From 6a5fce3070b178122ab73b4d52dd70b7e347968f Mon Sep 17 00:00:00 2001
From: "Philip (a-0)" <@ph:a-0.me>
Date: Tue, 13 Feb 2024 18:27:06 +0100
Subject: [PATCH] Added basic element update conflict resolution fo
 `message_processor`. Closes #14, #16

---
 ubisync/src/comm/conflict_resolution.rs | 15 +++++++++++++++
 ubisync/src/comm/message_processor.rs   | 15 ++++++++++++---
 ubisync/src/comm/mod.rs                 |  2 ++
 3 files changed, 29 insertions(+), 3 deletions(-)
 create mode 100644 ubisync/src/comm/conflict_resolution.rs

diff --git a/ubisync/src/comm/conflict_resolution.rs b/ubisync/src/comm/conflict_resolution.rs
new file mode 100644
index 0000000..57a8a83
--- /dev/null
+++ b/ubisync/src/comm/conflict_resolution.rs
@@ -0,0 +1,15 @@
+use ubisync_lib::types::{ContentUpdateStrategy, ElementContent, ElementId, MessageId};
+
+use crate::state::CommState;
+
+
+
+pub(crate) fn merge_element_contents(state: &CommState, id: ElementId, incoming: ElementContent, message: MessageId) -> Option<ElementContent> {
+    let element = state.get_element(id)?;
+    match element.update_strategy {
+        ContentUpdateStrategy::Overwrite => {
+            Some(incoming)
+        },
+        _ => None
+    }
+}
\ No newline at end of file
diff --git a/ubisync/src/comm/message_processor.rs b/ubisync/src/comm/message_processor.rs
index 93c2c28..41030ac 100644
--- a/ubisync/src/comm/message_processor.rs
+++ b/ubisync/src/comm/message_processor.rs
@@ -5,6 +5,7 @@ use ubisync_lib::types::{ContentUpdateStrategy, PeerId};
 
 use ubisync_lib::messages::{Message, MessageContent};
 
+use crate::comm::conflict_resolution::merge_element_contents;
 use crate::state::CommState;
 
 pub fn handle(state: &CommState, peer: &PeerId, message: Message) {
@@ -27,9 +28,17 @@ pub fn handle(state: &CommState, peer: &PeerId, message: Message) {
                 .expect("State failed");
         }
         MessageContent::UpdateElement { id, content } => {
-            state
-                .update_element_content(id.to_owned(), content.to_owned(), message.id().to_owned())
-                .expect("State failed");
+            if let Some(new_content) =
+                merge_element_contents(state, id.clone(), content.to_owned(), message.id().to_owned())
+            {
+                state
+                    .update_element_content(
+                        id.to_owned(),
+                        new_content.to_owned(),
+                        message.id().to_owned(),
+                    )
+                    .expect("State failed");
+            }
         }
         MessageContent::RemoveElement { id } => {
             state.remove_element(id.to_owned()).expect("State failed");
diff --git a/ubisync/src/comm/mod.rs b/ubisync/src/comm/mod.rs
index 6698745..08a67f4 100644
--- a/ubisync/src/comm/mod.rs
+++ b/ubisync/src/comm/mod.rs
@@ -1,4 +1,6 @@
 pub mod message_processor;
+mod conflict_resolution;
+
 use tracing::{debug, error, warn};
 use ubisync_lib::messages::Message;
 use ubisync_lib::types::PeerId;