using System;
using Deltares.Standard.Extensions;

namespace Deltares.Standard.Specifications
{
    /// <summary>
    /// Defines the abstract base class for the specification attributes 
    /// to derive more specific types from
    /// </summary>
    [AttributeUsage(AttributeTargets.Property | AttributeTargets.Property, Inherited = true, AllowMultiple = true)]
    public abstract class SpecificationBaseAttribute : Attribute
    {
        private readonly ISpecification specification;

        protected SpecificationBaseAttribute(Type specification, params object[] args)
        {
            if (args == null && !specification.HasDefaultConstructor())
                throw new ArgumentException("The specification type should have a default constructor or supply ");

            if (!typeof(ISpecification).IsAssignableFrom(specification))
                throw new ArgumentException("The specification type should implement interface ISpecification");

            this.specification = Activator.CreateInstance(specification, args) as ISpecification;
        }

        protected SpecificationBaseAttribute(Type specification) : this(specification, null)
        {
        }

        /// <summary>
        /// Gets or sets the name of the specification.
        /// </summary>
        /// <remarks>If this property is not set, the name of the specification (when available) will be used</remarks>
        /// <value>
        /// The name.
        /// </value>
        public string Name { get; set; }

        /// <summary>
        /// Gets or sets the text in case the specification is not satisfied
        /// </summary>
        /// <remarks>If this property is not set, the description of the specification (when available) will be used</remarks>
        /// <value>
        /// The not satisfied text.
        /// </value>
        public string NotSatisfiedText { get; set; }


        public string GroupName { get; set; }


        // This is a positional argument

        public ISpecification Specification
        {
            get { return this.specification; }
        }
    }

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Property | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
    public sealed class SpecificationAttribute : SpecificationBaseAttribute
    {
        public SpecificationAttribute(Type specification, params object[] args)
            : base(specification, args)
        {
        }

        public SpecificationAttribute(Type specification) : base(specification)
        {
        }
    }
}