// dnlib: See LICENSE.txt for more info

using System;
using System.Collections.Generic;
using dnlib.DotNet.Emit;

namespace dnlib.DotNet {
	/// <summary>
	/// Finds types, fields, methods, etc in a module. If nothing has been added to the module, it's
	/// faster to call ResolveMethodDef(), ResolveTypeRef() etc.
	/// </summary>
	public class MemberFinder {
		enum ObjectType {
			Unknown,
			EventDef,
			FieldDef,
			GenericParam,
			MemberRef,
			MethodDef,
			MethodSpec,
			PropertyDef,
			TypeDef,
			TypeRef,
			TypeSig,
			TypeSpec,
			ExportedType,
		}

		/// <summary>
		/// All found <see cref="CustomAttribute"/>s
		/// </summary>
		public readonly Dictionary<CustomAttribute, bool> CustomAttributes = new Dictionary<CustomAttribute, bool>();

		/// <summary>
		/// All found <see cref="EventDef"/>s
		/// </summary>
		public readonly Dictionary<EventDef, bool> EventDefs = new Dictionary<EventDef, bool>();

		/// <summary>
		/// All found <see cref="FieldDef"/>s
		/// </summary>
		public readonly Dictionary<FieldDef, bool> FieldDefs = new Dictionary<FieldDef, bool>();

		/// <summary>
		/// All found <see cref="GenericParam"/>s
		/// </summary>
		public readonly Dictionary<GenericParam, bool> GenericParams = new Dictionary<GenericParam, bool>();

		/// <summary>
		/// All found <see cref="MemberRef"/>s
		/// </summary>
		public readonly Dictionary<MemberRef, bool> MemberRefs = new Dictionary<MemberRef, bool>();

		/// <summary>
		/// All found <see cref="MethodDef"/>s
		/// </summary>
		public readonly Dictionary<MethodDef, bool> MethodDefs = new Dictionary<MethodDef, bool>();

		/// <summary>
		/// All found <see cref="MethodSpec"/>s
		/// </summary>
		public readonly Dictionary<MethodSpec, bool> MethodSpecs = new Dictionary<MethodSpec, bool>();

		/// <summary>
		/// All found <see cref="PropertyDef"/>s
		/// </summary>
		public readonly Dictionary<PropertyDef, bool> PropertyDefs = new Dictionary<PropertyDef, bool>();

		/// <summary>
		/// All found <see cref="TypeDef"/>s
		/// </summary>
		public readonly Dictionary<TypeDef, bool> TypeDefs = new Dictionary<TypeDef, bool>();

		/// <summary>
		/// All found <see cref="TypeRef"/>s
		/// </summary>
		public readonly Dictionary<TypeRef, bool> TypeRefs = new Dictionary<TypeRef, bool>();

		/// <summary>
		/// All found <see cref="TypeSig"/>s
		/// </summary>
		public readonly Dictionary<TypeSig, bool> TypeSigs = new Dictionary<TypeSig, bool>();

		/// <summary>
		/// All found <see cref="TypeSpec"/>s
		/// </summary>
		public readonly Dictionary<TypeSpec, bool> TypeSpecs = new Dictionary<TypeSpec, bool>();

		/// <summary>
		/// All found <see cref="ExportedType"/>s
		/// </summary>
		public readonly Dictionary<ExportedType, bool> ExportedTypes = new Dictionary<ExportedType, bool>();

		Stack<object> objectStack;
		ModuleDef validModule;

		/// <summary>
		/// Finds all types, fields, etc
		/// </summary>
		/// <param name="module">The module to scan</param>
		/// <returns>Itself</returns>
		public MemberFinder FindAll(ModuleDef module) {
			validModule = module;

			// This needs to be big. About 2048 entries should be enough for most though...
			objectStack = new Stack<object>(0x1000);

