/*-
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 *
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 *       notice, this list of conditions and the following disclaimer.
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 *       notice, this list of conditions and the following disclaimer in
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 *       from this software without specific prior written permission.
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 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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/**
 * \file
 * JSON-RPC 2.0 server implementation
 */

#ifndef SPDK_JSONRPC_H_
#define SPDK_JSONRPC_H_

#include "spdk/stdinc.h"

#include "spdk/json.h"

#ifdef __cplusplus
extern "C" {
#endif

/* Defined error codes in JSON-RPC specification 2.0 */
#define SPDK_JSONRPC_ERROR_PARSE_ERROR		-32700
#define SPDK_JSONRPC_ERROR_INVALID_REQUEST	-32600
#define SPDK_JSONRPC_ERROR_METHOD_NOT_FOUND	-32601
#define SPDK_JSONRPC_ERROR_INVALID_PARAMS	-32602
#define SPDK_JSONRPC_ERROR_INTERNAL_ERROR	-32603

/* Custom error codes in SPDK

 * Error codes from and including -32768 to -32000 are reserved for
 * predefined errors, hence custom error codes must be outside of the range.
 */
#define SPDK_JSONRPC_ERROR_INVALID_STATE	-1

struct spdk_jsonrpc_server;
struct spdk_jsonrpc_request;

struct spdk_jsonrpc_client;
struct spdk_jsonrpc_client_request;

struct spdk_jsonrpc_client_response {
	struct spdk_json_val *version;
	struct spdk_json_val *id;
	struct spdk_json_val *result;
	struct spdk_json_val *error;
};

/**
 * User callback to handle a single JSON-RPC request.
 *
 * The user should respond by calling one of spdk_jsonrpc_begin_result() or
 * spdk_jsonrpc_send_error_response().
 *
 * \param request JSON-RPC request to handle.
 * \param method Function to handle the request.
 * \param param Parameters passed to the function 'method'.
 */
typedef void (*spdk_jsonrpc_handle_request_fn)(
	struct spdk_jsonrpc_request *request,
	const struct spdk_json_val *method,
	const struct spdk_json_val *params);

struct spdk_jsonrpc_server_conn;

typedef void (*spdk_jsonrpc_conn_closed_fn)(struct spdk_jsonrpc_server_conn *conn, void *arg);

/**
 * Function for specific RPC method response parsing handlers.
 *
 * \param parser_ctx context where analysis are put.
 * \param result json values responsed to this method.
 *
 * \return 0 on success.
 *         SPDK_JSON_PARSE_INVALID on failure.
 */
typedef int (*spdk_jsonrpc_client_response_parser)(
	void *parser_ctx,
	const struct spdk_json_val *result);

/**
 * Create a JSON-RPC server listening on the required address.
 *
 * \param domain Socket family.
 * \param protocol Protocol.
 * \param listen_addr Listening address.
 * \param addrlen Length of address.
 * \param handle_request User callback to handle a JSON-RPC request.
 *
 * \return a pointer to the JSON-RPC server.
 */
struct spdk_jsonrpc_server *spdk_jsonrpc_server_listen(int domain, int protocol,
		struct sockaddr *listen_addr, socklen_t addrlen, spdk_jsonrpc_handle_request_fn handle_request);

/**
 * Poll the requests to the JSON-RPC server.
 *
 * This function does accept, receive, handle the requests and reply to them.
 *
 * \param server JSON-RPC server.
 *
 * \return 0 on success.
 */
int spdk_jsonrpc_server_poll(struct spdk_jsonrpc_server *server);

/**
 * Shutdown the JSON-RPC server.
 *
 * \param server JSON-RPC server.
 */
void spdk_jsonrpc_server_shutdown(struct spdk_jsonrpc_server *server);

/**
 * Return connection associated to \c request
 *
 * \param request JSON-RPC request
 * \return JSON RPC server connection
 */
struct spdk_jsonrpc_server_conn *spdk_jsonrpc_get_conn(struct spdk_jsonrpc_request *request);

