<?php declare(strict_types=1);

namespace Kilo;

use FFI;

trait MagicProperties {
	abstract public function __get(string $name);

	public function __set(string $name, $value)
	{
		if (property_exists($this, $name))
		{
			$this->$name = $value;
		}
	}

	public function __isset(string $name): bool
	{
		return isset($this->$name);
	}
}

class Key {
	public const ARROW_LEFT = 'a';//'ARROW_LEFT';
	public const ARROW_RIGHT = 'd';//ARROW_RIGHT';
	public const ARROW_UP = 'w';//'ARROW_UP';
	public const ARROW_DOWN = 's';//'ARROW_DOWN';
	public const DEL_KEY = 'DEL';
	public const HOME_KEY = 'HOME';
	public const END_KEY = 'END';
	public const PAGE_UP = 'PAGE_UP';
	public const PAGE_DOWN = 'PAGE_DOWN';
}

/**
 * @property-read int size
 * @property-read int rsize
 */
class Row {
	use MagicProperties;

	public string $chars = '';
	public string $render = '';

	public static function new(string $chars): self
	{
		return new self($chars);
	}

	private function __construct($chars)
	{
		$this->chars = $chars;
	}

	public function __get(string $name)
	{
		switch ($name)
		{
			case 'size':
				return strlen($this->chars);

			case 'rsize':
				return strlen($this->render);

			default:
				return NULL;
		}
	}
}

/**
 * @property-read int numRows
 */
class Editor {
	use MagicProperties;

	private FFI $ffi;
	private string $ab = '';

	protected int $cursorX = 0;
	protected int $cursorY = 0;
	protected int $renderX = 0;
	protected int $rowOffset = 0;
	protected int $colOffset = 0;
	protected int $screenRows = 0;
	protected int $screenCols = 0;

	/**
	 * Array of Row objects
	 */
	protected array $rows = [];

	protected string $filename = '';
	protected string $statusMsg = '';
	protected int $statusMsgTime;

	public static function new(FFI $ffi): Editor
	{
		return new self($ffi);
	}

	private function __construct($ffi)
	{
		$this->ffi = $ffi;
		$this->statusMsgTime = time();

		if ( ! $this->getWindowSize())
		{
			die('Failed to get screen size');
		}

		$this->screenRows -= 2;

		// print_r($this); die();
	}

	public function __get(string $name)
	{
		if ($name === 'numRows')
		{
			return count($this->rows);
		}

		return NULL;
	}

	// ------------------------------------------------------------------------
	// ! Terminal
	// ------------------------------------------------------------------------
	protected function readKey(): string
	{
		$c = read_stdin(1);

		if ($c === '\x1b')
		{
			$seq = read_stdin();

			if (strlen($seq) < 3)
			{
				return '\x1b';
			}

			if (strpos($seq, '[') === 0)
			{
				$seq1 = (int)$seq[1];

				if ($seq1 >= 0 && $seq1 <= 9)
				{
					if (strpos($seq, '~') === 2)
					{
						switch ($seq[1])
						{
							case '1':
							case '7':
								return Key::HOME_KEY;

							case '4':
							case '8':
								return Key::END_KEY;

							case '3': return Key::DEL_KEY;
							case '5': return Key::PAGE_UP;
							case '6': return Key::PAGE_DOWN;
						}
					}
				}
				else
				{
					switch ($seq[1])
					{
						case 'A': return Key::ARROW_UP;
						case 'B': return Key::ARROW_DOWN;
						case 'C': return Key::ARROW_RIGHT;
						case 'D': return Key::ARROW_LEFT;
						case 'H': return Key::HOME_KEY;
						case 'F': return Key::END_KEY;
					}
				}
			}
			else if (strpos($seq, 'O') === 0)
			{
				switch ($seq[1])
				{
					case 'H': return Key::HOME_KEY;
					case 'F': return Key::END_KEY;
				}
			}

			return '\x1b';
		}

		return $c;
	}

	/**
	 * @TODO fix
	 */
	private function getCursorPosition(): bool
	{
		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');
		}

		$this->screenRows = $rows;
		$this->screenCols = $cols;

		return TRUE;
	}

	private function getWindowSize(): bool
	{
		$ws = $this->ffi->new('struct winsize');
		$res = $this->ffi->ioctl(STDOUT_FILENO, TIOCGWINSZ, FFI::addr($ws));

