using DotNext;
using LinqToDB;
using LinqToDB.Data;
using LinqToDB.Mapping;

namespace Database;

/// <summary>
/// 用户类，表示用户信息
/// </summary>
public class User
{
    /// <summary>
    /// 用户的唯一标识符
    /// </summary>
    [PrimaryKey]
    public Guid ID { get; set; } = Guid.NewGuid();

    /// <summary>
    /// 用户的名称
    /// </summary>
    [NotNull]
    public required string Name { get; set; }

    /// <summary>
    /// 用户的电子邮箱
    /// </summary>
    [NotNull]
    public required string EMail { get; set; }

    /// <summary>
    /// 用户的密码（应该进行哈希处理）
    /// </summary>
    [NotNull]
    public required string Password { get; set; }

    /// <summary>
    /// 用户权限等级
    /// </summary>
    [NotNull]
    public required UserPermission Permission { get; set; }

    /// <summary>
    /// 绑定的实验板ID，如果未绑定则为空
    /// </summary>
    [Nullable]
    public Guid BoardID { get; set; }

    /// <summary>
    /// 用户绑定板子的过期时间
    /// </summary>
    [Nullable]
    public DateTime? BoardExpireTime { get; set; }

    /// <summary>
    /// 用户权限枚举
    /// </summary>
    public enum UserPermission
    {
        /// <summary>
        /// 管理员权限，可以管理用户和实验板
        /// </summary>
        Admin,

        /// <summary>
        /// 普通用户权限，只能使用实验板
        /// </summary>
        Normal,
    }
}

/// <summary>
/// FPGA 板子类，表示板子信息
/// </summary>
public class Board
{
    /// <summary>
    /// FPGA 板子的唯一标识符
    /// </summary>
    [PrimaryKey]
    public Guid ID { get; set; } = Guid.NewGuid();

    /// <summary>
    /// FPGA 板子的名称
    /// </summary>
    [NotNull]
    public required string BoardName { get; set; }

    /// <summary>
    /// FPGA 板子的IP地址
    /// </summary>
    [NotNull]
    public required string IpAddr { get; set; }

    /// <summary>
    /// FPGA 板子的通信端口
    /// </summary>
    [NotNull]
    public required int Port { get; set; }

    /// <summary>
    /// FPGA 板子的当前状态
    /// </summary>
    [NotNull]
    public required BoardStatus Status { get; set; }

    /// <summary>
    /// 占用该板子的用户的唯一标识符
    /// </summary>
    [Nullable]
    public Guid OccupiedUserID { get; set; }

    /// <summary>
    /// 占用该板子的用户的用户名
    /// </summary>
    [Nullable]
    public string? OccupiedUserName { get; set; }

    /// <summary>
    /// FPGA 板子的固件版本号
    /// </summary>
    [NotNull]
    public string FirmVersion { get; set; } = "1.0.0";

    /// <summary>
    /// FPGA 板子状态枚举
    /// </summary>
    public enum BoardStatus
    {
        /// <summary>
        /// 繁忙状态，正在被用户使用
        /// </summary>
        Busy,

        /// <summary>
        /// 可用状态，可以被分配给用户
        /// </summary>
        Available,
    }
}

/// <summary>
/// 应用程序数据连接类，用于与数据库交互
/// </summary>
public class AppDataConnection : DataConnection
{
    private static NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger();

    static readonly string DATABASE_FILEPATH = $"{Environment.CurrentDirectory}/Database.sqlite";

    static readonly LinqToDB.DataOptions options =
        new LinqToDB.DataOptions().UseSQLite($"Data Source={DATABASE_FILEPATH}");

    /// <summary>
    /// 初始化应用程序数据连接
    /// </summary>
    public AppDataConnection() : base(options)
    {
        if (!Path.Exists(DATABASE_FILEPATH))
        {
            logger.Info($"数据库文件不存在，正在创建新数据库: {DATABASE_FILEPATH}");
            LinqToDB.DataProvider.SQLite.SQLiteTools.CreateDatabase(DATABASE_FILEPATH);
            this.CreateAllTables();
            var user = new User()
            {
                Name = "Admin",
                EMail = "selfconfusion@gmail.com",
                Password = "12345678",
                Permission = Database.User.UserPermission.Admin,
            };
            this.Insert(user);
            logger.Info("默认管理员用户已创建");
        }
        else
        {
            logger.Info($"数据库连接已建立: {DATABASE_FILEPATH}");
        }
    }


