# Copyright (C) 2022 RozK
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from array import array

from engine import (
    INSTANCE_FLAG_SPAWNED, BATCH_MAX_SIZE, create_batch, draw_batch, destroy_batch)

class Batch:
    __slots__ = '_batch', 'max_size', 'flags', 'meshes', 'params'

    def __init__(self, max_size, params_format):
        assert max_size <= BATCH_MAX_SIZE
        self._batch = create_batch(max_size, params_format)
        self.max_size = max_size
        self.flags = array('B')
        self.meshes = array('I')
        self.params = [array('f') for _ in params_format]

    def __del__(self):
        destroy_batch(self._batch)

    def append(self, flags, mesh, params):
        assert len(params) == len(self.params)
        index = len(self.flags)
        assert index < self.max_size
        self.flags.append(flags | INSTANCE_FLAG_SPAWNED)
        self.meshes.append(mesh)
        for _params, param in zip(self.params, params):
            _params.extend(param)
        return index

    def set_param(self, param, index, value):
        size = len(value)
        self.params[param][index * size : index * size + size] = value

    def draw(self):
        draw_batch(self._batch, self.flags, self.meshes, self.params)