/****************************************************************************
 **
 **  Copyright (C) 2013 Valentina project All Rights Reserved.
 **
 **  This file is part of Valentina.
 **
 **  Tox 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 3 of the License, or
 **  (at your option) any later version.
 **
 **  Tox 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 Valentina.  If not, see <http://www.gnu.org/licenses/>.
 **
 ****************************************************************************/

#include "calculator.h"
#include <QDebug>

#define DELIMITER  1
#define VARIABLE   2
#define NUMBER     3
#define COMMAND    4
#define STRING     5
#define QUOTE      6
#define FINISHED   10
#define EOL        9

Calculator::Calculator(const VContainer *data):errorMsg(0), token(QString()), tok(0), token_type(0),
    prog(QString()), index(0), data(data), debugFormula(QString()){
}

qreal Calculator::eval(QString prog, QString *errorMsg){
    this->errorMsg = errorMsg;
    this->errorMsg->clear();
    debugFormula.clear();
    this->prog = prog;
    //qDebug()<<"Formula: "<<prog;
    index = 0;
    qreal result = get_exp();
    QString str = QString(" = %1").arg(result, 0, 'f', 3);
    debugFormula.append(str);
    //qDebug()<<"Result:"<<debugFormula;
    return result;
}

qreal Calculator::get_exp(){
    qreal result = 0;
    get_token();
    if(token.isEmpty()) {
        serror(2);
        return 0;
    }
    level2(&result);
    putback();
    return result;
}

void Calculator::level2(qreal *result){
    QChar op;
    qreal hold;

    level3(result);
    while((op=token[0]) == '+' || op == '-') {
        get_token();
        level3(&hold);
        arith(op,result,&hold);
    }
}

void Calculator::level3(qreal *result){
    QChar op;
    qreal hold;

    level4(result);

    while((op = token[0]) == '*' || op == '/' || op == '%') {
        get_token();
        level4(&hold);
        arith(op,result,&hold);
    }
}

void Calculator::level4(qreal *result){
    qreal hold;

    level5(result);
    if(token[0] == '^') {
        get_token();
        level4(&hold);
        arith('^', result, &hold);
    }
}

void Calculator::level5(qreal *result){
    QChar op;

    op = '\0';
    if((token_type==DELIMITER) && (token[0]=='+' || token[0]=='-')) {
        op = token[0];
        get_token();
    }
    level6(result);
    if(op != '\0')
        unary(op, result);
}

void Calculator::level6(qreal *result){
    if((token[0] == '(') && (token_type == DELIMITER)) {
        get_token();
        level2(result);
        if(token[0] != ')')
            serror(1);
        get_token();
    } else
        primitive(result);
}

void Calculator::primitive(qreal *result){
    QString str;
    switch(token_type) {
        case VARIABLE:
            *result = find_var(token);
            str = QString("%1").arg(*result, 0, 'f', 3);
            debugFormula.append(str);
            get_token();
            return;
        case NUMBER:
            *result  = token.toDouble();
            str = QString("%1").arg(*result, 0, 'f', 3);
            debugFormula.append(str);
            get_token();
            return;
        default:
            serror(0);
    }
}

void Calculator::arith(QChar o, qreal *r, qreal *h){
    qreal  t;

    switch(o.toLatin1()) {
        case '-':
            *r = *r-*h;
            break;
        case '+':
            *r = *r+*h;
            break;
        case '*':
            *r = *r * *h;
            break;
        case '/':
            *r = (*r)/(*h);
            break;
        case '%':
            t = (*r)/(*h);
            *r = *r-(t*(*h));
            break;
        case '^':
            *r = pow(*r, *h);
            break;    
      }
}

void Calculator::unary(QChar o, qreal *r){
    if(o=='-')
        *r = -(*r);
}

qreal Calculator::find_var(QString s){
    bool ok = false;
    qreal value = data->FindVar(s, &ok);
    if(!ok){
        qDebug()<<s;
        serror(4); /* don't variable */
        return 0;
    }
    return value;
}

void Calculator::serror(qint32 error){
    QString e[]= {
                 tr("Syntax error"),
                 tr("Parentheses do not match"),
                 tr("This is not an expression"),
                 tr("It is assumed the equality symbol"),
                 tr("Do not variable")
     };
    errorMsg->clear();
    *errorMsg = e[error];
    qDebug()<<e[error];
}

char Calculator::look_up(QString s){
    QString p;

    p = s;
    p = p.toLower();

    return 0;
}

bool Calculator::isdelim(QChar c){
    if(StrChr(" ;,+-<>/*%^=()",c) || c=='\n' || c=='\r' || c=='\0')
        return true;
    return false;
}

bool Calculator::iswhite(QChar c){
    if(c==' ' || c=='\t')
        return true;
    else
        return false;
}

void Calculator::get_token(){
    QString *temp;

    token_type=0; tok=0;
    token.clear();
    temp=&token;

    if(prog[index]=='\0')  { /* end of file */
        token="\0";
        tok=FINISHED;
        token_type=DELIMITER;
        return;
    }

    while(iswhite(prog[index])) ++index;  /* skip spaces */

    if(prog[index]=='\r') { /* crtl */
        ++index; ++index;
        tok= EOL; token='\r';
        token.append('\n');token.append("\0");
        token_type = DELIMITER;
        return;
    }

    if(StrChr("+-*^/%=;(),><", prog[index])) { /* delimiter */
        *temp=prog[index];
        index++; /* jump to the next position */
        temp->append("\0");
        token_type=DELIMITER;
        debugFormula.append(token);
        return;
    }
    if(prog[index]=='"')  { /* quoted string */
        index++;
        while(prog[index] != '"' && prog[index] != '\r'){
            temp->append(prog[index]);
            index++;
        }
        if(prog[index]=='\r')
            serror(1);
        index++;temp->append("\0");
        token_type=QUOTE;
        return;
    }
    if(prog[index].isDigit()) { /* number */
        while(!isdelim(prog[index])){
            temp->append(prog[index]);
            index++;
        }
        temp->append('\0');
        token_type = NUMBER;
        return;
    }

    if(prog[index].isPrint())  { /* variable or command */
        while(!isdelim(prog[index])){
            temp->append(prog[index]);
            index++;
        }
        token_type=STRING;
    }
    temp->append("\0");

    /* Seen if there is a command line or a variable */
    if(token_type==STRING) {
        tok=look_up(token);
        if(!tok)
            token_type = VARIABLE;
        else token_type = COMMAND; /* It is command */
     }
    return;
}

bool Calculator::StrChr(QString string, QChar c){
    return string.contains(c, Qt::CaseInsensitive);
}

void Calculator::putback(){
    QString t;
    t = token;
    index = index - t.size();
}