    /// <summary>
    /// 创建所有数据库表
    /// </summary>
    public void CreateAllTables()
    {
        logger.Info("正在创建数据库表...");
        this.CreateTable<User>();
        this.CreateTable<Board>();
        logger.Info("数据库表创建完成");
    }

    /// <summary>
    /// 删除所有数据库表
    /// </summary>
    public void DropAllTables()
    {
        logger.Warn("正在删除所有数据库表...");
        this.DropTable<User>();
        this.DropTable<Board>();
        logger.Warn("所有数据库表已删除");
    }

    /// <summary>
    /// 添加一个新的用户到数据库
    /// </summary>
    /// <param name="name">用户的名称</param>
    /// <param name="email">用户的电子邮箱地址</param>
    /// <param name="password">用户的密码</param>
    /// <returns>插入的记录数</returns>
    public int AddUser(string name, string email, string password)
    {
        var user = new User()
        {
            Name = name,
            EMail = email,
            Password = password,
            Permission = Database.User.UserPermission.Normal,
        };
        var result = this.Insert(user);
        logger.Info($"新用户已添加: {name} ({email})");
        return result;
    }

    /// <summary>
    /// 根据用户名获取用户信息
    /// </summary>
    /// <param name="name">用户名</param>
    /// <returns>包含用户信息的结果，如果未找到或出错则返回相应状态</returns>
    public Result<Optional<User>> GetUserByName(string name)
    {
        var user = this.UserTable.Where((user) => user.Name == name).ToArray();

        if (user.Length > 1)
        {
            logger.Error($"数据库中存在多个同名用户: {name}");
            return new(new Exception($"数据库中存在多个同名用户: {name}"));
        }

        if (user.Length == 0)
        {
            logger.Info($"未找到用户: {name}");
            return new(Optional<User>.None);
        }

        logger.Debug($"成功获取用户信息: {name}");
        return new(user[0]);
    }

    /// <summary>
    /// 根据电子邮箱获取用户信息
    /// </summary>
    /// <param name="email">用户的电子邮箱地址</param>
    /// <returns>包含用户信息的结果，如果未找到或出错则返回相应状态</returns>
    public Result<Optional<User>> GetUserByEMail(string email)
    {
        var user = this.UserTable.Where((user) => user.EMail == email).ToArray();

        if (user.Length > 1)
        {
            logger.Error($"数据库中存在多个相同邮箱的用户: {email}");
            return new(new Exception($"数据库中存在多个相同邮箱的用户: {email}"));
        }

        if (user.Length == 0)
        {
            logger.Info($"未找到邮箱对应的用户: {email}");
            return new(Optional<User>.None);
        }

        logger.Debug($"成功获取用户信息: {email}");
        return new(user[0]);
    }

    /// <summary>
    /// 验证用户密码
    /// </summary>
    /// <param name="name">用户名</param>
    /// <param name="password">用户密码</param>
    /// <returns>如果密码正确返回用户信息，否则返回空</returns>
    public Result<Optional<User>> CheckUserPassword(string name, string password)
    {
        var ret = this.GetUserByName(name);
        if (!ret.IsSuccessful)
            return new(ret.Error);

        if (!ret.Value.HasValue)
            return new(Optional<User>.None);

        var user = ret.Value.Value;

        if (user.Password == password)
        {
            logger.Info($"用户 {name} 密码验证成功");
            return new(user);
        }
        else
        {
            logger.Warn($"用户 {name} 密码验证失败");
            return new(Optional<User>.None);
        }
    }

    /// <summary>
    /// 绑定用户与实验板
    /// </summary>
    /// <param name="userId">用户的唯一标识符</param>
    /// <param name="boardId">实验板的唯一标识符</param>
    /// <param name="expireTime">绑定过期时间</param>
    /// <returns>更新的记录数</returns>
    public int BindUserToBoard(Guid userId, Guid boardId, DateTime expireTime)
    {
        // 获取用户信息
        var user = this.UserTable.Where(u => u.ID == userId).FirstOrDefault();
        if (user == null)
        {
            logger.Error($"未找到用户: {userId}");
            return 0;
        }

