erlang port commands and generated tests

1 files changed, 89 insertions, 15 deletions

diff --git a/lib/management/database.ml b/lib/management/database.ml
index 4fd43f1..1e68402 100644
--- a/lib/management/database.ml
+++ b/lib/management/database.ml
@@ -1,23 +1,97 @@
-module RelationMap = Map.Make (String)
+(** Database state management.
+
+    A database is a collection of relations with:
+    - A merkle tree of relation hashes (for integrity verification)
+    - A map of relation names to their actual Relation.t objects (integrated cache)
+    - A history of previous database hashes (for time-travel queries)
+
+    All mutations produce a new database state with a new hash.
+    The history chain allows reconstruction of any past state. *)
+
+module RelationMap = Map.Make(String)
 
 type t = {
   hash : Conventions.Hash.t;
   name : Conventions.Name.t;
-  tree : unit;
-  relations : Relation.t RelationMap.t;
+  tree : Merkle.t;
+  relations : Relation.t RelationMap.t;  (* Stores actual relations, not just hashes *)
+  history : Conventions.Hash.t list;
   timestamp : float;
 }
 
-let create_database (storage: Physical.Storage.t) ~name =
-  let relations =
-    RelationMap.of_list [("less_than", Prelude.Standard.less_than_natural)]
+let empty ~name = {
+  hash = "";
+  name;
+  tree = Merkle.empty;
+  relations = RelationMap.empty;
+  history = [];
+  timestamp = Unix.gettimeofday ();
+}
+
+(** Compute database hash from the merkle tree root *)
+let compute_hash db =
+  match Merkle.root_hash db.tree with
+  | Some root -> root
+  | None -> Conventions.Hash.hash_text db.name
+
+(** Update database with new relations map and tree *)
+let update_state db ~relations ~tree =
+  let new_hash =
+    match Merkle.root_hash tree with
+    | Some root -> root
+    | None -> Conventions.Hash.hash_text db.name
   in
-  let state =
-    {
-      hash = "";
-      name;
-      tree = ();
-      relations = relations;
-      timestamp = Unix.time ();
-    }
-  in Physical.Storage.write storage
+  let history = if db.hash = "" then db.history else db.hash :: db.history in
+  {
+    hash = new_hash;
+    name = db.name;
+    tree;
+    relations;
+    history;
+    timestamp = Unix.gettimeofday ();
+  }
+
+(** Get a relation by name *)
+let get_relation db name =
+  RelationMap.find_opt name db.relations
+
+(** Get a relation's hash by name *)
+let get_relation_hash db name =
+  match RelationMap.find_opt name db.relations with
+  | None -> None
+  | Some rel -> rel.Relation.hash
+
+let get_relation_names db =
+  RelationMap.fold (fun name _ acc -> name :: acc) db.relations []
+
+let has_relation db name =
+  RelationMap.mem name db.relations
+
+(** Add a relation to the database *)
+let add_relation db ~(relation : Relation.t) =
+  let relation_hash = Option.get relation.hash in
+  let tree = Merkle.insert relation_hash db.tree in
+  let relations = RelationMap.add relation.name relation db.relations in
+  update_state db ~relations ~tree
+
+(** Remove a relation from the database *)
+let remove_relation db ~name =
+  match RelationMap.find_opt name db.relations with
+  | None -> db
+  | Some relation ->
+    let relation_hash = Option.get relation.hash in
+    let tree = Merkle.delete relation_hash db.tree in
+    let relations = RelationMap.remove name db.relations in
+    update_state db ~relations ~tree
+
+(** Update a relation in the database (after tuple insert/delete) *)
+let update_relation db ~(relation : Relation.t) =
+  let name = relation.name in
+  match RelationMap.find_opt name db.relations with
+  | None -> db  (* Relation doesn't exist, no-op *)
+  | Some old_relation ->
+    let old_hash = Option.get old_relation.hash in
+    let new_hash = Option.get relation.hash in
+    let tree = db.tree |> Merkle.delete old_hash |> Merkle.insert new_hash in
+    let relations = RelationMap.add name relation db.relations in
+    update_state db ~relations ~tree