Adding a working bft-json-crdt implementation for the PoC

crates/bft-json-crdt/src/json_crdt.rs

@@ -0,0 +1,868 @@
+use std::{
+    collections::{HashMap, HashSet},
+    fmt::Display,
+};
+
+use crate::{
+    debug::{debug_op_on_primitive, DebugView},
+    keypair::{sha256, sign, AuthorId, SignedDigest},
+    list_crdt::ListCrdt,
+    lww_crdt::LwwRegisterCrdt,
+    op::{print_hex, print_path, Hashable, Op, OpId, PathSegment},
+};
+pub use bft_crdt_derive::*;
+use fastcrypto::traits::VerifyingKey;
+use fastcrypto::{
+    ed25519::{Ed25519KeyPair, Ed25519PublicKey, Ed25519Signature},
+    traits::{KeyPair, ToFromBytes},
+    // Verifier,
+};
+
+/// Anything that can be nested in a JSON CRDT
+pub trait CrdtNode: CrdtNodeFromValue + Hashable + Clone {
+    /// Create a new CRDT of this type
+    fn new(id: AuthorId, path: Vec<PathSegment>) -> Self;
+    /// Apply an operation to this CRDT, forwarding if necessary
+    fn apply(&mut self, op: Op<Value>) -> OpState;
+    /// Get a JSON representation of the value in this node
+    fn view(&self) -> Value;
+}
+
+/// Enum representing possible outcomes of applying an operation to a CRDT
+#[derive(Debug, PartialEq)]
+pub enum OpState {
+    /// Operation applied successfully
+    Ok,
+    /// Tried to apply an operation to a non-CRDT primative (i.e. f64, bool, etc.)
+    /// If you would like a mutable primitive, wrap it in a [`LWWRegisterCRDT`]
+    ErrApplyOnPrimitive,
+    /// Tried to apply an operation to a static struct CRDT
+    /// If you would like a mutable object, use a [`Value`]
+    ErrApplyOnStruct,
+    /// Tried to apply an operation that contains content of the wrong type.
+    /// In other words, the content cannot be coerced to the CRDT at the path specified.
+    ErrMismatchedType,
+    /// The signed digest of the message did not match the claimed author of the message.
+    /// This can happen if the message was tampered with during delivery
+    ErrDigestMismatch,
+    /// The hash of the message did not match the contents of the mesage.
+    /// This can happen if the author tried to perform an equivocation attack by creating an
+    /// operation and modifying it has already been created
+    ErrHashMismatch,
+    /// Tried to apply an operation to a non-existent path. The author may have forgotten to attach
+    /// a causal dependency
+    ErrPathMismatch,
+    /// Trying to modify/delete the sentinel (zero-th) node element that is used for book-keeping
+    ErrListApplyToEmpty,
+    /// We have not received all of the causal dependencies of this operation. It has been queued
+    /// up and will be executed when its causal dependencies have been delivered
+    MissingCausalDependencies,
+}
+
+/// The following types can be used as a 'terminal' type in CRDTs
+pub trait MarkPrimitive: Into<Value> + Default {}
+impl MarkPrimitive for bool {}
+impl MarkPrimitive for i32 {}
+impl MarkPrimitive for i64 {}
+impl MarkPrimitive for f64 {}
+impl MarkPrimitive for char {}
+impl MarkPrimitive for String {}
+impl MarkPrimitive for Value {}
+
+/// Implement CrdtNode for non-CRDTs
+/// This is a stub implementation so most functions don't do anything/log an error
+impl<T> CrdtNode for T
+where
+    T: CrdtNodeFromValue + MarkPrimitive + Hashable + Clone,
+{
+    fn apply(&mut self, _op: Op<Value>) -> OpState {
+        OpState::ErrApplyOnPrimitive
+    }
+
+    fn view(&self) -> Value {
+        self.to_owned().into()
+    }
+
+    fn new(_id: AuthorId, _path: Vec<PathSegment>) -> Self {
+        debug_op_on_primitive(_path);
+        Default::default()
+    }
+}
+
+/// The base struct for a JSON CRDT. Allows for declaring causal
+/// dependencies across fields. It only accepts messages of [`SignedOp`] for BFT.
