from libs import *

# https://iquilezles.org/articles/intersectors/
def intersect_tri(ro, rd, tv):
    e1 = tv[1] - tv[0]
    e2 = tv[2] - tv[0]
    to = ro - tv[0]
    n = np.cross(e1, e2)
    q = np.cross(to, rd)
    d = 1.0 / np.dot(rd, n)
    u = d * np.dot(-q, e2)
    v = d * np.dot(q, e1)
    t = d * np.dot(-n, to)
    if u > 0.0 and v > 0.0 and u + v < 1.0 and t > 1e-3:
        return t

class Entity:
    def __init__(self, verts, col, pos, **kwargs):
        self.verts = vec(verts)
        self.col = vec(col)
        self.pos = vec(pos)
        self.draw_mode = kwargs.get("mode", GL_TRIANGLE_STRIP)
        self.hud = kwargs.get("hud", False)
        self.orient = np.identity(4, dtype=FLOAT)
        self.onclick = lambda s, b, n: print(f"clicked {s}:{n} with button {b}")
        self.vao = None
        self.vbos = [[None, 0], [None, 0]]

    def col_list(self):
        return np.repeat(vec([self.col]), len(self.verts), 0)

    def update_attr(self, i, l=None):
        if l is None:
            l = self.verts if i == 0 else self.col_list()
        if self.vao:
            glBindBuffer(GL_ARRAY_BUFFER, self.vbos[i][0])
            if l.shape[0] != self.vbos[i][1]:
                glBufferData(GL_ARRAY_BUFFER, l.nbytes, l, GL_DYNAMIC_DRAW)
                self.vbos[i][1] = l.shape[0]
            else:
                glBufferSubData(GL_ARRAY_BUFFER, 0, l.nbytes, l)

    def build_vao(self):
        self.vao = glGenVertexArrays(1)
        glBindVertexArray(self.vao)
        for (i, l) in enumerate((self.verts, self.col_list())):
            self.vbos[i][0] = glGenBuffers(1)
            self.update_attr(i, l)
            glEnableVertexAttribArray(i)
            glVertexAttribPointer(i, l.shape[1], GL_FLOAT, GL_FALSE, 0, None)

    def translate(self):
        m = np.identity(4, dtype=FLOAT)
        m[:3, 3] = self.pos
        return m

    def rotate(self, theta, axis):
        x, y, z = axis
        c, s = np.cos(theta), np.sin(theta)
        t = 1 - c
        self.orient = vec([
            [t*x*x + c,   t*x*y - s*z, t*x*z + s*y, 0],
            [t*x*y + s*z, t*y*y + c,   t*y*z - s*x, 0],
            [t*x*z - s*y, t*y*z + s*x, t*z*z + c,   0],
            [0, 0, 0, 1]
        ]) @ self.orient

    def click(self, button, face):
        self.onclick(self, button, face)

    def raycast(self, ro, rd):
        if self.hud or self.draw_mode == GL_LINES:
            return
        elif self.draw_mode == GL_TRIANGLE_STRIP:
            tl = ((i, self.verts[i:i + 3]) for i in range(len(self.verts) - 2))
        elif self.draw_mode == GL_TRIANGLES:
            tl = ((i, self.verts[3 * i:3 * (i + 1)]) for i in range(len(self.verts) // 3))
        else:
            raise NotImplementedError
        d, n = None, None
        for (i, t) in tl:
            r = intersect_tri(ro, rd, np.dot(t, self.orient[:3, :3].T) + self.pos)
            if r and (d is None or r < d):
                d, n = r, i
        return d, n