<?php declare(strict_types=1);

namespace Aviat\Kilo;

use FFI;
use FFI\CData;

use Aviat\Kilo\Enum\C;

/**
 * An implicit singleton wrapper around terminal settings to simplify enabling/disabling raw mode
 */
class Termios {
	private CData $originalTermios;

	private function __construct()
	{
		$ffi = get_ffi();
		$termios = $ffi->new('struct termios');
		$res = $ffi->tcgetattr(C::STDIN_FILENO, FFI::addr($termios));
		if ($res === -1)
		{
			die('Failed to get terminal settings');
		}

		$this->originalTermios = $termios;
	}

	public static function enableRawMode(): void
	{
		static $run = FALSE;

		// Don't run this more than once!
		if ($run === TRUE)
		{
			return;
		}

		$run = TRUE;

		$instance = self::getInstance();

		// Make sure to restore normal mode on exit/die/crash
		register_shutdown_function([static::class, 'disableRawMode']);

		// So, the only thing that seems to really matter here is that c_oflag is 0...
		$termios = clone $instance->originalTermios;
		// $termios->c_iflag &= ~(C::BRKINT | C::ICRNL | C::INPCK | C::ISTRIP | C::IXON);
		// $termios->c_oflag &= ~(C::OPOST);
		$termios->c_iflag = 0;
		$termios->c_oflag = 0;
		$termios->c_cflag |= (C::CS8);
		$termios->c_lflag = $termios->c_lflag & ~( C::ECHO | C::ICANON | C::IEXTEN | C::ISIG );
		$termios->c_cc[C::VMIN] = 0;
		$termios->c_cc[C::VTIME] = 1;

		// Turn on raw mode
		$res = get_ffi()->tcsetattr(C::STDIN_FILENO, C::TCSAFLUSH, FFI::addr($termios));
		if ($res === -1)
		{
			die('Failed to set raw mode');
		}
	}

	public static function disableRawMode(): void
	{
		$instance = self::getInstance();

		write_stdout("\x1b[2J"); // Clear the screen
		write_stdout("\x1b[H"); // Reposition cursor to top-left
		echo "\n";

		$res = get_ffi()->tcsetattr(C::STDIN_FILENO, C::TCSAFLUSH, FFI::addr($instance->originalTermios));

		if ($res === -1)
		{
			die('Failed to restore terminal settings');
		}
	}

	private static function getInstance(): self
	{
		static $instance;

		if ($instance === NULL)
		{
			$instance = new self();
		}

		return $instance;
	}
}