//	Spludlow Software
//	Copyright © Samuel P. Ludlow 2020 All Rights Reserved
//	Distributed under the terms of the GNU General Public License version 3
//	Distributed WITHOUT ANY WARRANTY; without implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE
//	https://www.spludlow.co.uk/LICENCE.TXT
//	The Spludlow logo is a registered trademark of Samuel P. Ludlow and may not be used without permission
//	v1.14

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.IO;
using System.Data;

namespace Spludlow.Data
{
	public class JSON
	{
		public static void Write(DataSet dataSet, string filename)
		{
			using (FileStream stream = new FileStream(filename, FileMode.Create))
			{
				Write(dataSet, stream);
			}
		}
		public static void Write(DataSet dataSet, Stream stream)
		{
			Encoding encoding = new UTF8Encoding(false);

			using (StreamWriter writer = new StreamWriter(stream, encoding))
			{
				writer.WriteLine("{");

				for (int tableIndex = 0; tableIndex < dataSet.Tables.Count; ++tableIndex)
				{
					bool trailingComma = tableIndex == dataSet.Tables.Count - 1 ? false : true;

					Write(dataSet.Tables[tableIndex], writer, trailingComma);
				}

				writer.WriteLine("}");
			}
		}

		public static void Write(DataTable table, string filename)
		{
			using (FileStream stream = new FileStream(filename, FileMode.Create))
			{
				Write(table, stream);
			}
		}
		public static void Write(DataTable table, Stream stream)
		{
			Encoding encoding = new UTF8Encoding(false);

			using (StreamWriter writer = new StreamWriter(stream, encoding))
			{
				writer.WriteLine("{");

				Write(table, writer, false);

				writer.WriteLine("}");
			}
		}

		public static void Write(DataTable table, StreamWriter writer, bool trailingComma)
		{
			writer.Write("\t\"");
			writer.Write(table.TableName);
			writer.WriteLine("\": [");

			for (int rowIndex = 0; rowIndex < table.Rows.Count; ++rowIndex)
			{
				DataRow row = table.Rows[rowIndex];

				writer.WriteLine("\t\t{");

				Dictionary<string, string> rowData = new Dictionary<string, string>();

				foreach (DataColumn column in table.Columns)
				{
					if (row.IsNull(column) == true)
						continue;

					string value = null;

					switch (column.DataType.Name)
					{
						case "String":
							value = (string)row[column];
							if (value == "")
							{
								value = null;
							}
							else
							{
								value = "\"" + value.Replace(@"\", @"\\").Replace("\"", "\\\"") + "\"";
							}

							break;
						case "Int32":
							value = ((int)row[column]).ToString();
							if (value == "0")
								value = null;
							break;
						case "Boolean":
							value = ((bool)row[column]).ToString().ToLower();
							break;
						default:
							throw new ApplicationException(column.DataType.Name);
					}

					if (value != null)
						rowData.Add(column.ColumnName, value);
				}

				for (int columnIndex = 0; columnIndex < rowData.Keys.Count; ++columnIndex)
				{
					string columnName = rowData.Keys.ElementAt(columnIndex);

					writer.Write("\t\t\t\"");
					writer.Write(columnName);
					writer.Write("\":\t");
					writer.Write(rowData[columnName]);

					if (columnIndex < (rowData.Count - 1))
						writer.Write(",");
					writer.WriteLine();
				}

				writer.Write("\t\t}");
				if (rowIndex < (table.Rows.Count - 1))
					writer.Write(",");
				writer.WriteLine();
			}

			writer.Write("\t]");
			if (trailingComma == true)
				writer.Write(",");
			writer.WriteLine();
		}
	}
}