/*
	Copyright (c) 2015 Ki

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE.
*/

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;

namespace dnSpy.BamlDecompiler.Baml {
	internal abstract class BamlNode {
		public BamlBlockNode Parent { get; set; }
		public abstract BamlRecordType Type { get; }
		public object Annotation { get; set; }

		public abstract BamlRecord Record { get; }

		public static bool IsHeader(BamlRecord rec) {
			switch (rec.Type) {
				case BamlRecordType.ConstructorParametersStart:
				case BamlRecordType.DocumentStart:
				case BamlRecordType.ElementStart:
				case BamlRecordType.KeyElementStart:
				case BamlRecordType.NamedElementStart:
				case BamlRecordType.PropertyArrayStart:
				case BamlRecordType.PropertyComplexStart:
				case BamlRecordType.PropertyDictionaryStart:
				case BamlRecordType.PropertyListStart:
				case BamlRecordType.StaticResourceStart:
					return true;
			}
			return false;
		}

		public static bool IsFooter(BamlRecord rec) {
			switch (rec.Type) {
				case BamlRecordType.ConstructorParametersEnd:
				case BamlRecordType.DocumentEnd:
				case BamlRecordType.ElementEnd:
				case BamlRecordType.KeyElementEnd:
				case BamlRecordType.PropertyArrayEnd:
				case BamlRecordType.PropertyComplexEnd:
				case BamlRecordType.PropertyDictionaryEnd:
				case BamlRecordType.PropertyListEnd:
				case BamlRecordType.StaticResourceEnd:
					return true;
			}
			return false;
		}

		public static bool IsMatch(BamlRecord header, BamlRecord footer) {
			switch (header.Type) {
				case BamlRecordType.ConstructorParametersStart:
					return footer.Type == BamlRecordType.ConstructorParametersEnd;

				case BamlRecordType.DocumentStart:
					return footer.Type == BamlRecordType.DocumentEnd;

				case BamlRecordType.KeyElementStart:
					return footer.Type == BamlRecordType.KeyElementEnd;

				case BamlRecordType.PropertyArrayStart:
					return footer.Type == BamlRecordType.PropertyArrayEnd;

				case BamlRecordType.PropertyComplexStart:
					return footer.Type == BamlRecordType.PropertyComplexEnd;

				case BamlRecordType.PropertyDictionaryStart:
					return footer.Type == BamlRecordType.PropertyDictionaryEnd;

				case BamlRecordType.PropertyListStart:
					return footer.Type == BamlRecordType.PropertyListEnd;

				case BamlRecordType.StaticResourceStart:
					return footer.Type == BamlRecordType.StaticResourceEnd;

				case BamlRecordType.ElementStart:
				case BamlRecordType.NamedElementStart:
					return footer.Type == BamlRecordType.ElementEnd;
			}
			return false;
		}

		public static BamlNode Parse(BamlDocument document, CancellationToken token) {
			Debug.Assert(document.Count > 0 && document[0].Type == BamlRecordType.DocumentStart);

			BamlBlockNode current = null;
			var stack = new Stack<BamlBlockNode>();

			for (int i = 0; i < document.Count; i++) {
				token.ThrowIfCancellationRequested();

				if (IsHeader(document[i])) {
					var prev = current;

					current = new BamlBlockNode {
						Header = document[i]
					};

					if (prev is not null) {
						prev.Children.Add(current);
						current.Parent = prev;
						stack.Push(prev);
					}
				}
				else if (IsFooter(document[i])) {
					if (current is null)
						throw new Exception("Unexpected footer.");

					while (!IsMatch(current.Header, document[i])) {
						// End record can be omited (sometimes).
						if (stack.Count > 0)
							current = stack.Pop();
					}
					current.Footer = document[i];
					if (stack.Count > 0)
						current = stack.Pop();
				}
				else
					current.Children.Add(new BamlRecordNode(document[i]) { Parent = current });
			}
			Debug.Assert(stack.Count == 0);
			return current;
		}
	}

	internal class BamlRecordNode : BamlNode {
		BamlRecord record;

		public override BamlRecord Record => record;
		public override BamlRecordType Type => Record.Type;

		public BamlRecordNode(BamlRecord record) => this.record = record;
	}

	internal class BamlBlockNode : BamlNode {
		public BamlRecord Header { get; set; }
		public IList<BamlNode> Children { get; }
		public BamlRecord Footer { get; set; }

		public override BamlRecord Record => Header;
		public override BamlRecordType Type => Header.Type;

		public BamlBlockNode() => Children = new List<BamlNode>();
	}
}