/*
TShock, a server mod for Terraria
Copyright (C) 2011 The TShock Team

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
using System;
using System.Data;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using MySql.Data.MySqlClient;
using System.Text.RegularExpressions;

namespace TShockAPI.DB
{
	public class UserManager
	{
		private IDbConnection database;

		public UserManager(IDbConnection db)
		{
			database = db;

			var table = new SqlTable("Users",
			                         new SqlColumn("ID", MySqlDbType.Int32) {Primary = true, AutoIncrement = true},
			                         new SqlColumn("Username", MySqlDbType.VarChar, 32) {Unique = true},
			                         new SqlColumn("Password", MySqlDbType.VarChar, 128),
			                         new SqlColumn("Usergroup", MySqlDbType.Text),
			                         new SqlColumn("IP", MySqlDbType.VarChar, 16)
				);
			var creator = new SqlTableCreator(db,
			                                  db.GetSqlType() == SqlType.Sqlite
			                                  	? (IQueryBuilder) new SqliteQueryCreator()
			                                  	: new MysqlQueryCreator());
			creator.EnsureExists(table);
		}

		/// <summary>
		/// Adds a given username to the database
		/// </summary>
		/// <param name="user">User user</param>
		public void AddUser(User user)
		{
			if (!TShock.Groups.GroupExists(user.Group))
				throw new GroupNotExistsException(user.Group);

			int ret;
			try
			{
				ret = database.Query("INSERT INTO Users (Username, Password, UserGroup, IP) VALUES (@0, @1, @2, @3);", user.Name,
								   TShock.Utils.HashPassword(user.Password), user.Group, user.Address);
			}
			catch (Exception ex)
			{
				// Detect duplicate user using a regexp as Sqlite doesn't have well structured exceptions
				if (Regex.IsMatch(ex.Message, "Username.*not unique"))
					throw new UserExistsException(user.Name);
				throw new UserManagerException("AddUser SQL returned an error (" + ex.Message + ")", ex);
			}

			if (1 > ret)
				throw new UserExistsException(user.Name);
		}

		/// <summary>
		/// Removes a given username from the database
		/// </summary>
		/// <param name="user">User user</param>
		public void RemoveUser(User user)
		{
			try
			{
				int affected = -1;
				if (!string.IsNullOrEmpty(user.Address))
				{
					affected = database.Query("DELETE FROM Users WHERE IP=@0", user.Address);
				}
				else
				{
					affected = database.Query("DELETE FROM Users WHERE Username=@0", user.Name);
				}

				if (affected < 1)
					throw new UserNotExistException(string.IsNullOrEmpty(user.Address) ? user.Name : user.Address);
			}
			catch (Exception ex)
			{
				throw new UserManagerException("RemoveUser SQL returned an error", ex);
			}
		}


		/// <summary>
		/// Sets the Hashed Password for a given username
		/// </summary>
		/// <param name="user">User user</param>
		/// <param name="group">string password</param>
		public void SetUserPassword(User user, string password)
		{
			try
			{
				if (
					database.Query("UPDATE Users SET Password = @0 WHERE Username = @1;", TShock.Utils.HashPassword(password),
					               user.Name) == 0)
					throw new UserNotExistException(user.Name);
			}
			catch (Exception ex)
			{
				throw new UserManagerException("SetUserPassword SQL returned an error", ex);
			}
		}

		/// <summary>
		/// Sets the group for a given username
		/// </summary>
		/// <param name="user">User user</param>
		/// <param name="group">string group</param>
		public void SetUserGroup(User user, string group)
		{
			try
			{
				Group grp = TShock.Groups.GetGroupByName(group);
				if (null == grp)
					throw new GroupNotExistsException(group);

				if (database.Query("UPDATE Users SET UserGroup = @0 WHERE Username = @1;", group, user.Name) == 0)
					throw new UserNotExistException(user.Name);
				
				// Update player group reference for any logged in player
				foreach (var player in TShock.Players.Where(p => null != p && p.UserAccountName == user.Name))
				{
					player.Group = grp;
				}
			}
			catch (Exception ex)
			{
				throw new UserManagerException("SetUserGroup SQL returned an error", ex);
			}
		}

		public int GetUserID(string username)
		{
			try
			{
				using (var reader = database.QueryReader("SELECT * FROM Users WHERE Username=@0", username))
				{
					if (reader.Read())
					{
						return reader.Get<int>("ID");
					}
				}
			}
			catch (Exception ex)
			{
				Log.ConsoleError("FetchHashedPasswordAndGroup SQL returned an error: " + ex);
			}
			return -1;
		}