+pub struct BaseCrdt<T: CrdtNode> {
+    /// Public key of this CRDT
+    pub id: AuthorId,
+
+    /// Internal base CRDT
+    pub doc: T,
+
+    /// In a real world scenario, this would be a proper hashgraph that allows for
+    /// efficient reconciliation of missing dependencies. We naively keep a hashset
+    /// of messages we've seen (represented by their [`SignedDigest`]).
+    received: HashSet<SignedDigest>,
+    message_q: HashMap<SignedDigest, Vec<SignedOp>>,
+}
+
+/// An [`Op<Value>`] with a few bits of extra metadata
+#[derive(Clone)]
+pub struct SignedOp {
+    // Note that this can be different from the author of the inner op as the inner op could have been created
+    // by a different person
+    author: AuthorId,
+    /// Signed hash using priv key of author. Effectively [`OpID`] Use this as the ID to figure out what has been delivered already
+    pub signed_digest: SignedDigest,
+    pub inner: Op<Value>,
+    /// List of causal dependencies
+    pub depends_on: Vec<SignedDigest>,
+}
+
+impl SignedOp {
+    pub fn id(&self) -> OpId {
+        self.inner.id
+    }
+
+    pub fn author(&self) -> AuthorId {
+        self.author
+    }
+
+    /// Creates a digest of the following fields. Any changes in the fields will change the signed digest
+    ///  - id (hash of the following)
+    ///    - origin
+    ///    - author
+    ///    - seq
+    ///    - is_deleted
+    ///  - path
+    ///  - dependencies
+    fn digest(&self) -> [u8; 32] {
+        let path_string = print_path(self.inner.path.clone());
+        let dependency_string = self
+            .depends_on
+            .iter()
+            .map(print_hex)
+            .collect::<Vec<_>>()
+            .join("");
+        let fmt_str = format!("{:?},{path_string},{dependency_string}", self.id());
+        sha256(fmt_str)
+    }
+
+    /// Sign this digest with the given keypair. Shouldn't need to be called manually,
+    /// just use [`SignedOp::from_op`] instead
+    fn sign_digest(&mut self, keypair: &Ed25519KeyPair) {
+        self.signed_digest = sign(keypair, &self.digest()).sig.to_bytes()
+    }
+
+    /// Ensure digest was actually signed by the author it claims to be signed by
+    pub fn is_valid_digest(&self) -> bool {
+        let digest = Ed25519Signature::from_bytes(&self.signed_digest);
+        let pubkey = Ed25519PublicKey::from_bytes(&self.author());
+        match (digest, pubkey) {
+            (Ok(digest), Ok(pubkey)) => pubkey.verify(&self.digest(), &digest).is_ok(),
+            (_, _) => false,
+        }
+    }
+
+    /// Sign a normal op and add all the needed metadata
+    pub fn from_op<T: CrdtNode>(
+        value: Op<T>,
+        keypair: &Ed25519KeyPair,
+        depends_on: Vec<SignedDigest>,
+    ) -> Self {
+        let author = keypair.public().0.to_bytes();
+        let mut new = Self {
+            inner: Op {
+                content: value.content.map(|c| c.view()),
+                origin: value.origin,
+                author: value.author,
+                seq: value.seq,
+                path: value.path,
+                is_deleted: value.is_deleted,
+                id: value.id,
+            },
+            author,
+            signed_digest: [0u8; 64],
+            depends_on,
+        };
+        new.sign_digest(keypair);
+        new
+    }
+}
+
+impl<T: CrdtNode + DebugView> BaseCrdt<T> {
+    /// Crease a new BaseCRDT of the given type. Multiple BaseCRDTs
+    /// can be created from a single keypair but you are responsible for
+    /// routing messages to the right BaseCRDT. Usually you should just make a single
+    /// struct that contains all the state you need
+    pub fn new(keypair: &Ed25519KeyPair) -> Self {
+        let id = keypair.public().0.to_bytes();
+        Self {
+            id,
+            doc: T::new(id, vec![]),
+            received: HashSet::new(),
