# 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 math import radians, cos

from engine import *

from game.math import vec3_add, vec3_sub, vec3_scale, vec3_mul, vec3_dot

def _angles(start, end):
    cmin = round(cos(radians(start)), 6)
    cmax = round(cos(radians(end)), 6)
    return (cmin, cmax, 1.0 / (cmax - cmin))

def _floats(a, b):
    return (a, b - a)

def _colors(a, b):
    return (a, vec3_sub(b, a))

_light_color = (
    (_angles(180.0, 0.0), _colors((1.0, 1.0, 1.0), (1.0, 1.0, 1.0))),
)

_horizon_color = (
    (_angles(180.0, 0.0), _colors((0.75, 0.75, 1.0), (0.75, 0.75, 1.0))),
)

_sky_color = (
    (_angles(180.0, 0.0), _colors((0.0, 0.0, 0.5), (0.0, 0.0, 0.5))),
)

_sun_color = (
    (_angles(180.0, 0.0), _colors((8.0, 8.0, 4.0), (8.0, 8.0, 4.0))),
)

_light_power = (
    (_angles(180.0, 90.0), _floats(0.0, 0.0)),
    (_angles( 90.0,  0.0), _floats(0.0, 1.0))
)

def _resolve(ranges, c):
    for (cmin, cmax, crng), ab in ranges:
        if c >= cmin and c <= cmax:
            return ((c - cmin) * crng, ab)
    return None

def _resolve_float(ranges, c):
    w, (a, b) = _resolve(ranges, c)
    return a + (b * w)

def _resolve_color(ranges, c):
    w, (a, b) = _resolve(ranges, c)
    return vec3_add(a, vec3_scale(b, w))

def resolve_inputs(shader):
    light_direction = resolve_input(shader, b'u_light_direction')
    light_color = resolve_input(shader, b'u_light_color')
    horizon_color = resolve_input(shader, b'u_horizon_color')
    sky_color = resolve_input(shader, b'u_sky_color')
    sun_color = resolve_input(shader, b'u_sun_color')
    return (light_direction, light_color, horizon_color, sky_color, sun_color)

def from_sun(view, sun_direction, sun_power):
    c = vec3_dot(sun_direction, vec3_up)
    light_power = _resolve_float(_light_power, c) * sun_power
    light_color = vec3_scale(_resolve_color(_light_color, c), sun_power) # vec3_scale(_resolve_color(_light_color, c), light_power)
    horizon_color = vec3_mul(_resolve_color(_horizon_color, c), light_color)
    sky_color = vec3_mul(_resolve_color(_sky_color, c), light_color)
    sun_color = _resolve_color(_sun_color, c)
    light_direction = vec3()
    mat4_mul_vec3(light_direction, view, sun_direction, 0.0)
    return (light_direction, vec3(light_color), vec3(horizon_color), vec3(sky_color), vec3(sun_color))

def update_inputs(inputs, values):
    list(map(set_input_vec3, inputs, values))