#include <cstdint>

#include "graphic.hpp"
#include "font.hpp"

// left-align (with fill)
// right-align

struct bcd_t {
  uint32_t digits;
  int32_t length;

  auto operator<=>(const bcd_t&) const = default;
};

static inline constexpr bcd_t int_to_bcd(int32_t n)
{
  if (n < 0) n = 0; // are there negative numbers in pokemon?
  if (n == 0) return { 0, 1 };
  uint32_t bcd = 0;

  int32_t index = 0;
  while (n != 0) {
    bcd |= (n % 10) << (4 * index);
    n /= 10;
    index += 1;
  }
  return { bcd, index };
}

static_assert(int_to_bcd(0) == (bcd_t){0x0, 1});
static_assert(int_to_bcd(9) == (bcd_t){0x9, 1});
static_assert(int_to_bcd(20) == (bcd_t){0x20, 2});
static_assert(int_to_bcd(512) == (bcd_t){0x512, 3});

void draw_number_right_align(const uint32_t base_pattern,
			     const screen_cell_t& pos,
			     const int32_t n,
			     const int32_t width,
			     const uint8_t fill)
{
  const bcd_t bcd = int_to_bcd(n);

  int32_t index = 0;
  while (index < width) {
    const uint8_t digit = (index < bcd.length)
                        ? ascii_to_font('0' + ((bcd.digits >> (4 * index)) & 0b1111))
                        : fill;
    index++;
    put_char(base_pattern, (pos.x + width) - index, pos.y, digit);
  }
}

void draw_number_left_align(const uint32_t base_pattern,
			    const screen_cell_t& pos,
			    const int32_t n,
			    const int32_t width)
{
  const bcd_t bcd = int_to_bcd(n);

  int32_t index = 0;
  int32_t length = width < bcd.length ? width : bcd.length;
  while (index < length) {
    const uint8_t digit = ascii_to_font('0' + ((bcd.digits >> (4 * index)) & 0b1111));
    index++;
    put_char(base_pattern, pos.x + (length - index), pos.y, digit);
  }
}