From 10c45ca7899637a1476d00bb4dc599932be9807a Mon Sep 17 00:00:00 2001
From: Konstantinos Chalkias <kostas@mystenlabs.com>
Date: Wed, 18 May 2022 08:41:23 -0700
Subject: [PATCH] Chat smart contract - post and post_with_ref

---
 .../examples/nfts/sources/Chat.move           | 51 +++++++++++++------
 .../examples/nfts/tests/ChatTests.move        |  3 +-
 .../framework/sources/Transfer.move           |  2 +-
 3 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/sui_programmability/examples/nfts/sources/Chat.move b/sui_programmability/examples/nfts/sources/Chat.move
index a40c2e0ab5672..cca426844f001 100644
--- a/sui_programmability/examples/nfts/sources/Chat.move
+++ b/sui_programmability/examples/nfts/sources/Chat.move
@@ -2,8 +2,9 @@
 // SPDX-License-Identifier: Apache-2.0
 
 module NFTs::Chat {
-    use Sui::ID::{Self, ID, VersionedID};
     use Std::ASCII::{Self, String};
+    use Std::Option::{Self, Option, some};
+    use Sui::ID::{Self, ID, VersionedID};
     use Sui::Transfer;
     use Sui::TxContext::{Self, TxContext};
     use Std::Vector::length;
@@ -23,9 +24,8 @@ module NFTs::Chat {
         text: String,
         // Set if referencing an another object (i.e., due to a Like, Retweet, Reply etc).
         // We allow referencing any object type, not ony Chat NFTs.
-        // By convention applications can use the all zeros address, when no reference is required.
-        ref_id: ID,
-        // app-specific metadata.
+        ref_id: Option<ID>,
+        // app-specific metadata. We do not enforce a metadata format and delegate this to app layer.
         metadata: vector<u8>,
     }
 
@@ -35,26 +35,47 @@ module NFTs::Chat {
     }
 
     /// Mint (post) a Chat object.
-    /// TODO: Using `address` as `app_identifier` & `ref_identifier` type, because we cannot pass `ID` to entry
-    ///     functions. Using `vector<u8>` for `text` instead of `String`  for the same reason.
-    public(script) fun mint(
-            app_identifier: address,
-            text: vector<u8>,
-            ref_identifier: address,
-            metadata: vector<u8>,
-            ctx: &mut TxContext,
-        ) {
+    fun post_internal(
+        app_id: ID,
+        text: vector<u8>,
+        ref_id: Option<ID>,
+        metadata: vector<u8>,
+        ctx: &mut TxContext,
+    ) {
         assert!(length(&text) <= MAX_TEXT_LENGTH, ETextOverflow);
         let chat = Chat {
             id: TxContext::new_id(ctx),
-            app_id: ID::new(app_identifier),
+            app_id,
             text: ASCII::string(text),
-            ref_id: ID::new(ref_identifier),
+            ref_id,
             metadata,
         };
         Transfer::transfer(chat, TxContext::sender(ctx));
     }
 
+    /// Mint (post) a Chat object without referencing another object.
+    public(script) fun post(
+        app_identifier: address,
+        text: vector<u8>,
+        metadata: vector<u8>,
+        ctx: &mut TxContext,
+    ) {
+        post_internal(ID::new(app_identifier), text, Option::none(), metadata, ctx);
+    }
+
+    /// Mint (post) a Chat object and reference another object (i.e., to simulate retweet, reply, like, attach).
+    /// TODO: Using `address` as `app_identifier` & `ref_identifier` type, because we cannot pass `ID` to entry
+    ///     functions. Using `vector<u8>` for `text` instead of `String`  for the same reason.
+    public(script) fun post_with_ref(
+        app_identifier: address,
+        text: vector<u8>,
+        ref_identifier: address,
+        metadata: vector<u8>,
+        ctx: &mut TxContext,
+    ) {
+        post_internal(ID::new(app_identifier), text, some(ID::new(ref_identifier)), metadata, ctx);
+    }
+
     /// Burn a Chat object.
     public(script) fun burn(chat: Chat, _ctx: &mut TxContext) {
         let Chat { id, app_id: _, text: _, ref_id: _, metadata: _ } = chat;
diff --git a/sui_programmability/examples/nfts/tests/ChatTests.move b/sui_programmability/examples/nfts/tests/ChatTests.move
index d66e518f510b4..18df57ab9255f 100644
--- a/sui_programmability/examples/nfts/tests/ChatTests.move
+++ b/sui_programmability/examples/nfts/tests/ChatTests.move
@@ -15,10 +15,9 @@ module NFTs::ChatTests {
     public(script) fun test_chat() {
         let scenario = &mut TestScenario::begin(&USER1_ADDRESS);
         {
-            Chat::mint(
+            Chat::post(
                 @0xC001, // This should be an application object ID.
                 HELLO,
-                @0x0000, // We're referencing the all-zero bytes object (i.e., it's not a retweet or reply).
                 METADATA, // Some metadata (it could be empty).
                 TestScenario::ctx(scenario)
             );
diff --git a/sui_programmability/framework/sources/Transfer.move b/sui_programmability/framework/sources/Transfer.move
index 9d074551af40c..48e75c67f06e8 100644
--- a/sui_programmability/framework/sources/Transfer.move
+++ b/sui_programmability/framework/sources/Transfer.move
@@ -11,7 +11,7 @@ module Sui::Transfer {
     friend Sui::Collection;
 
     // When transferring a child object, this error is thrown if the child object
-    // doesn't match the ChildRef that represents the onwership.
+    // doesn't match the ChildRef that represents the ownership.
     const EChildIDMismatch: u64 = 0;
 
     /// Represents a reference to a child object, whose type is T.