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

using System.Dynamic.Utils;

namespace System.Linq.Expressions.Interpreter
{
    internal abstract class OrInstruction : Instruction
    {
        private static Instruction? s_SByte, s_Int16, s_Int32, s_Int64, s_Byte, s_UInt16, s_UInt32, s_UInt64, s_Boolean;

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

        private OrInstruction() { }

        private sealed class OrSByte : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((sbyte)((sbyte)left | (sbyte)right));
                return 1;
            }
        }

        private sealed class OrInt16 : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((short)((short)left | (short)right));
                return 1;
            }
        }

        private sealed class OrInt32 : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((int)left | (int)right);
                return 1;
            }
        }

        private sealed class OrInt64 : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((long)left | (long)right);
                return 1;
            }
        }

        private sealed class OrByte : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((byte)((byte)left | (byte)right));
                return 1;
            }
        }

        private sealed class OrUInt16 : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((ushort)((ushort)left | (ushort)right));
                return 1;
            }
        }

        private sealed class OrUInt32 : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((uint)left | (uint)right);
                return 1;
            }
        }

        private sealed class OrUInt64 : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? left = frame.Pop();
                object? right = frame.Pop();
                if (left == null || right == null)
                {
                    frame.Push(null);
                    return 1;
                }
                frame.Push((ulong)left | (ulong)right);
                return 1;
            }
        }

        private sealed class OrBoolean : OrInstruction
        {
            public override int Run(InterpretedFrame frame)
            {
                object? right = frame.Pop();
                object? left = frame.Pop();
                if (left == null)
                {
                    if (right == null)
                    {
                        frame.Push(null);
                    }
                    else
                    {
                        frame.Push((bool)right ? Utils.BoxedTrue : null);
                    }
                    return 1;
                }

                if (right == null)
                {
                    frame.Push((bool)left ? Utils.BoxedTrue : null);
                    return 1;
                }

                frame.Push((bool)left | (bool)right);
                return 1;
            }
        }

        public static Instruction Create(Type type)
        {
            return type.GetNonNullableType().GetTypeCode() switch
            {
                TypeCode.SByte => s_SByte ??= new OrSByte(),
                TypeCode.Int16 => s_Int16 ??= new OrInt16(),
                TypeCode.Int32 => s_Int32 ??= new OrInt32(),
                TypeCode.Int64 => s_Int64 ??= new OrInt64(),
                TypeCode.Byte => s_Byte ??= new OrByte(),
                TypeCode.UInt16 => s_UInt16 ??= new OrUInt16(),
                TypeCode.UInt32 => s_UInt32 ??= new OrUInt32(),
                TypeCode.UInt64 => s_UInt64 ??= new OrUInt64(),
                TypeCode.Boolean => s_Boolean ??= new OrBoolean(),
                _ => throw ContractUtils.Unreachable,
            };
        }
    }
}