Implement game loading

src/gui.rs

@@ -409,6 +409,7 @@ pub fn ranged_target(
 }
 
 pub fn main_menu(gs: &mut State, ctx: &mut Rltk) -> MainMenuResult {
+    let save_exists = crate::saveload_system::does_save_exist();
     let runstate = gs.ecs.fetch::<RunState>();
 
     ctx.print_color_centered(
@@ -438,20 +439,22 @@ pub fn main_menu(gs: &mut State, ctx: &mut Rltk) -> MainMenuResult {
             );
         }
 
-        if selection == MainMenuSelection::LoadGame {
-            ctx.print_color_centered(
-                25,
-                RGB::named(rltk::MAGENTA),
-                RGB::named(rltk::BLACK),
-                "Load Game",
-            );
-        } else {
-            ctx.print_color_centered(
-                25,
-                RGB::named(rltk::WHITE),
-                RGB::named(rltk::BLACK),
-                "Load Game",
-            );
+        if save_exists {
+            if selection == MainMenuSelection::LoadGame {
+                ctx.print_color_centered(
+                    25,
+                    RGB::named(rltk::MAGENTA),
+                    RGB::named(rltk::BLACK),
+                    "Load Game",
+                );
+            } else {
+                ctx.print_color_centered(
+                    25,
+                    RGB::named(rltk::WHITE),
+                    RGB::named(rltk::BLACK),
+                    "Load Game",
+                );
+            }
         }
 
         if selection == MainMenuSelection::Quit {

src/main.rs

@@ -110,7 +110,24 @@ impl GameState for State {
         ctx.cls();
 
         match newrunstate {
-            RunState::MainMenu { .. } => {}
+            RunState::MainMenu { .. } => match gui::main_menu(self, ctx) {
+                gui::MainMenuResult::NoSelection { selected } => {
+                    newrunstate = RunState::MainMenu {
+                        menu_selection: selected,
+                    }
+                }
+                gui::MainMenuResult::Selected { selected } => match selected {
+                    gui::MainMenuSelection::NewGame => newrunstate = RunState::PreRun,
+                    gui::MainMenuSelection::LoadGame => {
+                        saveload_system::load_game(&mut self.ecs);
+                        newrunstate = RunState::AwaitingInput;
+                        saveload_system::delete_save();
+                    }
+                    gui::MainMenuSelection::Quit => {
+                        ::std::process::exit(0);
+                    }
+                },
+            },
             _ => {
                 // Draw the UI
                 draw_map(&self.ecs, ctx);

src/saveload_system.rs

@@ -22,6 +22,21 @@ macro_rules! serialize_individually {
     };
 }
 
+macro_rules! deserialize_individually {
+    ($ecs:expr, $de:expr, $data:expr, $( $type:ty),*) => {
+        $(
+        DeserializeComponents::<NoError, _>::deserialize(
+            &mut ( &mut $ecs.write_storage::<$type>(), ),
+            &mut $data.0, // entities
+            &mut $data.1, // marker
+            &mut $data.2, // allocater
+            &mut $de,
+        )
+        .unwrap();
+        )*
+    };
+}
+
 pub fn save_game(ecs: &mut World) {
     // Create helper
     let mapcopy = ecs.get_mut::<crate::map::Map>().unwrap().clone();
@@ -77,3 +92,88 @@ pub fn save_game(ecs: &mut World) {
 pub fn does_save_exist() -> bool {
     Path::new("./savegame.json").exists()
 }
+
+pub fn load_game(ecs: &mut World) {
+    {
+        // Delete everything
+        let mut to_delete = Vec::new();
+        for e in ecs.entities().join() {
+            to_delete.push(e);
+        }
+
+        for del in to_delete.iter() {
+            ecs.delete_entity(*del).expect("Failed to delete entity");
+        }
+    }
+
+    let data = fs::read_to_string("./savegame.json").unwrap();
+    let mut de = serde_json::Deserializer::from_str(&data);
+
+    {
+        let mut d = (
+            &mut ecs.entities(),
+            &mut ecs.write_storage::<SimpleMarker<SerializeMe>>(),
+            &mut ecs.write_resource::<SimpleMarkerAllocator<SerializeMe>>(),
+        );
+
+        deserialize_individually!(
+            ecs,
+            de,
+            d,
+            Position,
+            Renderable,
+            Player,
+            Viewshed,
+            Monster,
+            Name,
+            BlocksTile,
+            CombatStats,
+            SufferDamage,
+            WantsToMelee,
+            Item,
+            Consumable,
+            Ranged,
+            InflictsDamage,
+            AreaOfEffect,
+            Confusion,
+            ProvidesHealing,
+            InBackpack,
+            WantsToPickupItem,
+            WantsToUseItem,
+            WantsToDropItem,
+            SerializationHelper
+        );
+    }
+
+    let mut deleteme: Option<Entity> = None;
+    {
+        let entities = ecs.entities();
+        let helper = ecs.read_storage::<SerializationHelper>();
+        let player = ecs.read_storage::<Player>();
+        let position = ecs.read_storage::<Position>();
+
+        for (e, h) in (&entities, &helper).join() {
+            let mut worldmap = ecs.write_resource::<crate::map::Map>();
+            *worldmap = h.map.clone();
+            worldmap.tile_content = vec![Vec::new(); crate::map::MAP_COUNT];
+            deleteme = Some(e);
+        }
+
+        for (e, _p, pos) in (&entities, &player, &position).join() {
+            let mut ppos = ecs.write_resource::<rltk::Point>();
+            *ppos = rltk::Point::new(pos.x, pos.y);
+
+            let mut player_resource = ecs.write_resource::<Entity>();
+            *player_resource = e;
+        }
+    }
+
+    ecs.delete_entity(deleteme.unwrap())
+        .expect("Unable to delete helper entitiy");
+}
+
+pub fn delete_save() {
+    if Path::new("./savegame.json").exists() {
+        std::fs::remove_file("./savegame.json").expect("Failed to delete save file.");
+    }
+}