dice.php: handle inline dice rolling markup

inc/functions/dice.php

@@ -1,6 +1,11 @@
 <?php
 namespace Vichan\Functions\Dice;
 
+function _get_or_default_int(array $arr, int $index, int $default) {
+	return (isset($arr[$index]) && is_numeric($arr[$index])) ? (int)$arr[$index] : $default;
+}
+
+
 /* Die rolling:
  * If "dice XdY+/-Z" is in the email field (where X or +/-Z may be
  * missing), X Y-sided dice are rolled and summed, with the modifier Z
@@ -59,3 +64,51 @@ function email_dice_roll($post) {
 		}
 	}
 }
+
+/**
+ * Rolls a dice and generates the appropriate html from the markup.
+ * @param array $matches The array of the matches according to the default configuration.
+ *                       1 -> The number of dices to roll.
+ *                       3 -> The number faces of the dices.
+ *                       4 -> The offset to apply to the dice.
+ * @param string $img_path Path to the image to use relative to the root. Null if none.
+ * @return string The html to replace the original markup with.
+ */
+function inline_dice_roll_markup(array $matches, ?string $img_path): string {
+	global $config;
+
+	$dice_count = _get_or_default_int($matches, 1, 1);
+	$dice_faces = _get_or_default_int($matches, 3, 6);
+	$dice_offset = _get_or_default_int($matches, 4, 0);
+
+	// Clamp between 1 and max_roll_count.
+	$dice_count = max(min($dice_count, $config['max_roll_count']), 1);
+	// Must be at least 2.
+	if ($dice_faces < 2) {
+		$dice_faces = 6;
+	}
+
+	$tot = 0;
+	for ($i = 0; $i < $dice_count; $i++) {
+		$tot += mt_rand(1, $dice_faces);
+	}
+	// Ensure that final result is at least an integer.
+	$tot = abs((int)($dice_offset + $tot));
+
+
+	if ($img_path !== null) {
+		$img_text = "<img src='{$config['root']}{$img_path}' alt='dice' title='dice' class=\"inline-dice\"/>";
+	} else {
+		$img_text = '';
+	}
+
+	if ($dice_offset === 0) {
+		$dice_offset_text = '';
+	} elseif ($dice_offset > 0) {
+		$dice_offset_text = "+{$dice_offset}";
+	} else {
+		$dice_offset_text = (string)$dice_offset;
+	}
+
+	return "<span>$img_text {$dice_count}d{$dice_faces}{$dice_offset_text} = <b>$tot</b></span>";
+}