<?php declare(strict_types=1);

namespace Kilo;

use FFI;

require_once __DIR__ . '/constants.php';

/** @var FFI\CData $original_termios */
$original_termios = get_ffi()->new('struct termios');

// ----------------------------------------------------------------------------
// ! Raw mode / Terminal size
// ----------------------------------------------------------------------------

function enable_raw_mode(): void
{
	global $original_termios;

	// Make sure to restore normal mode on exit/die/crash
	register_shutdown_function('Kilo\disable_raw_mode');

	$ffi = get_ffi();

	// Populate the original terminal settings
	$res = $ffi->tcgetattr(C::STDIN_FILENO, FFI::addr($original_termios));
	if ($res === -1)
	{
		die('tcgetattr');
	}

	// So, the only thing that seems to really matter here is that c_oflag is 0...
	$termios = clone $original_termios;
	$termios->c_iflag = 0; //$termios->c_iflag & ~(C::BRKINT | C::ICRNL | C::INPCK | C::ISTRIP | C::IXON);
	$termios->c_oflag = 0; // $termios->c_oflag && ~(C::OPOST);
	$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 = $ffi->tcsetattr(C::STDIN_FILENO, C::TCSAFLUSH, FFI::addr($termios));
	if ($res === -1)
	{
		die('tcsetattr');
	}
}

function disable_raw_mode(): void
{
	global $original_termios;

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

	echo "\n";

	if ($res === -1)
	{
		die('tcsetattr');
	}
}

/**
 * @TODO fix
 */
function get_cursor_position()
{
	write_stdout("\x1b[999C\x1b[999B");
	write_stdout("\x1b[6n");

	$rows = 0;
	$cols = 0;

	$buffer = read_stdout();

	$res = sscanf($buffer, '\x1b[%d;%dR', $rows, $cols);

	if ($res === -1 || $buffer[0] !== '\x1b' || $buffer[1] !== '[')
	{
		die('Failed to get screen size');
	}

	return [$rows, $cols];
}

function get_window_size()
{
	$ffi = get_ffi();

	$ws = $ffi->new('struct winsize');
	$res = $ffi->ioctl(C::STDOUT_FILENO, C::TIOCGWINSZ, FFI::addr($ws));

	if ($res === -1 || $ws->ws_col === 0)
	{
		return get_cursor_position();
	}

	return [$ws->ws_row, $ws->ws_col];
}

// ----------------------------------------------------------------------------
// ! C function/macro equivalents
// ----------------------------------------------------------------------------

/**
 * Do bit twiddling to convert a letter into
 * its Ctrl-letter equivalent ordinal ascii value
 *
 * @param string $char
 * @return int
 */
function ctrl_key(string $char): int
{
	if ( ! is_ascii($char))
	{
		return -1;
	}

	// b1,100,001 (a) & b0,011,111 (0x1f) = b0,000,001 (SOH)
	// b1,100,010 (b) & b0,011,111 (0x1f) = b0,000,010 (STX)
	// ...and so on
	return ord($char) & 0x1f;
}

/**
 * Does the one-character string contain an ascii ordinal value?
 *
 * @param string $single_char
 * @return bool
 */
function is_ascii(string $single_char): bool
{
	if (strlen($single_char) > 1)
	{
		return FALSE;
	}

	return ord($single_char) < 0x80;
}

/**
 * Does the one-character string contain an ascii control character?
 *
 * @param string $char
 * @return bool
 */
function is_cntrl(string $char): bool
{
	$c = ord($char);
	return is_ascii($char) && ( $c < 0x20 || $c === 0x7f );
}

/**
 * Does the one-character string contain an ascii number?
 *
 * @param string $char
 * @return bool
 */
function is_digit(string $char): bool
{
	$c = ord($char);
	return is_ascii($char) && ( $c > 0x2f && $c < 0x3a );
}

/**
 * Does the one-character string contain ascii whitespace?
 *
 * @param string $char
 * @return bool
 */
function is_space(string $char): bool
{
	$ws = [' ', "\t", "\n", "\r", "\xa", "\xb", "\xc"];
	return is_ascii($char) && in_array($char, $ws, TRUE);
}

// ----------------------------------------------------------------------------
// ! Helper functions
// ----------------------------------------------------------------------------