+            message_q: HashMap::new(),
+        }
+    }
+
+    /// Apply a signed operation to this BaseCRDT, verifying integrity and routing to the right
+    /// nested CRDT
+    pub fn apply(&mut self, op: SignedOp) -> OpState {
+        self.log_try_apply(&op);
+
+        #[cfg(feature = "bft")]
+        if !op.is_valid_digest() {
+            self.debug_digest_failure(op);
+            return OpState::ErrDigestMismatch;
+        }
+
+        let op_id = op.signed_digest;
+        if !op.depends_on.is_empty() {
+            for origin in &op.depends_on {
+                if !self.received.contains(origin) {
+                    self.log_missing_causal_dep(origin);
+                    self.message_q.entry(*origin).or_default().push(op);
+                    return OpState::MissingCausalDependencies;
+                }
+            }
+        }
+
+        // apply
+        self.log_actually_apply(&op);
+        let status = self.doc.apply(op.inner);
+        self.debug_view();
+        self.received.insert(op_id);
+
+        // apply all of its causal dependents if there are any
+        let dependent_queue = self.message_q.remove(&op_id);
+        if let Some(mut q) = dependent_queue {
+            for dependent in q.drain(..) {
+                self.apply(dependent);
+            }
+        }
+        status
+    }
+}
+
+/// An enum representing a JSON value
+#[derive(Clone, Debug, PartialEq)]
+pub enum Value {
+    Null,
+    Bool(bool),
+    Number(f64),
+    String(String),
+    Array(Vec<Value>),
+    Object(HashMap<String, Value>),
+}
+
+impl Display for Value {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                Value::Null => "null".to_string(),
+                Value::Bool(b) => b.to_string(),
+                Value::Number(n) => n.to_string(),
+                Value::String(s) => format!("\"{s}\""),
+                Value::Array(arr) => {
+                    if arr.len() > 1 {
+                        format!(
+                            "[\n{}\n]",
+                            arr.iter()
+                                .map(|x| format!("  {x}"))
+                                .collect::<Vec<_>>()
+                                .join(",\n")
+                        )
+                    } else {
+                        format!(
+                            "[ {} ]",
+                            arr.iter()
+                                .map(|x| x.to_string())
+                                .collect::<Vec<_>>()
+                                .join(", ")
+                        )
+                    }
+                }
+                Value::Object(obj) => format!(
+                    "{{ {} }}",
+                    obj.iter()
+                        .map(|(k, v)| format!("  \"{k}\": {v}"))
+                        .collect::<Vec<_>>()
+                        .join(",\n")
+                ),
+            }
+        )
+    }
+}
+
+impl Default for Value {
+    fn default() -> Self {
+        Self::Null
+    }
+}
+
+/// Allow easy conversion to and from serde's JSON format. This allows us to use the [`json!`]
+/// macro
+impl From<Value> for serde_json::Value {
+    fn from(value: Value) -> Self {
+        match value {
+            Value::Null => serde_json::Value::Null,
+            Value::Bool(x) => serde_json::Value::Bool(x),
+            Value::Number(x) => serde_json::Value::Number(serde_json::Number::from_f64(x).unwrap()),
+            Value::String(x) => serde_json::Value::String(x),
+            Value::Array(x) => {
+                serde_json::Value::Array(x.iter().map(|a| a.clone().into()).collect())
+            }
+            Value::Object(x) => serde_json::Value::Object(
+                x.iter()
+                    .map(|(k, v)| (k.clone(), v.clone().into()))
+                    .collect(),
+            ),
+        }
+    }
+}
+