			Add(module);
			ProcessAll();

			objectStack = null;

			return this;
		}

		void Push(object mr) {
			if (mr is null)
				return;
			objectStack.Push(mr);
		}

		void ProcessAll() {
			while (objectStack.Count > 0) {
				var o = objectStack.Pop();
				switch (GetObjectType(o)) {
				case ObjectType.Unknown: break;
				case ObjectType.EventDef:		Add((EventDef)o); break;
				case ObjectType.FieldDef:		Add((FieldDef)o); break;
				case ObjectType.GenericParam:	Add((GenericParam)o); break;
				case ObjectType.MemberRef:		Add((MemberRef)o); break;
				case ObjectType.MethodDef:		Add((MethodDef)o); break;
				case ObjectType.MethodSpec:		Add((MethodSpec)o); break;
				case ObjectType.PropertyDef:	Add((PropertyDef)o); break;
				case ObjectType.TypeDef:		Add((TypeDef)o); break;
				case ObjectType.TypeRef:		Add((TypeRef)o); break;
				case ObjectType.TypeSig:		Add((TypeSig)o); break;
				case ObjectType.TypeSpec:		Add((TypeSpec)o); break;
				case ObjectType.ExportedType:	Add((ExportedType)o); break;
				default: throw new InvalidOperationException($"Unknown type: {o.GetType()}");
				}
			}
		}

		readonly Dictionary<Type, ObjectType> toObjectType = new Dictionary<Type, ObjectType>();
		ObjectType GetObjectType(object o) {
			if (o is null)
				return ObjectType.Unknown;
			var type = o.GetType();
			if (toObjectType.TryGetValue(type, out var mrType))
				return mrType;
			mrType = GetObjectType2(o);
			toObjectType[type] = mrType;
			return mrType;
		}

		static ObjectType GetObjectType2(object o) {
			if (o is EventDef)		return ObjectType.EventDef;
			if (o is FieldDef)		return ObjectType.FieldDef;
			if (o is GenericParam)	return ObjectType.GenericParam;
			if (o is MemberRef)		return ObjectType.MemberRef;
			if (o is MethodDef)		return ObjectType.MethodDef;
			if (o is MethodSpec)	return ObjectType.MethodSpec;
			if (o is PropertyDef)	return ObjectType.PropertyDef;
			if (o is TypeDef)		return ObjectType.TypeDef;
			if (o is TypeRef)		return ObjectType.TypeRef;
			if (o is TypeSig)		return ObjectType.TypeSig;
			if (o is TypeSpec)		return ObjectType.TypeSpec;
			if (o is ExportedType)	return ObjectType.ExportedType;
			return ObjectType.Unknown;
		}

		void Add(ModuleDef mod) {
			Push(mod.ManagedEntryPoint);
			Add(mod.CustomAttributes);
			Add(mod.Types);
			Add(mod.ExportedTypes);
			if (mod.IsManifestModule)
				Add(mod.Assembly);
			Add(mod.VTableFixups);
			Add(mod.Resources);
		}

		void Add(VTableFixups fixups) {
			if (fixups is null)
				return;
			foreach (var fixup in fixups) {
				foreach (var method in fixup)
					Push(method);
			}
		}

		void Add(ResourceCollection resources) {
			foreach (var resource in resources) {
				Add(resource.CustomAttributes);
			}
		}

		void Add(AssemblyDef asm) {
			if (asm is null)
				return;
			Add(asm.DeclSecurities);
			Add(asm.CustomAttributes);
		}

		void Add(CallingConventionSig sig) {
			if (sig is null)
				return;

			if (sig is FieldSig fs) {
				Add(fs);
				return;
			}

			if (sig is MethodBaseSig mbs) {
				Add(mbs);
				return;
			}

			if (sig is LocalSig ls) {
				Add(ls);
				return;
			}

			if (sig is GenericInstMethodSig gims) {
				Add(gims);
				return;
			}
		}

		void Add(FieldSig sig) {
			if (sig is null)
				return;
			Add(sig.Type);
		}

		void Add(MethodBaseSig sig) {
			if (sig is null)
				return;
			Add(sig.RetType);
			Add(sig.Params);
			Add(sig.ParamsAfterSentinel);
		}

		void Add(LocalSig sig) {
			if (sig is null)
				return;
			Add(sig.Locals);
		}

		void Add(GenericInstMethodSig sig) {
			if (sig is null)
				return;
			Add(sig.GenericArguments);
		}

		void Add(IEnumerable<CustomAttribute> cas) {
			if (cas is null)
				return;
			foreach (var ca in cas)
				Add(ca);
		}

