// dnlib: See LICENSE.txt for more info

using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using dnlib.DotNet.MD;

namespace dnlib.DotNet {
	/// <summary>
	/// A high-level representation of a row in the ImplMap table
	/// </summary>
	[DebuggerDisplay("{Module} {Name}")]
	public abstract class ImplMap : IMDTokenProvider {
		/// <summary>
		/// The row id in its table
		/// </summary>
		protected uint rid;

		/// <inheritdoc/>
		public MDToken MDToken => new MDToken(Table.ImplMap, rid);

		/// <inheritdoc/>
		public uint Rid {
			get => rid;
			set => rid = value;
		}

		/// <summary>
		/// From column ImplMap.MappingFlags
		/// </summary>
		public PInvokeAttributes Attributes {
			get => (PInvokeAttributes)attributes;
			set => attributes = (int)value;
		}
		/// <summary>Attributes</summary>
		protected int attributes;

		/// <summary>
		/// From column ImplMap.ImportName
		/// </summary>
		public UTF8String Name {
			get => name;
			set => name = value;
		}
		/// <summary>Name</summary>
		protected UTF8String name;

		/// <summary>
		/// From column ImplMap.ImportScope
		/// </summary>
		public ModuleRef Module {
			get => module;
			set => module = value;
		}
		/// <summary/>
		protected ModuleRef module;

		/// <summary>
		/// Modify <see cref="attributes"/> property: <see cref="attributes"/> =
		/// (<see cref="attributes"/> &amp; <paramref name="andMask"/>) | <paramref name="orMask"/>.
		/// </summary>
		/// <param name="andMask">Value to <c>AND</c></param>
		/// <param name="orMask">Value to OR</param>
		void ModifyAttributes(PInvokeAttributes andMask, PInvokeAttributes orMask) =>
			attributes = (attributes & (int)andMask) | (int)orMask;

		/// <summary>
		/// Set or clear flags in <see cref="attributes"/>
		/// </summary>
		/// <param name="set"><c>true</c> if flags should be set, <c>false</c> if flags should
		/// be cleared</param>
		/// <param name="flags">Flags to set or clear</param>
		void ModifyAttributes(bool set, PInvokeAttributes flags) {
			if (set)
				attributes |= (int)flags;
			else
				attributes &= ~(int)flags;
		}

		/// <summary>
		/// Gets/sets the <see cref="PInvokeAttributes.NoMangle"/> bit
		/// </summary>
		public bool IsNoMangle {
			get => ((PInvokeAttributes)attributes & PInvokeAttributes.NoMangle) != 0;
			set => ModifyAttributes(value, PInvokeAttributes.NoMangle);
		}

		/// <summary>
		/// Gets/sets the char set
		/// </summary>
		public PInvokeAttributes CharSet {
			get => (PInvokeAttributes)attributes & PInvokeAttributes.CharSetMask;
			set => ModifyAttributes(~PInvokeAttributes.CharSetMask, value & PInvokeAttributes.CharSetMask);
		}

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CharSetNotSpec"/> is set
		/// </summary>
		public bool IsCharSetNotSpec => ((PInvokeAttributes)attributes & PInvokeAttributes.CharSetMask) == PInvokeAttributes.CharSetNotSpec;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CharSetAnsi"/> is set
		/// </summary>
		public bool IsCharSetAnsi => ((PInvokeAttributes)attributes & PInvokeAttributes.CharSetMask) == PInvokeAttributes.CharSetAnsi;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CharSetUnicode"/> is set
		/// </summary>
		public bool IsCharSetUnicode => ((PInvokeAttributes)attributes & PInvokeAttributes.CharSetMask) == PInvokeAttributes.CharSetUnicode;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CharSetAuto"/> is set
		/// </summary>
		public bool IsCharSetAuto => ((PInvokeAttributes)attributes & PInvokeAttributes.CharSetMask) == PInvokeAttributes.CharSetAuto;

