/*
 *  ====================================================================
 *    Licensed to the Apache Software Foundation (ASF) under one or more
 *    contributor license agreements.  See the NOTICE file distributed with
 *    this work for additional information regarding copyright ownership.
 *    The ASF licenses this file to You under the Apache License, Version 2.0
 *    (the "License"); you may not use this file except in compliance with
 *    the License.  You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 * ====================================================================
 */

package org.apache.poi.sl.draw.geom;

import static java.lang.Math.abs;
import static java.lang.Math.atan2;
import static java.lang.Math.cos;
import static java.lang.Math.max;
import static java.lang.Math.min;
import static java.lang.Math.sin;
import static java.lang.Math.sqrt;
import static java.lang.Math.tan;
import static java.lang.Math.toDegrees;
import static java.lang.Math.toRadians;

import org.apache.poi.sl.draw.binding.CTGeomGuide;

A simple pattern parser of shape guide formulas in DrawingML
/**
 * A simple pattern parser of shape guide formulas in DrawingML
 */
public class Guide implements Formula {
    enum Op {
        muldiv,addsub,adddiv,ifelse,val,abs,sqrt,max,min,at2,sin,cos,tan,cat2,sat2,pin,mod
    }

    private final String name, fmla;
    private final Op op;
    private final String[] operands;


    public Guide(CTGeomGuide gd) {
        this(gd.getName(), gd.getFmla());
    }

    public Guide(String nm, String fm){
        name = nm;
        fmla = fm;
        operands = fm.split("\\s+");
        op = Op.valueOf(operands[0].replace("*", "mul").replace("/", "div").replace("+", "add").replace("-", "sub").replace("?:", "ifelse"));
    }

    public String getName(){
        return name;
    }

    String getFormula(){
        return fmla;
    }

    @Override
    public double evaluate(Context ctx) {
        double x = (operands.length > 1) ? ctx.getValue(operands[1]) : 0;
        double y = (operands.length > 2) ? ctx.getValue(operands[2]) : 0;
        double z = (operands.length > 3) ? ctx.getValue(operands[3]) : 0;
        switch (op) {
            case abs:
                // Absolute Value Formula
                return abs(x);
            case adddiv:
                // Add Divide Formula
                return (x + y) / z;
            case addsub:
                // Add Subtract Formula
                return (x + y) - z;
            case at2:
                // ArcTan Formula: "at2 x y" = arctan( y / z ) = value of this guide
                return toDegrees(atan2(y, x)) * OOXML_DEGREE;
            case cos:
                // Cosine Formula: "cos x y" = (x * cos( y )) = value of this guide
                return x * cos(toRadians(y / OOXML_DEGREE));
            case cat2:
                // Cosine ArcTan Formula: "cat2 x y z" = (x * cos(arctan(z / y) )) = value of this guide
                return x*cos(atan2(z, y));
            case ifelse:
                // If Else Formula: "?: x y z" = if (x > 0), then y = value of this guide,
                // else z = value of this guide
                return x > 0 ? y : z;
            case val:
                // Literal Value Expression
                return x;
            case max:
                // Maximum Value Formula
                return max(x, y);
            case min:
                // Minimum Value Formula
                return min(x, y);
            case mod:
                // Modulo Formula: "mod x y z" = sqrt(x^2 + b^2 + c^2) = value of this guide
                return sqrt(x*x + y*y + z*z);
            case muldiv:
                // Multiply Divide Formula
                return (x * y) / z;
            case pin:
                // Pin To Formula: "pin x y z" = if (y < x), then x = value of this guide
                // else if (y > z), then z = value of this guide
                // else y = value of this guide
                if(y < x) {
                    return x;
                } else if (y > z) {
                    return z;
                } else {
                    return y;
                }
            case sat2:
                // Sine ArcTan Formula: "sat2 x y z" = (x*sin(arctan(z / y))) = value of this guide
                return x*sin(atan2(z, y));
            case sin:
                // Sine Formula: "sin x y" = (x * sin( y )) = value of this guide
                return x * sin(toRadians(y / OOXML_DEGREE));
            case sqrt:
                // Square Root Formula: "sqrt x" = sqrt(x) = value of this guide
                return sqrt(x);
            case tan:
                // Tangent Formula: "tan x y" = (x * tan( y )) = value of this guide
                return x * tan(toRadians(y / OOXML_DEGREE));
            default:
                return 0;
        }
    }
}