From ba2c7bec84e6cadce5e658f516fb210a1257a08f Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Thu, 7 Apr 2022 08:13:05 +0200
Subject: [PATCH] Create normalizeBech32

---
 CHANGELOG.md                         |  4 ++++
 packages/encoding/src/bech32.spec.ts | 22 +++++++++++++++++++++-
 packages/encoding/src/bech32.ts      | 11 +++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d83dce78..8fa3d3d1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Added
+
+- @cosmjs/encoding: Create `normalizeBech32`.
+
 ## [0.28.1] - 2022-03-30
 
 ### Added
diff --git a/packages/encoding/src/bech32.spec.ts b/packages/encoding/src/bech32.spec.ts
index a68545bb..1806ddc4 100644
--- a/packages/encoding/src/bech32.spec.ts
+++ b/packages/encoding/src/bech32.spec.ts
@@ -1,4 +1,4 @@
-import { fromBech32, toBech32 } from "./bech32";
+import { fromBech32, normalizeBech32, toBech32 } from "./bech32";
 import { fromHex } from "./hex";
 
 describe("bech32", () => {
@@ -89,4 +89,24 @@ describe("bech32", () => {
       expect(() => fromBech32("eth1n48g2mjh9Ezz7zjtya37wtgg5r5emr0drkwlgw")).toThrowError(/Mixed-case/i);
     });
   });
+
+  describe("normalizeBech32", () => {
+    it("works", () => {
+      expect(normalizeBech32("eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw")).toEqual(
+        "eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw",
+      );
+      expect(normalizeBech32("ETH1N48G2MJH9EZZ7ZJTYA37WTGG5R5EMR0DRKWLGW")).toEqual(
+        "eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw",
+      );
+    });
+
+    it("throws for mixed case addresses", () => {
+      // "Decoders MUST NOT accept strings where some characters are uppercase and some are lowercase (such strings are referred to as mixed case strings)."
+      // https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki
+      expect(() => normalizeBech32("Eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw")).toThrowError(/Mixed-case/i);
+      expect(() => normalizeBech32("eTh1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw")).toThrowError(/Mixed-case/i);
+      expect(() => normalizeBech32("ETH1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw")).toThrowError(/Mixed-case/i);
+      expect(() => normalizeBech32("eth1n48g2mjh9Ezz7zjtya37wtgg5r5emr0drkwlgw")).toThrowError(/Mixed-case/i);
+    });
+  });
 });
diff --git a/packages/encoding/src/bech32.ts b/packages/encoding/src/bech32.ts
index 38d4803e..d333611a 100644
--- a/packages/encoding/src/bech32.ts
+++ b/packages/encoding/src/bech32.ts
@@ -16,6 +16,17 @@ export function fromBech32(
   };
 }
 
+/**
+ * Takes a bech32 address and returns a normalized (i.e. lower case) representation of it.
+ *
+ * The input is validated along the way, which makes this significantly safer than
+ * using `address.toLowerCase()`.
+ */
+export function normalizeBech32(address: string): string {
+  const { prefix, data } = fromBech32(address);
+  return toBech32(prefix, data);
+}
+
 /**
  * @deprecated This class is deprecated and will be removed soon. Please use fromBech32() and toBech32() instead. For more details please refer to https://github.com/cosmos/cosmjs/issues/1053.
  */