//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="ExpLogic"
// Project: StgSharp
// AuthorGroup: Nitload Space
// Copyright (c) Nitload Space. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//     
// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Text;

namespace StgSharp.Script.Express
{
    public enum ExpLogicValue
    {

        True,
        False,
        Unknown

    }

    public struct ExpLogic
    {

        public static readonly ExpLogic False = new ExpLogic(ExpLogicValue.False);

        public static readonly ExpLogic True = new ExpLogic(ExpLogicValue.True);
        public static readonly ExpLogic Unknown = new ExpLogic(ExpLogicValue.Unknown);

        private readonly ExpLogicValue _value;

        public ExpLogic(ExpLogicValue value)
        {
            _value = value;
        }

        public bool IsTrue => _value == ExpLogicValue.True;

        public bool IsFalse => _value == ExpLogicValue.False;

        public bool IsUnknown => _value == ExpLogicValue.Unknown;

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public bool ToBoolean()
        {
            return _value == ExpLogicValue.True;
        }

        public override string ToString() => _value.ToString();

        public static bool TryParse(ReadOnlySpan<char> value, out ExpLogic result)
        {
            if (Enum.TryParse<ExpLogicValue>(value, out ExpLogicValue e))
            {
                result = new ExpLogic(e);
                return true;
            }
            result = default;
            return false;
        }

        // NOT !
        public static ExpLogic operator !(ExpLogic a)
        {
            return a.IsTrue ? False : a.IsFalse ? True : Unknown;
        }

        // AND &
        public static ExpLogic operator &(ExpLogic a, ExpLogic b)
        {
            if (a.IsFalse || b.IsFalse) {
                return False;
            }

            if (a.IsUnknown || b.IsUnknown) {
                return Unknown;
            }

            return True;
        }

        // XOR ^
        public static ExpLogic operator ^(ExpLogic a, ExpLogic b)
        {
            if (a.IsUnknown || b.IsUnknown) {
                return Unknown;
            }

            return (a.IsTrue ^ b.IsTrue) ? True : False;
        }

        // OR |
        public static ExpLogic operator |(ExpLogic a, ExpLogic b)
        {
            if (a.IsTrue || b.IsTrue) {
                return True;
            }

            if (a.IsUnknown || b.IsUnknown) {
                return Unknown;
            }

            return False;
        }

    }
}