/Source/facebook.Linq/Linq/FqlDataContext.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Data;

using System.Reflection;

using System.Collections;

using facebook;

using System.IO;



namespace facebook.Linq

{

	/// <summary>

	/// Represents a facebook/application database, as provided by the Facebook FQL API

	/// </summary>

	public abstract class FqlDataContext : IDisposable

	{

		protected FqlDataContext(API api)

		{

			Provider = new FqlProvider(api);

			Api = api;

			ReuseExistingInstances = true;

		}



		public API Api { get; private set; }

		internal IFqlProvider Provider;



		protected FqlTable<T> GetTable<T>()

		{

			return new FqlTable<T>(this);

		}



		#region Object Cache (re-uses instances that can be identified, such as user and photos, but not group memberships)



		/// <summary>

		/// When on, objects that are received from facebook and have an identity field will re-use the same instance to make databinding easier

		/// </summary>

		public bool ReuseExistingInstances { get; set; }



		/// <summary>

		/// Gets an object from the database cache given its key. When needed, it also queries facebook for the requested object.

		/// </summary>

		public virtual T GetObject<T>(object key, bool loadIfNeeded) where T : class // : FacebookObject

		{

			if (!ReuseExistingInstances || key == null)

				return null;

			var typ = typeof(T);

			if (ObjectCache.ContainsKey(typ))

			{

				if (ObjectCache[typ].ContainsKey(key))

					return ObjectCache[typ][key] as T;

			}

			if (loadIfNeeded)

			{

				T item = LoadObject<T>(key);

				if (item != null)

					StoreObject<T>(item, key);

				return item;

			}



			return null;

		}



		/// <summary>

		/// Stores an object in the database cache.

		/// </summary>

		public virtual void StoreObject<T>(T o, object key) where T : class// : FacebookObject

		{

			StoreObject(KnownTypeData.GetTypeData(typeof(T)),o, key);

		}



		internal virtual void StoreObject(TypeData td, object o, object key)

		{

			if (!ReuseExistingInstances || key == null)

				return;

			var typ = td.Type;

			if (!ObjectCache.ContainsKey(typ))

				ObjectCache.Add(typ, new Dictionary<object, object>());

			if (!ObjectCache[typ].ContainsKey(key))

				ObjectCache[typ].Add(key, o);

		}



		//Type / Key / Value

		Dictionary<Type, Dictionary<object, object>> ObjectCache = new Dictionary<Type, Dictionary<object, object>>();



		/// <summary>

		/// Performs a generic FQL query against facebook

		/// </summary>

		public IEnumerable<T> PerformGenericFql<T>(string fql) where T : class

		{

			var items = new List<T>();

			fql = FixQuery(fql);



			var result = Provider.ExecuteFqlQuery(fql);

			var reader = new FacebookDataReader(result);

			var td = KnownTypeData.GetTypeData(typeof(T));

			while (reader.Read())

      {

				T item = null;

				var elem = Activator.CreateInstance<T>();

				var fetched = false;

				if (td.IdentityProperty != null)

				{

					var idVal = reader[td.IdentityProperty.FqlFieldName];

					item = GetObject<T>(idVal,false);

					fetched = item != null;

				}

				if (!fetched)

				{

					item = Activator.CreateInstance<T>();

					//item.DataContext = this;

					if (item != null && td.IdentityProperty != null)

					{

						StoreObject<T>(item, reader[td.IdentityProperty.FqlFieldName]);

					}

				}



				foreach (var pData in td.Properties)

				{

					pData.Value.PropertyInfo.SetValue(item, reader[pData.Value.FqlFieldName], null);

				}

				items.Add(item);

			}

			return items;

		}



		internal static string FixQuery(string fql)

		{

			var words = fql.Split(' ');

			if (words.Length < 3)

				return fql;

			if (words[0].ToLower() != "select")

				return fql;

			if (words[2].ToLower() != "from")

				return fql;

			var replacement = words[1];

			if (replacement != "*")

				return fql;			

			var tableName = words[3].ToLower();

			if (tableName.StartsWith("app."))

				tableName = tableName.Substring(4);

			var td = KnownTypeData.GetTypeDataByTableName(tableName);

			if (td == null)

				throw new Exception();

			replacement = td.PropertiesByFieldName.Keys.StringConcat(",");

			if (replacement.IsNotNullOrEmpty())

				words[1] = replacement;

			return words.StringConcat(" ");

		}



		#region Overrides for LinqExtender



		public IDataReader ExecuteReader(CommandType cmdType, string sql)

		{

			var xml = this.Provider.ExecuteFqlQuery(sql);

			return new FacebookDataReader(xml);

		}

		

		#endregion



		private T LoadObject<T>(object key) where T : class //FacebookObject

		{

			var td = KnownTypeData.GetTypeData(typeof(T));

			var column = td.IdentityProperty;

			if (column==null)

				return null;

			var propsCSV = td.Properties.StringConcat(p=>p.Value.FqlFieldName,"",",","");

			var fql = String.Format("SELECT {0} from {1} where {2}={3} limit 1",

				propsCSV,

				td.FqlTableName,

				td.IdentityProperty.FqlFieldName,

				key);

			return (GetType().GetMethod("PerformGenericFql").MakeGenericMethod(typeof(T)).Invoke(this, new object[] { fql }) as IEnumerable<T>).FirstOrDefault();

		}



		#endregion





		public virtual void Dispose()

		{

			ObjectCache = null;

		}



		public TextWriter Log

		{

			get

			{

				return Provider.Log;

			}

			set

			{

				Provider.Log = value;

			}

		}

	}





	///// <summary>

	///// Represents an application database, as provided by the Facebook API

	///// </summary>

	//abstract class FqlApplicationDataContext : FqlDataContext

	//{

	//  protected FqlApplicationDataContext(API api)

	//    : base(api)

	//  {

	//    //KnownTypeData.GetTypeData

	//  }



	//  public void InsertOnSubmit<T>(T t) where T : class

	//  {

	//    if (!PendingObjects.ContainsKey(typeof(T)))

	//      PendingObjects.Add(typeof(T), new HashSet<object>());

	//    PendingObjects[typeof(T)].Add(t);

	//  }



	//  public void InsertAllOnSubmit<T>(IEnumerable<T> items) where T : class

	//  {

	//    if (!PendingObjects.ContainsKey(typeof(T)))

	//      PendingObjects.Add(typeof(T), new HashSet<object>());

	//    var l = PendingObjects[typeof(T)];

	//    foreach(var item in items)

	//      l.Add(item);

	//  }



	//  private Dictionary<string, string> BuildObjectDictionary(TypeData td, object o)

	//  {

	//    var ret = new Dictionary<string, string>();

	//    foreach (var p in td.Properties)

	//    {

	//      var fn = p.Value.FqlFieldName;

	//      var val = p.Value.PropertyInfo.GetValue(o, null); //TODO: Convert to either string or long or null				

	//      if (val == null)

	//        continue;

	//      if (!(val is string))

	//      {

	//        var l = ConvertToFacebookNumber(val);;

	//        if (l == 0)

	//          continue;

	//        else

	//          val = l;



	//      }

	//      ret.Add(fn, val.ToString());

	//    }

	//    return ret;

	//  }



	//  private long ConvertToFacebookNumber(object val)

	//  {

	//    //enums are not supported

	//    var vt = val.GetType();

	//    if (vt.IsEnum)

	//    {

	//      throw new Exception("Enums are not supported yet");

	//    }

	//    if (vt == typeof(long))

	//    {

	//      return (long)val;

	//    }

	//    if (vt == typeof(DateTime))

	//    {

	//      DateTime? dt = (DateTime)val;

	//      return Convert.ToInt64(DateHelper.ConvertDateToDouble(dt));

	//    }

	//    if (vt == typeof(DateTime?))

	//    {

	//      DateTime? dt = (DateTime?)val;

	//      val = DateHelper.ConvertDateToDouble(dt);

	//      return (long)val;

	//    }

	//    if (vt == typeof(bool))

	//    {

	//      bool b = (bool)val;

	//      return b ? 1 : 0;

	//    }

	//    throw new NotImplementedException();

	//  }



	//  public void SubmitChanges()

	//  {

	//    foreach (var typ in PendingObjects.Keys)

	//    {

	//      var td = KnownTypeData.GetTypeData(typ);

	//      foreach (var o in PendingObjects[typ])

	//      {

	//        var dict = BuildObjectDictionary(td, o);

	//        var newId = Api.data.createObject(td.FqlTableName, dict);

	//        if (td.IdentityProperty != null && td.IdentityProperty.FqlFieldName=="_id")

	//          td.IdentityProperty.PropertyInfo.SetValue(o, newId, null);

	//        StoreObject(td, o, newId);

	//      }

	//      PendingObjects[typ].Clear();

	//    }

	//  }



	//  private Dictionary<Type, HashSet<object>> PendingObjects = new Dictionary<Type, HashSet<object>>();  







	//  #region Model Maintenance

	//  private IEnumerable<PropertyInfo> TableProperties

	//  {

	//    get

	//    {

	//      return GetType().GetProperties().Where(p => p.PropertyType.IsGenericType && p.PropertyType.GetGenericTypeDefinition() == typeof(FqlTable<>));

	//    }

	//  }

		

	//  public void BuildModel()

	//  {

	//    BuildModel(false);

	//  }



	//  public void BuildModel(bool dropOldModel)

	//  {

	//    foreach (var tbl in TableProperties)

	//    {

	//      var itemType = tbl.PropertyType.GetGenericArguments()[0];

	//      var td = KnownTypeData.GetTypeData(itemType);

	//      var tblName = td.FqlTableName;



	//      if (dropOldModel)

	//      {

	//        try

	//        {

	//          Api.data.dropObjectType(tblName);

	//        }

	//        catch

	//        {

	//          //Drop failed, what can you do..

	//        }

	//      }



	//      Api.data.createObjectType(tblName);



	//      foreach (var pi in td.Properties)

	//      {

	//        var propName = pi.Key;

	//        var pd = pi.Value;



	//        //if (dropOldModel && pd.FqlFieldName!="_id")

	//        //{

	//        //  try

	//        //  {

	//        //    Api.data.undefineObjectProperty(tblName, pd.FqlFieldName);

	//        //  }

	//        //  catch

	//        //  {

	//        //    //Drop failed, what can one do..

	//        //  }

	//        //}



	//        var fbPropertyType = GetFacebookDataTypeId(pd.PropertyInfo.PropertyType);

	//        if (fbPropertyType == 0)

	//          throw new Exception("Invalid property type: " + pd.PropertyInfo.PropertyType + " for property " + tbl.Name + "." + pd.PropertyInfo.Name);



	//        if (pd.FqlFieldName == "_id")

	//          continue;

	//        Api.data.defineObjectProperty(tblName, pd.FqlFieldName, fbPropertyType);

	//      }

	//    }

	//  }



	//  public void DeleteModel()

	//  {

	//    foreach (var tbl in TableProperties)

	//    {

	//      var itemType = tbl.PropertyType.GetGenericArguments()[0];

	//      var td = KnownTypeData.GetTypeData(itemType);

	//      var tblName = td.FqlTableName;



	//      try

	//      {

	//        Api.data.dropObjectType(tblName);

	//      }

	//      catch

	//      {

	//        //Drop failed

	//      }

	//    }

	//  }



	//  public void VerifyModel()

	//  {

	//    throw new NotImplementedException();

	//  }



	//  private int GetFacebookDataTypeId(Type t)

	//  {

	//    int fbPropertyType = 0;

	//    //1 - long or nullable long

	//    //2 - short string

	//    //3 - long string

	//    if (t == typeof(long))

	//      fbPropertyType = 1;

	//    else if (t == typeof(long?))

	//      fbPropertyType = 1;

	//    else if (t == typeof(bool))

	//      fbPropertyType = 1;

	//    else if (t == typeof(DateTime))

	//      fbPropertyType = 1;

	//    else if (t == typeof(DateTime?))

	//      fbPropertyType = 1;

	//    else if (t == typeof(string))

	//      fbPropertyType = 3;

	//    else if (t.IsEnum)

	//      fbPropertyType = 0;			

	//    return fbPropertyType;



	//  }



	//  public bool ModelExists

	//  {

	//    get

	//    {

	//      foreach (var tbl in TableProperties)

	//      {

	//        var itemType = tbl.PropertyType.GetGenericArguments()[0];

	//        var td = KnownTypeData.GetTypeData(itemType);

	//        var tblName = td.FqlTableName;



	//        var fbtd = Api.data.getObjectType(tblName);



	//        foreach (var pi in td.Properties)

	//        {

	//          var propName = pi.Key;

	//          var pd = pi.Value;

	//          var fbPropertyType = GetFacebookDataTypeId(pd.PropertyInfo.PropertyType);

	//          if (fbPropertyType==0)

	//            throw new Exception("Invalid property type: " + pd.PropertyInfo.PropertyType + " for property " + tbl.Name + "." + pd.PropertyInfo.Name);

	//          if (pd.FqlFieldName == "_id")

	//            continue;

	//          if (fbtd.FirstOrDefault(t => t.data_type == fbPropertyType && t.name == pd.FqlFieldName) == null)

	//            return false;

	//        }

	//      }

	//      return true;

	//    }

	//  }



	//  #endregion

	//}

}