		void Add(CustomAttribute ca) {
			if (ca is null || CustomAttributes.ContainsKey(ca))
				return;
			CustomAttributes[ca] = true;
			Push(ca.Constructor);
			Add(ca.ConstructorArguments);
			Add(ca.NamedArguments);
		}

		void Add(IEnumerable<CAArgument> args) {
			if (args is null)
				return;
			foreach (var arg in args)
				Add(arg);
		}

		void Add(CAArgument arg) {
			// It's a struct so can't be null
			Add(arg.Type);
			if (arg.Value is TypeSig typeSig)
				Add(typeSig);
			else if (arg.Value is IList<CAArgument> args)
				Add(args);
			else if(arg.Value is CAArgument boxedArgument)
				Add(boxedArgument);
		}

		void Add(IEnumerable<CANamedArgument> args) {
			if (args is null)
				return;
			foreach (var arg in args)
				Add(arg);
		}

		void Add(CANamedArgument arg) {
			if (arg is null)
				return;
			Add(arg.Type);
			Add(arg.Argument);
		}

		void Add(IEnumerable<DeclSecurity> decls) {
			if (decls is null)
				return;
			foreach (var decl in decls)
				Add(decl);
		}

		void Add(DeclSecurity decl) {
			if (decl is null)
				return;
			Add(decl.SecurityAttributes);
			Add(decl.CustomAttributes);
		}

		void Add(IEnumerable<SecurityAttribute> secAttrs) {
			if (secAttrs is null)
				return;
			foreach (var secAttr in secAttrs)
				Add(secAttr);
		}

		void Add(SecurityAttribute secAttr) {
			if (secAttr is null)
				return;
			Add(secAttr.AttributeType);
			Add(secAttr.NamedArguments);
		}

		void Add(ITypeDefOrRef tdr) {
			if (tdr is TypeDef td) {
				Add(td);
				return;
			}

			if (tdr is TypeRef tr) {
				Add(tr);
				return;
			}

			if (tdr is TypeSpec ts) {
				Add(ts);
				return;
			}
		}

		void Add(IEnumerable<EventDef> eds) {
			if (eds is null)
				return;
			foreach (var ed in eds)
				Add(ed);
		}

		void Add(EventDef ed) {
			if (ed is null || EventDefs.ContainsKey(ed))
				return;
			if (ed.DeclaringType is not null && ed.DeclaringType.Module != validModule)
				return;
			EventDefs[ed] = true;
			Push(ed.EventType);
			Add(ed.CustomAttributes);
			Add(ed.AddMethod);
			Add(ed.InvokeMethod);
			Add(ed.RemoveMethod);
			Add(ed.OtherMethods);
			Add(ed.DeclaringType);
		}

		void Add(IEnumerable<FieldDef> fds) {
			if (fds is null)
				return;
			foreach (var fd in fds)
				Add(fd);
		}

		void Add(FieldDef fd) {
			if (fd is null || FieldDefs.ContainsKey(fd))
				return;
			if (fd.DeclaringType is not null && fd.DeclaringType.Module != validModule)
				return;
			FieldDefs[fd] = true;
			Add(fd.CustomAttributes);
			Add(fd.Signature);
			Add(fd.DeclaringType);
			Add(fd.MarshalType);
		}

		void Add(IEnumerable<GenericParam> gps) {
			if (gps is null)
				return;
			foreach (var gp in gps)
				Add(gp);
		}

		void Add(GenericParam gp) {
			if (gp is null || GenericParams.ContainsKey(gp))
				return;
			GenericParams[gp] = true;
			Push(gp.Owner);
			Push(gp.Kind);
			Add(gp.GenericParamConstraints);
			Add(gp.CustomAttributes);
		}

		void Add(IEnumerable<GenericParamConstraint> gpcs) {
			if (gpcs is null)
				return;
			foreach (var gpc in gpcs)
				Add(gpc);
		}

		void Add(GenericParamConstraint gpc) {
			if (gpc is null)
				return;
			Add(gpc.Owner);
			Push(gpc.Constraint);
			Add(gpc.CustomAttributes);
		}

		void Add(MemberRef mr) {
			if (mr is null || MemberRefs.ContainsKey(mr))
				return;
			if (mr.Module != validModule)
				return;
			MemberRefs[mr] = true;
			Push(mr.Class);
			Add(mr.Signature);
			Add(mr.CustomAttributes);
		}

