/* Copyright 2010-present MongoDB Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

using System;
using MongoDB.Bson.IO;

namespace MongoDB.Bson
{
    /// <summary>
    /// Represents a BSON int value.
    /// </summary>
    [Serializable]
    public class BsonInt32 : BsonValue, IComparable<BsonInt32>, IEquatable<BsonInt32>
    {
        #region static
        const int __minPrecreatedValue = -100;
        const int __maxPrecreatedValue = 100;
        private static readonly BsonInt32[] __precreatedInstances = new BsonInt32[__maxPrecreatedValue - __minPrecreatedValue + 1];

        static BsonInt32()
        {
            for (var i = __minPrecreatedValue; i <= __maxPrecreatedValue; i++)
            {
                var precreatedInstance = new BsonInt32(i);
                var index = i - __minPrecreatedValue;
                __precreatedInstances[index] = precreatedInstance;
            }
        }
        #endregion

        // private fields
        private readonly int _value;

        // constructors
        /// <summary>
        /// Creates a new instance of the BsonInt32 class.
        /// </summary>
        /// <param name="value">The value.</param>
        public BsonInt32(int value)
        {
            _value = value;
        }

        // public static properties
        /// <summary>
        /// Gets an instance of BsonInt32 that represents -1.
        /// </summary>
        [Obsolete("Use (BsonInt32)(-1) instead.")]
        public static BsonInt32 MinusOne
        {
            get { return (BsonInt32)(-1); }
        }

        /// <summary>
        /// Gets an instance of BsonInt32 that represents -0.
        /// </summary>
        [Obsolete("Use (BsonInt32)0 instead.")]
        public static BsonInt32 Zero
        {
            get { return (BsonInt32)0; }
        }

        /// <summary>
        /// Gets an instance of BsonInt32 that represents 1.
        /// </summary>
        [Obsolete("Use (BsonInt32)1 instead.")]
        public static BsonInt32 One
        {
            get { return (BsonInt32)1; }
        }

        /// <summary>
        /// Gets an instance of BsonInt32 that represents 2.
        /// </summary>
        [Obsolete("Use (BsonInt32)2 instead.")]
        public static BsonInt32 Two
        {
            get { return (BsonInt32)2; }
        }

        /// <summary>
        /// Gets an instance of BsonInt32 that represents 3.
        /// </summary>
        [Obsolete("Use (BsonInt32)3 instead.")]
        public static BsonInt32 Three
        {
            get { return (BsonInt32)3; }
        }

        // public properties
        /// <summary>
        /// Gets the BsonType of this BsonValue.
        /// </summary>
        public override BsonType BsonType
        {
            get { return BsonType.Int32; }
        }

        /// <summary>
        /// Gets the BsonInt32 as an int.
        /// </summary>
        [Obsolete("Use Value instead.")]
        public override object RawValue
        {
            get { return _value; }
        }

        /// <summary>
        /// Gets the value of this BsonInt32.
        /// </summary>
        public int Value
        {
            get { return _value; }
        }

        // public operators
        /// <summary>
        /// Converts an int to a BsonInt32.
        /// </summary>
        /// <param name="value">An int.</param>
        /// <returns>A BsonInt32.</returns>
        public static implicit operator BsonInt32(int value)
        {
            if (value >= __minPrecreatedValue && value <= __maxPrecreatedValue)
            {
                var index = value - __minPrecreatedValue;
                return __precreatedInstances[index];
            }
            return new BsonInt32(value);
        }

        /// <summary>
        /// Compares two BsonInt32 values.
        /// </summary>
        /// <param name="lhs">The first BsonInt32.</param>
        /// <param name="rhs">The other BsonInt32.</param>
        /// <returns>True if the two BsonInt32 values are not equal according to ==.</returns>
        public static bool operator !=(BsonInt32 lhs, BsonInt32 rhs)
        {
            return !(lhs == rhs);
        }

        /// <summary>
        /// Compares two BsonInt32 values.
        /// </summary>
        /// <param name="lhs">The first BsonInt32.</param>
        /// <param name="rhs">The other BsonInt32.</param>
        /// <returns>True if the two BsonInt32 values are equal according to ==.</returns>
        public static bool operator ==(BsonInt32 lhs, BsonInt32 rhs)
        {
            if (object.ReferenceEquals(lhs, null)) { return object.ReferenceEquals(rhs, null); }
            return lhs.OperatorEqualsImplementation(rhs);
        }

