From aab6b41d181c0220c66eb01b046bb48817143171 Mon Sep 17 00:00:00 2001
From: snit <snit@cock.li>
Date: Fri, 11 Oct 2024 00:08:47 -0500
Subject: [PATCH] more efficient entity array serialisation

---
 common/src/world.c | 20 ++++++++++++++------
 server/src/main.c  |  6 ++++++
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/common/src/world.c b/common/src/world.c
index dd35f07..cc4335d 100644
--- a/common/src/world.c
+++ b/common/src/world.c
@@ -5,7 +5,7 @@
 
 #include "world.h"
 
-static char const *const JSON_FMT = "{so, so, sI, sI}";
+static char const *const WORLD_JSON_FMT = "{so, so, sI, sI}";
 
 enum error_t world_init(struct world_t *self, size_t height, size_t width) {
     assert(self != NULL);
@@ -45,13 +45,13 @@ void world_free(struct world_t *self) {
 static enum error_t serialise(struct world_t *self, struct json_t **json) {
     assert(self != NULL);
     assert(json != NULL);
-    // TODO: (de)serialise the following:
-    // struct entity_t entities[MAX_ENTITIES];
 
     enum error_t err = ERR_OK;
 
     struct json_t *entities_json = json_array();
     for (size_t i = 0; i < MAX_ENTITIES; i++) {
+        if (self->entities[i].id == 0) continue;
+
         struct json_t *maybe_entity_json;
         err = entity_serialise(&self->entities[i], &maybe_entity_json);
         if (err != ERR_OK) goto error_cleanup_array;
@@ -62,7 +62,6 @@ static enum error_t serialise(struct world_t *self, struct json_t **json) {
             goto error_cleanup_array;
         }
     }
-    assert(json_array_size(entities_json) == MAX_ENTITIES);
 
     struct json_t *registered_entities_json;
     err = entity_registry_serialise(
@@ -71,7 +70,7 @@ static enum error_t serialise(struct world_t *self, struct json_t **json) {
     );
     if (err != ERR_OK) return err;
 
-    struct json_t *maybe_json = json_pack(JSON_FMT,
+    struct json_t *maybe_json = json_pack(WORLD_JSON_FMT,
         "entities", entities_json,
         "registered_entities", registered_entities_json,
         "height", self->height,
@@ -94,7 +93,7 @@ static enum error_t deserialise(struct world_t *self, struct json_t *json) {
 
     struct json_t *entities_json;
     struct json_t *registered_entities_json;
-    int json_err = json_unpack(json, JSON_FMT,
+    int json_err = json_unpack(json, WORLD_JSON_FMT,
         "entities", &entities_json,
         "registered_entities", &registered_entities_json,
         "height", &self->height,
@@ -103,6 +102,14 @@ static enum error_t deserialise(struct world_t *self, struct json_t *json) {
     if (json_err < 0) return ERR_JSON_DESERIALISE;
 
     for (size_t i = 0; i < MAX_ENTITIES; i++) {
+        // The entity array can have gaps, but the serialisation process shifts
+        // all entities forwards to fill them; this zeroes out the empty space
+        // at the end, to ensure no "ghost" entities remain
+        if (i >= json_array_size(entities_json)) {
+            self->entities[i].id = 0;
+            continue;
+        }
+
         struct json_t *entity_json = json_array_get(entities_json, i);
         if (entity_json == NULL) return ERR_JSON_DESERIALISE;
 
@@ -156,6 +163,7 @@ enum error_t world_deserialise(struct world_t *self, char const *str) {
     assert(self != NULL);
     assert(str != NULL);
 
+
     struct json_t *json = json_loads(str, 0, NULL);
     if (json == NULL) return ERR_JSON_DESERIALISE;
 
diff --git a/server/src/main.c b/server/src/main.c
index 1d7f75f..5e70365 100644
--- a/server/src/main.c
+++ b/server/src/main.c
@@ -71,6 +71,12 @@ int main(int argc, char **argv) {
     err = world_place_entity(&data.world, 1, 3, 7);
     if (err) goto handle_error_world;
 
+    err = world_register_entity(&data.world, "gilbert", 'g');
+    if (err) goto handle_error_world;
+
+    entity_init(&data.world.entities[26], 2, 2, 6);
+        // Make a gap in the entity array to see if "ghost" entities remain
+
     // Socket handling and run gameloop
     err = sock_loop(&data, game_loop);
     if (err) goto handle_error;