//------------------------------------------------------------------------------
// <copyright file="SmiMetaData.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
// <owner current="true" primary="false">Microsoft</owner>
//------------------------------------------------------------------------------

namespace Microsoft.SqlServer.Server {

    using System;
    using System.Collections.Generic;
    using System.Data;
    using System.Data.Common;
    using System.Data.SqlClient;
    using System.Diagnostics;
    using System.Globalization;

    // SmiMetaDataProperty defines an extended, optional property to be used on the SmiMetaData class
    //  This approach to adding properties is added combat the growing number of sparsely-used properties 
    //  that are specially handled on the base classes

    internal enum SmiPropertySelector {
        DefaultFields = 0x0,
        SortOrder = 0x1,
        UniqueKey = 0x2,
    }

    // Simple collection for properties.  Could extend to IDictionary support if needed in future.
    internal class SmiMetaDataPropertyCollection {
        private const int               SelectorCount = 3;  // number of elements in SmiPropertySelector

        private SmiMetaDataProperty[]   _properties;
        private bool                    _isReadOnly;

        internal static readonly SmiMetaDataPropertyCollection EmptyInstance;

        // Singleton empty instances to ensure each property is always non-null
        private static readonly SmiDefaultFieldsProperty    __emptyDefaultFields = new SmiDefaultFieldsProperty(new List<bool>());
        private static readonly SmiOrderProperty            __emptySortOrder = new SmiOrderProperty(new List<SmiOrderProperty.SmiColumnOrder>());
        private static readonly SmiUniqueKeyProperty        __emptyUniqueKey = new SmiUniqueKeyProperty(new List<bool>());

        static SmiMetaDataPropertyCollection() {
            EmptyInstance = new SmiMetaDataPropertyCollection();
            EmptyInstance.SetReadOnly();
        }

        internal SmiMetaDataPropertyCollection() {
            _properties = new SmiMetaDataProperty[SelectorCount];
            _isReadOnly = false;
            _properties[(int)SmiPropertySelector.DefaultFields]  = __emptyDefaultFields;
            _properties[(int)SmiPropertySelector.SortOrder]      = __emptySortOrder;
            _properties[(int)SmiPropertySelector.UniqueKey]      = __emptyUniqueKey;
        }

        internal SmiMetaDataProperty this[SmiPropertySelector key] {
            get {
                return _properties[(int)key];
            }
            set {
                if (null == value) {
                    throw ADP.InternalError(ADP.InternalErrorCode.InvalidSmiCall);
                }
                EnsureWritable();
                _properties[(int)key] = value;
            }
        }

        internal bool IsReadOnly {
            get {
                return _isReadOnly;
            }
        }

        internal IEnumerable<SmiMetaDataProperty> Values {
            get {
                return new List<SmiMetaDataProperty>(_properties);
            }
        }

        // Allow switching to read only, but not back.
        internal void SetReadOnly() {
            _isReadOnly = true;
        }

        private void EnsureWritable() {
            if (IsReadOnly) {
                throw System.Data.Common.ADP.InternalError(System.Data.Common.ADP.InternalErrorCode.InvalidSmiCall);
            }
        }
    }

    // Base class for properties
    internal abstract class SmiMetaDataProperty {
        internal abstract string TraceString();
    }

    // Property defining a list of column ordinals that define a unique key
    internal class SmiUniqueKeyProperty : SmiMetaDataProperty {
        private IList<bool> _columns;

        internal SmiUniqueKeyProperty(IList<bool> columnIsKey) {
            _columns = new List<bool>(columnIsKey).AsReadOnly();
        }

        // indexed by column ordinal indicating for each column whether it is key or not
        internal bool this[int ordinal] {
            get {
                if (_columns.Count <= ordinal) {
                    return false;
                }
                else {
                    return _columns[ordinal];
                }
            }
        }

