// dnlib: See LICENSE.txt for more info

using System.Collections.Generic;

namespace dnlib.DotNet {
	/// <summary>
	/// A <c>DeclSecurity</c> security attribute
	/// </summary>
	public sealed class SecurityAttribute : ICustomAttribute {
		ITypeDefOrRef attrType;
		readonly IList<CANamedArgument> namedArguments;

		/// <summary>
		/// Gets/sets the attribute type
		/// </summary>
		public ITypeDefOrRef AttributeType {
			get => attrType;
			set => attrType = value;
		}

		/// <summary>
		/// Gets the full name of the attribute type
		/// </summary>
		public string TypeFullName {
			get {
				var at = attrType;
				return at is null ? string.Empty : at.FullName;
			}
		}

		/// <summary>
		/// Gets all named arguments (field and property values)
		/// </summary>
		public IList<CANamedArgument> NamedArguments => namedArguments;

		/// <summary>
		/// <c>true</c> if <see cref="NamedArguments"/> is not empty
		/// </summary>
		public bool HasNamedArguments => namedArguments.Count > 0;

		/// <summary>
		/// Gets all <see cref="CANamedArgument"/>s that are field arguments
		/// </summary>
		public IEnumerable<CANamedArgument> Fields {
			get {
				var namedArguments = this.namedArguments;
				int count = namedArguments.Count;
				for (int i = 0; i < count; i++) {
					var namedArg = namedArguments[i];
					if (namedArg.IsField)
						yield return namedArg;
				}
			}
		}

		/// <summary>
		/// Gets all <see cref="CANamedArgument"/>s that are property arguments
		/// </summary>
		public IEnumerable<CANamedArgument> Properties {
			get {
				var namedArguments = this.namedArguments;
				int count = namedArguments.Count;
				for (int i = 0; i < count; i++) {
					var namedArg = namedArguments[i];
					if (namedArg.IsProperty)
						yield return namedArg;
				}
			}
		}

		/// <summary>
		/// Creates a <see cref="SecurityAttribute"/> from an XML string.
		/// </summary>
		/// <param name="module">Owner module</param>
		/// <param name="xml">XML</param>
		/// <returns>A new <see cref="SecurityAttribute"/> instance</returns>
		public static SecurityAttribute CreateFromXml(ModuleDef module, string xml) {
			var attrType = module.CorLibTypes.GetTypeRef("System.Security.Permissions", "PermissionSetAttribute");
			var utf8Xml = new UTF8String(xml);
			var namedArg = new CANamedArgument(false, module.CorLibTypes.String, "XML", new CAArgument(module.CorLibTypes.String, utf8Xml));
			var list = new List<CANamedArgument> { namedArg };
			return new SecurityAttribute(attrType, list);
		}

		/// <summary>
		/// Default constructor
		/// </summary>
		public SecurityAttribute()
			: this(null, null) {
		}

		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="attrType">Attribute type</param>
		public SecurityAttribute(ITypeDefOrRef attrType)
			: this(attrType, null) {
		}

		/// <summary>
		/// Constructor
		/// </summary>
		/// <param name="attrType">Attribute type</param>
		/// <param name="namedArguments">Named arguments that will be owned by this instance</param>
		public SecurityAttribute(ITypeDefOrRef attrType, IList<CANamedArgument> namedArguments) {
			this.attrType = attrType;
			this.namedArguments = namedArguments ?? new List<CANamedArgument>();
		}

		/// <inheritdoc/>
		public override string ToString() => TypeFullName;
	}
}