+impl From<serde_json::Value> for Value {
+    fn from(value: serde_json::Value) -> Self {
+        match value {
+            serde_json::Value::Null => Value::Null,
+            serde_json::Value::Bool(x) => Value::Bool(x),
+            serde_json::Value::Number(x) => Value::Number(x.as_f64().unwrap()),
+            serde_json::Value::String(x) => Value::String(x),
+            serde_json::Value::Array(x) => {
+                Value::Array(x.iter().map(|a| a.clone().into()).collect())
+            }
+            serde_json::Value::Object(x) => Value::Object(
+                x.iter()
+                    .map(|(k, v)| (k.clone(), v.clone().into()))
+                    .collect(),
+            ),
+        }
+    }
+}
+
+impl Value {
+    pub fn into_json(self) -> serde_json::Value {
+        self.into()
+    }
+}
+
+/// Conversions from primitive types to [`Value`]
+impl From<bool> for Value {
+    fn from(val: bool) -> Self {
+        Value::Bool(val)
+    }
+}
+
+impl From<i64> for Value {
+    fn from(val: i64) -> Self {
+        Value::Number(val as f64)
+    }
+}
+
+impl From<i32> for Value {
+    fn from(val: i32) -> Self {
+        Value::Number(val as f64)
+    }
+}
+
+impl From<f64> for Value {
+    fn from(val: f64) -> Self {
+        Value::Number(val)
+    }
+}
+
+impl From<String> for Value {
+    fn from(val: String) -> Self {
+        Value::String(val)
+    }
+}
+
+impl From<char> for Value {
+    fn from(val: char) -> Self {
+        Value::String(val.into())
+    }
+}
+
+impl<T> From<Option<T>> for Value
+where
+    T: CrdtNode,
+{
+    fn from(val: Option<T>) -> Self {
+        match val {
+            Some(x) => x.view(),
+            None => Value::Null,
+        }
+    }
+}
+
+impl<T> From<Vec<T>> for Value
+where
+    T: CrdtNode,
+{
+    fn from(value: Vec<T>) -> Self {
+        Value::Array(value.iter().map(|x| x.view()).collect())
+    }
+}
+
+/// Fallibly create a CRDT Node from a JSON Value
+pub trait CrdtNodeFromValue: Sized {
+    fn node_from(value: Value, id: AuthorId, path: Vec<PathSegment>) -> Result<Self, String>;
+}
+
+/// Fallibly cast a JSON Value into a CRDT Node
+pub trait IntoCrdtNode<T>: Sized {
+    fn into_node(self, id: AuthorId, path: Vec<PathSegment>) -> Result<T, String>;
+}
+
+/// [`CrdtNodeFromValue`] implies [`IntoCRDTNode<T>`]
+impl<T> IntoCrdtNode<T> for Value
+where
+    T: CrdtNodeFromValue,
+{
+    fn into_node(self, id: AuthorId, path: Vec<PathSegment>) -> Result<T, String> {
+        T::node_from(self, id, path)
+    }
+}
+
+/// Trivial conversion from Value to Value as CrdtNodeFromValue
+impl CrdtNodeFromValue for Value {
+    fn node_from(value: Value, _id: AuthorId, _path: Vec<PathSegment>) -> Result<Self, String> {
+        Ok(value)
+    }
+}
+
+/// Conversions from primitives to CRDTs
+impl CrdtNodeFromValue for bool {
+    fn node_from(value: Value, _id: AuthorId, _path: Vec<PathSegment>) -> Result<Self, String> {
+        if let Value::Bool(x) = value {
+            Ok(x)
+        } else {
+            Err(format!("failed to convert {value:?} -> bool"))
+        }
+    }
+}
+
+impl CrdtNodeFromValue for f64 {
+    fn node_from(value: Value, _id: AuthorId, _path: Vec<PathSegment>) -> Result<Self, String> {
+        if let Value::Number(x) = value {
+            Ok(x)
+        } else {
+            Err(format!("failed to convert {value:?} -> f64"))
+        }
+    }
+}
+
+impl CrdtNodeFromValue for i64 {
+    fn node_from(value: Value, _id: AuthorId, _path: Vec<PathSegment>) -> Result<Self, String> {
+        if let Value::Number(x) = value {
+            Ok(x as i64)
+        } else {
+            Err(format!("failed to convert {value:?} -> f64"))
+        }
+    }
+}
+
+impl CrdtNodeFromValue for String {
+    fn node_from(value: Value, _id: AuthorId, _path: Vec<PathSegment>) -> Result<Self, String> {
+        if let Value::String(x) = value {
+            Ok(x)
