using System;
using System.Collections.Generic;
using System.IO;
using Mono.Cecil;

namespace ICSharpCode.Decompiler.Console
{
	class CustomAssemblyResolver : DefaultAssemblyResolver
	{
		DotNetCorePathFinder dotNetCorePathFinder;
		readonly string assemblyFileName;
		readonly Dictionary<string, UnresolvedAssemblyNameReference> loadedAssemblyReferences;

		public string TargetFramework { get; set; }

		public CustomAssemblyResolver(string fileName)
		{
			this.assemblyFileName = fileName;
			this.loadedAssemblyReferences = new Dictionary<string, UnresolvedAssemblyNameReference>();
			AddSearchDirectory(Path.GetDirectoryName(fileName));
			RemoveSearchDirectory(".");
		}

		public override AssemblyDefinition Resolve(AssemblyNameReference name)
		{
			var targetFramework = TargetFramework.Split(new[] { ",Version=v" }, StringSplitOptions.None);
			string file = null;
			switch (targetFramework[0]) {
				case ".NETCoreApp":
				case ".NETStandard":
					if (targetFramework.Length != 2) goto default;
					if (dotNetCorePathFinder == null) {
						var version = targetFramework[1].Length == 3 ? targetFramework[1] + ".0" : targetFramework[1];
						dotNetCorePathFinder = new DotNetCorePathFinder(assemblyFileName, TargetFramework, version, this.loadedAssemblyReferences);
					}
					file = dotNetCorePathFinder.TryResolveDotNetCore(name);
					if (file == null) {
						string dir = Path.GetDirectoryName(assemblyFileName);
						if (File.Exists(Path.Combine(dir, name.Name + ".dll")))
							file = Path.Combine(dir, name.Name + ".dll");
						else if (File.Exists(Path.Combine(dir, name.Name + ".exe")))
							file = Path.Combine(dir, name.Name + ".exe");
					}
					if (file == null)
						return base.Resolve(name);
					else
						return ModuleDefinition.ReadModule(file, new ReaderParameters() { AssemblyResolver = this }).Assembly;
				default:
					return base.Resolve(name);
			}
		}

		public override AssemblyDefinition Resolve(AssemblyNameReference name, ReaderParameters parameters)
		{
			try {
				var targetFramework = TargetFramework.Split(new[] { ",Version=v" }, StringSplitOptions.None);
				string file = null;
				switch (targetFramework[0]) {
					case ".NETCoreApp":
					case ".NETStandard":
						if (targetFramework.Length != 2) goto default;
						if (dotNetCorePathFinder == null) {
							var version = targetFramework[1].Length == 3 ? targetFramework[1] + ".0" : targetFramework[1];
							dotNetCorePathFinder = new DotNetCorePathFinder(assemblyFileName, TargetFramework, version, this.loadedAssemblyReferences);
						}
						file = dotNetCorePathFinder.TryResolveDotNetCore(name);
						if (file == null) {
							string dir = Path.GetDirectoryName(assemblyFileName);
							if (File.Exists(Path.Combine(dir, name.Name + ".dll")))
								file = Path.Combine(dir, name.Name + ".dll");
							else if (File.Exists(Path.Combine(dir, name.Name + ".exe")))
								file = Path.Combine(dir, name.Name + ".exe");
						}
						if (file == null)
							return base.Resolve(name, parameters);
						else
							return ModuleDefinition.ReadModule(file, parameters).Assembly;
					default:
						return base.Resolve(name, parameters);
				}
			} catch (AssemblyResolutionException exception) {
				System.Console.WriteLine(exception.ToString());
				return null;
			}
		}
	}
}