        // 更新用户的板子绑定信息
        var userResult = this.UserTable
            .Where(u => u.ID == userId)
            .Set(u => u.BoardID, boardId)
            .Set(u => u.BoardExpireTime, expireTime)
            .Update();

        // 更新板子的用户绑定信息
        var boardResult = this.BoardTable
            .Where(b => b.ID == boardId)
            .Set(b => b.Status, Board.BoardStatus.Busy)
            .Set(b => b.OccupiedUserID, userId)
            .Set(b => b.OccupiedUserName, user.Name)
            .Update();

        logger.Info($"用户 {userId} ({user.Name}) 已绑定到实验板 {boardId}，过期时间: {expireTime}");
        return userResult + boardResult;
    }

    /// <summary>
    /// 解除用户与实验板的绑定
    /// </summary>
    /// <param name="userId">用户的唯一标识符</param>
    /// <returns>更新的记录数</returns>
    public int UnbindUserFromBoard(Guid userId)
    {
        // 获取用户当前绑定的板子ID
        var user = this.UserTable.Where(u => u.ID == userId).FirstOrDefault();
        Guid boardId = user?.BoardID ?? Guid.Empty;

        // 清空用户的板子绑定信息
        var userResult = this.UserTable
            .Where(u => u.ID == userId)
            .Set(u => u.BoardID, Guid.Empty)
            .Set(u => u.BoardExpireTime, (DateTime?)null)
            .Update();

        // 如果用户原本绑定了板子，则清空板子的用户绑定信息
        int boardResult = 0;
        if (boardId != Guid.Empty)
        {
            boardResult = this.BoardTable
                .Where(b => b.ID == boardId)
                .Set(b => b.Status, Board.BoardStatus.Available)
                .Set(b => b.OccupiedUserID, Guid.Empty)
                .Set(b => b.OccupiedUserName, (string?)null)
                .Update();
            logger.Info($"实验板 {boardId} 状态已设置为空闲，用户绑定信息已清空");
        }

        logger.Info($"用户 {userId} 已解除实验板绑定");
        return userResult + boardResult;
    }

    /// <summary>
    /// 添加一块新的 FPGA 板子到数据库
    /// </summary>
    /// <param name="name">FPGA 板子的名称</param>
    /// <param name="ipAddr">FPGA 板子的IP地址</param>
    /// <param name="port">FPGA 板子的通信端口</param>
    /// <returns>插入的记录数</returns>
    public int AddBoard(string name, string ipAddr, int port)
    {
        var board = new Board()
        {
            BoardName = name,
            IpAddr = ipAddr,
            Port = port,
            Status = Database.Board.BoardStatus.Available,
        };
        var result = this.Insert(board);
        logger.Info($"新实验板已添加: {name} ({ipAddr}:{port})");
        return result;
    }

    /// <summary>
    /// 根据名称删除实验板
    /// </summary>
    /// <param name="name">实验板的名称</param>
    /// <returns>删除的记录数</returns>
    public int DeleteBoardByName(string name)
    {
        // 先获取要删除的板子信息
        var board = this.BoardTable.Where(b => b.BoardName == name).FirstOrDefault();
        if (board == null)
        {
            logger.Warn($"未找到名称为 {name} 的实验板");
            return 0;
        }

        // 如果板子被占用，先解除绑定
        if (board.OccupiedUserID != Guid.Empty)
        {
            this.UserTable
                .Where(u => u.ID == board.OccupiedUserID)
                .Set(u => u.BoardID, Guid.Empty)
                .Set(u => u.BoardExpireTime, (DateTime?)null)
                .Update();
            logger.Info($"已解除用户 {board.OccupiedUserID} 与实验板 {name} 的绑定");
        }

        var result = this.BoardTable.Where(b => b.BoardName == name).Delete();
        logger.Info($"实验板已删除: {name}，删除记录数: {result}");
        return result;
    }

