#define INTERVALS_HALF_HOUR     1024 //example

#define BLIND_LEVELS            4

#define INTENSITY_MAX           255

typedef enum {
    MODE_CALIBRATE,
    MODE_MANUAL,
    MODE_AUTO_WARM,
    MODE_AUTO_COOL
} blind_mode;

typedef enum {
    BUTTON_NONE,
    BUTTON_MODE,
    BUTTON_UP,
    BUTTON_DOWN,
    BUTTON_CALIBRATE
} button_input;

int current_position; //the current "position" the blind is in
int position_levels[BLIND_LEVELS]; //an array of the intervals we should keep our blind at
int max_position; //the maximum "position" we can extend the blind to

int intensity_levels[BLIND_LEVELS];
int current_intensity; // 0 - 3 (representing intensity classes)

int interval_since_move; //how long it's been since we've last moved

blind_mode current_mode;

void setup() {
    //Set up data direction registers
    
    //Set up interrupts
    
    //Set up intensity classes
    intensity_levels[0] = (INTENSITY_MAX + 1) / BLIND_LEVELS;

    for (i = 1; i < BLIND_LEVELS; i++)
        intensity_levels[i] = intensity_levels[0] * i;

    //Put unit manual mode by default
}

void main() {
    setup();

    for( ; ; ) {
        switch (current_mode) {
            case MODE_MANUAL:
                manual_mode();
                break;
            case MODE_AUTO_WARM:
            case MODE_AUTO_COOL:
                auto_mode();
                break;
            case MODE_CALIBRATE:
                calibrate_mode();
                break
        }
    }
}

void manual_mode() {
    button_input button;

    while (MODE_MANUAL == current_mode) {
        button = check_buttons();
        if (BUTTON_UP == button) {
            //roll up
        } else if (BUTTON_DOWN == button) {
            //roll down
        } else if (BUTTON_MODE == button) {
            //toggle_mode();
        }
    }
}

void auto_mode(auto_mode mode) {
    int intensity_level, new_position_level = -1;

    while (MODE_AUTO_WARM == current_mode || MODE_AUTO_COOL == current_mode)  {

        if (interval_since_move > INTERVALS_HALF_HOUR) {
            //we have waited long enough, check if we should move
            intensity_level = check_intensity();

            if (intensity_level != current_intensity) {

                if (MODE_AUTO_WARM == current_mode)
                    new_position_level = (BLIND_LEVELS - 1) - intensity_level;
                else if (MODE_AUTO_COOL == current_mode) {
                    new_position_level = intensity_level;
                
                roll(position_levels[new_position_level]);
            }
        }
    }
}

//reads LDR and returns the intensity interval of the sensed light
unsigned char check_intensity_level() {
    unsigned char intensity = 0; //READ INTENSITY FROM SENSOR

    //SOME DAA / ADD IO
    
    return intensity / ((INTENSITY_MAX + 1) / BLIND_LEVELS);
}

void calibrate_mode() {
    //set position = max_position = 0
    //start timer

    while (BUTTON_CALIBRATE == check_buttons()) {
        //keep counting
        //(timer interrupt function will continue adding to position)
    }

    //end timer
    //save max_position = position

    position_levels[0] = max_position / BLIND_LEVELS;

    for (i = 1; i < BLIND_LEVELS; i++)
        position_levels[i] = position_levels[0] * i;
}

button_input check_buttons() {
}

void roll(int new_position) {
    //if new_position > current position, roll down
    //if new_position < current position, roll up
}