        // public static methods
        /// <summary>
        /// Creates a new BsonInt32.
        /// </summary>
        /// <param name="value">An object to be mapped to a BsonInt32.</param>
        /// <returns>A BsonInt32 or null.</returns>
        public new static BsonInt32 Create(object value)
        {
            if (value == null)
            {
                throw new ArgumentNullException("value");
            }

            return (BsonInt32)BsonTypeMapper.MapToBsonValue(value, BsonType.Int32);
        }

        // public methods
        /// <summary>
        /// Compares this BsonInt32 to another BsonInt32.
        /// </summary>
        /// <param name="other">The other BsonInt32.</param>
        /// <returns>A 32-bit signed integer that indicates whether this BsonInt32 is less than, equal to, or greather than the other.</returns>
        public int CompareTo(BsonInt32 other)
        {
            if (other == null) { return 1; }
            return _value.CompareTo(other._value);
        }

        /// <summary>
        /// Compares the BsonInt32 to another BsonValue.
        /// </summary>
        /// <param name="other">The other BsonValue.</param>
        /// <returns>A 32-bit signed integer that indicates whether this BsonInt32 is less than, equal to, or greather than the other BsonValue.</returns>
        public override int CompareTo(BsonValue other)
        {
            if (other == null) { return 1; }

            var otherInt32 = other as BsonInt32;
            if (otherInt32 != null)
            {
                return _value.CompareTo(otherInt32._value);
            }

            var otherInt64 = other as BsonInt64;
            if (otherInt64 != null)
            {
                return ((long)_value).CompareTo(otherInt64.Value);
            }

            var otherDouble = other as BsonDouble;
            if (otherDouble != null)
            {
                return ((double)_value).CompareTo(otherDouble.Value);
            }

            var otherDecimal128 = other as BsonDecimal128;
            if (otherDecimal128 != null)
            {
                return ((Decimal128)_value).CompareTo(otherDecimal128.Value);
            }

            return CompareTypeTo(other);
        }

        /// <summary>
        /// Compares this BsonInt32 to another BsonInt32.
        /// </summary>
        /// <param name="rhs">The other BsonInt32.</param>
        /// <returns>True if the two BsonInt32 values are equal.</returns>
        public bool Equals(BsonInt32 rhs)
        {
            if (object.ReferenceEquals(rhs, null) || GetType() != rhs.GetType()) { return false; }
            return _value == rhs._value;
        }

        /// <summary>
        /// Compares this BsonInt32 to another object.
        /// </summary>
        /// <param name="obj">The other object.</param>
        /// <returns>True if the other object is a BsonInt32 and equal to this one.</returns>
        public override bool Equals(object obj)
        {
            return Equals(obj as BsonInt32); // works even if obj is null or of a different type
        }

        /// <summary>
        /// Gets the hash code.
        /// </summary>
        /// <returns>The hash code.</returns>
        public override int GetHashCode()
        {
            // see Effective Java by Joshua Bloch
            int hash = 17;
            hash = 37 * hash + BsonType.GetHashCode();
            hash = 37 * hash + _value.GetHashCode();
            return hash;
        }

        /// <summary>
        /// Converts this BsonValue to a Boolean (using the JavaScript definition of truthiness).
        /// </summary>
        /// <returns>A Boolean.</returns>
        public override bool ToBoolean()
        {
            return _value != 0;
        }

        /// <inheritdoc/>
        public override decimal ToDecimal()
        {
            return (decimal)_value;
        }

        /// <inheritdoc/>
        public override Decimal128 ToDecimal128()
        {
            return (Decimal128)_value;
        }

        /// <summary>
        /// Converts this BsonValue to a Double.
        /// </summary>
        /// <returns>A Double.</returns>
        public override double ToDouble()
        {
            return (double)_value;
        }

        /// <summary>
        /// Converts this BsonValue to an Int32.
        /// </summary>
        /// <returns>An Int32.</returns>
        public override int ToInt32()
        {
            return _value;
        }

