/*
 * This program source code file is part of SystemK, a library in the KTag project.
 *
 * 🛡️ <https://ktag.clubk.club> 🃞
 *
 * Copyright © 2016-2025 Joseph P. Kearney and the KTag developers.
 *
 * 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.
 *
 * There should be a copy of the GNU Affero General Public License in the LICENSE
 * file in the root of this repository.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "SystemK.h"

#define RED_DELTA_MAX 15
#define GREEN_DELTA_MAX 8
#define MAX_RED 128
#define MIN_RED RED_DELTA_MAX
#define MIN_GREEN 1
#define LESS_GREEN_THAN_RED 20

static int16_t RedLevel = 0;
static int16_t GreenLevel = 0;

// From https://stackoverflow.com/a/1180465
static uint8_t lfsr113_Bits (uint32_t min, uint32_t max)
{
   static uint32_t z1 = 12345, z2 = 12345, z3 = 12345, z4 = 12345;
   uint32_t b;
   b  = ((z1 << 6) ^ z1) >> 13;
   z1 = ((z1 & 4294967294U) << 18) ^ b;
   b  = ((z2 << 2) ^ z2) >> 27; 
   z2 = ((z2 & 4294967288U) << 2) ^ b;
   b  = ((z3 << 13) ^ z3) >> 21;
   z3 = ((z3 & 4294967280U) << 7) ^ b;
   b  = ((z4 << 3) ^ z4) >> 12;
   z4 = ((z4 & 4294967168U) << 13) ^ b;
   uint64_t raw = (z1 ^ z2 ^ z3 ^ z4);
   uint32_t scaled = ((((max - min) * raw) + (UINT32_MAX / 2)) / UINT32_MAX) + min;
   return (uint8_t) scaled;
}

static void Reset(void * Data)
{
    RedLevel = MIN_RED;
    GreenLevel = MIN_GREEN;
}

// TODO: Need to reimplement this with HSB--see https://blog.adafruit.com/2012/03/14/constant-brightness-hsb-to-rgb-algorithm/
static AnimationStepResult_T NextStep(void)
{
    // get our next changes in red and green
    int16_t delta_red = (lfsr113_Bits(0, RED_DELTA_MAX*2) - RED_DELTA_MAX);
    int16_t delta_green = (lfsr113_Bits(0, GREEN_DELTA_MAX*2) - GREEN_DELTA_MAX);
    
    RedLevel = RedLevel + delta_red;
    
    if (RedLevel > MAX_RED)
    {
        RedLevel = MAX_RED;
    }
    else if (RedLevel < MIN_RED)
    {
        RedLevel = MIN_RED;
    }
    RedLevel = (uint8_t) RedLevel;
    
    GreenLevel = GreenLevel + delta_green;
    
    // Green has to be less than red, to keep the flame red-orange-yellow.
    if (RedLevel > LESS_GREEN_THAN_RED)
    {
        if (GreenLevel > (RedLevel - LESS_GREEN_THAN_RED))
        {
            GreenLevel = (RedLevel - LESS_GREEN_THAN_RED);
        }
        else if (GreenLevel < MIN_GREEN)
        {
            GreenLevel = MIN_GREEN;
        }
    }
    else
    {
        GreenLevel = MIN_GREEN;
    }
    GreenLevel = (uint8_t) GreenLevel;

    NeoPixels_Set_Color(NEOPIXEL_CHANNEL_BARREL, BARREL_FLASH_PIXEL, Color(0xFF, RedLevel, GreenLevel, 0x00));

    return ANIMATION_ONGOING;
}

Animation_T Flamethrower_Animation = 
{
    .Reset = Reset,
    .NextStep = NextStep
};