using System;
using System.Diagnostics;


namespace BotSharp.Algorithm.Bayesian
{
    /// <summary>
    /// Class StringToken. This class cannot be inherited.
    /// </summary>
    [DebuggerDisplay("{Value}")]
    public sealed class StringToken : IToken
    {
        /// <summary>
        /// Gets the value.
        /// </summary>
        /// <value>The value.</value>
        public string Value { get; private set; }

        /// <summary>
        /// Initializes a new instance of the <see cref="StringToken"/> class.
        /// </summary>
        /// <param name="value">The value.</param>
        public StringToken(string value)
        {
            if (ReferenceEquals(value, null)) throw new ArgumentNullException("value");
            Value = value;
        }
        
        /// <summary>
        /// Determines whether the specified <see cref="StringToken" /> is equal to this instance.
        /// </summary>
        /// <param name="other">The <see cref="T:System.Object" /> to compare with the current <see cref="T:System.Object" />.</param>
        /// <returns><see langword="true" /> if the specified <see cref="StringToken" /> is equal to this instance; otherwise, <see langword="false" />.</returns>
        private bool Equals(StringToken other)
        {
            return string.Equals(Value, other.Value);
        }

        /// <summary>
        /// Determines whether the specified <see cref="IToken" /> is equal to this instance.
        /// </summary>
        /// <param name="other">The <see cref="T:System.Object" /> to compare with the current <see cref="T:System.Object" />.</param>
        /// <returns><see langword="true" /> if the specified <see cref="StringToken" /> is equal to this instance; otherwise, <see langword="false" />.</returns>
        bool IEquatable<IToken>.Equals(IToken other)
        {
            var otherAsObject = (object)other;
            return Equals(otherAsObject);
        }

        /// <summary>
        /// Determines whether the specified <see cref="System.Object" /> is equal to this instance.
        /// </summary>
        /// <param name="obj">The <see cref="T:System.Object" /> to compare with the current <see cref="T:System.Object" />.</param>
        /// <returns><see langword="true" /> if the specified <see cref="System.Object" /> is equal to this instance; otherwise, <see langword="false" />.</returns>
        public override bool Equals(object obj)
        {
            // ReSharper disable once ConditionIsAlwaysTrueOrFalse
            if (ReferenceEquals(null, obj)) return false;
            if (ReferenceEquals(this, obj)) return true;
            return obj is StringToken && Equals((StringToken) obj);
        }

        /// <summary>
        /// Returns a hash code for this instance.
        /// </summary>
        /// <returns>A hash code for this instance, suitable for use in hashing algorithms and data structures like a hash table.</returns>
        public override int GetHashCode()
        {
            return Value.GetHashCode();
        }

        /// <summary>
        /// Returns a <see cref="System.String" /> that represents this instance.
        /// </summary>
        /// <returns>A <see cref="System.String" /> that represents this instance.</returns>
        public override string ToString()
        {
            return Value;
        }
    }
}