From fdd90e289e35a7001549c8f1f21a5723cf1d3c5a Mon Sep 17 00:00:00 2001
From: Timothy Warren <tim@timshomepage.net>
Date: Tue, 9 Mar 2021 12:46:30 -0500
Subject: [PATCH] Fix arrow key movement and use Position class for cursor and
 offset

---
 src/Editor.php    | 242 +++++++++++++++++++++++-----------------------
 src/Position.php  |  17 ++++
 src/functions.php |   2 +-
 3 files changed, 141 insertions(+), 120 deletions(-)
 create mode 100644 src/Position.php

diff --git a/src/Editor.php b/src/Editor.php
index 9dcb779..9eadaf9 100644
--- a/src/Editor.php
+++ b/src/Editor.php
@@ -12,14 +12,34 @@ use Aviat\Kilo\Tokens\PHP8;
 class Editor {
 	use Traits\MagicProperties;
 
+	/**
+	 * @var string The screen buffer
+	 */
 	private string $outputBuffer = '';
 
-	protected int $cursorX = 0;
-	protected int $cursorY = 0;
+	/**
+	 * @var Position The 0-based location of the cursor in the current viewport
+	 */
+	protected Position $cursor;
+
+	/**
+	 * @var Position The scroll offset of the file in the current viewport
+	 */
+	protected Position $offset;
+
+	/**
+	 * @var int The rendered cursor position
+	 */
 	protected int $renderX = 0;
-	protected int $rowOffset = 0;
-	protected int $colOffset = 0;
+
+	/**
+	 * @var int The size of the current terminal in rows
+	 */
 	protected int $screenRows = 0;
+
+	/**
+	 * @var int The size of the current terminal in columns
+	 */
 	protected int $screenCols = 0;
 
 	/**
@@ -45,6 +65,8 @@ class Editor {
 	private function __construct()
 	{
 		$this->statusMsgTime = time();
+		$this->cursor = Position::default();
+		$this->offset = Position::default();
 
 		[$this->screenRows, $this->screenCols] = Terminal::getWindowSize();
 
@@ -65,13 +87,11 @@ class Editor {
 	public function __debugInfo(): array
 	{
 		return [
-			'colOffset' => $this->colOffset,
-			'cursorX' => $this->cursorX,
-			'cursorY' => $this->cursorY,
+			'cursor' => $this->cursor,
+			'offset' => $this->offset,
 			'dirty' => $this->dirty,
 			'filename' => $this->filename,
 			'renderX' => $this->renderX,
-			'rowOffset' => $this->rowOffset,
 			'rows' => $this->rows,
 			'screenCols' => $this->screenCols,
 			'screenRows' => $this->screenRows,
@@ -257,41 +277,41 @@ class Editor {
 
 	protected function insertChar(string $c): void
 	{
-		if ($this->cursorY === $this->numRows)
+		if ($this->cursor->y === $this->numRows)
 		{
 			$this->insertRow($this->numRows, '');
 		}
-		$this->rows[$this->cursorY]->insertChar($this->cursorX, $c);
+		$this->rows[$this->cursor->y]->insertChar($this->cursor->x, $c);
 
 		// Re-tokenize the file
 		$this->refreshPHPSyntax();
 
-		$this->cursorX++;
+		$this->cursor->x++;
 	}
 
 	protected function insertNewline(): void
 	{
 		// @TODO attempt smart indentation on newline?
 
-		if ($this->cursorX === 0)
+		if ($this->cursor->x === 0)
 		{
-			$this->insertRow($this->cursorY, '');
+			$this->insertRow($this->cursor->y, '');
 		}
 		else
 		{
-			$row = $this->rows[$this->cursorY];
+			$row = $this->rows[$this->cursor->y];
 			$chars = $row->chars;
-			$newChars = substr($chars, 0, $this->cursorX);
+			$newChars = substr($chars, 0, $this->cursor->x);
 
 			// Truncate the previous row
 			$row->chars = $newChars;
 
 			// Add a new row, with the contents from the cursor to the end of the line
-			$this->insertRow($this->cursorY + 1, substr($chars, $this->cursorX));
+			$this->insertRow($this->cursor->y + 1, substr($chars, $this->cursor->x));
 		}
 
-		$this->cursorY++;
-		$this->cursorX = 0;
+		$this->cursor->y++;
+		$this->cursor->x = 0;
 