+        } else {
+            Err(format!("failed to convert {value:?} -> String"))
+        }
+    }
+}
+
+impl CrdtNodeFromValue for char {
+    fn node_from(value: Value, _id: AuthorId, _path: Vec<PathSegment>) -> Result<Self, String> {
+        if let Value::String(x) = value.clone() {
+            x.chars().next().ok_or(format!(
+                "failed to convert {value:?} -> char: found a zero-length string"
+            ))
+        } else {
+            Err(format!("failed to convert {value:?} -> char"))
+        }
+    }
+}
+
+impl<T> CrdtNodeFromValue for LwwRegisterCrdt<T>
+where
+    T: CrdtNode,
+{
+    fn node_from(value: Value, id: AuthorId, path: Vec<PathSegment>) -> Result<Self, String> {
+        let mut crdt = LwwRegisterCrdt::new(id, path);
+        crdt.set(value);
+        Ok(crdt)
+    }
+}
+
+impl<T> CrdtNodeFromValue for ListCrdt<T>
+where
+    T: CrdtNode,
+{
+    fn node_from(value: Value, id: AuthorId, path: Vec<PathSegment>) -> Result<Self, String> {
+        if let Value::Array(arr) = value {
+            let mut crdt = ListCrdt::new(id, path);
+            let result: Result<(), String> =
+                arr.into_iter().enumerate().try_for_each(|(i, val)| {
+                    crdt.insert_idx(i, val);
+                    Ok(())
+                });
+            result?;
+            Ok(crdt)
+        } else {
+            Err(format!("failed to convert {value:?} -> ListCRDT<T>"))
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use serde_json::json;
+
+    use crate::{
+        json_crdt::{add_crdt_fields, BaseCrdt, CrdtNode, IntoCrdtNode, OpState, Value},
+        keypair::make_keypair,
+        list_crdt::ListCrdt,
+        lww_crdt::LwwRegisterCrdt,
+        op::{print_path, ROOT_ID},
+    };
+
+    #[test]
+    fn test_derive_basic() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Player {
+            x: LwwRegisterCrdt<f64>,
+            y: LwwRegisterCrdt<f64>,
+        }
+
+        let keypair = make_keypair();
+        let crdt = BaseCrdt::<Player>::new(&keypair);
+        assert_eq!(print_path(crdt.doc.x.path), "x");
+        assert_eq!(print_path(crdt.doc.y.path), "y");
+    }
+
+    #[test]
+    fn test_derive_nested() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Position {
+            x: LwwRegisterCrdt<f64>,
+            y: LwwRegisterCrdt<f64>,
+        }
+
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Player {
+            pos: Position,
+            balance: LwwRegisterCrdt<f64>,
+            messages: ListCrdt<String>,
+        }
+
+        let keypair = make_keypair();
+        let crdt = BaseCrdt::<Player>::new(&keypair);
+        assert_eq!(print_path(crdt.doc.pos.x.path), "pos.x");
+        assert_eq!(print_path(crdt.doc.pos.y.path), "pos.y");
+        assert_eq!(print_path(crdt.doc.balance.path), "balance");
+        assert_eq!(print_path(crdt.doc.messages.path), "messages");
+    }
+
+    #[test]
+    fn test_lww_ops() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Test {
+            a: LwwRegisterCrdt<f64>,
+            b: LwwRegisterCrdt<bool>,
+            c: LwwRegisterCrdt<String>,
+        }
+
+        let kp1 = make_keypair();
+        let kp2 = make_keypair();
+        let mut base1 = BaseCrdt::<Test>::new(&kp1);
+        let mut base2 = BaseCrdt::<Test>::new(&kp2);
+
+        let _1_a_1 = base1.doc.a.set(3.0).sign(&kp1);
+        let _1_b_1 = base1.doc.b.set(true).sign(&kp1);
+        let _2_a_1 = base2.doc.a.set(1.5).sign(&kp2);
+        let _2_a_2 = base2.doc.a.set(2.13).sign(&kp2);
+        let _2_c_1 = base2.doc.c.set("abc".to_string()).sign(&kp2);
+
+        assert_eq!(base1.doc.a.view(), json!(3.0).into());
+        assert_eq!(base2.doc.a.view(), json!(2.13).into());
+        assert_eq!(base1.doc.b.view(), json!(true).into());
+        assert_eq!(base2.doc.c.view(), json!("abc").into());
+
