// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Globalization;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;

namespace System
{
    [Serializable]
    [StructLayout(LayoutKind.Sequential)]
    [TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
    public readonly struct Int32 : IComparable, IConvertible, IFormattable, IComparable<int>, IEquatable<int>, ISpanFormattable
    {
        private readonly int m_value; // Do not rename (binary serialization)

        public const int MaxValue = 0x7fffffff;
        public const int MinValue = unchecked((int)0x80000000);

        // Compares this object to another object, returning an integer that
        // indicates the relationship. 
        // Returns :
        // 0 if the values are equal
        // Negative number if _value is less than value
        // Positive number if _value is more than value
        // null is considered to be less than any instance, hence returns positive number
        // If object is not of type Int32, this method throws an ArgumentException.
        // 
        public int CompareTo(object value)
        {
            if (value == null)
            {
                return 1;
            }
            if (value is int)
            {
                // NOTE: Cannot use return (_value - value) as this causes a wrap
                // around in cases where _value - value > MaxValue.
                int i = (int)value;
                if (m_value < i) return -1;
                if (m_value > i) return 1;
                return 0;
            }
            throw new ArgumentException(SR.Arg_MustBeInt32);
        }

        public int CompareTo(int value)
        {
            // NOTE: Cannot use return (_value - value) as this causes a wrap
            // around in cases where _value - value > MaxValue.
            if (m_value < value) return -1;
            if (m_value > value) return 1;
            return 0;
        }

        public override bool Equals(object obj)
        {
            if (!(obj is int))
            {
                return false;
            }
            return m_value == ((int)obj).m_value;
        }

        [NonVersionable]
        public bool Equals(int obj)
        {
            return m_value == obj;
        }

        // The absolute value of the int contained.
        public override int GetHashCode()
        {
            return m_value;
        }

        public override string ToString()
        {
            return Number.FormatInt32(m_value, null, null);
        }

        public string ToString(string format)
        {
            return Number.FormatInt32(m_value, format, null);
        }

        public string ToString(IFormatProvider provider)
        {
            return Number.FormatInt32(m_value, null, provider);
        }

        public string ToString(string format, IFormatProvider provider)
        {
            return Number.FormatInt32(m_value, format, provider);
        }

        public bool TryFormat(Span<char> destination, out int charsWritten, ReadOnlySpan<char> format = default, IFormatProvider provider = null)
        {
            return Number.TryFormatInt32(m_value, format, provider, destination, out charsWritten);
        }

        public static int Parse(string s)
        {
            if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
            return Number.ParseInt32(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo);
        }

        public static int Parse(string s, NumberStyles style)
        {
            NumberFormatInfo.ValidateParseStyleInteger(style);
            if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
            return Number.ParseInt32(s, style, NumberFormatInfo.CurrentInfo);
        }

        // Parses an integer from a String in the given style.  If
        // a NumberFormatInfo isn't specified, the current culture's 
        // NumberFormatInfo is assumed.
        // 
        public static int Parse(string s, IFormatProvider provider)
        {
            if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
            return Number.ParseInt32(s, NumberStyles.Integer, NumberFormatInfo.GetInstance(provider));
        }

        // Parses an integer from a String in the given style.  If
        // a NumberFormatInfo isn't specified, the current culture's 
        // NumberFormatInfo is assumed.
        // 
        public static int Parse(string s, NumberStyles style, IFormatProvider provider)
        {
            NumberFormatInfo.ValidateParseStyleInteger(style);
            if (s == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.s);
            return Number.ParseInt32(s, style, NumberFormatInfo.GetInstance(provider));
        }

        public static int Parse(ReadOnlySpan<char> s, NumberStyles style = NumberStyles.Integer, IFormatProvider provider = null)
        {
            NumberFormatInfo.ValidateParseStyleInteger(style);
            return Number.ParseInt32(s, style, NumberFormatInfo.GetInstance(provider));
        }

        // Parses an integer from a String. Returns false rather
        // than throwing exceptin if input is invalid
        // 
        public static bool TryParse(string s, out int result)
        {
            if (s == null)
            {
                result = 0;
                return false;
            }

            return Number.TryParseInt32IntegerStyle(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo, out result) == Number.ParsingStatus.OK;
        }

        public static bool TryParse(ReadOnlySpan<char> s, out int result)
        {
            return Number.TryParseInt32IntegerStyle(s, NumberStyles.Integer, NumberFormatInfo.CurrentInfo, out result) == Number.ParsingStatus.OK;
        }

        // Parses an integer from a String in the given style. Returns false rather
        // than throwing exceptin if input is invalid
        // 
        public static bool TryParse(string s, NumberStyles style, IFormatProvider provider, out int result)
        {
            NumberFormatInfo.ValidateParseStyleInteger(style);

            if (s == null)
            {
                result = 0;
                return false;
            }

            return Number.TryParseInt32(s, style, NumberFormatInfo.GetInstance(provider), out result) == Number.ParsingStatus.OK;
        }

        public static bool TryParse(ReadOnlySpan<char> s, NumberStyles style, IFormatProvider provider, out int result)
        {
            NumberFormatInfo.ValidateParseStyleInteger(style);
            return Number.TryParseInt32(s, style, NumberFormatInfo.GetInstance(provider), out result) == Number.ParsingStatus.OK;
        }

        //
        // IConvertible implementation
        // 

        public TypeCode GetTypeCode()
        {
            return TypeCode.Int32;
        }

        bool IConvertible.ToBoolean(IFormatProvider provider)
        {
            return Convert.ToBoolean(m_value);
        }

        char IConvertible.ToChar(IFormatProvider provider)
        {
            return Convert.ToChar(m_value);
        }

        sbyte IConvertible.ToSByte(IFormatProvider provider)
        {
            return Convert.ToSByte(m_value);
        }

        byte IConvertible.ToByte(IFormatProvider provider)
        {
            return Convert.ToByte(m_value);
        }

        short IConvertible.ToInt16(IFormatProvider provider)
        {
            return Convert.ToInt16(m_value);
        }

        ushort IConvertible.ToUInt16(IFormatProvider provider)
        {
            return Convert.ToUInt16(m_value);
        }

        int IConvertible.ToInt32(IFormatProvider provider)
        {
            return m_value;
        }

        uint IConvertible.ToUInt32(IFormatProvider provider)
        {
            return Convert.ToUInt32(m_value);
        }

        long IConvertible.ToInt64(IFormatProvider provider)
        {
            return Convert.ToInt64(m_value);
        }

        ulong IConvertible.ToUInt64(IFormatProvider provider)
        {
            return Convert.ToUInt64(m_value);
        }

        float IConvertible.ToSingle(IFormatProvider provider)
        {
            return Convert.ToSingle(m_value);
        }

        double IConvertible.ToDouble(IFormatProvider provider)
        {
            return Convert.ToDouble(m_value);
        }

        decimal IConvertible.ToDecimal(IFormatProvider provider)
        {
            return Convert.ToDecimal(m_value);
        }

        DateTime IConvertible.ToDateTime(IFormatProvider provider)
        {
            throw new InvalidCastException(SR.Format(SR.InvalidCast_FromTo, "Int32", "DateTime"));
        }

        object IConvertible.ToType(Type type, IFormatProvider provider)
        {
            return Convert.DefaultToType((IConvertible)this, type, provider);
        }
    }
}