 		// Re-tokenize the file
 		$this->refreshPHPSyntax();
@@ -299,23 +319,23 @@ class Editor {
 
 	protected function deleteChar(): void
 	{
-		if ($this->cursorY === $this->numRows || ($this->cursorX === 0 && $this->cursorY === 0))
+		if ($this->cursor->y === $this->numRows || ($this->cursor->x === 0 && $this->cursor->y === 0))
 		{
 			return;
 		}
 
-		$row = $this->rows[$this->cursorY];
-		if ($this->cursorX > 0)
+		$row = $this->rows[$this->cursor->y];
+		if ($this->cursor->x > 0)
 		{
-			$row->deleteChar($this->cursorX - 1);
-			$this->cursorX--;
+			$row->deleteChar($this->cursor->x - 1);
+			$this->cursor->x--;
 		}
 		else
 		{
-			$this->cursorX = $this->rows[$this->cursorY - 1]->size;
-			$this->rows[$this->cursorY -1]->appendString($row->chars);
-			$this->deleteRow($this->cursorY);
-			$this->cursorY--;
+			$this->cursor->x = $this->rows[$this->cursor->y - 1]->size;
+			$this->rows[$this->cursor->y -1]->appendString($row->chars);
+			$this->deleteRow($this->cursor->y);
+			$this->cursor->y--;
 		}
 
 		// Re-tokenize the file
@@ -457,9 +477,9 @@ class Editor {
 			if ($match !== FALSE)
 			{
 				$lastMatch = $current;
-				$this->cursorY = (int)$current;
-				$this->cursorX = $this->rowRxToCx($row, $match);
-				$this->rowOffset = $this->numRows;
+				$this->cursor->y = (int)$current;
+				$this->cursor->x = $this->rowRxToCx($row, $match);
+				$this->offset->y = $this->numRows;
 
 				$savedHlLine = $current;
 				$savedHl = $row->hl;
@@ -473,10 +493,10 @@ class Editor {
 
 	protected function find(): void
 	{
-		$savedCx = $this->cursorX;
-		$savedCy = $this->cursorY;
-		$savedColOff = $this->colOffset;
-		$savedRowOff = $this->rowOffset;
+		$savedCx = $this->cursor->x;
+		$savedCy = $this->cursor->y;
+		$savedColOff = $this->offset->x;
+		$savedRowOff = $this->offset->y;
 
 		$query = $this->prompt('Search: %s (Use ESC/Arrows/Enter)', [$this, 'findCallback']);
 
@@ -484,10 +504,10 @@ class Editor {
 		// restore original cursor and scroll locations
 		if ($query === '')
 		{
-			$this->cursorX = $savedCx;
-			$this->cursorY = $savedCy;
-			$this->colOffset = $savedColOff;
-			$this->rowOffset = $savedRowOff;
+			$this->cursor->x = $savedCx;
+			$this->cursor->y = $savedCy;
+			$this->offset->x = $savedColOff;
+			$this->offset->y = $savedRowOff;
 		}
 	}
 
@@ -498,29 +518,29 @@ class Editor {
 	protected function scroll(): void
 	{
 		$this->renderX = 0;
-		if ($this->cursorY < $this->numRows)
+		if ($this->cursor->y < $this->numRows)
 		{
-			$this->renderX = $this->rowCxToRx($this->rows[$this->cursorY], $this->cursorX);
+			$this->renderX = $this->rowCxToRx($this->rows[$this->cursor->y], $this->cursor->x);
 		}
 
 		// Vertical Scrolling
-		if ($this->cursorY < $this->rowOffset)
+		if ($this->cursor->y < $this->offset->y)
 		{
-			$this->rowOffset = $this->cursorY;
+			$this->offset->y = $this->cursor->y;
 		}
-		if ($this->cursorY >= ($this->rowOffset + $this->screenRows))
+		else if ($this->cursor->y >= ($this->offset->y + $this->screenRows))
 		{
-			$this->rowOffset = $this->cursorY - $this->screenRows + 1;
+			$this->offset->y = $this->cursor->y - $this->screenRows + 1;
 		}
 