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "a": 3.0,
+                "b": true,
+                "c": null,
+            })
+        );
+        assert_eq!(
+            base2.doc.view().into_json(),
+            json!({
+                "a": 2.13,
+                "b": null,
+                "c": "abc",
+            })
+        );
+
+        assert_eq!(base2.apply(_1_a_1), OpState::Ok);
+        assert_eq!(base2.apply(_1_b_1), OpState::Ok);
+        assert_eq!(base1.apply(_2_a_1), OpState::Ok);
+        assert_eq!(base1.apply(_2_a_2), OpState::Ok);
+        assert_eq!(base1.apply(_2_c_1), OpState::Ok);
+
+        assert_eq!(base1.doc.view().into_json(), base2.doc.view().into_json());
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "a": 2.13,
+                "b": true,
+                "c": "abc"
+            })
+        )
+    }
+
+    #[test]
+    fn test_vec_and_map_ops() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Test {
+            a: ListCrdt<String>,
+        }
+
+        let kp1 = make_keypair();
+        let kp2 = make_keypair();
+        let mut base1 = BaseCrdt::<Test>::new(&kp1);
+        let mut base2 = BaseCrdt::<Test>::new(&kp2);
+
+        let _1a = base1.doc.a.insert(ROOT_ID, "a".to_string()).sign(&kp1);
+        let _1b = base1.doc.a.insert(_1a.id(), "b".to_string()).sign(&kp1);
+        let _2c = base2.doc.a.insert(ROOT_ID, "c".to_string()).sign(&kp2);
+        let _2d = base2.doc.a.insert(_1b.id(), "d".to_string()).sign(&kp2);
+
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "a": ["a", "b"],
+            })
+        );
+
+        // as _1b hasn't been delivered to base2 yet
+        assert_eq!(
+            base2.doc.view().into_json(),
+            json!({
+                "a": ["c"],
+            })
+        );
+
+        assert_eq!(base2.apply(_1b), OpState::MissingCausalDependencies);
+        assert_eq!(base2.apply(_1a), OpState::Ok);
+        assert_eq!(base1.apply(_2d), OpState::Ok);
+        assert_eq!(base1.apply(_2c), OpState::Ok);
+        assert_eq!(base1.doc.view().into_json(), base2.doc.view().into_json());
+    }
+
+    #[test]
+    fn test_causal_field_dependency() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Item {
+            name: LwwRegisterCrdt<String>,
+            soulbound: LwwRegisterCrdt<bool>,
+        }
+
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Player {
+            inventory: ListCrdt<Item>,
+            balance: LwwRegisterCrdt<f64>,
+        }
+
+        let kp1 = make_keypair();
+        let kp2 = make_keypair();
+        let mut base1 = BaseCrdt::<Player>::new(&kp1);
+        let mut base2 = BaseCrdt::<Player>::new(&kp2);
+
+        // require balance update to happen before inventory update
+        let _add_money = base1.doc.balance.set(5000.0).sign(&kp1);
+        let _spend_money = base1
+            .doc
+            .balance
+            .set(3000.0)
+            .sign_with_dependencies(&kp1, vec![&_add_money]);
+
+        let sword: Value = json!({
+            "name": "Sword",
+            "soulbound": true,
+        })
+        .into();
+        let _new_inventory_item = base1
+            .doc
+            .inventory
+            .insert_idx(0, sword)
+            .sign_with_dependencies(&kp1, vec![&_spend_money]);
+
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "balance": 3000.0,
+                "inventory": [
+                    {
+                        "name": "Sword",
+                        "soulbound": true
+                    }
+                ]
+            })
+        );
+
+        // do it completely out of order
+        assert_eq!(
+            base2.apply(_new_inventory_item),
+            OpState::MissingCausalDependencies
+        );
+        assert_eq!(
+            base2.apply(_spend_money),
+            OpState::MissingCausalDependencies
+        );
