#include <avr/io.h>
#include <avr/eeprom.h>

#include "lights.h"

#define AMBIENT_FAST_SHIFT 2	// running avg of ADC vals
#define AMBIENT_SLOW_SHIFT 6	// 1 << AMBIENT_SLOW_SHIFT times slower

static uint16_t ambient_fast, ambient_slow;
volatile unsigned char ambient_zone;
static unsigned char ambient_min, ambient_max, ambient_drop;

/* logging */
#define AMBIENT_LOG_SIZE 128
static unsigned char ambient_log_offset_stored EEMEM;
static unsigned char ambient_log_offset;
static unsigned char ambient_log[AMBIENT_LOG_SIZE] EEMEM;

/* My photodiode reads 0x00C5 .. 0x033B */
typedef struct {
	uint16_t lo, hi; // TODO: consider changing this to bytes
} ambient_zone_t;

/*
 * Note: these have to be sorted, starting with 0, ending with 0xFFFF
 * and having small overlaps in order to provide a bit of hysteresis.
 */
static ambient_zone_t ambient_zones[N_AMBIENT_ZONES] = {
	{ 0x0000, 0x0250 }, // dark
	{ 0x0240, 0x02e0 }, // evening
	{ 0x02c0, 0x0306 }, // dawn
	{ 0x02f8, 0xffff }, // day
};

void init_ambient()
{
	ambient_slow = 0;
	ambient_fast = 0;
	ambient_max = 0;
	ambient_min = 0xFF;
	ambient_zone = 1;
	ambient_drop = 0;

	ambient_log_offset = eeprom_read_byte(&ambient_log_offset_stored);

	if (ambient_log_offset == AMBIENT_LOG_SIZE)
		ambient_log_offset = 0; // start over
}

void susp_ambient()
{
	unsigned char stored_offset;

	ambient_log_min_max();

	stored_offset = eeprom_read_byte(&ambient_log_offset_stored);
	if (stored_offset != ambient_log_offset)
		eeprom_write_byte(&ambient_log_offset_stored,
			ambient_log_offset);
}

void ambient_log_min_max()
{
	if (ambient_log_offset >= AMBIENT_LOG_SIZE - 1)
		return;

	ambient_max -= ambient_min;
	ambient_max >>= 2;
	if (ambient_max > 15)
		ambient_max = 15;

	ambient_drop >>= 2;
	if (ambient_drop > 15)
		ambient_drop = 15;

	eeprom_write_byte(&ambient_log[ambient_log_offset++], ambient_min);
	eeprom_write_byte(&ambient_log[ambient_log_offset++],
		(ambient_max << 4) | ambient_drop);

	ambient_min = 0xFF;
	ambient_max = 0;
	ambient_drop = 0;
}

static inline void ambient_zone_changed()
{
	pwmled_select_brightness();
	pattern_reload();
}

static unsigned char val_to_zone(uint16_t ambient_val)
{
	unsigned char new_zone = ambient_zone;

	while (ambient_zones[new_zone].lo > ambient_val)
		new_zone--;

	while (ambient_zones[new_zone].hi < ambient_val)
		new_zone++;

	return new_zone;
}

void ambient_adc(uint16_t adcval)
{
	unsigned char new_zone, user_zone;
	unsigned char byte_fast, byte_slow, drop;
	uint16_t a_10bit;

	// running avg - shorter timespan
	ambient_fast += adcval - (ambient_fast >> AMBIENT_FAST_SHIFT);

	// running avg - longer timespan
	a_10bit = ambient_fast >> (AMBIENT_FAST_SHIFT + AMBIENT_ADC_SHIFT);
	ambient_slow += a_10bit - (ambient_slow >> AMBIENT_SLOW_SHIFT);

	// ambient zones are governed by shorter timespan by default
	new_zone = val_to_zone(a_10bit);

	if (new_zone > 1 && (
		new_zone == ambient_zone-1 || new_zone == ambient_zone+1)) {
		// but change to the neighbouring zone is governed by _slow,
		// except to the darkest zone, where we want fast reaction.
		new_zone = val_to_zone(ambient_slow >> AMBIENT_SLOW_SHIFT);
	}

	// user_param ambient zone override
	if ((user_zone = get_user_param(0)) > 0)
		new_zone = user_zone - 1;

	// TODO: maybe use these values instead of 10-bit?
	byte_fast = a_10bit >> 2;
	byte_slow = ambient_slow >> (AMBIENT_SLOW_SHIFT + 2);

	if (byte_slow > byte_fast) {
		drop = byte_slow - byte_fast;
		if (drop > ambient_drop)
			ambient_drop = drop;
	}

	if (ambient_min > byte_fast)
		ambient_min = byte_fast;

	if (ambient_max < byte_fast)
		ambient_max = byte_fast;

	if (new_zone != ambient_zone) {
		ambient_zone = new_zone;
#if 0
		log_byte(0xab);
		log_byte(ambient_zone);
		log_word(adcval);
		log_flush();
#endif
		ambient_zone_changed();
	}
}