From 3e0b863b642e6dd3476dd34dcab6560bd65e4c6d Mon Sep 17 00:00:00 2001
From: spaced4ndy <8711996+spaced4ndy@users.noreply.github.com>
Date: Thu, 25 Jan 2024 18:57:38 +0400
Subject: [PATCH] core: add cChatJsonLength function (#3753)

---
 src/Simplex/Chat/Mobile.hs | 7 +++++++
 tests/MobileTests.hs       | 9 +++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/Simplex/Chat/Mobile.hs b/src/Simplex/Chat/Mobile.hs
index 7c74a7325..57e062cd0 100644
--- a/src/Simplex/Chat/Mobile.hs
+++ b/src/Simplex/Chat/Mobile.hs
@@ -20,6 +20,7 @@ import qualified Data.ByteArray as BA
 import qualified Data.ByteString.Base64.URL as U
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
+import qualified Data.ByteString.Lazy.Char8 as LB
 import Data.Functor (($>))
 import Data.List (find)
 import qualified Data.List.NonEmpty as L
@@ -94,6 +95,8 @@ foreign export ccall "chat_password_hash" cChatPasswordHash :: CString -> CStrin
 
 foreign export ccall "chat_valid_name" cChatValidName :: CString -> IO CString
 
+foreign export ccall "chat_json_length" cChatJsonLength :: CString -> IO CInt
+
 foreign export ccall "chat_encrypt_media" cChatEncryptMedia :: StablePtr ChatController -> CString -> Ptr Word8 -> CInt -> IO CString
 
 foreign export ccall "chat_decrypt_media" cChatDecryptMedia :: CString -> Ptr Word8 -> CInt -> IO CString
@@ -176,6 +179,10 @@ cChatPasswordHash cPwd cSalt = do
 cChatValidName :: CString -> IO CString
 cChatValidName cName = newCString . mkValidName =<< peekCString cName
 
+-- | returns length of JSON encoded string
+cChatJsonLength :: CString -> IO CInt
+cChatJsonLength s = fromIntegral . subtract 2 . LB.length . J.encode . safeDecodeUtf8 <$> B.packCString s
+
 mobileChatOpts :: String -> ChatOpts
 mobileChatOpts dbFilePrefix =
   ChatOpts
diff --git a/tests/MobileTests.hs b/tests/MobileTests.hs
index 0ed1b30f5..2fb4446a6 100644
--- a/tests/MobileTests.hs
+++ b/tests/MobileTests.hs
@@ -68,6 +68,8 @@ mobileTests = do
       it "no exception on missing file" testMissingFileEncryptionCApi
     describe "validate name" $ do
       it "should convert invalid name to a valid name" testValidNameCApi
+    describe "JSON length" $ do
+      it "should compute length of JSON encoded string" testChatJsonLengthCApi
 
 noActiveUser :: LB.ByteString
 noActiveUser =
@@ -356,6 +358,13 @@ testValidNameCApi _ = do
   cName2 <- cChatValidName =<< newCString " @'Джон'  Доу   👍 "
   peekCString cName2 `shouldReturn` goodName
 
+testChatJsonLengthCApi :: FilePath -> IO ()
+testChatJsonLengthCApi _ = do
+  cInt1 <- cChatJsonLength =<< newCString "Hello!"
+  cInt1 `shouldBe` 6
+  cInt2 <- cChatJsonLength =<< newCString "こんにちは！"
+  cInt2 `shouldBe` 18
+
 jDecode :: FromJSON a => String -> IO (Maybe a)
 jDecode = pure . J.decode . LB.pack