#define	F_CPU   8000000UL

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <stdbool.h>

#define SPI_PORT PORTB
#define SPI_DDR DDRB
#define SPI_SCK PB5
#define SPI_MOSI PB3
#define SPI_SS PB2

#define LCD_CD PB0
#define LCD_RST PB1

#define ENC_A (PINB & (1 << PB6))
#define ENC_B (PINB & (1 << PB7))

const uint8_t splash[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xC0, 0xE0, 0xF0, 0xF0, 0xF8, 0xFC, 0xFC, 0xFE, 0xFE, 0xFE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0xFE, 0xFE, 0xFC, 0xFC, 0xF8, 0xF0, 0xF0, 0xE0, 0xC0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                          0x00, 0x00, 0x00, 0x00, 0x80, 0xF0, 0xFC, 0xFE, 0xFF, 0xFF, 0x7F, 0x3F, 0x1F, 0x3F, 0x3F, 0x7F, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x7F, 0x1F, 0x0F, 0x0F, 0x07, 0x07, 0x07, 0x03, 0xC3, 0xE3, 0x73, 0x37, 0x17, 0x07, 0x0F, 0x1E, 0x3C, 0xF0, 0x80, 0x00, 0x00, 0x00, 0x00,
                          0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xE7, 0xC3, 0x81, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0xFF, 0xFF, 0xFF, 0xFF, 0x0F, 0x00, 0x00, 0xFC, 0xFE, 0xFE, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0xFC, 0x30, 0x00, 0x00, 0xFF, 0x00, 0x00, 0x00, 0x00,
                          0x00, 0x00, 0x00, 0x00, 0x01, 0x0F, 0x3F, 0x4F, 0x9F, 0x3F, 0x3E, 0x3C, 0x7C, 0x7C, 0x7C, 0x7C, 0x3E, 0x3E, 0x3E, 0x1F, 0x1F, 0x0F, 0x07, 0x01, 0x00, 0x00, 0x00, 0x01, 0x03, 0x07, 0x07, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x07, 0x07, 0x03, 0x81, 0x40, 0x30, 0x0E, 0x01, 0x00, 0x00, 0x00, 0x00,
                          0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x04, 0x08, 0x08, 0x10, 0x20, 0x20, 0x40, 0x40, 0x40, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x40, 0x40, 0x40, 0x20, 0x20, 0x10, 0x08, 0x08, 0x04, 0x02, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                          0xE0, 0x60, 0xE0, 0x00, 0x00, 0xE0, 0x60, 0xE0, 0x00, 0x00, 0xE0, 0x60, 0xF8, 0x00, 0x00, 0xE0, 0xA0, 0xE0, 0x00, 0x00, 0xE0, 0x20, 0x60, 0x00, 0x00, 0xE0, 0xA0, 0xA0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xE0, 0x60, 0xE0, 0x00, 0x00, 0xE0, 0x20, 0x60, 0x00, 0x00, 0xE0, 0x60, 0xE0,
                          0x03, 0x02, 0x03, 0x00, 0x00, 0x03, 0x00, 0x03, 0x00, 0x00, 0x03, 0x02, 0x03, 0x00, 0x00, 0x03, 0x02, 0x02, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00, 0x02, 0x02, 0x03, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x03, 0x02, 0x03, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00, 0x0B, 0x0A, 0x0F};

static uint8_t enc = 0;

void spi_init(void) {
    SPI_DDR |= (1 << SPI_SCK) | (1 << SPI_MOSI) | (1 << SPI_SS);
    SPI_PORT |= (1 << SPI_SS);
    SPCR = (1 << SPE) | (1 << MSTR);
    SPSR = (1 << SPI2X);
}

uint8_t spi_byte(uint8_t data) {
   SPDR = data;
   while(!(SPSR & (1 << SPIF)));
   return SPDR;
 }

void lcd_write(uint8_t data) {
    SPI_PORT &= ~(1 << SPI_SS);
    spi_byte(data);
    SPI_PORT |= (1 << SPI_SS);
}

void lcd_init(void) {
    SPI_DDR |= (1 << LCD_CD) | (1 << LCD_RST);
    _delay_ms(1);
    SPI_PORT |= (1 << LCD_RST);
    _delay_ms(5);

    lcd_write(0x40); // (6)  Set Scroll Line: Display start line 0
    lcd_write(0xA1); // (13) Set SEG direction: SEG reverse
    lcd_write(0xC0); // (14) Set COM direction: Normal COM0 - COM63
    lcd_write(0xA6); // (11) Set Inverse Display: Display inverse off
    lcd_write(0xA2); // (17) Set LCD Bias Ratio: Set Bias 1/9 (Duty 1/65)
    lcd_write(0x2F); // (5)  Set Power Control: Booster, Regulator and Follower on
    lcd_write(0x27); // (8)  Set VLCD Resistor Ratio: Set Contrast
    lcd_write(0x81); // (9)  Set Electronic Volume: Set Contrast
    lcd_write(0x10); // (9)  Set Electronic Volume: Set Contrast
    lcd_write(0xAF); // (12) Set Display Enable: Display on
}

void lcd_fill(uint8_t data) {
    for (uint8_t i = 0; i < 8; i++) {
        SPI_PORT &= ~(1 << LCD_CD);
        lcd_write(0x00);
        lcd_write(0x10);
        lcd_write(0xB0 + i);
        SPI_PORT |= (1 << LCD_CD);

        for (uint8_t j = 0; j < 102; j++)
            lcd_write(data);
    }
}

void lcd_splash() {
    lcd_fill(0x00);

    for (uint8_t i = 0; i < 7; i++) {
        SPI_PORT &= ~(1 << LCD_CD);
        lcd_write(0x0B);
        lcd_write(0x11);
        lcd_write(0xB1 + i);
        SPI_PORT |= (1 << LCD_CD);

        for (uint8_t j = 0; j < 48; j++)
            lcd_write(splash[i * 48 + j]);
    }
}

// Encoder rotation interrupt
ISR(PCINT0_vect) {
    cli();

    switch(enc) {
    case 0:
        if (ENC_A && !ENC_B)
            enc = 1;
        else if (!ENC_A && ENC_B)
            enc = 3;
        break;
    case 1:
        if (ENC_A && ENC_B) {
            enc = 2;
        } else if (!ENC_A && !ENC_B) {
            enc = 0;
        }
        break;
    case 2:
        if (!ENC_A && ENC_B)
            enc = 3;
        else if (ENC_A && !ENC_B)
            enc = 1;
        break;
    case 3:
        if (!ENC_A && !ENC_B) {
            enc = 0;
        } else if (ENC_A && ENC_B) {
            enc = 2;
        }
        break;
    }

    // TODO: proper debounce and dechattering
    _delay_us(100);

    sei();
}

int main(void) {
    // FastPWM: 1.25kHz
    // TODO: Try to get the backlit even more dim
    TCCR0A = (1 << WGM01) | (1 << WGM00) | (1 << COM0B1);
    TCCR0B = (1 << CS01) | (1 << WGM02); // prescaler = 8;
    OCR0A = 100;
    OCR0B = 0;
    DDRD |= (1 << PD5);

    // SPI setup
    spi_init();
    lcd_init();

    // Encoder setup
    PORTB |= (1 << PB6) | (1 << PB7);
    PCICR |= (1 << PCIE0);
    PCMSK0 |= (1 << PCINT6) | (1 << PCINT7);

    // Show splash screen
    lcd_splash();

    // Enable interrupts
    sei();

    // Run...
    for (;;);
}