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

		$this->screenCols = $ws->ws_col;
		$this->screenRows = $ws->ws_row;

		return true;
	}

	// ------------------------------------------------------------------------
	// ! Row Operations
	// ------------------------------------------------------------------------

	protected function rowCxToRx(Row $row, int $cx): int
	{
		$rx = 0;
		for ($i = 0; $i < $cx; $i++)
		{
			if ($row->chars[$i] === "\t")
			{
				$rx += (KILO_TAB_STOP - 1) - ($rx % KILO_TAB_STOP);
			}
			$rx++;
		}

		return $rx;
	}

	protected function updateRow(Row $row): void
	{
		$idx = 0;

		for ($i = 0; $i < $row->size; $i++)
		{
			if ($row->chars[$i] === "\t")
			{
				$row->render[$idx++] = ' ';
				while ($idx % KILO_TAB_STOP !== 0)
				{
					$row->render[$idx++] = ' ';
				}
			}
			else
			{
				$row->render[$idx++] = $row->chars[$i];
			}
		}
	}

	protected function appendRow(string $s): void
	{
		$at = $this->numRows;
		$this->rows[$at] = Row::new($s);
		$this->updateRow($this->rows[$at]);
	}

	// ------------------------------------------------------------------------
	// ! File I/O
	// ------------------------------------------------------------------------

	public function open(string $filename): void
	{
		// Copy filename for display
		$this->filename = $filename;

		// Determine the full path to the file
		$baseFile = basename($filename);
		$basePath = str_replace($baseFile, '', $filename);
		$path = (is_dir($basePath)) ? $basePath : getcwd();

		$fullname = $path . '/' . $baseFile;


		// #TODO gracefully handle issues with loading a file
		$handle = fopen($fullname, 'rb');

		while (($line = fgets($handle)) !== FALSE)
		{
			$this->appendRow($line);
		}

		fclose($handle);
	}

	// ------------------------------------------------------------------------
	// ! Output
	// ------------------------------------------------------------------------

	protected function scroll(): void
	{
		$this->renderX = 0;
		if ($this->cursorY < $this->numRows)
		{
			$this->renderX = $this->rowCxToRx($this->rows[$this->cursorY], $this->cursorX);
		}

		// Vertical Scrolling
		if ($this->cursorY < $this->rowOffset)
		{
			$this->rowOffset = $this->cursorY;
		}
		if ($this->cursorY >= ($this->rowOffset + $this->screenRows))
		{
			$this->rowOffset = $this->cursorY - $this->screenRows + 1;
		}

		// Horizontal Scrolling
		if ($this->renderX < $this->colOffset)
		{
			$this->colOffset = $this->renderX;
		}
		if ($this->renderX >= ($this->colOffset + $this->screenCols))
		{
			$this->colOffset = $this->renderX - $this->screenCols + 1;
		}
	}

	protected function drawRows(): void
	{
		for ($y = 0; $y < $this->screenRows; $y++)
		{
			$filerow = $y + $this->rowOffset;
			if ($filerow >= $this->numRows)
			{
				if ($this->numRows === 0 && $y === $this->screenRows / 3)
				{
					$welcome = sprintf('PHP Kilo editor -- version %s', KILO_VERSION);
					$welcomelen = strlen($welcome);
					if ($welcomelen > $this->screenCols)
					{
						$welcomelen = $this->screenCols;
					}

					$padding = ($this->screenCols - $welcomelen) / 2;
					if ($padding > 0)
					{
						$this->ab .= '~';
						$padding--;
					}
					for (; $padding >= 0; $padding--)
					{
						$this->ab .= ' ';
					}

					$this->ab .= substr($welcome, 0, $welcomelen);
				}
				else
				{
					$this->ab .= '~';
				}
			}
			else
			{
				$len = $this->rows[$filerow]->rsize - $this->colOffset;
				if ($len < 0)
				{
					$len = 0;
				}
				if ($len > $this->screenCols)
				{
					$len = $this->screenCols;
				}

				$this->ab .= substr($this->rows[$filerow]->render, $this->colOffset, $len);
			}

			$this->ab .= "\x1b[K"; // Clear the current line
			$this->ab .= "\r\n";
		}
	}

	protected function drawStatusBar(): void
	{
		$this->ab .= "\x1b[7m";

		$statusFilename = $this->filename !== '' ? $this->filename : '[No Name]';
		$status = sprintf("%.20s - %d lines", $statusFilename, $this->numRows);
		$rstatus = sprintf("%d/%d", $this->cursorY + 1, $this->numRows);
		$len = strlen($status);
		$rlen = strlen($rstatus);
		if ($len > $this->screenCols)
		{
			$len = $this->screenCols;
		}
		$this->ab .= substr($status, 0, $len);
		while ($len < $this->screenCols)
		{
			if ($this->screenCols - $len === $rlen)
			{
				$this->ab .= substr($rstatus, 0, $rlen);
				break;
			}

