using System;
using System.Linq;

namespace RestSharp
{
	/// <summary>
	/// Base class for OAuth 2 Authenticators.
	/// </summary>
	/// <remarks>
	/// Since there are many ways to authenticate in OAuth2,
	/// this is used as a base class to differentiate between 
	/// other authenticators.
	/// 
	/// Any other OAuth2 authenticators must derive from this
	/// abstract class.
	/// </remarks>
	public abstract class OAuth2Authenticator : IAuthenticator
	{
	    /// <summary>
        /// Access token to be used when authenticating.
	    /// </summary>
	    private readonly string _accessToken;

	    /// <summary>
	    /// Initializes a new instance of the <see cref="OAuth2Authenticator"/> class.
	    /// </summary>
	    /// <param name="accessToken">
	    /// The access token.
	    /// </param>
	    public OAuth2Authenticator(string accessToken)
        {
            _accessToken = accessToken;
        }

	    /// <summary>
	    /// Gets the access token.
	    /// </summary>
	    public string AccessToken
        {
            get { return _accessToken; }
        }

        public abstract void Authenticate(RestClient client, RestRequest request);
	}

	/// <summary>
	/// The OAuth 2 authenticator using URI query parameter.
	/// </summary>
	/// <remarks>
	/// Based on http://tools.ietf.org/html/draft-ietf-oauth-v2-10#section-5.1.2
	/// </remarks>
	public class OAuth2UriQueryParameterAuthenticator : OAuth2Authenticator
	{
		/// <summary>
		/// Initializes a new instance of the <see cref="OAuth2UriQueryParameterAuthenticator"/> class.
		/// </summary>
		/// <param name="accessToken">
		/// The access token.
		/// </param>
		public OAuth2UriQueryParameterAuthenticator(string accessToken)
            : base(accessToken)
		{
		}

        public override void Authenticate(RestClient client, RestRequest request)
		{
			request.AddParameter("oauth_token", AccessToken, ParameterType.GetOrPost);
		}
	}

    /// <summary>
    /// The OAuth 2 authenticator using the authorization request header field.
    /// </summary>
    /// <remarks>
    /// Based on http://tools.ietf.org/html/draft-ietf-oauth-v2-10#section-5.1.1
    /// </remarks>
    public class OAuth2AuthorizationRequestHeaderAuthenticator : OAuth2Authenticator
    {
        /// <summary>
        /// Stores the Authoriztion header value as "OAuth accessToken". used for performance.
        /// </summary>
        private readonly string _authorizationValue;

        /// <summary>
        /// Initializes a new instance of the <see cref="OAuth2AuthorizationRequestHeaderAuthenticator"/> class.
        /// </summary>
        /// <param name="accessToken">
        /// The access token.
        /// </param>
        public OAuth2AuthorizationRequestHeaderAuthenticator(string accessToken)
            : base(accessToken)
        {
            // Conatenate during constructor so that it is only done once. can improve performance.
            _authorizationValue = "OAuth " + accessToken;
        }

        public override void Authenticate(RestClient client, RestRequest request)
        {
            // only add the Authorization parameter if it hasn't been added.
            if (!request.Parameters.Any(p => p.Name.Equals("Authorization", StringComparison.InvariantCultureIgnoreCase)))
            {
                request.AddParameter("Authorization", _authorizationValue, ParameterType.HttpHeader);
            }
        }
    }
}