 		// Horizontal Scrolling
-		if ($this->renderX < $this->colOffset)
+		if ($this->renderX < $this->offset->x)
 		{
-			$this->colOffset = $this->renderX;
+			$this->offset->x = $this->renderX;
 		}
-		if ($this->renderX >= ($this->colOffset + $this->screenCols))
+		else if ($this->renderX >= ($this->offset->x + $this->screenCols))
 		{
-			$this->colOffset = $this->renderX - $this->screenCols + 1;
+			$this->offset->x = $this->renderX - $this->screenCols + 1;
 		}
 	}
 
@@ -528,7 +548,7 @@ class Editor {
 	{
 		for ($y = 0; $y < $this->screenRows; $y++)
 		{
-			$filerow = $y + $this->rowOffset;
+			$filerow = $y + $this->offset->y;
 
 			($filerow >= $this->numRows)
 				? $this->drawPlaceholderRow($y)
@@ -541,7 +561,7 @@ class Editor {
 
 	protected function drawRow(int $rowIdx): void
 	{
-		$len = $this->rows[$rowIdx]->rsize - $this->colOffset;
+		$len = $this->rows[$rowIdx]->rsize - $this->offset->x;
 		if ($len < 0)
 		{
 			$len = 0;
@@ -551,8 +571,8 @@ class Editor {
 			$len = $this->screenCols;
 		}
 
-		$chars = substr($this->rows[$rowIdx]->render, $this->colOffset, (int)$len);
-		$hl = array_slice($this->rows[$rowIdx]->hl, $this->colOffset, (int)$len);
+		$chars = substr($this->rows[$rowIdx]->render, $this->offset->x, (int)$len);
+		$hl = array_slice($this->rows[$rowIdx]->hl, $this->offset->x, (int)$len);
 
 		$currentColor = -1;
 
@@ -639,7 +659,7 @@ class Editor {
 		$syntaxType = ($this->syntax !== NULL) ? $this->syntax->filetype : 'no ft';
 		$isDirty = ($this->dirty > 0) ? '(modified)' : '';
 		$status = sprintf('%.20s - %d lines %s', $statusFilename, $this->numRows, $isDirty);
-		$rstatus = sprintf('%s | %d/%d', $syntaxType, $this->cursorY + 1, $this->numRows);
+		$rstatus = sprintf('%s | %d/%d', $syntaxType, $this->cursor->y + 1, $this->numRows);
 		$len = strlen($status);
 		$rlen = strlen($rstatus);
 		if ($len > $this->screenCols)
@@ -692,8 +712,8 @@ class Editor {
 
 		// Specify the current cursor position
 		$this->outputBuffer .= ANSI::moveCursor(
-			$this->cursorY - $this->rowOffset,
-			$this->renderX - $this->colOffset
+			$this->cursor->y - $this->offset->y,
+			$this->renderX - $this->offset->x
 		);
 
 		$this->outputBuffer .= ANSI::SHOW_CURSOR;
@@ -753,58 +773,78 @@ class Editor {
 
 	protected function moveCursor(string $key): void
 	{
-		$row = ($this->cursorY >= $this->numRows)
-			? NULL
-			: $this->rows[$this->cursorY];
+		$row = $this->rows[$this->cursor->y];
 
 		switch ($key)
 		{
 			case KeyType::ARROW_LEFT:
-				if ($this->cursorX !== 0)
+				if ($this->cursor->x !== 0)
 				{
-					$this->cursorX--;
+					$this->cursor->x--;
 				}
-				else if ($this->cursorY > 0)
+				else if ($this->cursor->y > 0)
 				{
-					$this->cursorY--;
-					$this->cursorX = $this->rows[$this->cursorY]->size;
+					$this->cursor->y--;
+					$this->cursor->x = $this->rows[$this->cursor->y]->size;
 				}
 			break;
 
 			case KeyType::ARROW_RIGHT:
-				if ($row && $this->cursorX < $row->size)
+				if ($row && $this->cursor->x < $row->size)
 				{
-					$this->cursorX++;
+					$this->cursor->x++;
 				}
-				else if ($row && $this->cursorX === $row->size)
+				else if ($row && $this->cursor->x === $row->size)
 				{
-					$this->cursorY++;
-					$this->cursorX = 0;
+					$this->cursor->y++;
+					$this->cursor->x = 0;
 				}
 			break;
 
