From 32e3d21ead59efd6cac5389d2a9ba84b36507ef6 Mon Sep 17 00:00:00 2001
From: Andrew Poelstra <apoelstra@wpsoftware.net>
Date: Mon, 27 Mar 2023 21:47:52 +0000
Subject: [PATCH] codex32: provide user-readable error types

Github-Pull: #27351
Rebased-From: 1fa04b11b2452a2f15906d97cf1370d43f0dc23e
---
 src/codex32.cpp | 20 ++++++++++++++++++++
 src/codex32.h   |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/src/codex32.cpp b/src/codex32.cpp
index 13b5361129..2fd2271902 100644
--- a/src/codex32.cpp
+++ b/src/codex32.cpp
@@ -219,6 +219,26 @@ uint8_t lagrange_coefficient(std::vector<uint8_t>& indices, uint8_t idx, uint8_t
 
 } // namespace
 
+std::string ErrorString(Error e) {
+    switch (e) {
+    case OK: return "ok";
+    case BAD_CHECKSUM: return "bad checksum";
+    case BECH32_DECODE: return "bech32 decode failure (invalid character, no HRP, or inconsistent case)";
+    case INVALID_HRP: return "hrp differed from 'ms'";
+    case INVALID_ID_LEN: return "seed ID was not 4 characters";
+    case INVALID_ID_CHAR: return "seed ID used a non-bech32 character";
+    case INVALID_LENGTH: return "invalid length";
+    case INVALID_K: return "invalid threshold (k) value";
+    case INVALID_SHARE_IDX: return "invalid share index";
+    case TOO_FEW_SHARES: return "tried to derive a share but did not have enough input shares";
+    case DUPLICATE_SHARE: return "tried to derive a share but two input shares had the same index";
+    case MISMATCH_K: return "tried to derive a share but input shares had inconsistent threshold (k) values";
+    case MISMATCH_ID: return "tried to derive a share but input shares had inconsistent seed IDs";
+    case MISMATCH_LENGTH: return "tried to derive a share but input shares had inconsistent lengths";
+    }
+    assert(0);
+}
+
 /** Encode a codex32 string. */
 std::string Result::Encode() const {
     assert(IsValid());
diff --git a/src/codex32.h b/src/codex32.h
index 6f2f9ba1bf..93d9f813f9 100644
--- a/src/codex32.h
+++ b/src/codex32.h
@@ -41,6 +41,8 @@ enum Error {
     MISMATCH_LENGTH,
 };
 
+std::string ErrorString(Error e);
+
 class Result
 {
 public: