#ifndef __OPKELE_OAUTH_CONSUMER_H
#define __OPKELE_OAUTH_CONSUMER_H

#include <string>
#include <opkele/types.h>
#include <opkele/oauth.h>
#include <opkele/curl.h>

namespace opkele {
    /**
     * @brief OAuth support namespace
     */
    namespace oauth {
	using std::string;

	/**
	 * oauth parameter passing method
	 */
	enum oauth_method_t {
	    /**
	     * via WWW-Authenticate header
	     */
	    oauth_auth_header,
	    /**
	     * via POST body
	     */
	    oauth_post_body,
	    /**
	     * via GET query string
	     */
	    oauth_url_query,
	    /**
	     * default method
	     */
	    oauth_method_default = oauth_auth_header
	};

	/**
	 * Service endpoint description
	 */
	struct service_endpoint_t {
	    /**
	     * endpoint URI
	     */
	    string url;
	    /**
	     * signature method
	     */
	    string signature_method;
	    /**
	     * OAuth parameter passing method
	     */
	    oauth_method_t oauth_method;

	    service_endpoint_t() : oauth_method(oauth_method_default) { }
	    /**
	     * @param u endpoint URI
	     * @param sm signature method
	     * @param om OAuth parameter passing method
	     */
	    service_endpoint_t(const string& u,const string& sm,oauth_method_t om=oauth_method_default)
		: url(u), signature_method(sm), oauth_method(om) { }
	};

	/**
	 * Base class for OAuth provider endpoints description
	 */
	class basic_provider_endpoints {
	    public:

		virtual ~basic_provider_endpoints() { }

		/**
		 * Retrieve endpoint for obtaining an unauthorized request token
		 * @return service endpoint description
		 */
		virtual const service_endpoint_t& get_request_token_endpoint() const = 0;
		/**
		 * Retrieve endpoint for user authorization
		 * @return service endpoint description
		 */
		virtual const service_endpoint_t& get_authorize_user_endpoint() const = 0;
		/**
		 * Retrieve endpoint for obtaining an access token from the
		 * authorized request token
		 * @return service endpoint description
		 */
		virtual const service_endpoint_t& get_access_token_endpoint() const = 0;

		/**
		 * Make up an endpoint description give an URI
		 * @param sep reference to the service endpoint description object to fill in
		 * @param url endpoint URL
		 * @return reference to sep
		 */
		virtual service_endpoint_t& get_url_endpoint(service_endpoint_t& sep,
			const string& url) const = 0;
	};

	/**
	 * HTTP request information
	 */
	struct http_request_t {
	    /**
	     * WWW-Authenticate header
	     */
	    string authorize_header;
	    /**
	     * HTTP method
	     */
	    string method;
	    /**
	     * Target URL
	     */
	    string url;
	    /**
	     * POST body
	     */
	    string body;

	    /**
	     * curl-ready headers
	     */
	    util::curl_slist_t _curl_headers_list;

	    /**
	     * @param m HTTP method
	     * @param u target URL
	     */
	    http_request_t(const string& m,const string& u)
		: method(m), url(u) { }

	    /**
	     * Set relevant curl handle options
	     */
	    void setup_curl(CURL *curl);
	};

	/**
	 * OAuth consumer base class
	 */
	class basic_consumer {
	    public:
		/**
		 * Consumer token
		 */
		token_t consumer_token;

		/**
		 * @param ct consumer token
		 */
		basic_consumer(const token_t& ct)
		    : consumer_token(ct) { }
		virtual ~basic_consumer() { }

		/**
		 * Retrieve reference to the provider endpoints description object
		 * @return reference to the provider endpoints description object
		 */
		virtual const basic_provider_endpoints& get_endpoints() const = 0;
		/**
		 * Allocate nonce
		 * @param ts request timestamp
		 * @return nonce string
		 */
		virtual const string allocate_nonce(time_t ts) = 0;

		/**
		 * Obtain an unauthorized request token
		 * @return request token
		 */
		token_t get_request_token();
		/**
		 * Retrieve the user authorization URL
		 * @param rt unauthorized request token
		 * @param callback callback URL to be passed to oauth provider
		 * to redirect user to upon authorization
		 * @return user authorization URL
		 */
		const string get_authorize_url(const token_t& rt,const string& callback="");
		/**
		 * Trade an authorized request token for an access token
		 * @param rt authorized request token
		 * @return access token
		 */
		token_t get_access_token(const token_t& rt);

