yay

server/utils/crackdown.js

@@ -0,0 +1,72 @@
+//   ____                _    ____
+//  / ___|_ __ __ _  ___| | _|  _ \  _____      ___ __
+// | |   | '__/ _` |/ __| |/ / | | |/ _ \ \ /\ / / '_ \
+// | |___| | | (_| | (__|   <| |_| | (_) \ V  V /| | | |
+//  \____|_|  \__,_|\___|_|\_\____/ \___/ \_/\_/ |_| |_|
+//
+//
+//  _ __   __ _ _ __ ___  ___ _ __
+// | '_ \ / _` | '__/ __|/ _ \ '__|
+// | |_) | (_| | |  \__ \  __/ |
+// | .__/ \__,_|_|  |___/\___|_|
+// |_|
+
+const capture = "([a-z0-9:()-](?:.*[a-zA-Z:().!-])?)";
+const skipSpace = "\\s*";
+
+const htmlEscapeRegex = /[&<>"'`]/g; // used to escape html characters
+
+/**
+ * @type {Array.string[]}
+ *
+ * The order of the elements of this array matters.
+ */
+const opcodes = [
+    ["(^|\\n)=", "($|\\n)", "$1<h1>$2</h1>$3"],
+    ["(^|\\n)==", "($|\\n)", "$1<h2>$2</h2>$3"],
+    ["---", "---", "<span class='strike'>$1</span>"],
+    ["___", "___", "<span class='underline'>$1</span>"],
+    ["(?:[,]{3})", "(?:[,]{3})", "<span class='undercurl'>$1</span>"],
+    ["(?:[(]{2})", "(?:[)]{2})", "<span class='faint'>$1</span>"],
+    ["_", "_", "<span class='italic'>$1</span>"],
+    ["\\*", "\\*", "<span class='bold'>$1</span>"],
+    ["\\[\\[([a-zA-Z0-9_ ]+)\\[\\[", "\\]\\]", "<span class='$1'>$2</span>"],
+];
+/** @type{Array.Array.<Regexp,string>} */
+const regexes = [];
+
+//
+// Pre-compile all regexes
+for (const [left, right, replacement] of opcodes) {
+    regexes.push([new RegExp(left + skipSpace + capture + skipSpace + right, "gi"), replacement]);
+}
+
+/** @param {string} text */
+export function crackdown(text) {
+    text.replace(htmlEscapeRegex, (c) => {
+        switch (c) {
+            case "&":
+                return "&amp;";
+            case "<":
+                return "&lt;";
+            case ">":
+                return "&gt;";
+            case '"':
+                return "&quot;";
+            case "'":
+                return "&#039;";
+            case "`":
+                return "&#096;";
+            default:
+                return c;
+        }
+    });
+    for (const k in regexes) {
+        const [regex, replacement] = regexes[k];
+        text = text.replace(regex, replacement);
+    }
+
+    console.debug("crack output", text);
+
+    return text;
+}