namespace Common;

using System;
using System.Collections;

/*
	Simple configuration syntax
	"
	key = value
	#comment

	key = multi
		line
		value

	[Section]
	key = value
	"

	this(String input)
	ToString(String buffer)

	SetValue(section, name, value)
	GetValue(section, name) : StringValue

*/
class Config
{
	private (StringView, StringView) _latest = ("", "");
	private Dictionary<String, Dictionary<String, String>> _data = new .()
		{
			(new String(""), new .()) //Unsectioned data
		};

	public this(StringView content)
	{
		for (var line in content.Split('\n'))
			_ParseLine(line);
	}

	public ~this()
	{
		for (var d in _data)
			DeleteDictionaryAndKeysAndValues!(d.value);
		DeleteDictionaryAndKeys!(_data);
	}


	public void Serialize(String buffer)
	{
		buffer.Clear();
		for (var entry in _data[""])
		{
			if (!entry.value.Contains('\n'))
				buffer.Append(scope $"{entry.key} = {entry.value}\n");
			else
			{
				var parts = entry.value.Split('\n');
				buffer.Append(scope $"{entry.key} = {parts.GetNext().Value}\n");
				for (var part in parts)
					buffer.Append(scope $"	{part}\n");
			}
		}

		for (var section in _data)
		{
			if (section.key == "")
				continue;

			buffer.Append(scope $"[{section.key}]\n");

			for (var entry in section.value)
			{
				if (!entry.value.Contains('\n'))
					buffer.Append(scope $"{entry.key} = {entry.value}\n");
				else
				{
					var parts = entry.value.Split('\n');
					buffer.Append(scope $"{entry.key} = {parts.GetNext().Value}\n");
					for (var part in parts)
						buffer.Append(scope $"	{part}\n");
				}
			}
		}

		while (buffer.EndsWith('\n'))
			buffer.RemoveFromEnd(1);
	}

	public Result<StringView> GetValue(StringView section, StringView name)
	{
		if (!_data.ContainsKeyAlt<StringView>(section))
			return .Err;

		var dict = _data[scope .(section)];

		if (!dict.ContainsKeyAlt<StringView>(name))
			return .Err;

		return .Ok(dict[scope .(name)]);
	}

	public void SetValue(StringView section, StringView name, StringView value)
	{
		if (!_data.ContainsKeyAlt<StringView>(section))
			_data.Add(new .(section), new .());

		var dict = _data[scope .(section)];

		if (!dict.ContainsKeyAlt<StringView>(name))
		{
			dict.Add(new .(name), new .(value));
			return;
		}

		dict[scope .(name)].Set(value);
	}

	private void _ParseLine(StringView line)
	{
		var line;
		if (line.IsEmpty || line.StartsWith('#') || (line[0] == '\t' && line.Length == 1))
			return;

		if (line.StartsWith('\t'))
		{
			if (_latest.0 == "" && _latest.1 == "")
				return;

			//This is safe under the assumption, that _latest did not get changed by external uses
			_data.GetValue(scope .(_latest.0))
				.Value.GetValue(scope .(_latest.1))
				.Value.Append(scope $"\n{line.Substring(1)}");
			return;
		}

		if (line.StartsWith('[') && !line.EndsWith(']'))
			return;

		else if (line.StartsWith('[') && line.EndsWith(']'))
		{
			if (line.Length - 2 < 0)
				return;

			var section = new String(line.Substring(1, line.Length - 2));
			if (!_data.ContainsKeyAlt<StringView>(section))
				_data.Add(section, new .());
			_latest.0 = section;
			_latest.1 = "";
		}

		if (!line.Contains(" = "))
			return;

		var parts = line.Split(" = ");
		var name = parts.GetNext();
		var text = new String(parts.Remnant);

		if (_data.GetValue(scope .(_latest.0)) case .Ok(var val))
			if (!val.ContainsKeyAlt<StringView>(name))
			{
				val.Add(new .(name), text);
				_latest.1 = name;
			}
	}


}