using System;

using System.Collections;

using System.Collections.Generic;

using System.Data;

namespace DataBoss.Data

{

public class DataReaderSchemaTable : IEnumerable<DataReaderSchemaRow>

{

readonly List<DataReaderSchemaRow> rows = new();

public int Count => rows.Count;

public DataReaderSchemaRow this[int index] => rows[index];

public void Add(string name, int ordinal, Type dataType, bool allowDBNull, int? columnSize = null, string dataTypeName = null, Type providerSpecificDataType = null) {

var o = rows.Count;

rows.Add(new DataReaderSchemaRow {

ColumnName = name,

Ordinal = ordinal,

DataType = dataType,

ProviderSpecificDataType = providerSpecificDataType ?? dataType,

AllowDBNull = allowDBNull,

ColumnSize = columnSize,

DataTypeName = dataTypeName,

});

if (o != ordinal)

rows.Sort((a, b) => a.Ordinal.CompareTo(b.Ordinal));

}

public int GetOrdinal(string name) {

var n = rows.FindIndex(x => x.ColumnName == name);

return n != -1 ? n : throw new InvalidOperationException($"No column named '{name}' found");

}

public DataTable ToDataTable() {

var schema = new DataTable();

var columnName = schema.Columns.Add(DataReaderSchemaColumns.ColumnName);

var columnOrdinal = schema.Columns.Add(DataReaderSchemaColumns.ColumnOrdinal);

var columnSize = schema.Columns.Add(DataReaderSchemaColumns.ColumnSize);

var allowDBNull = schema.Columns.Add(DataReaderSchemaColumns.AllowDBNull);

var dataType = schema.Columns.Add(DataReaderSchemaColumns.DataType);

var dataTypeName = schema.Columns.Add(DataReaderSchemaColumns.DataTypeName);

var isKey = schema.Columns.Add(DataReaderSchemaColumns.IsKey);

var providerSpecificDataType = schema.Columns.Add(DataReaderSchemaColumns.ProviderSpecificDataType);

foreach (var item in rows) {

var r = schema.NewRow();

r[columnName] = item.ColumnName;

r[columnOrdinal] = item.Ordinal;

r[columnSize] = item.ColumnSize ?? (object)DBNull.Value;

r[allowDBNull] = item.AllowDBNull;

r[dataType] = item.DataType;

r[providerSpecificDataType] = item.ProviderSpecificDataType;

r[dataTypeName] = item.DataTypeName;

r[isKey] = false;

schema.Rows.Add(r);

}

return schema;

}

public IEnumerator<DataReaderSchemaRow> GetEnumerator() => rows.GetEnumerator();

IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();

}

}