/**
 * A 'singleton' function to replace a global variable
 *
 * @return FFI
 */
function get_ffi(): FFI
{
	static $ffi;

	if ($ffi === NULL)
	{
		$ffi = FFI::load(__DIR__ . '/ffi.h');
	}

	return $ffi;
}

/**
 * Does the one-character string contain a character that separates tokens?
 *
 * @param string $char
 * @return bool
 */
function is_separator(string $char): bool
{
	if ( ! is_ascii($char))
	{
		return FALSE;
	}

	// `strpos` is used instead of `strchr`/`strstr` as we don't care about the actual match
	// while `strchr` would match the C version, it also returns the match
	$isSep = (strpos(',.()+-/*=~%<>[];', $char) !== FALSE);

	return is_space($char) || $char === "\0" || $isSep;
}

/**
 * Pull input from the stdin stream.
 *
 * @param int $len
 * @return string
 */
function read_stdin(int $len = 128): string
{
	$handle = fopen('php://stdin', 'rb');
	$input = fread($handle, $len);
	fclose($handle);

	return $input;
}

/**
 * Write to the stdout stream
 *
 * @param string $str
 * @param int|NULL $len
 * @return int
 */
function write_stdout(string $str, int $len = NULL): int
{
	$handle = fopen('php://stdout', 'ab');
	$res = (is_int($len))
		? fwrite($handle, $str, $len)
		: fwrite($handle, $str);

	fclose($handle);

	return $res;
}

function read_stdout(int $len = 128): string
{
	$handle = fopen('php://stdout', 'rb');
	$input = fread($handle, $len);

	$input = rtrim($input);
	fclose($handle);

	return $input;
}

/**
 * Replaces a slice of an array with the same value
 *
 * @param array $array The array to update
 * @param int $offset The index of the first location to update
 * @param int $length The number of indices to update
 * @param mixed $value The value to replace in the range
 */
function array_replace_range(array &$array, int $offset, int $length, $value):void
{
	if ($length === 1)
	{
		$array[$offset] = $value;
		return;
	}

	$replacement = array_fill(0, $length, $value);
	array_splice($array, $offset, $length, $replacement);

	/* $end = $offset + $length;
	for ($i = $offset; $i < $end; $i++)
	{
		$array[$i] = $value;
	} */
}

/**
 * Get the ASCII color escape number for the specified syntax type
 *
 * @param int $hl
 * @return int
 */
function syntax_to_color(int $hl): int
{
	$map = [
		Highlight::COMMENT => Color::FG_CYAN,
		Highlight::ML_COMMENT => Color::FG_BRIGHT_BLACK,
		Highlight::KEYWORD1 => Color::FG_YELLOW,
		Highlight::KEYWORD2 => Color::FG_GREEN,
		Highlight::STRING => Color::FG_MAGENTA,
		Highlight::NUMBER => Color::FG_RED,
		Highlight::OPERATOR => Color::FG_BRIGHT_GREEN,
		Highlight::VARIABLE => Color::FG_BRIGHT_CYAN,
		Highlight::DELIMITER => Color::FG_BLUE,
		Highlight::INVALID => Color::BG_BRIGHT_RED,
		Highlight::MATCH => Color::INVERT,
	];

	return (array_key_exists($hl, $map))
		? $map[$hl]
		: Color::FG_WHITE;
}

/**
 * Use 'token_get_all' to get the tokens for a file,
 * organized by row number
 *
 * @param string $code
 * @return array
 */
function get_php_tokens(string $code): array
{
	$raw_tokens = token_get_all($code);
	$tokens = [];
	$lineNum = 1;
	$line = [];
	foreach($raw_tokens as $token)
	{
		// Simple characters, usually delimiters or single character operators
		if ( ! is_array($token))
		{
			$line[] = [
				'type' => -1,
				'typeName' => 'RAW',
				'char' => $token,
			];
			continue;
		}

		[$type, $char, $currentLine] = $token;

		// Only return the first line of a multi-line token
		if ($char !== "\n" && strpos($char, "\n") !== FALSE)
		{
			$char = explode("\n", $char)[0];
		}

		$current = [
			'type' => $type,
			'typeName' => token_name($type),
			'char' => $char,
			'line' => $currentLine,
		];

		if ($currentLine !== $lineNum)
		{
			$tokens[$lineNum] = $line;

			// Make sure to insert empty arrays for empty lines
			// So the array of tokens isn't sparse
			for ($i = $lineNum; $i < $currentLine; $i++)
			{
				if ( ! array_key_exists($i, $tokens))
				{
					$tokens[$i] = [];
				}
			}

			$lineNum = $currentLine;
			$line = [];
		}

		$line[] = $current;
	}

	$tokens[$lineNum] = $line;

	return $tokens;
}