// Copyright (c) 2018 Siegfried Pammer
// 
// 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.IO;
using System.Linq;
using System.Reflection.Metadata.Ecma335;

using ICSharpCode.Decompiler.DebugInfo;
using ICSharpCode.Decompiler.Metadata;
using ICSharpCode.Decompiler.Util;

using Mono.Cecil;
using Mono.Cecil.Pdb;
using SRM = System.Reflection.Metadata;

namespace ICSharpCode.Decompiler.PdbProvider
{
	public class MonoCecilDebugInfoProvider : IDebugInfoProvider
	{
		readonly Dictionary<SRM.MethodDefinitionHandle, (IList<SequencePoint> SequencePoints, IList<Variable> Variables)> debugInfo;

		public unsafe MonoCecilDebugInfoProvider(PEFile module, string pdbFileName, string description = null)
		{
			if (module == null) {
				throw new ArgumentNullException(nameof(module));
			}

			if (!module.Reader.IsEntireImageAvailable) {
				throw new ArgumentException("This provider needs access to the full image!");
			}

			this.Description = description ?? $"Loaded from PDB file: {pdbFileName}";

			var image = module.Reader.GetEntireImage();
			this.debugInfo = new Dictionary<SRM.MethodDefinitionHandle, (IList<SequencePoint> SequencePoints, IList<Variable> Variables)>();
			using (UnmanagedMemoryStream stream = new UnmanagedMemoryStream(image.Pointer, image.Length))
			using (var moduleDef = ModuleDefinition.ReadModule(stream)) {
				moduleDef.ReadSymbols(new PdbReaderProvider().GetSymbolReader(moduleDef, pdbFileName));

				foreach (var method in module.Metadata.MethodDefinitions) {
					var cecilMethod = moduleDef.LookupToken(MetadataTokens.GetToken(method)) as MethodDefinition;
					var debugInfo = cecilMethod?.DebugInformation;
					if (debugInfo == null)
						continue;
					IList<SequencePoint> sequencePoints = EmptyList<SequencePoint>.Instance;
					if (debugInfo.HasSequencePoints) {
						sequencePoints = new List<SequencePoint>(debugInfo.SequencePoints.Count);
						foreach (var point in debugInfo.SequencePoints) {
							sequencePoints.Add(new SequencePoint {
								Offset = point.Offset,
								StartLine = point.StartLine,
								StartColumn = point.StartColumn,
								EndLine = point.EndLine,
								EndColumn = point.EndColumn,
								DocumentUrl = point.Document.Url
							});
						}
					}
					var variables = new List<Variable>();
					foreach (var scope in debugInfo.GetScopes()) {
						if (!scope.HasVariables)
							continue;
						foreach (var v in scope.Variables) {
							variables.Add(new Variable(v.Index, v.Name));
						}
					}
					this.debugInfo.Add(method, (sequencePoints, variables));
				}
			}
		}

		public string Description { get; }

		public IList<SequencePoint> GetSequencePoints(SRM.MethodDefinitionHandle handle)
		{
			if (!debugInfo.TryGetValue(handle, out var info)) {
				return EmptyList<SequencePoint>.Instance;
			}

			return info.SequencePoints;
		}

		public IList<Variable> GetVariables(SRM.MethodDefinitionHandle handle)
		{
			if (!debugInfo.TryGetValue(handle, out var info)) {
				return EmptyList<Variable>.Instance;
			}

			return info.Variables;
		}

		public bool TryGetName(SRM.MethodDefinitionHandle handle, int index, out string name)
		{
			name = null;
			if (!debugInfo.TryGetValue(handle, out var info)) {
				return false;
			}

			var variable = info.Variables.FirstOrDefault(v => v.Index == index);
			name = variable.Name;
			return name != null;
		}
	}
}
