[FieldType(Name = "Page", Shorthand = "Page")]
public class PageInfoField : IField, IEquatable<PageInfoField>
{
    /// <summary>
    /// Gets/sets the media id.
    /// </summary>
    /// <returns></returns>
    public Guid? Id { get; set; }

    /// <summary>
    /// Gets/sets the related page object.
    /// </summary>
    [JsonIgnore]
    public Piranha.Models.PageInfo Page { get; private set; }

    /// <summary>
    /// Gets if the field has a page object available.
    /// </summary>
    public bool HasValue => Page != null;

    /// <summary>
    /// Gets the list item title if this field is used in
    /// a collection regions.
    /// </summary>
    public virtual string GetTitle()
    {
        return Page?.Title;
    }

    /// <summary>
    /// Initializes the field for client use.
    /// </summary>
    /// <param name="api">The current api</param>
    public virtual void Init(IApi api)
    {
        if (Id.HasValue)
        {
            Page = api.Pages.GetById<Piranha.Models.PageInfo>(Id.Value);

            if (Page == null)
            {
                // The page has been removed, remove the
                // missing id.
                Id = null;
            }
        }
    }

    /// <summary>
    /// Gets the referenced page.
    /// </summary>
    /// <param name="api">The current api</param>
    /// <returns>The referenced page</returns>
    public virtual T GetPageAsync<T>(IApi api) where T : Piranha.Models.GenericPage<T>
    {
        if (Id.HasValue)
            return api.Pages.GetById<T>(Id.Value);
        return null;
    }

    /// <summary>
    /// Implicit operator for converting a Guid id to a field.
    /// </summary>
    /// <param name="str">The string value</param>
    public static implicit operator PageInfoField(Guid guid)
    {
        return new PageInfoField { Id = guid };
    }

    /// <summary>
    /// Implicit operator for converting a page object to a field.
    /// </summary>
    /// <param name="page">The page object</param>
    public static implicit operator PageInfoField(Piranha.Models.PageBase page)
    {
        return new PageInfoField { Id = page.Id };
    }

    /// <summary>
    /// Gets the hash code for the field.
    /// </summary>
    public override int GetHashCode()
    {
        return Id.HasValue ? Id.GetHashCode() : 0;
    }

    /// <summary>
    /// Checks if the given object is equal to the field.
    /// </summary>
    /// <param name="obj">The object</param>
    /// <returns>True if the fields are equal</returns>
    public override bool Equals(object obj)
    {
        if (obj is PageInfoField field)
        {
            return Equals(field);
        }
        return false;
    }

    /// <summary>
    /// Checks if the given field is equal to the field.
    /// </summary>
    /// <param name="obj">The field</param>
    /// <returns>True if the fields are equal</returns>
    public virtual bool Equals(PageInfoField obj)
    {
        if (obj == null)
        {
            return false;
        }
        return Id == obj.Id;
    }

    /// <summary>
    /// Checks if the fields are equal.
    /// </summary>
    /// <param name="field1">The first field</param>
    /// <param name="field2">The second field</param>
    /// <returns>True if the fields are equal</returns>
    public static bool operator ==(PageInfoField field1, PageInfoField field2)
    {
        if ((object)field1 != null && (object)field2 != null)
        {
            return field1.Equals(field2);
        }
        return false;
    }

    /// <summary>
    /// Checks if the fields are not equal.
    /// </summary>
    /// <param name="field1">The first field</param>
    /// <param name="field2">The second field</param>
    /// <returns>True if the fields are equal</returns>
    public static bool operator !=(PageInfoField field1, PageInfoField field2)
    {
        return !(field1 == field2);
    }
}