using System;

using System.Collections.Generic;

using System.Data;

using System.Reflection;



namespace ODX.Core

{

    internal static class DataSetBuilder

    {

        internal static DataSet BuildDataSet(Polymorpher pm)

        {

            DataSet ds = new DataSet();

            foreach (string table in pm.GetTables())

            {

                DataTable dt = ds.Tables.Add(table);



                DataColumn id = dt.Columns.Add("ID", typeof (string));

                AddProperties(new ColumnInfo(id.ColumnName, true, 22), id);



                dt.Constraints.Add("PK_" + dt.TableName, id, true);



                if (pm.DoesTableVersioned(table))

                {

                    DataColumn dc = dt.Columns.Add(SpecialColumns.RowVersion, typeof (string));

                    AddProperties(new ColumnInfo(dc.ColumnName, false, 22), dc);

                }

            }



            foreach (string table in pm.GetTables())

            {

                string parent = pm.GetTypeTable(pm.GetRootTypeForTable(table).BaseType);

                if ( parent != null )

                {

                    DataTable baseTable = ds.Tables[parent];

                    DataTable inheritedTable = ds.Tables[table];



                    CreateRelation(ds, baseTable.TableName, inheritedTable.TableName, new ColumnInfo("ID", false, 22));

                }

            }



            foreach ( Type type in pm.GetTypes() )

            {

                string table = pm.GetTypeTable(type);

                if ( table == null )

                    continue;



                DataTable dt = ds.Tables[table];



                if (BuilderUtils.IsHierarchyRoot(type))

                {

                    DataColumn dc = dt.Columns.Add(Session.TypeDefField, typeof (string));

                    AddProperties(new ColumnInfo(dc.ColumnName,false,22), dc);

                }



                foreach (PropertyInfo pi in type.GetProperties(BuilderUtils.PropertyFilter))

                {

                    if ( !BuilderUtils.IsAutoProperty(pi) )

                        continue;



                    if (pi.PropertyType.IsSubclassOf(typeof(Entity)))

                        CreateParent(pi, dt, pm);

                    else if (new List<Type>(pi.PropertyType.GetInterfaces()).Contains(typeof(IEntityListBase)))

                        CreateList(pi, dt, pm);

                    else

                        CreateAtom(pi, dt);

                }

            }



            foreach ( DataTable dt in ds.Tables )

            {

                foreach ( Constraint c in dt.Constraints )

                {

                    // Single-column unique constraints are created by assigning DataColumn.Unique property

                    // So it's much easier to rename constraints. Otherwise they is named "constraint1", ...

                    UniqueConstraint uc = c as UniqueConstraint;

                    if (uc != null && !uc.IsPrimaryKey && uc.Columns.Length == 1)

                        uc.ConstraintName = "UC_" + uc.Columns[0].ColumnName;

                }



                Type t = pm.GetRootTypeForTable(dt.TableName);

                if ( t == null )

                    continue;



                UniqueConstraintAttribute[] attrs = (UniqueConstraintAttribute[])t.GetCustomAttributes(typeof(UniqueConstraintAttribute), false);

                foreach (UniqueConstraintAttribute a in attrs)

                {

                    List<DataColumn> cols = new List<DataColumn>();

                    foreach ( string col in a.Columns )

                        cols.Add(dt.Columns[col]);

                    dt.Constraints.Add(

                        "UC_" + string.Join("_", a.Columns),

                        cols.ToArray(),

                        false);

                }

            }



            return ds;

        }



        private static void CreateList(PropertyInfo pi, DataTable dt, Polymorpher pm)

        {

            LinkTableAttribute[] linkAttrs = (LinkTableAttribute[])pi.GetCustomAttributes(typeof(LinkTableAttribute), false);

            if ( linkAttrs.Length > 0 )

            {

                CreateLink(dt, linkAttrs[0].Name, linkAttrs[0].ParentColumn, linkAttrs[0].ChildColumn, pi, pm);

            }

            else

            {

                ColumnInfo ci = BuilderUtils.GetColumnInfo(pi);



                if ( ci == null ) // this is many-To-Manu relation with autogenerated link table name

                    CreateLink(dt, null, null, null, pi, pm);

                else

                    CreateRelation(dt.DataSet, dt.TableName, BuilderUtils.GetRelatedTableName(pi, pm), ci);

            }

        }



        private static void CreateLink(DataTable dt, string linkTableName, string parentColName, string childColName, PropertyInfo pi, Polymorpher pm)

        {

            string thisTable = dt.TableName;

            string childTable = BuilderUtils.GetRelatedTableName(pi, pm);

            string thisFK = parentColName ?? thisTable + "ID";

            string childFK = childColName ?? childTable + "ID";



            if ( (childFK == thisFK) || (linkTableName == null && thisTable == childTable) )

                throw new OdxException(

                    "When self-associating table you should use explicit link table name & FK names in link table attribute.");



            if (linkTableName == null)

                linkTableName = thisTable.CompareTo(childTable) > 0 ? thisTable + childTable : childTable + thisTable;



            if (dt.DataSet.Tables.Contains(linkTableName))

                return;



            DataTable link = dt.DataSet.Tables.Add(linkTableName);

            DataColumn linkID = link.Columns.Add("ID", typeof (string));

            link.PrimaryKey = new DataColumn[] { linkID };

            AddProperties(new ColumnInfo(linkID.ColumnName, true, 22), linkID);



            CreateRelation(dt.DataSet, thisTable, link.TableName, new ColumnInfo(thisFK, false, 22));

            CreateRelation(dt.DataSet, childTable, link.TableName, new ColumnInfo(childFK, false, 22));



            link.Constraints.Add(

                "UC_" + thisFK + "_" + childFK,

                new DataColumn[] {link.Columns[thisFK], link.Columns[childFK]},

                false);

        }



        private static void CreateParent(PropertyInfo pi, DataTable dt, Polymorpher pm)

        {

            ColumnInfo ci = BuilderUtils.GetColumnInfo(pi);

            CreateRelation(dt.DataSet, BuilderUtils.GetRelatedTableName(pi, pm), dt.TableName, ci);

        }



        private static void CreateRelation(DataSet ds, string parentTableName, string tableName, ColumnInfo ci)

        {

            string name = "FK_" + parentTableName + "_" + tableName + "_" + ci.Name;

            if ( ds.Relations.Contains(name) )

                return;



            DataTable parent = ds.Tables[parentTableName];

            DataTable child = ds.Tables[tableName];



            DataColumn dc;

            if (child.Columns.Contains(ci.Name))

                dc = child.Columns[ci.Name];

            else

                dc = child.Columns.Add(ci.Name, typeof (string));



            dc.Unique |= ci.IsUnique;



            ds.Relations.Add(name, parent.PrimaryKey[0], dc);



            AddProperties(ci,dc);

        }



        private static void CreateAtom(PropertyInfo pi, DataTable dt)

        {

            Type type = pi.PropertyType;

            if (type.IsEnum)

                type = typeof (int);

            if (type == typeof(Guid))

                type = typeof (string);



            ColumnInfo ci = BuilderUtils.GetColumnInfo(pi);

            DataColumn dc = dt.Columns.Add(ci.Name, type);

            dc.Unique = ci.IsUnique;



            AddProperties(ci, dc);

        }



        private static void AddProperties(ColumnInfo ci, DataColumn dc)

        {

            if ( ci.DbType != null )

                dc.ExtendedProperties["dbType"] = ci.DbType;

            dc.ExtendedProperties["dbMaxLength"] = ci.MaxLength;

            dc.ExtendedProperties["dbScale"] = ci.Scale;

        }

    }

}