Remove terminal height requirement (#128)

* Ensure a minimimum scroll height of 1

* Allow the terminal dimensions to be recalculated

* Remove exception for minimum terminal height

* Add additional helper methods for moving the cursor

* Only re-render within the visible terminal height

src/Concerns/Cursor.php

@@ -60,4 +60,20 @@ public function moveCursor(int $x, int $y = 0): void
 
         static::writeDirectly($sequence);
     }
+
+    /**
+     * Move the cursor to the given column.
+     */
+    public function moveCursorToColumn(int $column): void
+    {
+        static::writeDirectly("\e[{$column}G");
+    }
+
+    /**
+     * Move the cursor up by the given number of lines.
+     */
+    public function moveCursorUp(int $lines): void
+    {
+        static::writeDirectly("\e[{$lines}A");
+    }
 }

src/Concerns/FakesInputOutput.php

@@ -27,6 +27,7 @@ public static function fake(array $keys = []): void
         $mock->shouldReceive('restoreTty')->byDefault();
         $mock->shouldReceive('cols')->byDefault()->andReturn(80);
         $mock->shouldReceive('lines')->byDefault()->andReturn(24);
+        $mock->shouldReceive('initDimensions')->byDefault();
 
         foreach ($keys as $key) {
             $mock->shouldReceive('read')->once()->andReturn($key);

src/Concerns/Scrolling.php

@@ -38,7 +38,7 @@ protected function reduceScrollingToFitTerminal(): void
     {
         $reservedLines = ($renderer = $this->getRenderer()) instanceof ScrollingRenderer ? $renderer->reservedLines() : 0;
 
-        $this->scroll = min($this->scroll, $this->terminal()->lines() - $reservedLines);
+        $this->scroll = max(1, min($this->scroll, $this->terminal()->lines() - $reservedLines));
     }
 
     /**

src/Prompt.php

@@ -208,6 +208,8 @@ public static function validateUsing(Closure $callback): void
      */
     protected function render(): void
     {
+        $this->terminal()->initDimensions();
+
         $frame = $this->renderTheme();
 
         if ($frame === $this->prevFrame) {
@@ -223,35 +225,14 @@ protected function render(): void
             return;
         }
 
-        $this->resetCursorPosition();
-
-        // Ensure that the full frame is buffered so subsequent output can see how many trailing newlines were written.
-        if ($this->state === 'submit') {
-            $this->eraseDown();
-            static::output()->write($frame);
+        $terminalHeight = $this->terminal()->lines();
+        $previousFrameHeight = count(explode(PHP_EOL, $this->prevFrame));
+        $renderableLines = array_slice(explode(PHP_EOL, $frame), abs(min(0, $terminalHeight - $previousFrameHeight)));
 
-            $this->prevFrame = '';
-
-            return;
-        }
-
-        $diff = $this->diffLines($this->prevFrame, $frame);
-
-        if (count($diff) === 1) { // Update the single line that changed.
-            $diffLine = $diff[0];
-            $this->moveCursor(0, $diffLine);
-            $this->eraseLines(1);
-            $lines = explode(PHP_EOL, $frame);
-            static::output()->write($lines[$diffLine]);
-            $this->moveCursor(0, count($lines) - $diffLine - 1);
-        } elseif (count($diff) > 1) { // Re-render everything past the first change
-            $diffLine = $diff[0];
-            $this->moveCursor(0, $diffLine);
-            $this->eraseDown();
-            $lines = explode(PHP_EOL, $frame);
-            $newLines = array_slice($lines, $diffLine);
-            static::output()->write(implode(PHP_EOL, $newLines));
-        }
+        $this->moveCursorToColumn(1);
+        $this->moveCursorUp(min($terminalHeight, $previousFrameHeight) - 1);
+        $this->eraseDown();
+        $this->output()->write(implode(PHP_EOL, $renderableLines));
 
         $this->prevFrame = $frame;
     }
@@ -268,40 +249,6 @@ protected function submit(): void
         }
     }
 
-    /**
-     * Reset the cursor position to the beginning of the previous frame.
-     */
-    private function resetCursorPosition(): void
-    {
-        $lines = count(explode(PHP_EOL, $this->prevFrame)) - 1;
-
-        $this->moveCursor(-999, $lines * -1);
-    }
-
-    /**
-     * Get the difference between two strings.
-     *
-     * @return array<int>
-     */
-    private function diffLines(string $a, string $b): array
-    {
-        if ($a === $b) {
-            return [];
-        }
-
-        $aLines = explode(PHP_EOL, $a);
-        $bLines = explode(PHP_EOL, $b);
-        $diff = [];
-
-        for ($i = 0; $i < max(count($aLines), count($bLines)); $i++) {
-            if (! isset($aLines[$i]) || ! isset($bLines[$i]) || $aLines[$i] !== $bLines[$i]) {
-                $diff[] = $i;
-            }
-        }
-
-        return $diff;
-    }
-
     /**
      * Handle a key press and determine whether to continue.
      */

src/Terminal.php

@@ -2,6 +2,7 @@
 
 namespace Laravel\Prompts;
 
+use ReflectionClass;
 use RuntimeException;
 use Symfony\Component\Console\Terminal as SymfonyTerminal;
 
@@ -13,14 +14,17 @@ class Terminal
     protected ?string $initialTtyMode;
 
     /**
-     * The number of columns in the terminal.
+     * The Symfony Terminal instance.
      */
-    protected int $cols;
+    protected SymfonyTerminal $terminal;
 
     /**
-     * The number of lines in the terminal.
+     * Create a new Terminal instance.
      */
-    protected int $lines;
+    public function __construct()
+    {
+        $this->terminal = new SymfonyTerminal();
+    }
 
     /**
      * Read a line from the terminal.
@@ -59,15 +63,25 @@ public function restoreTty(): void
      */
     public function cols(): int
     {
-        return $this->cols ??= (new SymfonyTerminal())->getWidth();
+        return $this->terminal->getWidth();
     }
 
     /**
      * Get the number of lines in the terminal.
      */
     public function lines(): int
     {
-        return $this->lines ??= (new SymfonyTerminal())->getHeight();
+        return $this->terminal->getHeight();
+    }
+
+    /**
+     * (Re)initialize the terminal dimensions.
+     */
+    public function initDimensions(): void
+    {
+        (new ReflectionClass($this->terminal))
+            ->getMethod('initDimensions')
+            ->invoke($this->terminal);
     }
 
     /**

src/Themes/Default/Renderer.php

@@ -5,7 +5,6 @@
 use Laravel\Prompts\Concerns\Colors;
 use Laravel\Prompts\Concerns\Truncation;
 use Laravel\Prompts\Prompt;
-use RuntimeException;
 
 abstract class Renderer
 {
@@ -22,7 +21,7 @@ abstract class Renderer
      */
     public function __construct(protected Prompt $prompt)
     {
-        $this->checkTerminalSize($prompt);
+        //
     }
 
     /**
@@ -100,19 +99,4 @@ public function __toString()
             .$this->output
             .(in_array($this->prompt->state, ['submit', 'cancel']) ? PHP_EOL : '');
     }
-
-    /**
-     * Check that the terminal is large enough to render the prompt.
-     */
-    private function checkTerminalSize(Prompt $prompt): void
-    {
-        $required = 8;
-        $actual = $prompt->terminal()->lines();
-
-        if ($actual < $required) {
-            throw new RuntimeException(
-                "The terminal height must be at least [$required] lines but is currently [$actual]. Please increase the height or reduce the font size."
-            );
-        }
-    }
 }