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 };
        }
    }
}