		/// <summary>
		/// Returns a Group for a ip from the database
		/// </summary>
		/// <param name="ply">string ip</param>
		public Group GetGroupForIP(string ip)
		{
			try
			{
				using (var reader = database.QueryReader("SELECT * FROM Users WHERE IP=@0", ip))
				{
					if (reader.Read())
					{
						string group = reader.Get<string>("UserGroup");
						return TShock.Utils.GetGroup(group);
					}
				}
			}
			catch (Exception ex)
			{
				Log.ConsoleError("GetGroupForIP SQL returned an error: " + ex);
			}
			return TShock.Utils.GetGroup(TShock.Config.DefaultGuestGroupName);
		}

		public Group GetGroupForIPExpensive(string ip)
		{
			try
			{
				using (var reader = database.QueryReader("SELECT IP, UserGroup FROM Users"))
				{
					while (reader.Read())
					{
						if (TShock.Utils.GetIPv4Address(reader.Get<string>("IP")) == ip)
						{
							return TShock.Utils.GetGroup(reader.Get<string>("UserGroup"));
						}
					}
				}
			}
			catch (Exception ex)
			{
				Log.ConsoleError("GetGroupForIP SQL returned an error: " + ex);
			}
			return TShock.Utils.GetGroup(TShock.Config.DefaultGuestGroupName);
		}


		public User GetUserByName(string name)
		{
			try
			{
				return GetUser(new User {Name = name});
			}
			catch (UserManagerException)
			{
				return null;
			}
		}

		public User GetUserByID(int id)
		{
			try
			{
				return GetUser(new User {ID = id});
			}
			catch (UserManagerException)
			{
				return null;
			}
		}

		public User GetUserByIP(string ip)
		{
			try
			{
				return GetUser(new User {Address = ip});
			}
			catch (UserManagerException)
			{
				return null;
			}
		}

		public User GetUser(User user)
		{
			try
			{
				QueryResult result;
				if (0 != user.ID)
					result = database.QueryReader("SELECT * FROM Users WHERE ID=@0", user.ID);
				else if (string.IsNullOrEmpty(user.Address))
					result = database.QueryReader("SELECT * FROM Users WHERE Username=@0", user.Name);
				else
					result = database.QueryReader("SELECT * FROM Users WHERE IP=@0", user.Address);

				if (result.Read())
				{
					user = LoadUserFromResult(user, result);
					// Check for multiple matches
					if (!result.Read())
						return user;

					if (0 != user.ID)
						throw new UserManagerException(String.Format("Multiple users found for id '{0}'", user.ID));
					else if (string.IsNullOrEmpty(user.Address))
						throw new UserManagerException(String.Format("Multiple users found for name '{0}'", user.Name));
					else
						throw new UserManagerException(String.Format("Multiple users found for ip '{0}'", user.Address));
				}
			}
			catch (Exception ex)
			{
				throw new UserManagerException("GetUser SQL returned an error (" + ex.Message + ")", ex);
			}
			throw new UserNotExistException(string.IsNullOrEmpty(user.Address) ? user.Name : user.Address);
		}

		public List<User> GetUsers()
		{
			try
			{
				List<User> users = new List<User>();
				using (var reader = database.QueryReader("SELECT * FROM Users"))
				{
					while (reader.Read())
					{
						users.Add(LoadUserFromResult(new User(), reader));
					}
					return users;
				}
			}
			catch (Exception ex)
			{
				Log.Error(ex.ToString());
			}
			return null;
		}

		private User LoadUserFromResult(User user, QueryResult result)
		{
			user.ID = result.Get<int>("ID");
			user.Group = result.Get<string>("Usergroup");
			user.Password = result.Get<string>("Password");
			user.Name = result.Get<string>("Username");
			user.Address = result.Get<string>("IP");
			return user;
		}
	}

	public class User
	{
		public int ID { get; set; }
		public string Name { get; set; }
		public string Password { get; set; }
		public string Group { get; set; }
		public string Address { get; set; }

		public User(string ip, string name, string pass, string group)
		{
			Address = ip;
			Name = name;
			Password = pass;
			Group = group;
		}

		public User()
		{
			Address = "";
			Name = "";
			Password = "";
			Group = "";
		}
	}

	[Serializable]
	public class UserManagerException : Exception
	{
		public UserManagerException(string message)
			: base(message)
		{
		}

		public UserManagerException(string message, Exception inner)
			: base(message, inner)
		{
		}
	}

	[Serializable]
	public class UserExistsException : UserManagerException
	{
		public UserExistsException(string name)
			: base("User '" + name + "' already exists")
		{
		}
	}

	[Serializable]
	public class UserNotExistException : UserManagerException
	{
		public UserNotExistException(string name)
			: base("User '" + name + "' does not exist")
		{
		}
	}

	[Serializable]
	public class GroupNotExistsException : UserManagerException
	{
		public GroupNotExistsException(string group)
			: base("Group '" + group + "' does not exist")
		{
		}
	}
}