// dnlib: See LICENSE.txt for more info

using System.Collections.Generic;

namespace dnlib.DotNet.Emit {
	/// <summary>
	/// A CIL opcode
	/// </summary>
	public sealed class OpCode {
		/// <summary>
		/// The opcode name
		/// </summary>
		public readonly string Name;

		/// <summary>
		/// The opcode as a <see cref="Code"/> enum
		/// </summary>
		public readonly Code Code;

		/// <summary>
		/// Operand type
		/// </summary>
		public readonly OperandType OperandType;

		/// <summary>
		/// Flow control info
		/// </summary>
		public readonly FlowControl FlowControl;

		/// <summary>
		/// Opcode type
		/// </summary>
		public readonly OpCodeType OpCodeType;

		/// <summary>
		/// Push stack behavior
		/// </summary>
		public readonly StackBehaviour StackBehaviourPush;

		/// <summary>
		/// Pop stack behavior
		/// </summary>
		public readonly StackBehaviour StackBehaviourPop;

		/// <summary>
		/// Gets the value which is compatible with <see cref="System.Reflection.Emit.OpCode.Value"/>
		/// </summary>
		public short Value => (short)Code;

		/// <summary>
		/// Gets the size of the opcode. It's either 1 or 2 bytes.
		/// </summary>
		public int Size => Code < (Code)0x100 || Code == Code.UNKNOWN1 ? 1 : 2;

		/// <summary>
		/// Constructs an experimental opcode.
		/// </summary>
		public OpCode(string name, byte first, byte second, OperandType operandType, FlowControl flowControl, StackBehaviour push, StackBehaviour pop)
			: this(name, (Code)((first << 8) | second), operandType, flowControl, OpCodeType.Experimental, push, pop, true) {
		}

		internal OpCode(string name, Code code, OperandType operandType, FlowControl flowControl, OpCodeType opCodeType, StackBehaviour push, StackBehaviour pop, bool experimental = false) {
			Name = name;
			Code = code;
			OperandType = operandType;
			FlowControl = flowControl;
			OpCodeType = opCodeType;
			StackBehaviourPush = push;
			StackBehaviourPop = pop;
			if (!experimental) {
				if (((ushort)code >> 8) == 0)
					OpCodes.OneByteOpCodes[(byte)code] = this;
				else if (((ushort)code >> 8) == 0xFE)
					OpCodes.TwoByteOpCodes[(byte)code] = this;
			}
		}

		/// <summary>
		/// Creates a new instruction with no operand
		/// </summary>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction() => Instruction.Create(this);

		/// <summary>
		/// Creates a new instruction with a <see cref="byte"/> operand
		/// </summary>
		/// <param name="value">The value</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(byte value) => Instruction.Create(this, value);

		/// <summary>
		/// Creates a new instruction with a <see cref="sbyte"/> operand
		/// </summary>
		/// <param name="value">The value</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(sbyte value) => Instruction.Create(this, value);

		/// <summary>
		/// Creates a new instruction with an <see cref="int"/> operand
		/// </summary>
		/// <param name="value">The value</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(int value) => Instruction.Create(this, value);

		/// <summary>
		/// Creates a new instruction with a <see cref="long"/> operand
		/// </summary>
		/// <param name="value">The value</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(long value) => Instruction.Create(this, value);

		/// <summary>
		/// Creates a new instruction with a <see cref="float"/> operand
		/// </summary>
		/// <param name="value">The value</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(float value) => Instruction.Create(this, value);

		/// <summary>
		/// Creates a new instruction with a <see cref="double"/> operand
		/// </summary>
		/// <param name="value">The value</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(double value) => Instruction.Create(this, value);

		/// <summary>
		/// Creates a new instruction with a string operand
		/// </summary>
		/// <param name="s">The string</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(string s) => Instruction.Create(this, s);

		/// <summary>
		/// Creates a new instruction with an instruction target operand
		/// </summary>
		/// <param name="target">Target instruction</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(Instruction target) => Instruction.Create(this, target);

		/// <summary>
		/// Creates a new instruction with an instruction target list operand
		/// </summary>
		/// <param name="targets">The targets</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(IList<Instruction> targets) => Instruction.Create(this, targets);

		/// <summary>
		/// Creates a new instruction with a type operand
		/// </summary>
		/// <param name="type">The type</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(ITypeDefOrRef type) => Instruction.Create(this, type);

		/// <summary>
		/// Creates a new instruction with a type operand
		/// </summary>
		/// <param name="type">The type</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(CorLibTypeSig type) => Instruction.Create(this, type.TypeDefOrRef);

		/// <summary>
		/// Creates a new instruction with a method/field operand
		/// </summary>
		/// <param name="mr">The method/field</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(MemberRef mr) => Instruction.Create(this, mr);

		/// <summary>
		/// Creates a new instruction with a field operand
		/// </summary>
		/// <param name="field">The field</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(IField field) => Instruction.Create(this, field);

		/// <summary>
		/// Creates a new instruction with a method operand
		/// </summary>
		/// <param name="method">The method</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(IMethod method) => Instruction.Create(this, method);

		/// <summary>
		/// Creates a new instruction with a token operand
		/// </summary>
		/// <param name="token">The token</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(ITokenOperand token) => Instruction.Create(this, token);

		/// <summary>
		/// Creates a new instruction with a method signature operand
		/// </summary>
		/// <param name="methodSig">The method signature</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(MethodSig methodSig) => Instruction.Create(this, methodSig);

		/// <summary>
		/// Creates a new instruction with a method parameter operand
		/// </summary>
		/// <param name="parameter">The method parameter</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(Parameter parameter) => Instruction.Create(this, parameter);

		/// <summary>
		/// Creates a new instruction with a method local operand
		/// </summary>
		/// <param name="local">The method local</param>
		/// <returns>A new <see cref="Instruction"/> instance</returns>
		public Instruction ToInstruction(Local local) => Instruction.Create(this, local);

		/// <inheritdoc/>
		public override string ToString() => Name;
	}
}