#include <kernel/tty.h>
#include <stdint.h>
#include <stdbool.h>
#include <strlib.h>

static inline uint8_t inb(uint16_t port)
{
    uint8_t ret;
    __asm__ volatile ( "inb %w1, %b0"
                   : "=a"(ret)
                   : "Nd"(port)
                   : "memory");
    return ret;
}

static bool is_in_shift;

static unsigned char keyboard_char(unsigned char scancode) 
{
    if (0x01 < scancode && scancode < 0x0B) {
        return scancode - 2 + '1';
    }

    if (scancode == 0x0B) {
        return '0';
    }

    switch (scancode) {
        case 0x10:
            return 'Q';
        case 0x11:
            return 'W';
        case 0x12:
            return 'E';
        case 0x13:
            return 'R';
        case 0x14:
            return 'T';
        case 0x15:
            return 'Y';
        case 0x16:
            return 'U';
        case 0x17:
            return 'I';
        case 0x18:
            return 'O';
        case 0x19:
            return 'P';
        case 0x1a:
            return '[';
        case 0x1b:
            return ']';
        case 0x1c:
            return '\n';
        case 0x1d:
            return '\b';
        case 0x1e:
            return 'A';
        case 0x1f:
            return 'S';
        case 0x20:
            return 'D';
        case 0x21:
            return 'F';
        case 0x22:
            return 'G';
        case 0x23:
            return 'H';
        case 0x24:
            return 'J';
        case 0x25:
            return 'K';
        case 0x26:
            return 'L';
        case 0x27:
            return ';';
        case 0x28:
            return '\'';
        case 0x29:
            return '`';
        case 0x2a:
            is_in_shift = true;
            break;
        case 0x2b:
            return '\\';
        case 0x2c:
            return 'Z';
        case 0x2d:
            return 'X';
        case 0x2e:
            return 'C';
        case 0x2f:
            return 'V';
        case 0x30:
            return 'B';
        case 0x31:
            return 'N';
        case 0x32:
            return 'M';
        case 0x33:
            return ',';
        case 0x34:
            return '.';
        case 0x35:
            return '/';
        case 0x36:
            is_in_shift = true;
            break;
        case 0x39:
            return ' ';
        case 0xaa:
            is_in_shift = false;
            break;
        case 0xb6:
            is_in_shift = false;
            break;
    }

    return -1;
}

char get_last_key_pressed() 
{
    char scancode = inb(0x60);

    if (is_in_shift) {
        return keyboard_char(scancode);
    }

    return to_lower_char(keyboard_char(scancode));
}

void print_hex_digit(uint8_t digit)
{
    digit = digit & 0xf;
    if (digit < 0xA) {
        terminal_putchar(digit + 0x30);
    } else {
        terminal_putchar(digit + 0x41 - 0xA);
    }
}

void print_hex_byte(uint8_t byte) 
{
    int upper = byte >> 4;
    int lower = byte & 0x0F;

    print_hex_digit(upper);
    print_hex_digit(lower);
}

void print_hex_bytes(void* bytes, size_t len) 
{
    uint8_t* value = bytes;
    for (size_t i = len; i > 0; i--) {
        print_hex_byte(value[i - 1]);
    }
}