add ai, photo_mode and radio

core/game_state/game_state.gd

@@ -0,0 +1,32 @@
+extends Node
+
+const SAVE_PATH: String = "user://savegame.json"
+
+var save_data: SaveGameData = SaveGameData.new()
+var is_loaded: bool = false
+
+func _ready() -> void:
+	load_game()
+
+func save_game() -> void:
+	var save_file = FileAccess.open(SAVE_PATH, FileAccess.WRITE)
+	var json_string = JSON.stringify(save_data.to_dictionary())
+	save_file.store_line(json_string)
+
+func load_game() -> void:
+	if not FileAccess.file_exists(SAVE_PATH):
+		save_data = SaveGameData.new()
+		is_loaded = true
+		return
+		
+	var file = FileAccess.open(SAVE_PATH, FileAccess.READ)
+	var json_string = file.get_as_text()
+	
+	var json = JSON.new()
+	var parse_result = json.parse(json_string)
+	
+	save_data = SaveGameData.new()
+	if parse_result == OK and json.data is Dictionary:
+		save_data = SaveGameData.from_dictionary(json.data)
+	
+	is_loaded = true