        /// <summary>
        /// Converts this BsonValue to an Int64.
        /// </summary>
        /// <returns>An Int32.</returns>
        public override long ToInt64()
        {
            return (long)_value;
        }

        /// <summary>
        /// Returns a string representation of the value.
        /// </summary>
        /// <returns>A string representation of the value.</returns>
        public override string ToString()
        {
            return JsonConvert.ToString(_value);
        }

        // protected methods
        /// <inheritdoc/>
        protected override TypeCode IConvertibleGetTypeCodeImplementation()
        {
            return TypeCode.Int32;
        }

        /// <inheritdoc/>
        protected override bool IConvertibleToBooleanImplementation(IFormatProvider provider)
        {
            return Convert.ToBoolean(_value, provider);
        }

        /// <inheritdoc/>
        protected override byte IConvertibleToByteImplementation(IFormatProvider provider)
        {
            return Convert.ToByte(_value, provider);
        }

        /// <inheritdoc/>
        protected override char IConvertibleToCharImplementation(IFormatProvider provider)
        {
            return Convert.ToChar(_value, provider);
        }

        /// <inheritdoc/>
        protected override decimal IConvertibleToDecimalImplementation(IFormatProvider provider)
        {
            return Convert.ToDecimal(_value, provider);
        }

        /// <inheritdoc/>
        protected override double IConvertibleToDoubleImplementation(IFormatProvider provider)
        {
            return Convert.ToDouble(_value, provider);
        }

        /// <inheritdoc/>
        protected override short IConvertibleToInt16Implementation(IFormatProvider provider)
        {
            return Convert.ToInt16(_value, provider);
        }

        /// <inheritdoc/>
        protected override int IConvertibleToInt32Implementation(IFormatProvider provider)
        {
            return _value;
        }

        /// <inheritdoc/>
        protected override long IConvertibleToInt64Implementation(IFormatProvider provider)
        {
            return Convert.ToInt64(_value, provider);
        }

        /// <inheritdoc/>
#pragma warning disable 3002
        protected override sbyte IConvertibleToSByteImplementation(IFormatProvider provider)
        {
            return Convert.ToSByte(_value, provider);
        }
#pragma warning restore

        /// <inheritdoc/>
        protected override float IConvertibleToSingleImplementation(IFormatProvider provider)
        {
            return Convert.ToSingle(_value, provider);
        }

        /// <inheritdoc/>
        protected override string IConvertibleToStringImplementation(IFormatProvider provider)
        {
            return Convert.ToString(_value, provider);
        }

        /// <inheritdoc/>
#pragma warning disable 3002
        protected override ushort IConvertibleToUInt16Implementation(IFormatProvider provider)
        {
            return Convert.ToUInt16(_value, provider);
        }
#pragma warning restore

        /// <inheritdoc/>
#pragma warning disable 3002
        protected override uint IConvertibleToUInt32Implementation(IFormatProvider provider)
        {
            return Convert.ToUInt32(_value, provider);
        }
#pragma warning restore

        /// <inheritdoc/>
#pragma warning disable 3002
        protected override ulong IConvertibleToUInt64Implementation(IFormatProvider provider)
        {
            return Convert.ToUInt64(_value, provider);
        }
#pragma warning restore

        /// <summary>
        /// Compares this BsonInt32 against another BsonValue.
        /// </summary>
        /// <param name="rhs">The other BsonValue.</param>
        /// <returns>True if this BsonInt32 and the other BsonValue are equal according to ==.</returns>
        protected override bool OperatorEqualsImplementation(BsonValue rhs)
        {
            var rhsInt32 = rhs as BsonInt32;
            if (rhsInt32 != null)
            {
                return _value == rhsInt32._value;
            }

            var rhsInt64 = rhs as BsonInt64;
            if (rhsInt64 != null)
            {
                return (long)_value == rhsInt64.Value;
            }

            var rhsDouble = rhs as BsonDouble;
            if (rhsDouble != null)
            {
                return (double)_value == rhsDouble.Value; // use == instead of Equals so NaN is handled correctly
            }

            var rhsDecimal128 = rhs as BsonDecimal128;
            if (rhsDecimal128 != null)
            {
                return _value == (int)rhsDecimal128.Value; // use == instead of Equals so NaN is handled correctly
            }

            return this.Equals(rhs);
        }
    }
}