/**
 * peano.c
 *
 * Basic peano arithmetic
 *
 * (c) 2017 Simon Brooke <simon@journeyman.cc>
 * Licensed under GPL version 2.0, or, at your option, any later version.
 */

#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "consspaceobject.h"
#include "conspage.h"
#include "equal.h"
#include "integer.h"
#include "intern.h"
#include "lispops.h"
#include "print.h"
#include "read.h"
#include "real.h"
#include "stack.h"

/**
 * Add an indefinite number of numbers together
 * @param env the evaluation environment - ignored;
 * @param frame the stack frame.
 * @return a pointer to an integer or real.
 */
struct cons_pointer
lisp_plus(struct stack_frame *frame, struct cons_pointer env) {
    struct cons_pointer result = NIL;
    long int i_accumulator = 0;
    long double d_accumulator = 0;
    bool is_int = true;
    
    for (int i = 0; i < args_in_frame && !nilp(frame->arg[i]); i++) {
        struct cons_space_object arg = pointer2cell(frame->arg[i]);
        
        switch (arg.tag.value) {
        case INTEGERTV:
            i_accumulator += arg.payload.integer.value;
            d_accumulator += numeric_value( frame->arg[i]);
            break;
        case REALTV:
            d_accumulator += arg.payload.real.value;
            is_int = false;
        default:
            lisp_throw(
                    c_string_to_lisp_string("Cannot add: not a number"), 
                                            frame);
        }
        
        if (! nilp(frame->more)) {
            lisp_throw(
                    c_string_to_lisp_string("Cannot yet add more than 8 numbers"), 
                                            frame);
        }

        if ( is_int) {
            result = make_integer( i_accumulator);
        } else {
            result = make_real( d_accumulator);
        }
    }
    
    return result;    
}