using System.ComponentModel.DataAnnotations.Resources;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;

namespace System.ComponentModel.DataAnnotations
{
    /// <summary>
    /// Used for specifying a range constraint
    /// </summary>
    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter, AllowMultiple = false)]
    [SuppressMessage("Microsoft.Design", "CA1019:DefineAccessorsForAttributeArguments", Justification = "We want it to be accessible via method on parent.")]
    [SuppressMessage("Microsoft.Performance", "CA1813:AvoidUnsealedAttributes", Justification = "We want users to be able to extend this class")]
    public class RangeAttribute : ValidationAttribute
    {
        /// <summary>
        /// Gets the minimum value for the range
        /// </summary>
        public object Minimum { get; private set; }

        /// <summary>
        /// Gets the maximum value for the range
        /// </summary>
        public object Maximum { get; private set; }

        /// <summary>
        /// Gets the type of the <see cref="Minimum"/> and <see cref="Maximum"/> values (e.g. Int32, Double, or some custom type)
        /// </summary>
        public Type OperandType { get; private set; }

        private Func<object, object> Conversion { get; set; }

        /// <summary>
        /// Constructor that takes integer minimum and maximum values
        /// </summary>
        /// <param name="minimum">The minimum value, inclusive</param>
        /// <param name="maximum">The maximum value, inclusive</param>
        public RangeAttribute(int minimum, int maximum)
            : this()
        {
            this.Minimum = minimum;
            this.Maximum = maximum;
            this.OperandType = typeof(int);
        }

        /// <summary>
        /// Constructor that takes double minimum and maximum values
        /// </summary>
        /// <param name="minimum">The minimum value, inclusive</param>
        /// <param name="maximum">The maximum value, inclusive</param>
        public RangeAttribute(double minimum, double maximum)
            : this()
        {
            this.Minimum = minimum;
            this.Maximum = maximum;
            this.OperandType = typeof(double);
        }

        /// <summary>
        /// Allows for specifying range for arbitrary types. The minimum and maximum strings will be converted to the target type.
        /// </summary>
        /// <param name="type">The type of the range parameters. Must implement IComparable.</param>
        /// <param name="minimum">The minimum allowable value.</param>
        /// <param name="maximum">The maximum allowable value.</param>
        public RangeAttribute(Type type, string minimum, string maximum)
            : this()
        {
            this.OperandType = type;
            this.Minimum = minimum;
            this.Maximum = maximum;
        }

        private RangeAttribute()
            : base(() => DataAnnotationsResources.RangeAttribute_ValidationError)
        {
        }

        private void Initialize(IComparable minimum, IComparable maximum, Func<object, object> conversion)
        {
            if (minimum.CompareTo(maximum) > 0)
            {
                throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture, DataAnnotationsResources.RangeAttribute_MinGreaterThanMax, maximum, minimum));
            }

            this.Minimum = minimum;
            this.Maximum = maximum;
            this.Conversion = conversion;
        }

        /// <summary>
        /// Returns true if the value falls between min and max, inclusive.
        /// </summary>
        /// <param name="value">The value to test for validity.</param>
        /// <returns><c>true</c> means the <paramref name="value"/> is valid</returns>
        /// <exception cref="InvalidOperationException"> is thrown if the current attribute is ill-formed.</exception>
        internal override bool IsValid(object value)
        {
            // Validate our properties and create the conversion function
            this.SetupConversion();

            // Automatically pass if value is null or empty. RequiredAttribute should be used to assert a value is not empty.
            if (value == null)
            {
                return true;
            }
            string s = value as string;
            if (s != null && String.IsNullOrEmpty(s))
            {
                return true;
            }

            object convertedValue = null;

            try
            {
                convertedValue = this.Conversion(value);
            }
            catch (FormatException)
            {
                return false;
            }
            catch (InvalidCastException)
            {
                return false;
            }
            catch (NotSupportedException)
            {
                return false;
            }

            IComparable min = (IComparable)this.Minimum;
            IComparable max = (IComparable)this.Maximum;
            return min.CompareTo(convertedValue) <= 0 && max.CompareTo(convertedValue) >= 0;
        }

        /// <summary>
        /// Override of <see cref="ValidationAttribute.FormatErrorMessage"/>
        /// </summary>
        /// <remarks>This override exists to provide a formatted message describing the minimum and maximum values</remarks>
        /// <param name="name">The user-visible name to include in the formatted message.</param>
        /// <returns>A localized string describing the minimum and maximum values</returns>
        /// <exception cref="InvalidOperationException"> is thrown if the current attribute is ill-formed.</exception>
        public override string FormatErrorMessage(string name)
        {
            this.SetupConversion();

            return String.Format(CultureInfo.CurrentCulture, ErrorMessageString, name, this.Minimum, this.Maximum);
        }

        /// <summary>
        /// Validates the properties of this attribute and sets up the conversion function.
        /// This method throws exceptions if the attribute is not configured properly.
        /// If it has once determined it is properly configured, it is a NOP.
        /// </summary>
        private void SetupConversion()
        {
            if (this.Conversion == null)
            {
                object minimum = this.Minimum;
                object maximum = this.Maximum;

                if (minimum == null || maximum == null)
                {
                    throw new InvalidOperationException(DataAnnotationsResources.RangeAttribute_Must_Set_Min_And_Max);
                }

                // Careful here -- OperandType could be int or double if they used the long form of the ctor.
                // But the min and max would still be strings.  Do use the type of the min/max operands to condition
                // the following code.
                Type operandType = minimum.GetType();

                if (operandType == typeof(int))
                {
                    this.Initialize((int)minimum, (int)maximum, v => Convert.ToInt32(v, CultureInfo.InvariantCulture));
                }
                else if (operandType == typeof(double))
                {
                    this.Initialize((double)minimum, (double)maximum, v => Convert.ToDouble(v, CultureInfo.InvariantCulture));
                }
                else
                {
                    Type type = this.OperandType;
                    if (type == null)
                    {
                        throw new InvalidOperationException(DataAnnotationsResources.RangeAttribute_Must_Set_Operand_Type);
                    }
                    Type comparableType = typeof(IComparable);
                    if (!comparableType.IsAssignableFrom(type))
                    {
                        throw new InvalidOperationException(
                            String.Format(
                                CultureInfo.CurrentCulture,
                                DataAnnotationsResources.RangeAttribute_ArbitraryTypeNotIComparable,
                                type.FullName,
                                comparableType.FullName));
                    }

                    Func<object, object> conversion = value => (value != null && value.GetType() == type) ? value : Convert.ChangeType(value, type, CultureInfo.CurrentCulture);
                    IComparable min = (IComparable)conversion(minimum);
                    IComparable max = (IComparable)conversion(maximum);

                    this.Initialize(min, max, conversion);
                }
            }
        }
    }
}