#include "ws2801.h"

#include "fader.h"

int16_t fadestep = 1;

int somethingChanged = 0; // indicates when a ws2801 update is required

struct Colour {
	int16_t red, green, blue; // value range is 0 to 255
};

struct Colour curColour[MAX_NUM_MODULES];
struct Colour targetColour[MAX_NUM_MODULES];

void fader_init(void)
{
	for(uint32_t i = 0; i < ws2801_num_modules; i++) {
		curColour[i].red   = targetColour[i].red   = 0;
		curColour[i].green = targetColour[i].green = 0;
		curColour[i].blue  = targetColour[i].blue  = 0;
	}
}

void fader_set_colour(uint32_t module, uint8_t r, uint8_t g, uint8_t b)
{
	curColour[module].red   = targetColour[module].red   = r;
	curColour[module].green = targetColour[module].green = g;
	curColour[module].blue  = targetColour[module].blue  = b;

	somethingChanged = 1;
}

void fader_fade_colour(uint32_t module, uint8_t r, uint8_t g, uint8_t b)
{
	targetColour[module].red   = r;
	targetColour[module].green = g;
	targetColour[module].blue  = b;
}

void fader_add_colour(uint32_t module, uint8_t r, uint8_t g, uint8_t b)
{
	curColour[module].red   += r;
	curColour[module].green += g;
	curColour[module].blue  += b;

	if(curColour[module].red > 255) { curColour[module].red = 255; }
	if(curColour[module].green > 255) { curColour[module].green = 255; }
	if(curColour[module].blue > 255) { curColour[module].blue = 255; }

	targetColour[module].red   += r;
	targetColour[module].green += g;
	targetColour[module].blue  += b;

	if(targetColour[module].red > 255) { targetColour[module].red = 255; }
	if(targetColour[module].green > 255) { targetColour[module].green = 255; }
	if(targetColour[module].blue > 255) { targetColour[module].blue = 255; }

	somethingChanged = 1;
}

void fader_set_fadestep(uint8_t newFadestep)
{
	fadestep = newFadestep;
}

/*!
 * Fade the colour value in cur towards target.
 *
 * \param cur      The colour value to update.
 * \param target   The target value that should be reached.
 * \param changed  Output value which is set to 1 if cur was changed.
 */
static void fade_colour(int16_t *cur, const int16_t *target, int *changed)
{
	int16_t diff;
	if(*cur > *target) {
		diff = *cur - *target;
		if(diff < fadestep) {
			*cur = *target;
		} else {
			*cur -= fadestep;
		}

		*changed = 1;
	} else if(*cur < *target) {
		diff = *target - *cur;
		if(diff < fadestep) {
			*cur = *target;
		} else {
			*cur += fadestep;
		}

		*changed = 1;
	}
}

void fader_update(void)
{
	for(uint32_t i = 0; i < ws2801_num_modules; i++) {
		fade_colour(&(curColour[i].red), &(targetColour[i].red), &somethingChanged);
		fade_colour(&(curColour[i].green), &(targetColour[i].green), &somethingChanged);
		fade_colour(&(curColour[i].blue), &(targetColour[i].blue), &somethingChanged);

		ws2801_set_colour(i,
				(uint8_t)curColour[i].red,
				(uint8_t)curColour[i].green,
				(uint8_t)curColour[i].blue);
	}

	if(somethingChanged) {
		ws2801_send_update();
		somethingChanged = 0;
	}
}