#pragma once

#include <stdbool.h>
#include <pb.h>
#include <ch.h>
#include <hal.h>
#include <paatti.pb.h>

// Start handling RPC calls on the IO channel.
// Exits when a RPC function calls rpc_abort().
void rpc_server(BaseChannel *io);

/******************************************************************
 * The functions below should be called only during the execution *
 * of a function called from rpc_server.                          *
 ******************************************************************/

// The rpc_t type contains a state machine. The functions should be used
// in order, though not all calls are necessary.
//
// START -+-> rpc_receive() ---------FALSE------------------> END
//        |                `-----TRUE---,                      ^
//        |                             v                      |
//        `---> Do whatever the RPC call should do             |
//                |                       |                    |
//             SUCCESS                 FAILURE                 |
//                v                       v                    |
//            rpc_prepare() -FALSE-> rpc_error() --------------+
//                |                                            |
//              TRUE                                           |
//                v                                            |
//            rpc_respond() -----------------------------------´

typedef struct _rpc_t rpc_t;

// Decode request packet payload using nanopb.
// False means that pb_decode failed or the checksum of the packet was wrong.
// If that happens, just return. rpc_protocol_error or rpc_abort has already
// been called.
bool rpc_receive(rpc_t *rpc, void *dest);

// Compute response packet size. rpc_respond will call this automatically
// if you don't do it manually. However, by doing it manually, you can still
// recover if the pb_encode fails, as nothing has been transmitted.
// Note: only for success responses.
bool rpc_prepare(rpc_t *rpc, const void *src);

// Send response packet. Payload is encoded using nanopb.
// Pass NULL for the argument to send an empty response.
// Note: only for success responses.
// Returns false if pb_encode or write fails midway of the response.
// Cleanup and return, rpc_abort has already been called.
bool rpc_respond(rpc_t *rpc, const void *src);

// Send error response.
void rpc_error(rpc_t *rpc, const ErrorResponse *error);

// Shortcuts for sending error messages of a specific type.
void rpc_protocol_error(rpc_t *rpc, const char *message);
void rpc_resources_error(rpc_t *rpc, const char *message);

// Abort the RPC server.
// The RPC server will exit after the current request is processed.
void rpc_abort(rpc_t *rpc);