From bd1fcb295ea4ef921d9e38b44cb27f212d55f644 Mon Sep 17 00:00:00 2001
From: Josh Kingsley <josh@joshkingsley.me>
Date: Thu, 13 Nov 2025 11:50:32 +0200
Subject: feat(crdt): add crdt crate

---
 crdt/src/lib.rs | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 crdt/src/lib.rs

(limited to 'crdt/src/lib.rs')

diff --git a/crdt/src/lib.rs b/crdt/src/lib.rs
new file mode 100644
index 0000000..dcef55c
--- /dev/null
+++ b/crdt/src/lib.rs
@@ -0,0 +1,92 @@
+mod vector_clock;
+
+use uuid::Uuid;
+
+use crate::vector_clock::VectorClock;
+
+pub struct Doc {
+    ops: Vec<Op>,
+}
+
+impl Doc {
+    pub fn new(actor_id: &Uuid) -> Self {
+        Self {
+            ops: vec![Op {
+                id: Uuid::now_v7(),
+                clock: VectorClock::new().inc(actor_id),
+                payload: OpPayload::Init,
+            }],
+        }
+    }
+
+    pub fn append_op(&mut self, payload: OpPayload, actor_id: &Uuid) {
+        let clock = self
+            .ops
+            .last()
+            .expect("doc should have at least an Init op")
+            .clock
+            .inc(actor_id);
+
+        self.ops.push(Op {
+            id: Uuid::now_v7(),
+            clock,
+            payload,
+        });
+    }
+
+    pub fn realize(&self) -> RealizedDoc {
+        let mut realized = RealizedDoc::default();
+        for op in &self.ops {
+            op.apply(&mut realized);
+        }
+        realized
+    }
+}
+
+pub struct Op {
+    id: Uuid,
+    payload: OpPayload,
+    clock: VectorClock,
+}
+
+impl Op {
+    fn apply(&self, realized: &mut RealizedDoc) {
+        match self.payload {
+            OpPayload::Init => {}
+            OpPayload::ChangeSubdivisions { rowId } => {}
+        }
+    }
+}
+
+pub enum OpPayload {
+    Init,
+    ChangeSubdivisions { rowId: Uuid },
+}
+
+pub struct RealizedDoc {
+    grids: Vec<Grid>,
+}
+
+impl Default for RealizedDoc {
+    fn default() -> Self {
+        RealizedDoc {
+            grids: vec![Grid {}],
+        }
+    }
+}
+
+pub struct Grid {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn realize_doc() {
+        let actor_id = Uuid::now_v7();
+        let doc = Doc::new(&actor_id);
+        let realized = doc.realize();
+
+        assert!(realized.grids.len() == 1);
+    }
+}
-- 
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