//      calculadoraNumerosRomanos.c
//
//      Copyright 2011 marcelo moran <marcelo@marcelo-laptop>
//
//      This program is free software; you can redistribute it and/or modify
//      it under the terms of the GNU General Public License as published by
//      the Free Software Foundation; either version 2 of the License, or
//      (at your option) any later version.
//
//      This program is distributed in the hope that it will be useful,
//      but WITHOUT ANY WARRANTY; without even the implied warranty of
//      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//      GNU General Public License for more details.
//
//      You should have received a copy of the GNU General Public License
//      along with this program; if not, write to the Free Software
//      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
//      MA 02110-1301, USA.


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX 20

int romanoAdecimal( char romano[ ] );
int calculadora( int dec1, int dec2, char operador );
void mensaje( void );

int main(int argc, char **argv)
{
    char num1[ MAX ];
    char num2[ MAX ];

    int dec1, dec2;
    char operador;

    mensaje( );

    printf( "Ingrese el primer numero romano: " );
    fgets( num1, strlen( num1 ), stdin );

    dec1 = romanoAdecimal( num1 );

    printf( "Ingrese el operador: " );
    scanf( "%c", &operador );

    getchar();

    printf( "Ingrese el segundo numero romano: " );
    fgets( num2, strlen( num2 ), stdin );
    dec2 = romanoAdecimal( num2 );

    printf( "\nEl resultado es: %d %c %d = %d\n",dec1, operador, dec2, calculadora( dec1, dec2, operador ) );

    return 0;
}

int romanoAdecimal( char romano[ ] ){
    int i; //contador for loop
    int decimal = 0; //resultado
    int ultimoValor = 0;//ultima suma realizada

    if( strlen( romano ) == 0  ){ return 0; }

    char caracter;//el caracter que se esta analizando
    int valor;//valor del caracter en decimal

    char simbolos[  ] = "MDCLXVI";
    int valores[  ] = { 1000, 500, 100, 50, 10, 5, 1 };
    int indice;// indice del elemento del array valores que queremos sumar

    for( i = 0; i < strlen( romano )-1; i++ ){
        caracter = romano[ i ]; //guardamos el caracter actual

        int j;//contador for loop
        for( j = 0; j < strlen( simbolos ); j++ ){ // obtenemos el indice del simbolo( caracter )
            if( caracter == simbolos[ j ] ){
                indice = j;
                break;
                }
            }
        valor = valores[ indice ];

        if( indice >= 0 ){
            decimal += valor;

            if( valores[ indice ] > ultimoValor ){
                decimal -= 2 * ultimoValor;
                }

            ultimoValor = valores[ indice ];
            }

        }
    return decimal;
    }

int calculadora( int dec1, int dec2, char operador ){

    switch( operador ){
        case '+':
            return dec1 + dec2;
        break;

        case '-':
            return dec1 - dec2;
        break;

        case '*':
            return dec1 * dec2;
        break;

        case '/':
            if( dec2 != 0 ){
                return dec1 / dec2;
                }else{
                    printf( "\nERROR. Division entre cero\n" );
                    exit( -1 );
                    }
        break;

        case '%':
            if( dec2 != 0 ){
                return dec1 % dec2;
                }else{
                    printf( "\nERROR. Division entre cero\n" );
                    exit( -1 );
                    }
        break;

        default:
            return 0;
        break;
        }
    }

void mensaje( void ){
    printf( "\t\tCALCULADORA DE NUMEROS ROMANOS\nAsegurese de ingresar correctamente los numeros romanos.\n"
            "La calculadora asume que los operandos estan correctamente escritos.\n\n" );
    }