#include "math_functions.h"

#include <math.h>
#include <errno.h>

#define MAKE_FUNCTION_1_ARG(name) \
    static enum eval_result mf_##name(double *y, const double *args) { \
        errno = 0; \
        *y = name(args[0]); \
        if (errno) \
            return EVAL_ERROR; \
        return EVAL_OK; \
    }

MAKE_FUNCTION_1_ARG(fabs)
MAKE_FUNCTION_1_ARG(exp)
MAKE_FUNCTION_1_ARG(log)
MAKE_FUNCTION_1_ARG(log10)
MAKE_FUNCTION_1_ARG(sin)
MAKE_FUNCTION_1_ARG(cos)
MAKE_FUNCTION_1_ARG(tan)
MAKE_FUNCTION_1_ARG(asin)
MAKE_FUNCTION_1_ARG(acos)
MAKE_FUNCTION_1_ARG(atan)
MAKE_FUNCTION_1_ARG(sinh)
MAKE_FUNCTION_1_ARG(cosh)
MAKE_FUNCTION_1_ARG(tanh)
MAKE_FUNCTION_1_ARG(floor)
MAKE_FUNCTION_1_ARG(ceil)

static double mf_sgn(double *y, const double *args) {
    if (args[0] < 0.0)
        *y = -1.0;
    else if (args[0] > 0.0)
        *y = 1.0;
    else
        *y = 0.0;

    return EVAL_OK;
}

static double mf_min(double *y, const double *args) {
    if (args[0] < args[1])
        *y = args[0];
    else
        *y = args[1];

    return EVAL_OK;
}

static double mf_max(double *y, const double *args) {
    if (args[0] > args[1])
        *y = args[0];
    else
        *y = args[1];

    return EVAL_OK;
}

static double mf_mod(double *y, const double *args) {
    errno = 0;
    *y = fmod(args[0], args[1]);

    if (errno)
        return EVAL_ERROR;
    
    return EVAL_OK;
}

const struct math_function *fns_get(void) {
    static const struct math_function fns[] = {
        { "abs",    1,  mf_fabs     },
        { "exp",    1,  mf_exp      },
        { "ln",     1,  mf_log      },
        { "log",    1,  mf_log10    },
        { "sin",    1,  mf_sin      },
        { "cos",    1,  mf_cos      },
        { "tan",    1,  mf_tan      },
        { "asin",   1,  mf_asin     },
        { "acos",   1,  mf_acos     },
        { "atan",   1,  mf_atan     },
        { "sinh",   1,  mf_sinh     },
        { "cosh",   1,  mf_cosh     },
        { "tanh",   1,  mf_tanh     },
        { "min",    2,  mf_min      },
        { "max",    2,  mf_max      },
        { "mod",    2,  mf_mod      },
        { "sgn",    1,  mf_sgn      },
        { "floor",  1,  mf_floor    },
        { "ceil",   1,  mf_ceil     },
        { NULL }
    };

    return fns;
}