        [Conditional("DEBUG")]
        internal void CheckCount(int countToMatch) {
            Debug.Assert(0 == _columns.Count || countToMatch == _columns.Count, 
                    "SmiDefaultFieldsProperty.CheckCount: DefaultFieldsProperty size (" + _columns.Count +
                    ") not equal to checked size (" + countToMatch + ")" );
        }

        internal override string TraceString() {
            string returnValue = "UniqueKey(";
            bool delimit = false;
            for (int columnOrd = 0; columnOrd < _columns.Count; columnOrd++) {
                if (delimit) {
                    returnValue += ",";
                }
                else {
                    delimit = true;
                }
                if (_columns[columnOrd]) {
                    returnValue += columnOrd.ToString(CultureInfo.InvariantCulture);
                }
            }
            returnValue += ")";

            return returnValue;
        }
    }

    // Property defining a sort order for a set of columns (by ordinal and ASC/DESC).
    internal class SmiOrderProperty : SmiMetaDataProperty {
        internal struct SmiColumnOrder {
            internal int SortOrdinal;
            internal SortOrder Order;

            internal string TraceString() {
                return String.Format(CultureInfo.InvariantCulture, "{0} {1}", SortOrdinal, Order);
            }
        }

        private IList<SmiColumnOrder> _columns;

        internal SmiOrderProperty(IList<SmiColumnOrder> columnOrders) {
            _columns = new List<SmiColumnOrder>(columnOrders).AsReadOnly();
        }

        // Readonly list of the columnorder instances making up the sort order
        //  order in list indicates precedence
        internal SmiColumnOrder this[int ordinal] {
            get {
                if (_columns.Count <= ordinal) {
                    SmiColumnOrder order = new SmiColumnOrder();
                    order.Order = SortOrder.Unspecified;
                    order.SortOrdinal = -1;
                    return order;
                }
                else {
                    return _columns[ordinal];
                }
            }
        }


        [Conditional("DEBUG")]
        internal void CheckCount(int countToMatch) {
            Debug.Assert(0 == _columns.Count || countToMatch == _columns.Count, 
                    "SmiDefaultFieldsProperty.CheckCount: DefaultFieldsProperty size (" + _columns.Count +
                    ") not equal to checked size (" + countToMatch + ")" );
        }

        internal override string TraceString() {
            string returnValue = "SortOrder(";
            bool delimit = false;
            foreach(SmiColumnOrder columnOrd in _columns) {
                if (delimit) {
                    returnValue += ",";
                }
                else {
                    delimit = true;
                }

                if (System.Data.SqlClient.SortOrder.Unspecified != columnOrd.Order) {
                    returnValue += columnOrd.TraceString();
                }
            }
            returnValue += ")";

            return returnValue;
         }
    }

    // property defining inheritance relationship(s)
    internal class SmiDefaultFieldsProperty : SmiMetaDataProperty {
        #region private fields

        private IList<bool>     _defaults;

        #endregion

        #region internal interface

        internal SmiDefaultFieldsProperty(IList<bool> defaultFields) {
            _defaults = new List<bool>(defaultFields).AsReadOnly();
        }

        internal bool this[int ordinal] {
            get {
                if (_defaults.Count <= ordinal) {
                    return false;
                }
                else {
                    return _defaults[ordinal];
                }
            }
        }

        [Conditional("DEBUG")]
        internal void CheckCount(int countToMatch) {
            Debug.Assert(0 == _defaults.Count || countToMatch == _defaults.Count, 
                    "SmiDefaultFieldsProperty.CheckCount: DefaultFieldsProperty size (" + _defaults.Count +
                    ") not equal to checked size (" + countToMatch + ")" );
        }

        internal override string TraceString() {
            string returnValue = "DefaultFields(";
            bool delimit = false;
            for(int columnOrd = 0; columnOrd < _defaults.Count; columnOrd++) {
                if (delimit) {
                    returnValue += ",";
                }
                else {
                    delimit = true;
                }

                if (_defaults[columnOrd]) {
                    returnValue += columnOrd;
                }
            }
            returnValue += ")";

            return returnValue;
         }

        #endregion
    }
}