable:
            return mesh_from_binary_stl(filename)

    return mesh_from_ascii_stl(filename)

def mesh_from_ascii_stl(filename):
    f = open(filename)

    vertices = []
    triangles = []
    vertex_map = {}

    while True:
        line = f.readline()

        if line == '':
            break

        if not line.strip().startswith('vertex'):
            continue

        triangle = [None]*3
        for i in range(3):
            vertex = tuple([float(s) for s in line.strip().split()[1:]])

            if vertex not in vertex_map:
                vertices.append(vertex)
                vertex_map[vertex] = len(vertices) - 1

            triangle[i] = vertex_map[vertex]

            if i < 3:
                line = f.readline()

        triangles.append(triangle)

    f.close()

    return Mesh(np.array(vertices), np.array(triangles, dtype=np.uint32))

def mesh_from_binary_stl(filename):
    f = open(filename)

    vertices = []
    triangles = []
    vertex_map = {}

    f.read(80)
    ntriangles = struct.unpack('<I', f.read(4))[0]

    for i in range(ntriangles):
        f.read(12)

        triangle = [None]*3
        for j in range(3):
            vertex = tuple(struct.unpack('<fff', f.read(12)))

            if vertex not in vertex_map:
                vertices.append(vertex)
                vertex_map[vertex] = len(vertices) - 1

            triangle[j] = vertex_map[vertex]

        triangles.append(triangle)

        f.read(2)

    f.close()

    return Mesh(np.array(vertices), np.array(triangles, dtype=np.uint32))