<?php declare(strict_types=1);

namespace Aviat\Kilo;

use Aviat\Kilo\Enum\{Color, Highlight, KeyCode};

// ----------------------------------------------------------------------------
// ! 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_ctrl(string $char): bool
{
	$c = ord($char);
	return is_ascii($char) && ( $c === 0x7f || $c < 0x20 );
}

/**
 * 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 $char): bool
{
	return match($char) {
		KeyCode::CARRIAGE_RETURN,
		KeyCode::FORM_FEED,
		KeyCode::NEWLINE,
		KeyCode::SPACE,
		KeyCode::TAB,
		KeyCode::VERTICAL_TAB => true,

		default => false,
	};
}

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

/**
 * 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;
	}

	$isSep = str_contains(',.()+-/*=~%<>[];', $char);

	return is_space($char) || $char === KeyCode::NULL || $isSep;
}

/**
 * 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, mixed $value):void
{
	if ($length === 1)
	{
		$array[$offset] = $value;
		return;
	}

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

/**
 * Does the string $haystack contain $str, optionally searching from $offset?
 *
 * @param string $haystack
 * @param string $str
 * @param int|null $offset
 * @return bool
 */
function str_contains(string $haystack, string $str, ?int $offset = NULL): bool
{
	if (empty($str))
	{
		return FALSE;
	}

	return ($offset !== NULL)
		? strpos($haystack, $str, $offset) !== FALSE
		: \str_contains($haystack, $str);
}

/**
 * Get the ASCII color escape number for the specified syntax type
 *
 * @param int $hl
 * @return int
 */
function syntax_to_color(int $hl): int
{
	return match ($hl)
	{
		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_BRIGHT_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,
		Highlight::IDENTIFIER => Color::FG_BRIGHT_WHITE,
		default => Color::FG_WHITE,
	};
}

/**
 * Replace tabs with the specified number of spaces.
 *
 * @param string $str
 * @param int $number
 * @return string
 */
function tabs_to_spaces(string $str, int $number = KILO_TAB_STOP): string
{
	return str_replace(KeyCode::TAB, str_repeat(KeyCode::SPACE, $number), $str);
}