		/// <summary>
		/// Gets/sets best fit
		/// </summary>
		public PInvokeAttributes BestFit {
			get => (PInvokeAttributes)attributes & PInvokeAttributes.BestFitMask;
			set => ModifyAttributes(~PInvokeAttributes.BestFitMask, value & PInvokeAttributes.BestFitMask);
		}

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.BestFitUseAssem"/> is set
		/// </summary>
		public bool IsBestFitUseAssem => ((PInvokeAttributes)attributes & PInvokeAttributes.BestFitMask) == PInvokeAttributes.BestFitUseAssem;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.BestFitEnabled"/> is set
		/// </summary>
		public bool IsBestFitEnabled => ((PInvokeAttributes)attributes & PInvokeAttributes.BestFitMask) == PInvokeAttributes.BestFitEnabled;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.BestFitDisabled"/> is set
		/// </summary>
		public bool IsBestFitDisabled => ((PInvokeAttributes)attributes & PInvokeAttributes.BestFitMask) == PInvokeAttributes.BestFitDisabled;

		/// <summary>
		/// Gets/sets throw on unmappable char
		/// </summary>
		public PInvokeAttributes ThrowOnUnmappableChar {
			get => (PInvokeAttributes)attributes & PInvokeAttributes.ThrowOnUnmappableCharMask;
			set => ModifyAttributes(~PInvokeAttributes.ThrowOnUnmappableCharMask, value & PInvokeAttributes.ThrowOnUnmappableCharMask);
		}

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.ThrowOnUnmappableCharUseAssem"/> is set
		/// </summary>
		public bool IsThrowOnUnmappableCharUseAssem => ((PInvokeAttributes)attributes & PInvokeAttributes.ThrowOnUnmappableCharMask) == PInvokeAttributes.ThrowOnUnmappableCharUseAssem;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.ThrowOnUnmappableCharEnabled"/> is set
		/// </summary>
		public bool IsThrowOnUnmappableCharEnabled => ((PInvokeAttributes)attributes & PInvokeAttributes.ThrowOnUnmappableCharMask) == PInvokeAttributes.ThrowOnUnmappableCharEnabled;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.ThrowOnUnmappableCharDisabled"/> is set
		/// </summary>
		public bool IsThrowOnUnmappableCharDisabled => ((PInvokeAttributes)attributes & PInvokeAttributes.ThrowOnUnmappableCharMask) == PInvokeAttributes.ThrowOnUnmappableCharDisabled;

		/// <summary>
		/// Gets/sets the <see cref="PInvokeAttributes.SupportsLastError"/> bit
		/// </summary>
		public bool SupportsLastError {
			get => ((PInvokeAttributes)attributes & PInvokeAttributes.SupportsLastError) != 0;
			set => ModifyAttributes(value, PInvokeAttributes.SupportsLastError);
		}

		/// <summary>
		/// Gets/sets calling convention
		/// </summary>
		public PInvokeAttributes CallConv {
			get => (PInvokeAttributes)attributes & PInvokeAttributes.CallConvMask;
			set => ModifyAttributes(~PInvokeAttributes.CallConvMask, value & PInvokeAttributes.CallConvMask);
		}

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CallConvWinapi"/> is set
		/// </summary>
		public bool IsCallConvWinapi => ((PInvokeAttributes)attributes & PInvokeAttributes.CallConvMask) == PInvokeAttributes.CallConvWinapi;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CallConvCdecl"/> is set
		/// </summary>
		public bool IsCallConvCdecl => ((PInvokeAttributes)attributes & PInvokeAttributes.CallConvMask) == PInvokeAttributes.CallConvCdecl;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CallConvStdcall"/> is set
		/// </summary>
		public bool IsCallConvStdcall => ((PInvokeAttributes)attributes & PInvokeAttributes.CallConvMask) == PInvokeAttributes.CallConvStdcall;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CallConvThiscall"/> is set
		/// </summary>
		public bool IsCallConvThiscall => ((PInvokeAttributes)attributes & PInvokeAttributes.CallConvMask) == PInvokeAttributes.CallConvThiscall;