 			case KeyType::ARROW_UP:
-				if ($this->cursorY !== 0)
+				if ($this->cursor->y !== 0)
 				{
-					$this->cursorY--;
+					$this->cursor->y--;
 				}
 			break;
 
 			case KeyType::ARROW_DOWN:
-				if ($this->cursorY < $this->numRows)
+				if ($this->cursor->y < $this->numRows)
 				{
-					$this->cursorY++;
+					$this->cursor->y++;
 				}
 			break;
+
+			case KeyType::PAGE_UP:
+				$this->cursor->y = ($this->cursor->y > $this->screenRows)
+					? $this->cursor->y - $this->screenRows
+					: 0;
+			break;
+
+			case KeyType::PAGE_DOWN:
+				$this->cursor->y = ($this->cursor->y + $this->screenRows < $this->numRows)
+					? $this->cursor->y + $this->screenRows
+					: $this->numRows;
+			break;
+
+			case KeyType::HOME_KEY:
+				$this->cursor->x = 0;
+			break;
+
+			case KeyType::END_KEY:
+				if ($this->cursor->y < $this->numRows)
+				{
+					$this->cursor->x = $this->rows[$this->cursor->y]->size - 1;
+				}
+			break;
+
+			default:
+				// Do nothing
 		}
 
-		$row = ($this->cursorY >= $this->numRows)
-			? NULL
-			: $this->rows[$this->cursorY];
-		$rowlen = $row->size ?? 0;
-		if ($this->cursorX > $rowlen)
+		if ($this->cursor->x > $row->size)
 		{
-			$this->cursorX = $rowlen;
+			$this->cursor->x = $row->size;
 		}
 	}
 
@@ -834,25 +874,12 @@ class Editor {
 					return '';
 				}
 				Terminal::clear();
-
-				return NULL;
-			break;
+			return NULL;
 
 			case KeyCode::CTRL('s'):
 				$this->save();
 			break;
 
-			case KeyType::HOME_KEY:
-				$this->cursorX = 0;
-			break;
-
-			case KeyType::END_KEY:
-				if ($this->cursorY < $this->numRows)
-				{
-					$this->cursorX = $this->rows[$this->cursorY]->size - 1;
-				}
-			break;
-
 			case KeyCode::CTRL('f'):
 				$this->find();
 			break;
@@ -866,15 +893,14 @@ class Editor {
 				$this->deleteChar();
 			break;
 
-			case KeyType::PAGE_UP:
-			case KeyType::PAGE_DOWN:
-				$this->pageUpOrDown($c);
-			break;
-
 			case KeyType::ARROW_UP:
 			case KeyType::ARROW_DOWN:
 			case KeyType::ARROW_LEFT:
 			case KeyType::ARROW_RIGHT:
+			case KeyType::PAGE_UP:
+			case KeyType::PAGE_DOWN:
+			case KeyType::HOME_KEY:
+			case KeyType::END_KEY:
 				$this->moveCursor($c);
 			break;
 
@@ -893,28 +919,6 @@ class Editor {
 		return $c;
 	}
 
-	public function pageUpOrDown(string $c): void
-	{
-		if ($c === KeyType::PAGE_UP)
-		{
-			$this->cursorY = $this->rowOffset;
-		}
-		else if ($c === KeyType::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 === KeyType::PAGE_UP ? KeyType::ARROW_UP : KeyType::ARROW_DOWN);
-		}
-	}
-
 	protected function refreshSyntax(): void
 	{
 		// Update the syntax highlighting for all the rows of the file
diff --git a/src/Position.php b/src/Position.php
new file mode 100644
index 0000000..2bfb297
--- /dev/null
+++ b/src/Position.php
@@ -0,0 +1,17 @@
+<?php declare(strict_types=1);
+
+namespace Aviat\Kilo;
+
+class Position {
+	private function __construct(public int $x, public int $y) {}
+
+	public static function new(int $x, int $y): self
+	{
+		return new Position($x, $y);
+	}
+
+	public static function default(): self
+	{
+		return new Position(0, 0);
+	}
+}
\ No newline at end of file
diff --git a/src/functions.php b/src/functions.php
index 3e3391c..03f841a 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -118,7 +118,7 @@ function is_separator(string $char): bool
  * @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, $value):void
+function array_replace_range(array &$array, int $offset, int $length, mixed $value):void
 {
 	if ($length === 1)
 	{