		void Add(IEnumerable<MethodDef> methods) {
			if (methods is null)
				return;
			foreach (var m in methods)
				Add(m);
		}

		void Add(MethodDef md) {
			if (md is null || MethodDefs.ContainsKey(md))
				return;
			if (md.DeclaringType is not null && md.DeclaringType.Module != validModule)
				return;
			MethodDefs[md] = true;
			Add(md.Signature);
			Add(md.ParamDefs);
			Add(md.GenericParameters);
			Add(md.DeclSecurities);
			Add(md.MethodBody);
			Add(md.CustomAttributes);
			Add(md.Overrides);
			Add(md.DeclaringType);
		}

		void Add(MethodBody mb) {
			if (mb is CilBody cb)
				Add(cb);
		}

		void Add(CilBody cb) {
			if (cb is null)
				return;
			Add(cb.Instructions);
			Add(cb.ExceptionHandlers);
			Add(cb.Variables);
		}

		void Add(IEnumerable<Instruction> instrs) {
			if (instrs is null)
				return;
			foreach (var instr in instrs) {
				if (instr is null)
					continue;
				switch (instr.OpCode.OperandType) {
				case OperandType.InlineTok:
				case OperandType.InlineType:
				case OperandType.InlineMethod:
				case OperandType.InlineField:
					Push(instr.Operand);
					break;

				case OperandType.InlineSig:
					Add(instr.Operand as CallingConventionSig);
					break;

				case OperandType.InlineVar:
				case OperandType.ShortInlineVar:
					var local = instr.Operand as Local;
					if (local is not null) {
						Add(local);
						break;
					}
					var arg = instr.Operand as Parameter;
					if (arg is not null) {
						Add(arg);
						break;
					}
					break;
				}
			}
		}

		void Add(IEnumerable<ExceptionHandler> ehs) {
			if (ehs is null)
				return;
			foreach (var eh in ehs)
				Push(eh.CatchType);
		}

		void Add(IEnumerable<Local> locals) {
			if (locals is null)
				return;
			foreach (var local in locals)
				Add(local);
		}

		void Add(Local local) {
			if (local is null)
				return;
			Add(local.Type);
		}

		void Add(IEnumerable<Parameter> ps) {
			if (ps is null)
				return;
			foreach (var p in ps)
				Add(p);
		}

		void Add(Parameter param) {
			if (param is null)
				return;
			Add(param.Type);
			Add(param.Method);
		}

		void Add(IEnumerable<ParamDef> pds) {
			if (pds is null)
				return;
			foreach (var pd in pds)
				Add(pd);
		}

		void Add(ParamDef pd) {
			if (pd is null)
				return;
			Add(pd.DeclaringMethod);
			Add(pd.CustomAttributes);
			Add(pd.MarshalType);
		}

		void Add(MarshalType mt) {
			if (mt is null)
				return;

			switch (mt.NativeType) {
			case NativeType.SafeArray:
				Add(((SafeArrayMarshalType)mt).UserDefinedSubType);
				break;

			case NativeType.CustomMarshaler:
				Add(((CustomMarshalType)mt).CustomMarshaler);
				break;
			}
		}

		void Add(IEnumerable<MethodOverride> mos) {
			if (mos is null)
				return;
			foreach (var mo in mos)
				Add(mo);
		}

		void Add(MethodOverride mo) {
			// It's a struct so can't be null
			Push(mo.MethodBody);
			Push(mo.MethodDeclaration);
		}

		void Add(MethodSpec ms) {
			if (ms is null || MethodSpecs.ContainsKey(ms))
				return;
			if (ms.Method is not null && ms.Method.DeclaringType is not null && ms.Method.DeclaringType.Module != validModule)
				return;
			MethodSpecs[ms] = true;
			Push(ms.Method);
			Add(ms.Instantiation);
			Add(ms.CustomAttributes);
		}

		void Add(IEnumerable<PropertyDef> pds) {
			if (pds is null)
				return;
			foreach (var pd in pds)
				Add(pd);
		}

