# -*- encoding: utf-8 -*-
##
## Copyright (C) 2011 Thibaut Girka <thib@sitedethib.com>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published
## by the Free Software Foundation; version 3 only.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##

from libc.stdlib cimport malloc, free

import ctypes

from struct import pack
from itertools import chain

from pyglet.gl import *

from .texture import TextureManager
from .sprite cimport get_sprite_rendering_data
from .background import get_background_rendering_data


MAX_ELEMENTS = 10000


cdef struct Vertex:
    int x, y, z
    float u, v
    unsigned char r, g, b, a


cdef class GameRenderer:
    cdef public texture_manager
    cdef public game
    cdef public background

    cdef Vertex *vertex_buffer


    def __cinit__(self):
        # Allocate buffers
        self.vertex_buffer = <Vertex*> malloc(MAX_ELEMENTS * sizeof(Vertex))


    def __dealloc__(self):
        free(self.vertex_buffer)


    def __init__(self, resource_loader, game=None, background=None):
        self.texture_manager = TextureManager(resource_loader)

        self.game = game
        self.background = background


    cdef render_elements(self, elements):
        cdef unsigned short nb_vertices = 0

        indices_by_texture = {}

        for element in elements:
            sprite = element._sprite
            if sprite:
                ox, oy = element.x, element.y
                key, (vertices, uvs, colors) = get_sprite_rendering_data(sprite)
                rec = indices_by_texture.setdefault(key, [])

                # Pack data in buffer
                (x1, y1, z1), (x2, y2, z2), (x3, y3, z3), (x4, y4, z4) = vertices
                r1, g1, b1, a1, r2, g2, b2, a2, r3, g3, b3, a3, r4, g4, b4, a4 = colors
                u1, v1, u2, v2, u3, v3, u4, v4 = uvs
                self.vertex_buffer[nb_vertices] = Vertex(x1 + ox, y1 + oy, z1, u1, v1, r1, g1, b1, a1)
                self.vertex_buffer[nb_vertices+1] = Vertex(x2 + ox, y2 + oy, z2, u2, v2, r2, g2, b2, a2)
                self.vertex_buffer[nb_vertices+2] = Vertex(x3 + ox, y3 + oy, z3, u3, v3, r3, g3, b3, a3)
                self.vertex_buffer[nb_vertices+3] = Vertex(x4 + ox, y4 + oy, z4, u4, v4, r4, g4, b4, a4)

                # Add indices
                index = nb_vertices
                rec.extend((index, index + 1, index + 2, index + 3))

                nb_vertices += 4

        for (texture_key, blendfunc), indices in indices_by_texture.items():
            glVertexPointer(3, GL_INT, 24, <long> &self.vertex_buffer[0].x)
            glTexCoordPointer(2, GL_FLOAT, 24, <long> &self.vertex_buffer[0].u)
            glColorPointer(4, GL_UNSIGNED_BYTE, 24, <long> &self.vertex_buffer[0].r)

            nb_indices = len(indices)
            indices = pack(str(nb_indices) + 'H', *indices)
            glBlendFunc(GL_SRC_ALPHA, (GL_ONE_MINUS_SRC_ALPHA, GL_ONE)[blendfunc])
            glBindTexture(GL_TEXTURE_2D, self.texture_manager[texture_key].id)
            glDrawElements(GL_QUADS, nb_indices, GL_UNSIGNED_SHORT, indices)


    def render(self):
        glClear(GL_DEPTH_BUFFER_BIT)

        back = self.background
        game = self.game
        texture_manager = self.texture_manager

        if back is not None:
            fog_b, fog_g, fog_r, fog_start, fog_end = back.fog_interpolator.values
            x, y, z = back.position_interpolator.values
            dx, dy, dz = back.position2_interpolator.values

            glFogi(GL_FOG_MODE, GL_LINEAR)
            glFogf(GL_FOG_START, fog_start)
            glFogf(GL_FOG_END,  fog_end)
            glFogfv(GL_FOG_COLOR, (GLfloat * 4)(fog_r / 255., fog_g / 255., fog_b / 255., 1.))

            glMatrixMode(GL_MODELVIEW)
            glLoadIdentity()
            # Some explanations on the magic constants:
            # 192. = 384. / 2. = width / 2.
            # 224. = 448. / 2. = height / 2.
            # 835.979370 = 224./math.tan(math.radians(15)) = (height/2.)/math.tan(math.radians(fov/2))
            # This is so that objects on the (O, x, y) plane use pixel coordinates
            gluLookAt(192., 224., - 835.979370 * dz,
                      192. + dx, 224. - dy, 0., 0., -1., 0.)
            glTranslatef(-x, -y, -z)

            glEnable(GL_DEPTH_TEST)
            for (texture_key, blendfunc), (nb_vertices, vertices, uvs, colors) in get_background_rendering_data(back):
                glBlendFunc(GL_SRC_ALPHA, (GL_ONE_MINUS_SRC_ALPHA, GL_ONE)[blendfunc])
                glBindTexture(GL_TEXTURE_2D, texture_manager[texture_key].id)
                glVertexPointer(3, GL_FLOAT, 0, vertices)
                glTexCoordPointer(2, GL_FLOAT, 0, uvs)
                glColorPointer(4, GL_UNSIGNED_BYTE, 0, colors)
                glDrawArrays(GL_QUADS, 0, nb_vertices)
            glDisable(GL_DEPTH_TEST)
        else:
            glClear(GL_COLOR_BUFFER_BIT)

        if game is not None:
            glMatrixMode(GL_MODELVIEW)
            glLoadIdentity()
            # Some explanations on the magic constants:
            # 192. = 384. / 2. = width / 2.
            # 224. = 448. / 2. = height / 2.
            # 835.979370 = 224./math.tan(math.radians(15)) = (height/2.)/math.tan(math.radians(fov/2))
            # This is so that objects on the (O, x, y) plane use pixel coordinates
            gluLookAt(192., 224., - 835.979370,
                      192., 224., 0., 0., -1., 0.)

            glDisable(GL_FOG)
            self.render_elements(game.enemies)
            self.render_elements(game.effects)
            self.render_elements(chain(game.players_bullets,
                                       game.players,
                                       *(player.objects() for player in game.players)))
            self.render_elements(chain(game.bullets, game.cancelled_bullets, game.items))
            #TODO: display item indicators
            glEnable(GL_FOG)