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//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0, as
// published by the Free Software Foundation.
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// with the separately licensed software that they have included with
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//
// Without limiting anything contained in the foregoing, this file,
// which is part of MySQL Connector/NET, is also subject to the
// Universal FOSS Exception, version 1.0, a copy of which can be found at
// http://oss.oracle.com/licenses/universal-foss-exception.
//
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// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License, version 2.0, for more details.
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// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using System;
using System.Collections.Generic;
using System.Data;

namespace MySql.Data.MySqlClient
{
    /// <summary>
    /// Represents a schema and its contents.
    /// </summary>
    public partial class MySqlSchemaCollection
    {
        private readonly List<SchemaColumn> _columns = new List<SchemaColumn>();
        private readonly List<MySqlSchemaRow> _rows = new List<MySqlSchemaRow>();
        private readonly DataTable _table = null;

        public MySqlSchemaCollection()
        {
            this.Mapping = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase);
            this.LogicalMappings = new Dictionary<int, int>();
        }

        public MySqlSchemaCollection(string name) : this()
        {
            this.Name = name;
        }

        public MySqlSchemaCollection(DataTable dt) : this()
        {
            // cache the original datatable to avoid the overhead of creating again whenever possible.
            this._table = dt;
            int i = 0;
            foreach (DataColumn dc in dt.Columns)
            {
                this.Columns.Add(new SchemaColumn() { Name = dc.ColumnName, Type = dc.DataType });
                this.Mapping.Add(dc.ColumnName, i++);
                this.LogicalMappings[this.Columns.Count - 1] = this.Columns.Count - 1;
            }

            foreach (DataRow dr in dt.Rows)
            {
                MySqlSchemaRow row = new MySqlSchemaRow(this);
                for (i = 0; i < this.Columns.Count; i++)
                {
                    row[i] = dr[i];
                }

                this.Rows.Add(row);
            }
        }

        internal Dictionary<string, int> Mapping;
        internal Dictionary<int, int> LogicalMappings;

        /// <summary>
        /// Gets or sets the name of the schema.
        /// </summary>
        public string Name { get; set; }

        /// <summary>
        /// Gets the list of columns in the schema.
        /// </summary>
        public IList<SchemaColumn> Columns => this._columns;

        /// <summary>
        /// Gets the list of rows in the schema.
        /// </summary>
        public IList<MySqlSchemaRow> Rows => this._rows;

        internal SchemaColumn AddColumn(string name, Type t)
        {
            SchemaColumn c = new SchemaColumn
            {
                Name = name,
                Type = t
            };

            this._columns.Add(c);
            this.Mapping.Add(name, this._columns.Count - 1);
            this.LogicalMappings[this._columns.Count - 1] = this._columns.Count - 1;
            return c;
        }

        internal int ColumnIndex(string name)
        {
            int index = -1;
            for (int i = 0; i < this._columns.Count; i++)
            {
                SchemaColumn c = this._columns[i];
                if (String.Compare(c.Name, name, StringComparison.OrdinalIgnoreCase) != 0)
                {
                    continue;
                }

                index = i;
                break;
            }

            return index;
        }

        internal void RemoveColumn(string name)
        {
            int index = this.ColumnIndex(name);
            if (index == -1)
            {
                throw new InvalidOperationException();
            }

            this._columns.RemoveAt(index);
            for (int i = index; i < this.Columns.Count; i++)
            {
                this.LogicalMappings[i] = this.LogicalMappings[i] + 1;
            }
        }

        internal bool ContainsColumn(string name)
        {
            return this.ColumnIndex(name) >= 0;
        }

        internal MySqlSchemaRow AddRow()
        {
            MySqlSchemaRow r = new MySqlSchemaRow(this);
            this._rows.Add(r);
            return r;
        }

        internal MySqlSchemaRow NewRow()
        {
            MySqlSchemaRow r = new MySqlSchemaRow(this);
            return r;
        }

        internal DataTable AsDataTable()
        {
            if (this._table != null)
            {
                return this._table;
            }

            DataTable dt = new DataTable(this.Name);
            foreach (SchemaColumn col in this.Columns)
            {
                dt.Columns.Add(col.Name, col.Type);
            }

            foreach (MySqlSchemaRow row in this.Rows)
            {
                DataRow newRow = dt.NewRow();
                for (int i = 0; i < dt.Columns.Count; i++)
                {
                    newRow[i] = row[i] == null ? DBNull.Value : row[i];
                }

                dt.Rows.Add(newRow);
            }

            return dt;
        }
    }

    /// <summary>
    /// Represents a row within a schema.
    /// </summary>
    public class MySqlSchemaRow
    {
        private Dictionary<int, object> _data;

        public MySqlSchemaRow(MySqlSchemaCollection c)
        {
            this.Collection = c;
            this.InitMetadata();
        }

        internal void InitMetadata()
        {
            this._data = new Dictionary<int, object>();
        }

        internal MySqlSchemaCollection Collection { get; }

        internal object this[string s]
        {
            get { return this.GetValueForName(s); }
            set { this.SetValueForName(s, value); }
        }

        internal object this[int i]
        {
            get
            {
                int idx = this.Collection.LogicalMappings[i];
                if (!this._data.ContainsKey(idx))
                {
                    this._data[idx] = null;
                }

                return this._data[idx];
            }
            set { this._data[this.Collection.LogicalMappings[i]] = value; }
        }

        private void SetValueForName(string colName, object value)
        {
            int index = this.Collection.Mapping[colName];
            this[index] = value;
        }

        private object GetValueForName(string colName)
        {
            int index = this.Collection.Mapping[colName];
            if (!this._data.ContainsKey(index))
            {
                this._data[index] = null;
            }

            return this[index];
        }

        internal void CopyRow(MySqlSchemaRow row)
        {
            if (this.Collection.Columns.Count != row.Collection.Columns.Count)
            {
                throw new InvalidOperationException("column count doesn't match");
            }

            for (int i = 0; i < this.Collection.Columns.Count; i++)
            {
                row[i] = this[i];
            }
        }
    }

    /// <summary>
    /// Represents a column within a schema.
    /// </summary>
    public class SchemaColumn
    {
        /// <summary>
        /// The name of the column.
        /// </summary>
        public string Name { get; set; }

        /// <summary>
        /// The type of the column.
        /// </summary>
        public Type Type { get; set; }
    }
}