		/// <summary>
		/// <c>true</c> if <see cref="PInvokeAttributes.CallConvFastcall"/> is set
		/// </summary>
		public bool IsCallConvFastcall => ((PInvokeAttributes)attributes & PInvokeAttributes.CallConvMask) == PInvokeAttributes.CallConvFastcall;

		/// <summary>
		/// Checks whether this <see cref="ImplMap"/> is a certain P/Invoke method
		/// </summary>
		/// <param name="dllName">Name of the DLL</param>
		/// <param name="funcName">Name of the function within the DLL</param>
		/// <returns><c>true</c> if it's the specified P/Invoke method, else <c>false</c></returns>
		public bool IsPinvokeMethod(string dllName, string funcName) => IsPinvokeMethod(dllName, funcName, IsWindows());

		/// <summary>
		/// Checks whether this <see cref="ImplMap"/> is a certain P/Invoke method
		/// </summary>
		/// <param name="dllName">Name of the DLL</param>
		/// <param name="funcName">Name of the function within the DLL</param>
		/// <param name="treatAsWindows">Treat as Windows</param>
		/// <returns><c>true</c> if it's the specified P/Invoke method, else <c>false</c></returns>
		public bool IsPinvokeMethod(string dllName, string funcName, bool treatAsWindows) {
			if (name != funcName)
				return false;
			var mod = module;
			if (mod is null)
				return false;
			return GetDllName(dllName, treatAsWindows).Equals(GetDllName(mod.Name, treatAsWindows), StringComparison.OrdinalIgnoreCase);
		}

		static string GetDllName(string dllName, bool treatAsWindows) {
			if (treatAsWindows)
				dllName = dllName.TrimEnd(trimChars);
			if (dllName.EndsWith(".dll", StringComparison.OrdinalIgnoreCase))
				return dllName.Substring(0, dllName.Length - 4);
			return dllName;
		}

		static bool IsWindows() =>
#if NETSTANDARD || NETCOREAPP
			RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
#else
			Path.DirectorySeparatorChar == '\\' || Path.AltDirectorySeparatorChar == '\\';
#endif

		static readonly char[] trimChars = { ' ' };
	}

	/// <summary>
	/// An ImplMap row created by the user and not present in the original .NET file
	/// </summary>
	public class ImplMapUser : ImplMap {
		/// <summary>
		/// Default constructor
		/// </summary>
		public ImplMapUser() {
		}

		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="scope">Scope</param>
		/// <param name="name">Name</param>
		/// <param name="flags">Flags</param>
		public ImplMapUser(ModuleRef scope, UTF8String name, PInvokeAttributes flags) {
			module = scope;
			this.name = name;
			attributes = (int)flags;
		}
	}

	/// <summary>
	/// Created from a row in the ImplMap table
	/// </summary>
	sealed class ImplMapMD : ImplMap, IMDTokenProviderMD {
		readonly uint origRid;

		/// <inheritdoc/>
		public uint OrigRid => origRid;

		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="readerModule">The module which contains this <c>ImplMap</c> row</param>
		/// <param name="rid">Row ID</param>
		/// <exception cref="ArgumentNullException">If <paramref name="readerModule"/> is <c>null</c></exception>
		/// <exception cref="ArgumentException">If <paramref name="rid"/> is invalid</exception>
		public ImplMapMD(ModuleDefMD readerModule, uint rid) {
#if DEBUG
			if (readerModule is null)
				throw new ArgumentNullException("readerModule");
			if (readerModule.TablesStream.ImplMapTable.IsInvalidRID(rid))
				throw new BadImageFormatException($"ImplMap rid {rid} does not exist");
#endif
			origRid = rid;
			this.rid = rid;
			bool b = readerModule.TablesStream.TryReadImplMapRow(origRid, out var row);
			Debug.Assert(b);
			attributes = row.MappingFlags;
			name = readerModule.StringsStream.ReadNoNull(row.ImportName);
			module = readerModule.ResolveModuleRef(row.ImportScope);
		}
	}
}