From 22f450740d507e57a25038d92d3092c29c3ebe9e Mon Sep 17 00:00:00 2001
From: Andrey Puzankov <ardk.puzankov@gmail.com>
Date: Thu, 3 Aug 2023 16:24:05 +0800
Subject: [PATCH 1/3] Add custom string index support

---
 lib/metadata.js | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/metadata.js b/lib/metadata.js
index d02e4a1..bb59a8c 100644
--- a/lib/metadata.js
+++ b/lib/metadata.js
@@ -62,7 +62,13 @@ class Indexes {
   extract(key, field) {
     const { index, primary, unique, many } = field;
     const isIndex = Array.isArray(index || primary || unique);
-    if (isIndex || many) this[key] = field;
+    const isStringIndex =
+      typeof index === 'string' &&
+      index.indexOf('(') !== -1 &&
+      index.lastIndexOf(')') !== -1 &&
+      index.substring(index.indexOf('('), index.lastIndexOf(')')).trim()
+        .length !== 0;
+    if (isIndex || isStringIndex || many) this[key] = field;
     return isIndex;
   }
 }

From 3b0d17322cc457aee474e3bc869be7ef14a54ed1 Mon Sep 17 00:00:00 2001
From: Andrey Puzankov <ardk.puzankov@gmail.com>
Date: Thu, 3 Aug 2023 18:08:56 +0800
Subject: [PATCH 2/3] Add custom string index support

- Added custom string index support
- Optimized calculating logical expressions with return-early pattern
- Fixed: return value only checked if the index was an array
---
 lib/metadata.js | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/lib/metadata.js b/lib/metadata.js
index bb59a8c..dc9bcf5 100644
--- a/lib/metadata.js
+++ b/lib/metadata.js
@@ -61,14 +61,18 @@ class Options {
 class Indexes {
   extract(key, field) {
     const { index, primary, unique, many } = field;
-    const isIndex = Array.isArray(index || primary || unique);
-    const isStringIndex =
-      typeof index === 'string' &&
-      index.indexOf('(') !== -1 &&
-      index.lastIndexOf(')') !== -1 &&
-      index.substring(index.indexOf('('), index.lastIndexOf(')')).trim()
-        .length !== 0;
-    if (isIndex || isStringIndex || many) this[key] = field;
+    const chosenIndex = index || primary || unique;
+    const isStringIndex = (index) => {
+      if (typeof index !== 'string') return false;
+      if (index.indexOf('(') === -1 && index.indexOf(')') === -1) return false;
+      const expression = index.substring(
+        index.indexOf('(') + 1,
+        index.lastIndexOf(')'),
+      );
+      return expression.trim().length !== 0;
+    };
+    const isIndex = Array.isArray(chosenIndex) || isStringIndex(chosenIndex);
+    if (isIndex || many) this[key] = field;
     return isIndex;
   }
 }

From 5bac2a3a99dbebe93c8a3bd5edd27a5d6f3ad239 Mon Sep 17 00:00:00 2001
From: Andrey Puzankov <ardk.puzankov@gmail.com>
Date: Fri, 11 Aug 2023 00:50:38 +0800
Subject: [PATCH 3/3] Add custom string index support

String index check moved to util.js
---
 lib/metadata.js | 10 +---------
 lib/util.js     | 15 ++++++++++++++-
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/lib/metadata.js b/lib/metadata.js
index dc9bcf5..efadfe7 100644
--- a/lib/metadata.js
+++ b/lib/metadata.js
@@ -1,6 +1,7 @@
 'use strict';
 
 const { getKindMetadata } = require('./kinds.js');
+const { isStringIndex } = require('./util.js');
 
 const errPrefix = 'Field';
 const OPTIONS = ['validate', 'parse', 'serialize', 'format'];
@@ -62,15 +63,6 @@ class Indexes {
   extract(key, field) {
     const { index, primary, unique, many } = field;
     const chosenIndex = index || primary || unique;
-    const isStringIndex = (index) => {
-      if (typeof index !== 'string') return false;
-      if (index.indexOf('(') === -1 && index.indexOf(')') === -1) return false;
-      const expression = index.substring(
-        index.indexOf('(') + 1,
-        index.lastIndexOf(')'),
-      );
-      return expression.trim().length !== 0;
-    };
     const isIndex = Array.isArray(chosenIndex) || isStringIndex(chosenIndex);
     if (isIndex || many) this[key] = field;
     return isIndex;
diff --git a/lib/util.js b/lib/util.js
index 84b09e9..1b529e6 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const { isFirstLetter } = require('metautil');
+const { isFirstLetter, validateBracketBalance } = require('metautil');
 
 const formatters = {
   type: (type, req = true) => {
@@ -41,9 +41,22 @@ const firstKey = (obj) => Object.keys(obj).find(isFirstLetter);
 
 const isInstanceOf = (obj, constrName) => obj?.constructor?.name === constrName;
 
+const isStringIndex = (index) => {
+  if (typeof index !== 'string') return false;
+  const brackets = ['(', ')'];
+  if (brackets.some((bracket) => index.indexOf(bracket) === -1)) return false;
+  if (!validateBracketBalance(index, brackets.join(''))) return false;
+  const expression = index.substring(
+    index.indexOf(brackets[0]) + 1,
+    index.lastIndexOf(brackets[1]),
+  );
+  return expression.trim().length !== 0;
+};
+
 module.exports = {
   formatters,
   checks,
   firstKey,
   isInstanceOf,
+  isStringIndex,
 };