using System;
using System.Collections.Generic;
using System.ComponentModel;

namespace StackExchange.Redis
{
    /// <summary>
    /// Describes a hash-field (a name/value pair)
    /// </summary>
    public readonly struct HashEntry : IEquatable<HashEntry>
    {
        internal readonly RedisValue name, value;

        /// <summary>
        /// Initializes a <see cref="HashEntry"/> value.
        /// </summary>
        /// <param name="name">The name for this hash entry.</param>
        /// <param name="value">The value for this hash entry.</param>
        public HashEntry(RedisValue name, RedisValue value)
        {
            this.name = name;
            this.value = value;
        }

        /// <summary>
        /// The name of the hash field
        /// </summary>
        public RedisValue Name => name;

        /// <summary>
        /// The value of the hash field
        /// </summary>
        public RedisValue Value => value;

        /// <summary>
        /// The name of the hash field
        /// </summary>
        [Browsable(false)]
        [EditorBrowsable(EditorBrowsableState.Never), Obsolete("Please use Name", false)]
        public RedisValue Key { get { return name; } }

        /// <summary>
        /// Converts to a key/value pair
        /// </summary>
        /// <param name="value">The <see cref="HashEntry"/> to create a <see cref="KeyValuePair{TKey, TValue}"/> from.</param>
        public static implicit operator KeyValuePair<RedisValue, RedisValue>(HashEntry value) =>
            new KeyValuePair<RedisValue, RedisValue>(value.name, value.value);

        /// <summary>
        /// Converts from a key/value pair
        /// </summary>
        /// <param name="value">The <see cref="KeyValuePair{TKey, TValue}"/> to get a <see cref="HashEntry"/> from.</param>
        public static implicit operator HashEntry(KeyValuePair<RedisValue, RedisValue> value) =>
            new HashEntry(value.Key, value.Value);

        /// <summary>
        /// See Object.ToString()
        /// </summary>
        public override string ToString() => name + ": " + value;

        /// <summary>
        /// See Object.GetHashCode()
        /// </summary>
        public override int GetHashCode() => name.GetHashCode() ^ value.GetHashCode();

        /// <summary>
        /// Compares two values for equality.
        /// </summary>
        /// <param name="obj">The <see cref="HashEntry"/> to compare to.</param>
        public override bool Equals(object obj) => obj is HashEntry heObj && Equals(heObj);

        /// <summary>
        /// Compares two values for equality.
        /// </summary>
        /// <param name="other">The <see cref="HashEntry"/> to compare to.</param>
        public bool Equals(HashEntry other) => name == other.name && value == other.value;

        /// <summary>
        /// Compares two values for equality
        /// </summary>
        /// <param name="x">The first <see cref="HashEntry"/> to compare.</param>
        /// <param name="y">The second <see cref="HashEntry"/> to compare.</param>
        public static bool operator ==(HashEntry x, HashEntry y) => x.name == y.name && x.value == y.value;

        /// <summary>
        /// Compares two values for non-equality
        /// </summary>
        /// <param name="x">The first <see cref="HashEntry"/> to compare.</param>
        /// <param name="y">The second <see cref="HashEntry"/> to compare.</param>
        public static bool operator !=(HashEntry x, HashEntry y) => x.name != y.name || x.value != y.value;
    }
}
