// R API is C
#include <R.h>
#include <Rinternals.h>
#include <R_ext/Rdynload.h>

// an array of pointers to the actual functions
// in the native GC code -- these are initialised
// once the shared library has been loaded via
// a call to initialiseFunctions()
//
// for this test we only have one function
// GC.display() to make sure the concept works
static SEXP (*fn[6])();

// if we haven't been initialised don't even try
// to dereference the function pointers !!
static int initialised = 0;

// stub methods, call the GC routines if they've been initialised
SEXP GCdisplay() { if (initialised) return fn[0](); else return NULL; }
SEXP GCathlete() { if (initialised) return fn[1](); else return NULL; }
SEXP GCathleteHome() { if (initialised) return fn[2](); else return NULL; }
SEXP GCactivities() { if (initialised) return fn[3](); else return NULL; }
SEXP GCactivity() { if (initialised) return fn[4](); else return NULL; }
SEXP GCmetrics() { if (initialised) return fn[5](); else return NULL; }

SEXP GCinitialiseFunctions(SEXP (*functions[1])())
{
    //fprintf(stderr, "RGoldenCheetah initialise functions\n");

    // initialise all the function pointers
    for(int i=0; i<6; i++) fn[i] = functions[i];
    initialised = 1;

    return 0;
}

// this function is called by R when the dynamic library
// is loaded via the R command > dyn.load("RGoldenCheetah.so")
// and is expected to register all the C functions to make
// available via the C interface
//
// By return, a number of functions will be created that provide
// wrappers in R (i.e. they call with the .C(xxx) notation and
//
// We so this to avoid using Rcpp / RInside which are not
// compatible with MSVC
void
R_init_RGoldenCheetah(DllInfo *info)
{
    //fprintf(stderr, "RGoldenCheetah init is called!\n");

    // initialise the parameter table
    R_CMethodDef cMethods[] = {
        { "GCinitialiseFunctions", (DL_FUNC) &GCinitialiseFunctions, 0 },
        { "GC.display", (DL_FUNC) &GCdisplay, 0 },
        { "GC.athlete", (DL_FUNC) &GCathlete, 0 },
        { "GC.athlete.home", (DL_FUNC) &GCathleteHome, 0 },
        { "GC.activities", (DL_FUNC) &GCactivities, 0 },
        { "GC.activity", (DL_FUNC) &GCactivity, 0 },
        { "GC.metrics", (DL_FUNC) &GCmetrics, 0 },
        { NULL, NULL, 0 }
    };
    R_CallMethodDef callMethods[] = {
        { "GCinitialiseFunctions", (DL_FUNC) &GCinitialiseFunctions, 0 },
        { "GC.display", (DL_FUNC) &GCdisplay, 0 },
        { "GC.athlete", (DL_FUNC) &GCathlete, 0 },
        { "GC.athlete.home", (DL_FUNC) &GCathleteHome, 0 },
        { "GC.activities", (DL_FUNC) &GCactivities, 0 },
        { "GC.activity", (DL_FUNC) &GCactivity, 0 },
        { "GC.metrics", (DL_FUNC) &GCmetrics, 0 },
        { NULL, NULL, 0 }
    };

    // set them up
    R_registerRoutines(info, cMethods, callMethods, NULL, NULL);

    // make the initialiseFunctions callable from C
    R_RegisterCCallable("RGoldenCheetah", "GCinitialiseFunctions", (DL_FUNC)&GCinitialiseFunctions);
}