+        assert_eq!(base2.apply(_add_money), OpState::Ok);
+        assert_eq!(base1.doc.view().into_json(), base2.doc.view().into_json());
+    }
+
+    #[test]
+    fn test_2d_grid() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Game {
+            grid: ListCrdt<ListCrdt<LwwRegisterCrdt<bool>>>,
+        }
+
+        let kp1 = make_keypair();
+        let kp2 = make_keypair();
+        let mut base1 = BaseCrdt::<Game>::new(&kp1);
+        let mut base2 = BaseCrdt::<Game>::new(&kp2);
+
+        // init a 2d grid
+        let row0: Value = json!([true, false]).into();
+        let row1: Value = json!([false, true]).into();
+        let construct1 = base1.doc.grid.insert_idx(0, row0).sign(&kp1);
+        let construct2 = base1.doc.grid.insert_idx(1, row1).sign(&kp1);
+
+        assert_eq!(base2.apply(construct1), OpState::Ok);
+        assert_eq!(base2.apply(construct2.clone()), OpState::Ok);
+
+        assert_eq!(base1.doc.view().into_json(), base2.doc.view().into_json());
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "grid": [[true, false], [false, true]]
+            })
+        );
+
+        let set1 = base1.doc.grid[0][0].set(false).sign(&kp1);
+        let set2 = base2.doc.grid[1][1].set(false).sign(&kp2);
+        assert_eq!(base1.apply(set2), OpState::Ok);
+        assert_eq!(base2.apply(set1), OpState::Ok);
+
+        assert_eq!(base1.doc.view().into_json(), base2.doc.view().into_json());
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "grid": [[false, false], [false, false]]
+            })
+        );
+
+        let topright = base1.doc.grid[0].id_at(1).unwrap();
+        base1.doc.grid[0].delete(topright);
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "grid": [[false], [false, false]]
+            })
+        );
+
+        base1.doc.grid.delete(construct2.id());
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "grid": [[false]]
+            })
+        );
+    }
+
+    #[test]
+    fn test_arb_json() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Test {
+            reg: LwwRegisterCrdt<Value>,
+        }
+
+        let kp1 = make_keypair();
+        let mut base1 = BaseCrdt::<Test>::new(&kp1);
+
+        let base_val: Value = json!({
+            "a": true,
+            "b": "asdf",
+            "c": {
+                "d": [],
+                "e": [ false ]
+            }
+        })
+        .into();
+        base1.doc.reg.set(base_val).sign(&kp1);
+        assert_eq!(
+            base1.doc.view().into_json(),
+            json!({
+                "reg": {
+                    "a": true,
+                    "b": "asdf",
+                    "c": {
+                        "d": [],
+                        "e": [ false ]
+                    }
+                }
+            })
+        );
+    }
+
+    #[test]
+    fn test_wrong_json_types() {
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Nested {
+            list: ListCrdt<f64>,
+        }
+
+        #[add_crdt_fields]
+        #[derive(Clone, CrdtNode)]
+        struct Test {
+            reg: LwwRegisterCrdt<bool>,
+            strct: ListCrdt<Nested>,
+        }
+
+        let key = make_keypair();
+        let mut crdt = BaseCrdt::<Test>::new(&key);
+
+        // wrong type should not go through
+        crdt.doc.reg.set(32);
+        assert_eq!(crdt.doc.reg.view(), json!(null).into());
+        crdt.doc.reg.set(true);
+        assert_eq!(crdt.doc.reg.view(), json!(true).into());
+
+        // set nested
+        let mut list_view: Value = crdt.doc.strct.view().into();
+        assert_eq!(list_view, json!([]).into());
+
+        // only keeps actual numbers
+        let list: Value = json!({"list": [0, 123, -0.45, "char", []]}).into();
+        crdt.doc.strct.insert_idx(0, list);
+        list_view = crdt.doc.strct.view().into();
+        assert_eq!(list_view, json!([{ "list": [0, 123, -0.45]}]).into());
+    }
+}