// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics;
using System.Dynamic.Utils;

namespace System.Linq.Expressions.Interpreter
{
    internal abstract class LessThanOrEqualInstruction : Instruction
    {
        private readonly object? _nullValue;
        private static Instruction? s_SByte, s_Int16, s_Char, s_Int32, s_Int64, s_Byte, s_UInt16, s_UInt32, s_UInt64, s_Single, s_Double;
        private static Instruction? s_liftedToNullSByte, s_liftedToNullInt16, s_liftedToNullChar, s_liftedToNullInt32, s_liftedToNullInt64, s_liftedToNullByte, s_liftedToNullUInt16, s_liftedToNullUInt32, s_liftedToNullUInt64, s_liftedToNullSingle, s_liftedToNullDouble;

        public override int ConsumedStack => 2;
        public override int ProducedStack => 1;
        public override string InstructionName => "LessThanOrEqual";

        private LessThanOrEqualInstruction(object? nullValue)
        {
            _nullValue = nullValue;
        }

        private sealed class LessThanOrEqualSByte : LessThanOrEqualInstruction
        {
            public LessThanOrEqualSByte(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((sbyte)left <= (sbyte)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualInt16 : LessThanOrEqualInstruction
        {
            public LessThanOrEqualInt16(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((short)left <= (short)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualChar : LessThanOrEqualInstruction
        {
            public LessThanOrEqualChar(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((char)left <= (char)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualInt32 : LessThanOrEqualInstruction
        {
            public LessThanOrEqualInt32(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((int)left <= (int)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualInt64 : LessThanOrEqualInstruction
        {
            public LessThanOrEqualInt64(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((long)left <= (long)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualByte : LessThanOrEqualInstruction
        {
            public LessThanOrEqualByte(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((byte)left <= (byte)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualUInt16 : LessThanOrEqualInstruction
        {
            public LessThanOrEqualUInt16(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((ushort)left <= (ushort)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualUInt32 : LessThanOrEqualInstruction
        {
            public LessThanOrEqualUInt32(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((uint)left <= (uint)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualUInt64 : LessThanOrEqualInstruction
        {
            public LessThanOrEqualUInt64(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((ulong)left <= (ulong)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualSingle : LessThanOrEqualInstruction
        {
            public LessThanOrEqualSingle(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((float)left <= (float)right);
                }
                return 1;
            }
        }

        private sealed class LessThanOrEqualDouble : LessThanOrEqualInstruction
        {
            public LessThanOrEqualDouble(object? nullValue)
                : base(nullValue)
            {
            }

            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(_nullValue);
                }
                else
                {
                    frame.Push((double)left <= (double)right);
                }
                return 1;
            }
        }

        public static Instruction Create(Type type, bool liftedToNull = false)
        {
            Debug.Assert(!type.IsEnum);
            if (liftedToNull)
            {
                return type.GetNonNullableType().GetTypeCode() switch
                {
                    TypeCode.SByte => s_liftedToNullSByte ??= new LessThanOrEqualSByte(null),
                    TypeCode.Int16 => s_liftedToNullInt16 ??= new LessThanOrEqualInt16(null),
                    TypeCode.Char => s_liftedToNullChar ??= new LessThanOrEqualChar(null),
                    TypeCode.Int32 => s_liftedToNullInt32 ??= new LessThanOrEqualInt32(null),
                    TypeCode.Int64 => s_liftedToNullInt64 ??= new LessThanOrEqualInt64(null),
                    TypeCode.Byte => s_liftedToNullByte ??= new LessThanOrEqualByte(null),
                    TypeCode.UInt16 => s_liftedToNullUInt16 ??= new LessThanOrEqualUInt16(null),
                    TypeCode.UInt32 => s_liftedToNullUInt32 ??= new LessThanOrEqualUInt32(null),
                    TypeCode.UInt64 => s_liftedToNullUInt64 ??= new LessThanOrEqualUInt64(null),
                    TypeCode.Single => s_liftedToNullSingle ??= new LessThanOrEqualSingle(null),
                    TypeCode.Double => s_liftedToNullDouble ??= new LessThanOrEqualDouble(null),
                    _ => throw ContractUtils.Unreachable,
                };
            }
            else
            {
                return type.GetNonNullableType().GetTypeCode() switch
                {
                    TypeCode.SByte => s_SByte ??= new LessThanOrEqualSByte(Utils.BoxedFalse),
                    TypeCode.Int16 => s_Int16 ??= new LessThanOrEqualInt16(Utils.BoxedFalse),
                    TypeCode.Char => s_Char ??= new LessThanOrEqualChar(Utils.BoxedFalse),
                    TypeCode.Int32 => s_Int32 ??= new LessThanOrEqualInt32(Utils.BoxedFalse),
                    TypeCode.Int64 => s_Int64 ??= new LessThanOrEqualInt64(Utils.BoxedFalse),
                    TypeCode.Byte => s_Byte ??= new LessThanOrEqualByte(Utils.BoxedFalse),
                    TypeCode.UInt16 => s_UInt16 ??= new LessThanOrEqualUInt16(Utils.BoxedFalse),
                    TypeCode.UInt32 => s_UInt32 ??= new LessThanOrEqualUInt32(Utils.BoxedFalse),
                    TypeCode.UInt64 => s_UInt64 ??= new LessThanOrEqualUInt64(Utils.BoxedFalse),
                    TypeCode.Single => s_Single ??= new LessThanOrEqualSingle(Utils.BoxedFalse),
                    TypeCode.Double => s_Double ??= new LessThanOrEqualDouble(Utils.BoxedFalse),
                    _ => throw ContractUtils.Unreachable,
                };
            }
        }
    }
}