implement game config support

App/Data/GameConfig.cs

@@ -0,0 +1,5 @@
+namespace Game.Data {
+    internal record GameConfig {
+        public string databasePath;
+    }
+}

App/Data/GameFiles.cs

@@ -0,0 +1,50 @@
+using System.Text;
+
+namespace Game.Data {
+    internal class GameFiles {
+        private const string CONFIG_FILENAME = "quiz_game_config.dat";
+        private const string DEFAULT_DATABASE_PATH = "bank.txt";
+        private static readonly byte[] CONFIG_FILE_MAGIC_BYTES = new byte[] { 0x7f, 0x57, 0x77, 0x74, 0x42, 0x00 };
+        public static bool IsFirstTimePlaying() {
+            return IsValidConfigFilePresent();
+        }
+
+        public static bool IsValidConfigFilePresent() {
+            return File.Exists(CONFIG_FILENAME);
+        }
+
+        public static GameConfig? ReadGameConfig() {
+            try {
+                using FileStream configFile = new FileStream(CONFIG_FILENAME, FileMode.Open, FileAccess.Read);
+                using BinaryReader rd = new BinaryReader(configFile);
+
+                if (configFile.Length < 6) return null;
+                byte[] magic = rd.ReadBytes(6);
+                if (magic.Equals(CONFIG_FILE_MAGIC_BYTES)) {
+                    return null;
+                }
+
+                ushort version = rd.ReadUInt16();
+                if (version == 1) return ReadConfigV1(rd);
+                else return null;
+            } catch (FileNotFoundException) {
+                return null;
+            }
+        }
+
+        public static GameConfig CreateDefaultGameConfig() {
+            using FileStream configFile = new FileStream(CONFIG_FILENAME, FileMode.OpenOrCreate, FileAccess.Write);
+            using BinaryWriter wr = new BinaryWriter(configFile, Encoding.UTF8);
+            wr.Write(CONFIG_FILE_MAGIC_BYTES);
+            wr.Write((ushort)1); // config file version
+            wr.Write(DEFAULT_DATABASE_PATH);
+            return new GameConfig() { databasePath = DEFAULT_DATABASE_PATH };
+        }
+
+        public static GameConfig? ReadConfigV1(BinaryReader rd) {
+            FileStream file = (FileStream)rd.BaseStream;
+            string databasePath = rd.ReadString();
+            return new GameConfig() { databasePath = databasePath };
+        }
+    }
+}

App/Program.cs

@@ -1,4 +1,5 @@
-using Game.UI;
+using Game.Data;
+using Game.UI;
 
 namespace Game {
     internal class Program {
@@ -14,6 +15,21 @@ namespace Game {
             display.ShowSplash();
             Thread.Sleep(2500);
 
+            GameConfig gameConfig;
+            try {
+                GameConfig? existingGameConfig = GameFiles.ReadGameConfig();
+                if (existingGameConfig == null) {
+                    gameConfig = GameFiles.CreateDefaultGameConfig();
+                } else {
+                    gameConfig = existingGameConfig;
+                }
+            } catch {
+                display.ShowFatalError("Произошла неизвестная ошибка при чтении/создании файла настроек");
+                Console.ReadKey();
+                return 2;
+            }
+
+            string databaseFileName = gameConfig.databasePath;
 
             display.ResetWindow();