    /// <summary>
    /// 根据ID删除实验板
    /// </summary>
    /// <param name="id">实验板的唯一标识符</param>
    /// <returns>删除的记录数</returns>
    public int DeleteBoardByID(Guid id)
    {
        // 先获取要删除的板子信息
        var board = this.BoardTable.Where(b => b.ID == id).FirstOrDefault();
        if (board == null)
        {
            logger.Warn($"未找到ID为 {id} 的实验板");
            return 0;
        }

        // 如果板子被占用，先解除绑定
        if (board.OccupiedUserID != Guid.Empty)
        {
            this.UserTable
                .Where(u => u.ID == board.OccupiedUserID)
                .Set(u => u.BoardID, Guid.Empty)
                .Set(u => u.BoardExpireTime, (DateTime?)null)
                .Update();
            logger.Info($"已解除用户 {board.OccupiedUserID} 与实验板 {id} 的绑定");
        }

        var result = this.BoardTable.Where(b => b.ID == id).Delete();
        logger.Info($"实验板已删除: {id}，删除记录数: {result}");
        return result;
    }

    /// <summary>
    /// 根据实验板ID获取实验板信息
    /// </summary>
    /// <param name="id">实验板的唯一标识符</param>
    /// <returns>包含实验板信息的结果，如果未找到则返回空</returns>
    public Result<Optional<Board>> GetBoardByID(Guid id)
    {
        var boards = this.BoardTable.Where(board => board.ID == id).ToArray();

        if (boards.Length > 1)
        {
            logger.Error($"数据库中存在多个相同ID的实验板: {id}");
            return new(new Exception($"数据库中存在多个相同ID的实验板: {id}"));
        }

        if (boards.Length == 0)
        {
            logger.Info($"未找到ID对应的实验板: {id}");
            return new(Optional<Board>.None);
        }

        logger.Debug($"成功获取实验板信息: {id}");
        return new(boards[0]);
    }

    /// <summary>
    /// 获取所有实验板信息
    /// </summary>
    /// <returns>所有实验板的数组</returns>
    public Board[] GetAllBoard()
    {
        var boards = this.BoardTable.ToArray();
        logger.Debug($"获取所有实验板，共 {boards.Length} 块");
        return boards;
    }

    /// <summary>
    /// 获取一块可用的实验板并将其状态设置为繁忙
    /// </summary>
    /// <param name="userId">要分配板子的用户ID</param>
    /// <param name="expireTime">绑定过期时间</param>
    /// <returns>可用的实验板，如果没有可用的板子则返回空</returns>
    public Optional<Board> GetAvailableBoard(Guid userId, DateTime expireTime)
    {
        var boards = this.BoardTable.Where(
                (board) => board.Status == Database.Board.BoardStatus.Available
            ).ToArray();

        if (boards.Length == 0)
        {
            logger.Warn("没有可用的实验板");
            return new(null);
        }
        else
        {
            var board = boards[0];
            var user = this.UserTable.Where(u => u.ID == userId).FirstOrDefault();
            
            if (user == null)
            {
                logger.Error($"未找到用户: {userId}");
                return new(null);
            }

            // 更新板子状态和用户绑定信息
            this.BoardTable
                .Where(target => target.ID == board.ID)
                .Set(target => target.Status, Board.BoardStatus.Busy)
                .Set(target => target.OccupiedUserID, userId)
                .Set(target => target.OccupiedUserName, user.Name)
                .Update();

            // 更新用户的板子绑定信息
            this.UserTable
                .Where(u => u.ID == userId)
                .Set(u => u.BoardID, board.ID)
                .Set(u => u.BoardExpireTime, expireTime)
                .Update();

            board.Status = Database.Board.BoardStatus.Busy;
            board.OccupiedUserID = userId;
            board.OccupiedUserName = user.Name;

            logger.Info($"实验板 {board.BoardName} ({board.ID}) 已分配给用户 {user.Name} ({userId})，过期时间: {expireTime}");
            return new(board);
        }
    }

    /// <summary>
    /// 用户表
    /// </summary>
    public ITable<User> UserTable => this.GetTable<User>();

    /// <summary>
    /// FPGA 板子表
    /// </summary>
    public ITable<Board> BoardTable => this.GetTable<Board>();
}