<?php declare(strict_types=1);

namespace Aviat\Kilo;

use Aviat\Kilo\Enum\Highlight;
use Aviat\Kilo\Enum\RawKeyCode;
use Aviat\Kilo\Terminal\Enum\Color;
use Aviat\Kilo\Terminal\Enum\Color256;

// -----------------------------------------------------------------------------
// ! App Constants
// -----------------------------------------------------------------------------

const KILO_VERSION = '0.3.0';
const KILO_TAB_STOP = 4;
const KILO_QUIT_TIMES = 3;

const NO_MATCH = -1;
const T_RAW = -1;

// -----------------------------------------------------------------------------
// ! App Config
// -----------------------------------------------------------------------------

/**
 * Configure syntax highlighting colors
 */
function get_syntax_color(Highlight $hl): Color | Color256 | int {
	return match ($hl)
	{
		Highlight::Comment => Color::FG_CYAN,
		Highlight::MultiLineComment => Color::FG_BRIGHT_BLACK,
		Highlight::Keyword1 => Color::FG_YELLOW,
		Highlight::Keyword2 => Color::FG_GREEN,
		Highlight::String => Color::FG_MAGENTA,
		Highlight::Character => Color::FG_BRIGHT_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::SearchMatch => Color::INVERT,
		Highlight::Identifier => Color::FG_BRIGHT_WHITE,
		default => Color::FG_WHITE,
	};
}

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

/**
 * Do bit twiddling to convert a letter into
 * its Ctrl-letter equivalent ordinal ascii value
 */
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?
 */
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?
 */
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?
 */
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?
 */
function is_space(string $char): bool
{
	return match($char) {
		RawKeyCode::CARRIAGE_RETURN,
		RawKeyCode::FORM_FEED,
		RawKeyCode::NEWLINE,
		RawKeyCode::SPACE,
		RawKeyCode::TAB,
		RawKeyCode::VERTICAL_TAB => true,

		default => false,
	};
}

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

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

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

	return is_space($char) || $char === RawKeyCode::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
 */
function str_has(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);
}

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

function error_code_name(int $code): string
{
	return 	match ($code) {
		E_ERROR => 'Error',
		E_WARNING => 'Warning',
		E_PARSE => 'Parse Error',
		E_NOTICE => 'Notice',
		E_CORE_ERROR => 'Core Error',
		E_CORE_WARNING => 'Core Warning',
		E_COMPILE_ERROR => 'Compile Error',
		E_COMPILE_WARNING => 'Compile Warning',
		E_USER_ERROR => 'User Error',
		E_USER_WARNING => 'User Warning',
		E_USER_NOTICE => 'User Notice',
		E_RECOVERABLE_ERROR => 'Recoverable Error',
		E_DEPRECATED => 'Deprecated',
		E_USER_DEPRECATED => 'User Deprecated',
		default => 'Unknown',
	};
}

/**
 * Adds two numbers to at most the $max value
 */
function saturating_add(int $a, int $b, int $max): int
{
	return ($a + $b > $max) ? $max : $a + $b;
}

/**
 * Delete one number from another, down to zero at the least
 */
function saturating_sub(int $a, int $b): int
{
	if ($b > $a)
	{
		return 0;
	}

	return $a - $b;
}