/* file   : evalExp.c */
/* author : Harmen de Weerd (harmen.de.weerd@rug.nl) */

/* Description:
 * Implementation of evaluation of simple 
 * calculation expressions.
 *
 * Note that this implementation explicitly depends 
 * on the implementation of recognition of expressions.
 */

#include "scanner.h"
#include "scannerStructs.h"

#include "evalExp.h"
#include "recognizeEq.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

int valueNumber(List **list, double *value) {
	if (*list != NULL && (*list)->type == NUMBER) {
		*value = ((*list)->token).number;
		*list = (*list)->next;
		return 1;
	}
	return 0;
}

/*int valueTerm(List **list, double *value) {
	double operandValue ;
	while (* list != NULL ) {
		if ( acceptSymbol ( ’* ’ , list ) ) {
			if ( valueNumber ( list , & operandValue ) ) {
				* value *= operandValue ;
			} else {
				return 0;
			}
		} else if ( acceptSymbol ( ’/ ’ , list ) ) {
			if ( valueFactor ( list , & operandValue ) ) {
				* value /= operandValue ;
			} else {
				return 0;
			}
		} else {
			return 1;
		}
	}
	return 1;
}*/

int valueTerm(List **list, double *numbersValue, double *coefValue, int *ok) { 
	double operandValue;
	if(valueNumber(list, &operandValue)) {
		if(acceptIdentifier(list)) {
			*ok = 1;
			*coefValue = operandValue;
			//*list = (*list)->next; ///next
			return 1;
		}
		*numbersValue = operandValue;
		*ok = 0;
		//*list = (*list)->next; ///next
		return 1;
	} else if(acceptIdentifier(list)) {
		*coefValue = 1;
		*ok = 1;
		//*list = (*list)->next; ///next
		return 1;
		}

	return 0;
}

int valueExpression(List **list, double *numbersValue, double *coefValue) {
	//printf("in expression function\n");
	double nValue, cValue;
	int ok = -1;
	if (acceptSymbol('-',list)) {
		if (valueTerm(list, &nValue, &cValue, &ok)){
			if (ok==0) {
				*numbersValue = *numbersValue - nValue;
			} else {
				*coefValue = *coefValue - cValue;
			}
			*list = (*list)->next; ///next
			while(*list != NULL) {
				
				//printf("inwhile1\n");
				if(acceptSymbol('+', list)) {
					if(valueTerm(list, &nValue, &cValue, &ok)) {
						if (ok==0) {
							*numbersValue += nValue;
						} else {
							*coefValue += cValue;
						}
					} 
				} else if (acceptSymbol('-',list)) {
					if(valueTerm(list, &nValue, &cValue, &ok)) {
						if (ok==0) {
							*numbersValue -= nValue;
						} else {
							*coefValue -= cValue;
						}
					}
				} else return 1;
				*list = (*list)->next;
				/*if(*list != NULL && (*list)->type == SYMBOL && ((*list)->token).symbol == '=' )  {
						printf("outofwhile\n");
						return 1;
					}*/
				
			}
		} 
	} else if(valueTerm(list, &nValue, &cValue, &ok)) {
		//printf("startswterm\n");
				if (ok==0) {
					*numbersValue -= nValue;
				} else {
					*coefValue -= cValue;
				}
				while(*list != NULL) {
					
					//printf("inwhile2\n");
					if(acceptSymbol('+', list)) {
						if(valueTerm(list, &nValue, &cValue, &ok)) {
							if (ok==0) {
								*numbersValue += nValue;
							} else {
								*coefValue += cValue;
							}
						} 
					} else if (acceptSymbol('-',list)) {
						if(valueTerm(list, &nValue, &cValue, &ok)) {
							if (ok==0) {
								*numbersValue -= nValue;
							} else {
								*coefValue -= cValue;
							}
						} 
					} else return 1;
				*list = (*list)->next;
				/*if(*list != NULL && (*list)->type == SYMBOL && ((*list)->token).symbol == '=' )  {
						printf("outofwhile\n");
						return 1;
					}*/
			}
	}
return 1;
}

int solution(List *list) {
	double sol, numbersValue1 = 0, coefValue1 = 0, numbersValue2 = 0, coefValue2 = 0;

	if(valueExpression(&list, &numbersValue1, &coefValue1)) {
		printf("exp1\n");
		printf("numbersValue1: %f\ncoefValue1: %f\n",numbersValue1, coefValue1);
		if(acceptSymbol('=',&list)) {
			printf("equal\n");
			if(valueExpression(&list, &numbersValue2, &coefValue2)) {
				printf("exp2\n");
				printf("numbersValue2: %f\ncoefValue2: %f\n",numbersValue2, coefValue2);				
				sol = (numbersValue2 - numbersValue1)/(coefValue1 - coefValue2); 
				printf("solution: %f\n",sol);
			}
		}
	}
	if(sol > -0.0005 && sol < 0) sol=0;
	return sol;
}