From b1c23ee53ac95d13ab9581a73829e705c3628ba4 Mon Sep 17 00:00:00 2001
From: Jordan Bancino <jordan@bancino.net>
Date: Fri, 7 Jul 2023 03:15:13 +0000
Subject: [PATCH] Begin prototyping state resolution API.

---
 src/State.c         | 85 +++++++++++++++++++++++++++++++++++++++++++++
 src/include/Event.h |  1 +
 src/include/State.h | 46 ++++++++++++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 src/State.c
 create mode 100644 src/include/State.h

diff --git a/src/State.c b/src/State.c
new file mode 100644
index 0000000..d8dc22b
--- /dev/null
+++ b/src/State.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2022-2023 Jordan Bancino <@jordan:bancino.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <State.h>
+
+#include <HashMap.h>
+#include <Array.h>
+
+#include <Room.h>
+#include <Event.h>
+
+static HashMap *
+StateResolveV1(Array *states)
+{
+    return NULL;
+}
+
+static HashMap *
+StateResolveV2(Array *states)
+{
+    return NULL;
+}
+
+HashMap *
+StateResolve(Room *room, HashMap *event)
+{
+    Array *states;
+    size_t i;
+
+    Array *prevEvents;
+
+    if (!room || !event)
+    {
+        return NULL;
+    }
+
+    /* TODO: Return cached state if it exists */
+
+    states = ArrayCreate();
+    if (!states)
+    {
+        return NULL;
+    }
+
+    prevEvents = HashMapGet(event, "prev_events");
+
+    for (i = 0; i < ArraySize(prevEvents); i++)
+    {
+        HashMap *prevEvent = ArrayGet(prevEvents, i);
+        HashMap *state = StateResolve(room, prevEvent);
+
+        /* TODO: Apply prevEvent to state if it is a state event */
+
+        ArrayAdd(states, state);
+    }
+
+    switch (RoomVersionGet(room))
+    {
+        case 1:
+            return StateResolveV1(states);
+        default:
+            return StateResolveV2(states);
+    }
+}
diff --git a/src/include/Event.h b/src/include/Event.h
index cff349b..5246b17 100644
--- a/src/include/Event.h
+++ b/src/include/Event.h
@@ -49,6 +49,7 @@ extern char * EventContentHash(HashMap *);
  * an event comes in from the federation APIs or the
  * homeserver has finished generating a PDU for a client
  * event.
+ */
 extern char * EventIdGet(Room *, HashMap *);
 
 #endif /* TELODENDRIA_EVENT_H */
diff --git a/src/include/State.h b/src/include/State.h
new file mode 100644
index 0000000..08f13b4
--- /dev/null
+++ b/src/include/State.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2022-2023 Jordan Bancino <@jordan:bancino.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef TELODENDRIA_STATE_H
+#define TELODENDRIA_STATE_H
+
+/***
+ * @Nm State
+ * @Nd The Matrix state resolution algorithms.
+ * @Dd July 6 2023
+ *
+ * .Nm implements the state resolution algorithms required
+ * to maintain room state.
+ */
+
+#include <HashMap.h>
+
+#include <Room.h>
+
+/**
+ * Compute the room state before the specified event was sent.
+ */
+extern HashMap * StateResolve(Room *, HashMap *);
+
+#endif /* TELODENDRIA_STATE_H */