			$this->ab .= ' ';
			$len++;
		}
		$this->ab .= "\x1b[m";
		$this->ab .= "\r\n";
	}

	protected function drawMessageBar(): void
	{
		$this->ab .= "\x1b[K";
		$len = strlen($this->statusMsg);
		if ($len > $this->screenCols)
		{
			$len = $this->screenCols;
		}

		if ($len > 0 && (time() - $this->statusMsgTime) < 5)
		{
			$this->ab .= substr($this->statusMsg, 0, $len);
		}
	}

	public function refreshScreen(): void
	{
		$this->scroll();

		$this->ab = '';

		$this->ab .= "\x1b[?25l"; // Hide the cursor
		$this->ab .= "\x1b[H"; // Reposition cursor to top-left

		$this->drawRows();
		$this->drawStatusBar();
		$this->drawMessageBar();

		// Specify the current cursor position
		$this->ab .= sprintf("\x1b[%d;%dH",
			($this->cursorY - $this->rowOffset) + 1,
			($this->renderX - $this->colOffset) + 1
		);

		$this->ab .= "\x1b[?25h"; // Show the cursor

		echo $this->ab;
	}

	public function setStatusMessage(string $fmt, ...$args): void
	{
		$this->statusMsg = (count($args) > 0)
			? sprintf($fmt, ...$args)
			: $fmt;
		$this->statusMsgTime = time();
	}

	// ------------------------------------------------------------------------
	// ! Input
	// ------------------------------------------------------------------------

	protected function moveCursor(string $key): void
	{
		$row = ($this->cursorY >= $this->numRows)
			? NULL
			: $this->rows[$this->cursorY];

		switch ($key)
		{
			case Key::ARROW_LEFT:
				if ($this->cursorX !== 0)
				{
					$this->cursorX--;
				}
				else if ($this->cursorX > 0)
				{
					$this->cursorY--;
					$this->cursorX = $this->rows[$this->cursorY]->size;
				}
			break;

			case Key::ARROW_RIGHT:
				if ($row && $this->cursorX < $row->size)
				{
					$this->cursorX++;
				}
				else if ($row && $this->cursorX === $row->size)
				{
					$this->cursorY++;
					$this->cursorX = 0;
				}
			break;

			case Key::ARROW_UP:
				if ($this->cursorY !== 0)
				{
					$this->cursorY--;
				}
			break;

			case Key::ARROW_DOWN:
				if ($this->cursorY < $this->numRows)
				{
					$this->cursorY++;
				}
			break;
		}

		$row = ($this->cursorY >= $this->numRows)
			? NULL
			: $this->rows[$this->cursorY];
		$rowlen = $row ? $row->size : 0;
		if ($this->cursorX > $rowlen)
		{
			$this->cursorX = $rowlen;
		}
	}

	public function processKeypress(): ?string
	{
		$c = $this->readKey();

		if ($c === "\0")
		{
			return '';
		}

		switch ($c)
		{
			case Key::HOME_KEY:
				$this->cursorX = 0;
			break;

			case Key::END_KEY:
				if ($this->cursorY < $this->numRows)
				{
					$this->cursorX = $this->rows[$this->cursorY]->size;
				}
			break;

			case Key::PAGE_UP:
			case Key::PAGE_DOWN:
				$this->pageUpOrDown($c);
			break;

			case Key::ARROW_UP:
			case Key::ARROW_DOWN:
			case Key::ARROW_LEFT:
			case Key::ARROW_RIGHT:
				$this->moveCursor($c);
			break;

			case chr(ctrl_key('q')):
				write_stdout("\x1b[2J"); // Clear the screen
				write_stdout("\x1b[H"); // Reposition cursor to top-left
				return NULL;
			break;

			default:
				return $c;
		}

		return $c;
	}

	private function pageUpOrDown(string $c): void
	{
		if ($c === Key::PAGE_UP)
		{
			$this->cursorY = $this->rowOffset;
		}
		else if ($c === Key::PAGE_DOWN)
		{
			$this->cursorY = $this->rowOffset + $this->screenRows - 1;
			if ($this->cursorY > $this->numRows)
			{
				$this->cursorY = $this->numRows;

			}
		}

		$times = $this->screenRows;
		for (; $times > 0; $times--)
		{
			$this->moveCursor($c === Key::PAGE_UP ? Key::ARROW_UP : Key::ARROW_DOWN);
		}
	}
}