		/**
		 * Prepare http request parameters
		 * @param req request description to fill in
		 * @param qf query string parameters
		 * @param pf post body parameters
		 * @param om OAuth method
		 * @param sm signature method
		 * @param t pointer to the token to use to sign request, if any.
		 * @param realm authorization realm
		 * @return reference to req
		 */
		http_request_t& prepare_request(
			http_request_t& req,
			const basic_fields& qf,const basic_fields& pf,
			oauth_method_t om,const string& sm,
			const token_t *t=0,const string& realm="");
		/**
		 * Prepare http request parameters
		 * @param req request description to fill in
		 * @param qf query string parameters
		 * @param pf post body parameters
		 * @param sep service endpoint description
		 * @param t pointer to the token to use to sign request, if any.
		 * @param realm authorization realm
		 * @return reference to req
		 */
		http_request_t& prepare_request(
			http_request_t& req,
			const basic_fields& qf,const basic_fields& pf,
			const service_endpoint_t& sep,
			const token_t *t=0,const string& realm="");
		/**
		 * Prepare http request parameters
		 * @param req request description to fill in
		 * @param qf query string parameters
		 * @param pf post body parameters
		 * @param t pointer to the token to use to sign request, if any.
		 * @param realm authorization realm
		 * @return reference to req
		 */
		http_request_t& prepare_request(
			http_request_t& req,
			const basic_fields& qf,const basic_fields& pf,
			const token_t *t=0,const string& realm="");

		/**
		 * Calculate request signature
		 * @param method http method
		 * @param url the url being invoked
		 * @param fields all request fields (query string, auth header,
		 * post body)
		 * @param rt pointer to the request token to be used for
		 * signing, if any.
		 */
		const string signature(
			const string& method,
			const string& url,
			const basic_fields& fields,
			const token_t* rt=0);

		/**
		 * Acquire token from an OAuth provider
		 * @param sep service endpoint description
		 * @param rt pointer to the request token to use for signing,
		 * if any
		 * @return the acquired token
		 */
		token_t acquire_token(
			const service_endpoint_t& sep,
			const token_t* rt=0);
	};

	class simple_provider_endpoints : public basic_provider_endpoints {
	    public:
		service_endpoint_t sep_request_token;
		service_endpoint_t sep_authorize_user;
		service_endpoint_t sep_access_token;
		service_endpoint_t sep_generic;

		/**
		 * @param rt request token endpoint URL
		 * @param au user authorization endpoint URL
		 * @param at access token endpoint URL
		 * @param sm signature method
		 * @param ams authentication method for service endpoints
		 * @param amr authentication method for resource access
		 */
		simple_provider_endpoints(
			const string& rt,const string& au,const string& at,
			const string& sm,
			oauth_method_t ams=oauth_post_body,
			oauth_method_t amr=oauth_auth_header )
		    : sep_request_token(rt,sm,ams),
		    sep_authorize_user(au,sm,oauth_url_query),
		    sep_access_token(at,sm,ams),
		    sep_generic("",sm,amr) { }

		const service_endpoint_t& get_request_token_endpoint() const;
		const service_endpoint_t& get_authorize_user_endpoint() const;
		const service_endpoint_t& get_access_token_endpoint() const;
		service_endpoint_t& get_url_endpoint(service_endpoint_t& sep,
			const string& url) const;
	};

	class simple_consumer : public basic_consumer {
	    public:
		simple_provider_endpoints peps;

		/**
		 * @param eps provider endpoints
		 * @param ct consumer token
		 * @see simple_provider_endpoints
		 * @see token_t
		 */
		simple_consumer(const simple_provider_endpoints& eps,
			const token_t& ct)
		    : basic_consumer(ct), peps(eps) { }

		const basic_provider_endpoints& get_endpoints() const;
		const string allocate_nonce(time_t ts);
	};

    }
}

#endif /* __OPKELE_OAUTH_CONSUMER_H */