using System;
using System.Diagnostics;
using System.Globalization;
using Flee.ExpressionElements.Literals.Integral;


namespace Flee.ExpressionElements.Base.Literals
{
    internal abstract class IntegralLiteralElement : LiteralElement
    {
        protected IntegralLiteralElement()
        {
        }

        /// <summary>
        /// Attempt to find the first type of integer that a number can fit into
        /// </summary>
        /// <param name="image"></param>
        /// <param name="isHex"></param>
        /// <param name="negated"></param>
        /// <param name="services"></param>
        /// <returns></returns>
        public static LiteralElement Create(string image, bool isHex, bool negated, IServiceProvider services)
        {
            StringComparison comparison = StringComparison.OrdinalIgnoreCase;

            if (isHex == false)
            {
                // Create a real element if required
                LiteralElement realElement = RealLiteralElement.CreateFromInteger(image, services);

                if ((realElement != null))
                {
                    return realElement;
                }
            }

            bool hasUSuffix = image.EndsWith("u", comparison) & !image.EndsWith("lu", comparison);
            bool hasLSuffix = image.EndsWith("l", comparison) & !image.EndsWith("ul", comparison);
            bool hasUlSuffix = image.EndsWith("ul", comparison) | image.EndsWith("lu", comparison);
            bool hasSuffix = hasUSuffix | hasLSuffix | hasUlSuffix;

            LiteralElement constant = default(LiteralElement);
            System.Globalization.NumberStyles numStyles = NumberStyles.Integer;

            if (isHex == true)
            {
                numStyles = NumberStyles.AllowHexSpecifier;
                image = image.Remove(0, 2);
            }

            if (hasSuffix == false)
            {
                // If the literal has no suffix, it has the first of these types in which its value can be represented: int, uint, long, ulong.
                constant = Int32LiteralElement.TryCreate(image, isHex, negated);

                if ((constant != null))
                {
                    return constant;
                }

                constant = UInt32LiteralElement.TryCreate(image, numStyles);

                if ((constant != null))
                {
                    return constant;
                }

                constant = Int64LiteralElement.TryCreate(image, isHex, negated);

                if ((constant != null))
                {
                    return constant;
                }

                return new UInt64LiteralElement(image, numStyles);
            }
            else if (hasUSuffix == true)
            {
                image = image.Remove(image.Length - 1);
                // If the literal is suffixed by U or u, it has the first of these types in which its value can be represented: uint, ulong.

                constant = UInt32LiteralElement.TryCreate(image, numStyles);

                if ((constant != null))
                {
                    return constant;
                }
                else
                {
                    return new UInt64LiteralElement(image, numStyles);
                }
            }
            else if (hasLSuffix == true)
            {
                // If the literal is suffixed by L or l, it has the first of these types in which its value can be represented: long, ulong.
                image = image.Remove(image.Length - 1);

                constant = Int64LiteralElement.TryCreate(image, isHex, negated);

                if ((constant != null))
                {
                    return constant;
                }
                else
                {
                    return new UInt64LiteralElement(image, numStyles);
                }
            }
            else
            {
                // If the literal is suffixed by UL, Ul, uL, ul, LU, Lu, lU, or lu, it is of type ulong.
                Debug.Assert(hasUlSuffix == true, "expecting ul suffix");
                image = image.Remove(image.Length - 2);
                return new UInt64LiteralElement(image, numStyles);
            }
        }
    }
}