CookieJar.cs

using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Flurl.Util;

namespace Flurl.Http
{
	/// <summary>
	/// A collection of FlurlCookies that can be attached to one or more FlurlRequests, either explicitly via WithCookies
	/// or implicitly via a CookieSession. Stores cookies received via Set-Cookie response headers.
	/// </summary>
	public class CookieJar : IReadOnlyCollection<FlurlCookie>
	{
		private readonly ConcurrentDictionary<string, FlurlCookie> _dict = new ConcurrentDictionary<string, FlurlCookie>();

		/// <summary>
		/// Adds a cookie to the jar or replaces one with the same Name/Domain/Path.
		/// Throws InvalidCookieException if cookie is invalid.
		/// </summary>
		/// <param name="name">Name of the cookie.</param>
		/// <param name="value">Value of the cookie.</param>
		/// <param name="originUrl">URL of request that sent the original Set-Cookie header.</param>
		/// <param name="dateReceived">Date/time that original Set-Cookie header was received. Defaults to current date/time. Important for Max-Age to be enforced correctly.</param>
		public CookieJar AddOrReplace(string name, object value, string originUrl, DateTimeOffset? dateReceived = null) =>
			AddOrReplace(new FlurlCookie(name, value.ToInvariantString(), originUrl, dateReceived));

		/// <summary>
		/// Adds a cookie to the jar or replaces one with the same Name/Domain/Path.
		/// Throws InvalidCookieException if cookie is invalid.
		/// </summary>
		public CookieJar AddOrReplace(FlurlCookie cookie) {
			if (!TryAddOrReplace(cookie, out var reason))
				throw new InvalidCookieException(reason);

			return this;
		}

		/// <summary>
		/// Adds a cookie to the jar or updates if one with the same Name/Domain/Path already exists,
		/// but only if it is valid and not expired.
		/// </summary>
		/// <returns>true if cookie is valid and was added or updated. If false, provides descriptive reason.</returns>
		public bool TryAddOrReplace(FlurlCookie cookie, out string reason) {
			if (!cookie.IsValid(out reason))
				return false;

			if (cookie.IsExpired(out reason)) {
				// when server sends an expired cookie, it's effectively an instruction for client to delete it.
				// https://stackoverflow.com/a/53573622/62600
				_dict.TryRemove(cookie.GetKey(), out _);
				return false;
			}

			cookie.Lock(); // makes immutable
			_dict[cookie.GetKey()] = cookie;

			return true;
		}

		/// <summary>
		/// Removes all cookies matching the given predicate.
		/// </summary>
		public CookieJar Remove(Func<FlurlCookie, bool> predicate) {
			var keys = _dict.Where(kv => predicate(kv.Value)).Select(kv => kv.Key).ToList();
			foreach (var key in keys)
				_dict.TryRemove(key, out _);
			return this;
		}

		/// <summary>
		/// Removes all cookies from this CookieJar
		/// </summary>
		public CookieJar Clear() {
			_dict.Clear();
			return this;
		}

		/// <summary>
		/// Writes this CookieJar to a TextWriter. Useful for persisting to a file.
		/// </summary>
		public void WriteTo(TextWriter writer) {
			foreach (var cookie in _dict.Values)
				cookie.WriteTo(writer);
		}

		/// <summary>
		/// Instantiates a CookieJar that was previously persisted using WriteTo.
		/// </summary>
		public static CookieJar LoadFrom(TextReader reader) {
			if (reader == null) return null;
			var jar = new CookieJar();
			while (reader.Peek() >= 0) {
				var cookie = FlurlCookie.LoadFrom(reader);
				if (cookie != null)
					jar.AddOrReplace(cookie);
			}
			return jar;
		}

		/// <summary>
		/// Returns a string representing this CookieJar.
		/// </summary>
		public override string ToString() {
			var writer = new StringWriter();
			WriteTo(writer);
			return writer.ToString();
		}

		/// <summary>
		/// Instantiates a CookieJar that was previously persisted using ToString.
		/// </summary>
		public static CookieJar LoadFromString(string s) => LoadFrom(new StringReader(s));

		/// <inheritdoc/>
		public IEnumerator<FlurlCookie> GetEnumerator() => _dict.Values.GetEnumerator();

		/// <inheritdoc/>
		IEnumerator IEnumerable.GetEnumerator() => _dict.GetEnumerator();

		/// <inheritdoc/>
		public int Count => _dict.Count;
	}

	/// <summary>
	/// Exception thrown when attempting to add or update an invalid FlurlCookie to a CookieJar.
	/// </summary>
	public class InvalidCookieException : Exception
	{
		/// <summary>
		/// Creates a new InvalidCookieException.
		/// </summary>
		public InvalidCookieException(string reason) : base(reason) { }
	}
}