#region Copyright & License Information
/*
 * Copyright (c) The OpenRA Developers and Contributors
 * This file is part of OpenRA, which is free software. It is made
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version. For more
 * information, see COPYING.
 */
#endregion

using System;
using System.Collections.Frozen;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Text;
using OpenRA.Primitives;

namespace OpenRA
{
	public static class FieldSaver
	{
		public static MiniYaml Save(object o)
		{
			var nodes = new List<MiniYamlNode>();

			foreach (var fieldInfo in FieldLoader.GetTypeLoadInfo(o.GetType()))
			{
				if (fieldInfo.Field.FieldType.IsGenericType && fieldInfo.Field.FieldType.IsAssignableTo(typeof(System.Collections.IDictionary)))
				{
					var dict = (System.Collections.IDictionary)fieldInfo.Field.GetValue(o);
					var dictNodes = new List<MiniYamlNode>();
					foreach (var kvp in dict)
					{
						var key = ((System.Collections.DictionaryEntry)kvp).Key;
						var value = ((System.Collections.DictionaryEntry)kvp).Value;
						dictNodes.Add(new MiniYamlNode(FormatValue(key), FormatValue(value)));
					}

					nodes.Add(new MiniYamlNode(fieldInfo.YamlName, "", dictNodes));
				}
				else
					nodes.Add(new MiniYamlNode(fieldInfo.YamlName, FormatValue(o, fieldInfo.Field)));
			}

			return new MiniYaml(null, nodes);
		}

		public static MiniYaml SaveDifferences(object o, object from)
		{
			if (o.GetType() != from.GetType())
				throw new InvalidOperationException("FieldSaver: can't diff objects of different types");

			var fields = FieldLoader.GetTypeLoadInfo(o.GetType())
				.Where(info => FormatValue(o, info.Field) != FormatValue(from, info.Field));

			return new MiniYaml(
				null,
				fields.Select(info => new MiniYamlNode(info.YamlName, FormatValue(o, info.Field))));
		}

		public static MiniYamlNode SaveField(object o, string field)
		{
			return new MiniYamlNode(field, FormatValue(o, o.GetType().GetField(field)));
		}

		public static string FormatValue(object v)
		{
			if (v == null)
				return "";

			var t = v.GetType();
			if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(BitSet<>))
				return ((IEnumerable<string>)v).Select(FormatValue).JoinWith(", ");

			if (t.IsArray && t.GetArrayRank() == 1)
				return ((Array)v).Cast<object>().Select(FormatValue).JoinWith(", ");

			if (t.IsGenericType &&
				t.GetGenericTypeDefinition() == typeof(ImmutableArray<>))
			{
				try
				{
					return ((System.Collections.IEnumerable)v).Cast<object>().Select(FormatValue).JoinWith(", ");
				}
				catch (InvalidOperationException)
				{
					return "";
				}
			}

			if (t.IsGenericType &&
				(t.GetGenericTypeDefinition() == typeof(List<>) ||
				t.GetGenericTypeDefinition() == typeof(HashSet<>) ||
				t.GetGenericTypeDefinition()
					.BaseTypes()
					.Select(bt => bt.IsGenericType ? bt.GetGenericTypeDefinition() : null)
					.Any(bt => bt == typeof(FrozenSet<>))))
				return ((System.Collections.IEnumerable)v).Cast<object>().Select(FormatValue).JoinWith(", ");

			// This is only for documentation generation
			if (t.IsGenericType &&
				(t.GetGenericTypeDefinition() == typeof(Dictionary<,>) ||
				t.GetGenericTypeDefinition()
					.BaseTypes()
					.Select(bt => bt.IsGenericType ? bt.GetGenericTypeDefinition() : null)
					.Any(bt => bt == typeof(FrozenDictionary<,>))))
			{
				var result = new StringBuilder();
				var dict = (System.Collections.IDictionary)v;
				foreach (var kvp in dict)
				{
					var key = ((System.Collections.DictionaryEntry)kvp).Key;
					var value = ((System.Collections.DictionaryEntry)kvp).Value;

					var formattedKey = FormatValue(key);
					var formattedValue = FormatValue(value);

					result.Append(CultureInfo.InvariantCulture, $"{formattedKey}: {formattedValue}{Environment.NewLine}");
				}

				return result.ToString();
			}

			if (v is DateTime d)
				return d.ToString("yyyy-MM-dd HH-mm-ss", CultureInfo.InvariantCulture);

			// Try the TypeConverter
			var conv = TypeDescriptor.GetConverter(t);
			if (conv.CanConvertTo(typeof(string)))
			{
				try
				{
					return conv.ConvertToInvariantString(v);
				}
				catch
				{
				}
			}

			return v.ToString();
		}

		public static string FormatValue(object o, FieldInfo f)
		{
			return FormatValue(f.GetValue(o));
		}
	}
}