// 
// System.Web.HttpCachePolicy
//
// Authors:
// 	Patrik Torstensson (Patrik.Torstensson@labs2.com)
// 	Tim Coleman (tim@timcoleman.com)
//	Gonzalo Paniagua Javier (gonzalo@ximian.com)
//
using System;
using System.Collections;
using System.Text;
using System.Web.UI;

namespace System.Web {
	public sealed class HttpCachePolicy {

		internal HttpCachePolicy ()
		{
		}

		#region Fields

		HttpCacheVaryByHeaders varyByHeaders = new HttpCacheVaryByHeaders ();
		HttpCacheVaryByParams varyByParams = new HttpCacheVaryByParams ();
		ArrayList validationCallbacks;
		StringBuilder cacheExtension;
		HttpCacheability cacheability;
		string etag;
		bool etagFromFileDependencies;
		bool haveExpireDate;
		DateTime expireDate;
		bool haveLastModified;
		DateTime lastModified;
		bool lastModifiedFromFileDependencies;
		bool noServerCaching;
		bool noStore;
		bool noTransforms;
		HttpCacheRevalidation revalidation;
		bool slidingSpiration;
		bool validUntilExpires;
		string varyByCustom;
		bool haveMaxAge;
		TimeSpan maxAge;
		bool haveProxyMaxAge;
		TimeSpan proxyMaxAge;
		ArrayList fields;
		bool slidingExpiration;

		#endregion

		#region Properties

		public HttpCacheVaryByHeaders VaryByHeaders {
			get { return varyByHeaders; }
		}

		public HttpCacheVaryByParams VaryByParams {
			get { return varyByParams; }
		}

		#endregion // Properties

		#region Methods

		public void AddValidationCallback (HttpCacheValidateHandler handler, object data)
		{
			if (handler == null)
				throw new ArgumentNullException ("handler");

			if (validationCallbacks == null)
				validationCallbacks = new ArrayList ();

			validationCallbacks.Add (new Pair (handler, data));
		}

		public void AppendCacheExtension (string extension)
		{
			if (extension == null)
				throw new ArgumentNullException ("extension");

			if (cacheExtension == null)
				cacheExtension = new StringBuilder (extension);
			else
				cacheExtension.Append (", " + extension);
		}

		public void SetCacheability (HttpCacheability cacheability)
		{
			if (cacheability < HttpCacheability.NoCache || cacheability > HttpCacheability.Public)
				throw new ArgumentOutOfRangeException ("cacheability");

			if (cacheability > this.cacheability)
				return;

			this.cacheability = cacheability;
		}

		public void SetCacheability (HttpCacheability cacheability, string field)
		{
			if (field == null)
				throw new ArgumentNullException ("field");

			if (cacheability != HttpCacheability.Private &&
			    cacheability != HttpCacheability.NoCache)
				throw new ArgumentException ("Must be NoCache or Private", "cacheability");

			if (fields == null)
				fields = new ArrayList ();

			fields.Add (new Pair (cacheability, field));
		}

		public void SetETag (string etag)
		{
			if (etag == null)
				throw new ArgumentNullException ("etag");

			if (this.etag != null)
				throw new InvalidOperationException ("The ETag header has already been set");

			if (etagFromFileDependencies)
				throw new InvalidOperationException ("SetEtagFromFileDependencies has already been called");

			this.etag = etag;
		}

		public void SetETagFromFileDependencies ()
		{
			if (this.etag != null)
				throw new InvalidOperationException ("The ETag header has already been set");

			etagFromFileDependencies = true;
		}

		public void SetExpires (DateTime date)
		{
			if (haveExpireDate && date > expireDate)
				return;

			haveExpireDate = true;
			expireDate = date;
		}

		public void SetLastModified (DateTime date)
		{
			if (date > DateTime.Now)
				throw new ArgumentOutOfRangeException ("date");

			if (haveLastModified && date < lastModified)
				return;

			haveLastModified = true;
			lastModified = date;
		}

		public void SetLastModifiedFromFileDependencies ()
		{
			lastModifiedFromFileDependencies = true;
		}

		public void SetMaxAge (TimeSpan date)
		{
			if (date < TimeSpan.Zero)
				throw new ArgumentOutOfRangeException ("date");

			if (haveMaxAge && maxAge < date)
				return;

			proxyMaxAge = date;
		}

		public void SetNoServerCaching ()
		{
			noServerCaching = true;
		}

		public void SetNoStore ()
		{
			noStore = true;
		}

		public void SetNoTransforms ()
		{
			noTransforms = true;
		}

		public void SetProxyMaxAge (TimeSpan delta)
		{
			if (delta < TimeSpan.Zero)
				throw new ArgumentOutOfRangeException ("delta");

			if (haveProxyMaxAge && proxyMaxAge < delta)
				return;

			proxyMaxAge = delta;
		}

		public void SetRevalidation (HttpCacheRevalidation revalidation)
		{
			if (revalidation < HttpCacheRevalidation.AllCaches ||
			    revalidation > HttpCacheRevalidation.None)
				throw new ArgumentOutOfRangeException ("revalidation");

			if (this.revalidation > revalidation)
				this.revalidation = revalidation;
		}

		public void SetSlidingExpiration (bool slide)
		{
			slidingExpiration = slide;
		}

		public void SetValidUntilExpires (bool validUntilExpires)
		{
			this.validUntilExpires = validUntilExpires;
		}

		public void SetVaryByCustom (string custom)
		{
			if (custom == null)
				throw new ArgumentNullException ("custom");

			if (varyByCustom != null)
				throw new InvalidOperationException ("VaryByCustom has already been set.");

			varyByCustom = custom;
		}

		#endregion // Methods
	}
}