/**
 * Add callback called when connection is closed. Pair of  \c cb and \c ctx must be unique or error is returned.
 * Registered callback is called only once and there is no need to call  \c spdk_jsonrpc_conn_del_close_cb
 * inside from \c cb.
 *
 * \note Current implementation allow only one close callback per connection.
 *
 * \param conn JSON RPC server connection
 * \param cb calback function
 * \param ctx argument for \c cb
 *
 * \return 0 on success, or negated errno code:
 *  -EEXIST \c cb and \c ctx is already registered
 *  -ENOTCONN Callback can't be added because connection is closed.
 *  -ENOSPC no more space to register callback.
 */
int spdk_jsonrpc_conn_add_close_cb(struct spdk_jsonrpc_server_conn *conn,
				   spdk_jsonrpc_conn_closed_fn cb, void *ctx);

/**
 * Remove registered close callback.
 *
 * \param conn JSON RPC server connection
 * \param cb calback function
 * \param ctx argument for \c cb
 *
 * \return 0 on success, or negated errno code:
 *  -ENOENT \c cb and \c ctx pair is not registered
 */
int spdk_jsonrpc_conn_del_close_cb(struct spdk_jsonrpc_server_conn *conn,
				   spdk_jsonrpc_conn_closed_fn cb, void *ctx);

/**
 * Begin building a response to a JSON-RPC request.
 *
 * If this function returns non-NULL, the user must call spdk_jsonrpc_end_result()
 * on the request after writing the desired response object to the spdk_json_write_ctx.
 *
 * \param request JSON-RPC request to respond to.

 * \return Non-NULL pointer to JSON write context to write the response object to.
 */
struct spdk_json_write_ctx *spdk_jsonrpc_begin_result(struct spdk_jsonrpc_request *request);

/**
 * Complete and send a JSON-RPC response.
 *
 * \param request Request to complete the response for.
 * \param w JSON write context returned from spdk_jsonrpc_begin_result().
 */
void spdk_jsonrpc_end_result(struct spdk_jsonrpc_request *request, struct spdk_json_write_ctx *w);

/**
 * Send an error response to a JSON-RPC request.
 *
 * This is shorthand for spdk_jsonrpc_begin_result() + spdk_jsonrpc_end_result()
 * with an error object.
 *
 * \param request JSON-RPC request to respond to.
 * \param error_code Integer error code to return (may be one of the
 * SPDK_JSONRPC_ERROR_ errors, or a custom error code).
 * \param msg String error message to return.
 */
void spdk_jsonrpc_send_error_response(struct spdk_jsonrpc_request *request,
				      int error_code, const char *msg);

/**
 * Send an error response to a JSON-RPC request.
 *
 * This is shorthand for printf() + spdk_jsonrpc_send_error_response().
 *
 * \param request JSON-RPC request to respond to.
 * \param error_code Integer error code to return (may be one of the
 * SPDK_JSONRPC_ERROR_ errors, or a custom error code).
 * \param fmt Printf-like format string.
 */
void spdk_jsonrpc_send_error_response_fmt(struct spdk_jsonrpc_request *request,
		int error_code, const char *fmt, ...) __attribute__((format(printf, 3, 4)));

/**
 * Begin building a JSON-RPC request.
 *
 * If this function returns non-NULL, the user must call spdk_jsonrpc_end_request()
 * on the request after writing the desired request object to the spdk_json_write_ctx.
 *
 * \param request JSON-RPC request.
 * \param id ID index for the request. If < 0 skip ID.
 * \param method Name of the RPC method. If NULL caller will have to create "method" key.
 *
 * \return JSON write context or NULL in case of error.
 */
struct spdk_json_write_ctx *
spdk_jsonrpc_begin_request(struct spdk_jsonrpc_client_request *request, int32_t id,
			   const char *method);

