#include <stdarg.h>
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
#include <limits.h>
#include <system/system.h>
#include <sysdefs/devctl.h>
#include <write/write.h>

char *utoa(uintmax_t v, int base, bool uppercase) {
  if (base < 2 || base > 36) {
    return NULL;
  }

  static char buf[sizeof(uintmax_t) * CHAR_BIT + 3];
  const char *digits = uppercase ? "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" : "0123456789abcdefghijklmnopqrstuvwxyz";

  size_t i = sizeof(buf) - 1;
  buf[i] = '\0';

  if (v == 0) {
    buf[--i] = '0';
    return &buf[i];
  }

  while (v != 0) {
    if (i == 0) {
      return NULL;
    }
    buf[--i] = digits[v % base];
    v /= base;
  }

  return &buf[i];
}

char *itoa(intmax_t v, int base, bool uppercase) {
  if (base < 2 || base > 36) {
    return NULL;
  }

  static char buf[sizeof(uintmax_t) * CHAR_BIT + 3];
  const char *digits = uppercase ? "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" : "0123456789abcdefghijklmnopqrstuvwxyz";

  size_t i = sizeof(buf) - 1;
  buf[i] = '\0';

  if (v == 0) {
    buf[--i] = '0';
    return &buf[i];
  }

  bool neg = (v < 0);
  uintmax_t u;
  if (neg) {
    u = (uintmax_t)(-(v + 1)) + 1;
  } else {
    u = (uintmax_t)v;
  }

  while (u != 0) {
    if (i == 0) {
      return NULL;
    }
    buf[--i] = digits[u % base];
    u /= base;
  }

  if (neg) {
    if (i == 0) {
      return NULL;
    }
    buf[--i] = '-';
  }

  return &buf[i];
}

#define FMTBUF_MAX 2048

extern Dev_t termdev;

enum {
  WRITE_FORMATMODE,
  WRITE_NORMALMODE,
};

const char *convstr1 = "0123456789abcdef";
const char *convstr2 = "0123456789ABCDEF";

void writefmt(char *fmt, ...) {
  va_list list;
  va_start(list, fmt);
  writevfmt(fmt, list);
  va_end(list);
}

#define ITOA_BUF_SIZE 32

void writevsfmt(char *buf, char *fmt, va_list list) {
  size_t c = 0;
  int WRITE_STATE = WRITE_NORMALMODE;

  for (size_t i = 0; fmt[i] != '\0'; i++) {
    if (WRITE_STATE == WRITE_NORMALMODE) {
      switch (fmt[i]) {
        case '{':
          WRITE_STATE = WRITE_FORMATMODE;
          break;
        default:
          buf[c++] = fmt[i];
          break;
      }
    } else if (WRITE_STATE == WRITE_FORMATMODE) {
      switch (fmt[i]) {
        case '}':
          WRITE_STATE = WRITE_NORMALMODE;
          break;
        case 's': {
          char *string = va_arg(list, char *);
          while (*string) { buf[c++] = *string; string++; }
        } break;
        case 'd': {
          int int1 = va_arg(list, int);
          char *string = itoa(int1, 10, false);
          while (*string) { buf[c++] = *string; string++; }
        } break;
        case 'x': {
          unsigned int int1 = va_arg(list, unsigned int);
          char *string = utoa(int1, 16, false);
          while (*string) { buf[c++] = *string; string++; }
        } break;
        case 'X': {
          unsigned int int1 = va_arg(list, unsigned int);
          char *string = utoa(int1, 16, true);
          while (*string) { buf[c++] = *string; string++; }
        } break;
        case 'p': {
          uintptr_t ptr = (uintptr_t)va_arg(list, void *);
          char *string = utoa(ptr, 16, false);
          while (*string) { buf[c++] = *string; string++; }
        } break;
        case 'P': {
          uintptr_t ptr = (uintptr_t)va_arg(list, void *);
          char *string = utoa(ptr, 16, true);
          while (*string) { buf[c++] = *string; string++; }
        } break;
        case 'c': {
          char c1 = (char)va_arg(list, char);
          buf[c++] = c1;
        } break;
      }
    }
  }
}

void writevfmt(char *fmt, va_list list) {
  char buf[FMTBUF_MAX];
  writevsfmt(buf, fmt, list); 
  devctl(&termdev, 0x00, buf, sizeof(buf), 0);
}