#include <amd64/debug.h>
#include <amd64/io.h>
#include <libk/printf.h>
#include <libk/std.h>
#include <libk/string.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>

/// Port for printing to serial
#define PORT_COM1 0x03F8
/// \ref debugprintf buffer size
#define BUFFER_SIZE 1024
/// Lock, which ensures that prints to the serial port are atomic
static spin_lock_t serial_lock = SPIN_LOCK_INIT;

static bool debug_init = false;

/// Block until TX buffer is empty
static bool amd64_debug_serial_tx_empty (void) {
  return (bool)(amd64_io_inb (PORT_COM1 + 5) & 0x20);
}

/// Write a single character to serial
static void amd64_debug_serial_write (char x) {
  while (!amd64_debug_serial_tx_empty ())
    ;
  amd64_io_outb (PORT_COM1, (uint8_t)x);
}

/**
 * @brief Formatted printing to serial. \ref serial_lock ensures that
 * all prints are atomic.
 */
void debugprintf (const char* fmt, ...) {
  if (!debug_init)
    return;

  char buffer[BUFFER_SIZE];
  memset (buffer, 0, sizeof (buffer));

  va_list ap;
  va_start (ap, fmt);
  vsnprintf (buffer, sizeof (buffer), fmt, ap);
  va_end (ap);

  buffer[sizeof (buffer) - 1] = '\0';

  const char* p = buffer;

  spin_lock (&serial_lock);

  while (*p) {
    amd64_debug_serial_write (*p);
    p++;
  }

  spin_unlock (&serial_lock);
}

/// Initialize serial
void amd64_debug_init (void) {
  amd64_io_outb (PORT_COM1 + 1, 0x00);
  amd64_io_outb (PORT_COM1 + 3, 0x80);
  amd64_io_outb (PORT_COM1 + 0, 0x03);
  amd64_io_outb (PORT_COM1 + 1, 0x00);
  amd64_io_outb (PORT_COM1 + 3, 0x03);
  amd64_io_outb (PORT_COM1 + 2, 0xC7);
  amd64_io_outb (PORT_COM1 + 4, 0x0B);

  debug_init = true;
}