/**
 * Complete a JSON-RPC request.
 *
 * \param request JSON-RPC request.
 * \param w JSON write context returned from spdk_jsonrpc_begin_request().
 */
void spdk_jsonrpc_end_request(struct spdk_jsonrpc_client_request *request,
			      struct spdk_json_write_ctx *w);

/**
 * Connect to the specified RPC server.
 *
 * \param addr RPC socket address.
 * \param addr_family Protocol families of address.
 *
 * \return JSON-RPC client on success, NULL on failure and errno set to indicate
 * the cause of the error.
 */
struct spdk_jsonrpc_client *spdk_jsonrpc_client_connect(const char *addr, int addr_family);

/**
 * Close JSON-RPC connection and free \c client object.
 *
 * This function is not thread safe and should only be called from one thread at
 * a time while no other threads are actively \c client object.
 *
 * \param client JSON-RPC client.
 */
void spdk_jsonrpc_client_close(struct spdk_jsonrpc_client *client);

/**
 * Create one JSON-RPC request. Returned request must be passed to
 * \c spdk_jsonrpc_client_send_request when done or to \c spdk_jsonrpc_client_free_request
 * if discaded.
 *
 * \return pointer to JSON-RPC request object.
 */
struct spdk_jsonrpc_client_request *spdk_jsonrpc_client_create_request(void);

/**
 * Free one JSON-RPC request.
 *
 * \param req pointer to JSON-RPC request object.
 */
void spdk_jsonrpc_client_free_request(struct spdk_jsonrpc_client_request *req);

/**
 * Send the JSON-RPC request in JSON-RPC client. Library takes ownership of the
 * request object and will free it when done.
 *
 * This function is not thread safe and should only be called from one thread at
 * a time while no other threads are actively \c client object.
 *
 * \param client JSON-RPC client.
 * \param req JSON-RPC request.
 *
 * \return 0 on success or negative error code.
 * -ENOSPC - no space left to queue another request. Try again later.
 */
int spdk_jsonrpc_client_send_request(struct spdk_jsonrpc_client *client,
				     struct spdk_jsonrpc_client_request *req);

/**
 * Poll the JSON-RPC client. When any response is available use
 * \c spdk_jsonrpc_client_get_response to retrieve it.
 *
 * This function is not thread safe and should only be called from one thread at
 * a time while no other threads are actively \c client object.
 *
 * \param client JSON-RPC client.
 * \param timeout Time in miliseconds this function will block. -1 block forever, 0 don't block.
 *
 * \return If no error occurred, this function returns a non-negative number indicating how
 * many ready responses can be retrieved. If an error occurred, this function returns one of
 * the following negated errno values:
 *  -ENOTCONN - not connected yet. Try again later.
 *  -EINVAL - response is detected to be invalid. Client connection should be terminated.
 *  -ENOSPC - no space to receive another response. User need to retrieve waiting responses.
 *  -EIO - connection terminated (or other critical error). Client connection should be terminated.
 *  -ENOMEM - out of memory
 */
int spdk_jsonrpc_client_poll(struct spdk_jsonrpc_client *client, int timeout);

/**
 * Return JSON RPC response object representing next available response from client connection.
 * Returned pointer must be freed using \c spdk_jsonrpc_client_free_response
 *
 * This function is not thread safe and should only be called from one thread at
 * a time while no other threads are actively \c client object.
 *
 * \param client
 * \return pointer to JSON RPC response object or NULL if no response available.
 */
struct spdk_jsonrpc_client_response *spdk_jsonrpc_client_get_response(struct spdk_jsonrpc_client
		*client);

/**
 * Free response object obtained from \c spdk_jsonrpc_client_get_response
 *
 * \param resp pointer to JSON RPC response object. If NULL no operation is performed.
 */
void spdk_jsonrpc_client_free_response(struct spdk_jsonrpc_client_response *resp);


#ifdef __cplusplus
}
#endif

#endif