		void Add(PropertyDef pd) {
			if (pd is null || PropertyDefs.ContainsKey(pd))
				return;
			if (pd.DeclaringType is not null && pd.DeclaringType.Module != validModule)
				return;
			PropertyDefs[pd] = true;
			Add(pd.Type);
			Add(pd.CustomAttributes);
			Add(pd.GetMethods);
			Add(pd.SetMethods);
			Add(pd.OtherMethods);
			Add(pd.DeclaringType);
		}

		void Add(IEnumerable<TypeDef> tds) {
			if (tds is null)
				return;
			foreach (var td in tds)
				Add(td);
		}

		void Add(TypeDef td) {
			if (td is null || TypeDefs.ContainsKey(td))
				return;
			if (td.Module != validModule)
				return;
			TypeDefs[td] = true;
			Push(td.BaseType);
			Add(td.Fields);
			Add(td.Methods);
			Add(td.GenericParameters);
			Add(td.Interfaces);
			Add(td.DeclSecurities);
			Add(td.DeclaringType);
			Add(td.Events);
			Add(td.Properties);
			Add(td.NestedTypes);
			Add(td.CustomAttributes);
		}

		void Add(IEnumerable<InterfaceImpl> iis) {
			if (iis is null)
				return;
			foreach (var ii in iis)
				Add(ii);
		}

		void Add(InterfaceImpl ii) {
			if (ii is null)
				return;
			Push(ii.Interface);
			Add(ii.CustomAttributes);
		}

		void Add(TypeRef tr) {
			if (tr is null || TypeRefs.ContainsKey(tr))
				return;
			if (tr.Module != validModule)
				return;
			TypeRefs[tr] = true;
			Push(tr.ResolutionScope);
			Add(tr.CustomAttributes);
		}

		void Add(IEnumerable<TypeSig> tss) {
			if (tss is null)
				return;
			foreach (var ts in tss)
				Add(ts);
		}

		void Add(TypeSig ts) {
			if (ts is null || TypeSigs.ContainsKey(ts))
				return;
			if (ts.Module != validModule)
				return;
			TypeSigs[ts] = true;

			for (; ts is not null; ts = ts.Next) {
				switch (ts.ElementType) {
				case ElementType.Void:
				case ElementType.Boolean:
				case ElementType.Char:
				case ElementType.I1:
				case ElementType.U1:
				case ElementType.I2:
				case ElementType.U2:
				case ElementType.I4:
				case ElementType.U4:
				case ElementType.I8:
				case ElementType.U8:
				case ElementType.R4:
				case ElementType.R8:
				case ElementType.String:
				case ElementType.ValueType:
				case ElementType.Class:
				case ElementType.TypedByRef:
				case ElementType.I:
				case ElementType.U:
				case ElementType.Object:
					var tdrs = (TypeDefOrRefSig)ts;
					Push(tdrs.TypeDefOrRef);
					break;

				case ElementType.FnPtr:
					var fps = (FnPtrSig)ts;
					Add(fps.Signature);
					break;

				case ElementType.GenericInst:
					var gis = (GenericInstSig)ts;
					Add(gis.GenericType);
					Add(gis.GenericArguments);
					break;

				case ElementType.CModReqd:
				case ElementType.CModOpt:
					var ms = (ModifierSig)ts;
					Push(ms.Modifier);
					break;

				case ElementType.End:
				case ElementType.Ptr:
				case ElementType.ByRef:
				case ElementType.Var:
				case ElementType.Array:
				case ElementType.ValueArray:
				case ElementType.R:
				case ElementType.SZArray:
				case ElementType.MVar:
				case ElementType.Internal:
				case ElementType.Module:
				case ElementType.Sentinel:
				case ElementType.Pinned:
				default:
					break;
				}
			}
		}

		void Add(TypeSpec ts) {
			if (ts is null || TypeSpecs.ContainsKey(ts))
				return;
			if (ts.Module != validModule)
				return;
			TypeSpecs[ts] = true;
			Add(ts.TypeSig);
			Add(ts.CustomAttributes);
		}

		void Add(IEnumerable<ExportedType> ets) {
			if (ets is null)
				return;
			foreach (var et in ets)
				Add(et);
		}

		void Add(ExportedType et) {
			if (et is null || ExportedTypes.ContainsKey(et))
				return;
			if (et.Module != validModule)
				return;
			ExportedTypes[et] = true;
			Add(et.CustomAttributes);
			Push(et.Implementation);
		}
	}
}