/*
 * $Id$
 * Copyright (C) 2001 The Apache Software Foundation. All rights reserved.
 * For details on use and redistribution please refer to the
 * LICENSE file included with these sources.
 */

package org.apache.fop.pdf;

// Java...
import java.util.ArrayList;

/**
 * class representing a PDF Function.
 *
 * PDF Functions represent parameterized mathematical formulas and sampled representations with
 * arbitrary resolution. Functions are used in two areas: device-dependent
 * rasterization information for halftoning and transfer
 * functions, and color specification for smooth shading (a PDF 1.3 feature).
 *
 * All PDF Functions have a FunctionType (0,2,3, or 4), a Domain, and a Range.
 */
public class PDFFunction extends PDFObject {
    // Guts common to all function types

    /**
     * Required: The Type of function (0,2,3,4) default is 0.
     */
    protected int functionType = 0;    // Default

    /**
     * Required: 2 * m Array of Double numbers which are possible inputs to the function
     */
    protected ArrayList domain = null;

    /**
     * Required: 2 * n Array of Double numbers which are possible outputs to the function
     */
    protected ArrayList range = null;

    /* ********************TYPE 0***************************** */
    // FunctionType 0 specific function guts

    /**
     * Required: Array containing the Integer size of the Domain and Range, respectively.
     * Note: This is really more like two seperate integers, sizeDomain, and sizeRange,
     * but since they're expressed as an array in PDF, my implementation reflects that.
     */
    protected ArrayList size = null;

    /**
     * Required for Type 0: Number of Bits used to represent each sample value. Limited to 1,2,4,8,12,16,24, or 32
     */
    protected int bitsPerSample = 1;

    /**
     * Optional for Type 0: order of interpolation between samples. Limited to linear (1) or cubic (3). Default is 1
     */
    protected int order = 1;

    /**
     * Optional for Type 0: A 2 * m array of Doubles which provides a linear mapping of input values to the domain.
     *
     * Required for Type 3: A 2 * k array of Doubles that, taken in pairs, map each subset of the domain defined by Domain and the Bounds array to the domain of the corresponding function.
     * Should be two values per function, usually (0,1), as in [0 1 0 1] for 2 functions.
     */
    protected ArrayList encode = null;

    /**
     * Optinoal for Type 0: A 2 * n array of Doubles which provides a linear mapping of sample values to the range. Defaults to Range.
     */
    protected ArrayList decode = null;

    /**
     * Optional For Type 0: A stream of sample values
     */

    /**
     * Required For Type 4: Postscript Calculator function composed of arithmetic, boolean, and stack operators + boolean constants
     */
    protected StringBuffer functionDataStream = null;

    /**
     * Required (?) For Type 0: A vector of Strings for the various filters to be used to decode the stream.
     * These are how the string is compressed. Flate, LZW, etc.
     */
    protected ArrayList filter = null;
    /* *************************TYPE 2************************** */

    /**
     * Required For Type 2: An Array of n Doubles defining the function result when x=0. Default is [0].
     */
    protected ArrayList cZero = null;

    /**
     * Required For Type 2: An Array of n Doubles defining the function result when x=1. Default is [1].
     */
    protected ArrayList cOne = null;

    /**
     * Required for Type 2: The interpolation exponent.
     * Each value x will return n results.
     * Must be greater than 0.
     */
    protected double interpolationExponentN = 1;

    /* *************************TYPE 3************************** */

    /**
     * Required for Type 3: An vector of PDFFunctions which form an array of k single input functions making up the stitching function.
     */
    protected ArrayList functions = null;

    /**
     * Optional for Type 3: An array of (k-1) Doubles that, in combination with Domain, define the intervals to which each function from the Functions array apply. Bounds elements must be in order of increasing magnitude, and each value must be within the value of Domain.
     * k is the number of functions.
     * If you pass null, it will output (1/k) in an array of k-1 elements.
     * This makes each function responsible for an equal amount of the stitching function.
     * It makes the gradient even.
     */
    protected ArrayList bounds = null;
    // See encode above, as it's also part of Type 3 Functions.

    /* *************************TYPE 4************************** */
    // See 'data' above.

    /**
     * create an complete Function object of Type 0, A Sampled function.
     *
     * Use null for an optional object parameter if you choose not to use it.
     * For optional int parameters, pass the default.
     *
     * @param theDomain ArrayList objects of Double objects.
     * This is the domain of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theRange ArrayList objects of Double objects.
     * This is the Range of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theSize A ArrayList object of Integer objects.
     * This is the number of samples in each input dimension.
     * I can't imagine there being more or less than two input dimensions,
     * so maybe this should be an array of length 2.
     *
     * See page 265 of the PDF 1.3 Spec.
     * @param theBitsPerSample An int specifying the number of bits user to represent each sample value.
     * Limited to 1,2,4,8,12,16,24 or 32.
     * See page 265 of the 1.3 PDF Spec.
     * @param theOrder The order of interpolation between samples. Default is 1 (one). Limited
     * to 1 (one) or 3, which means linear or cubic-spline interpolation.
     *
     * This attribute is optional.
     *
     * See page 265 in the PDF 1.3 spec.
     * @param theEncode ArrayList objects of Double objects.
     * This is the linear mapping of input values intop the domain
     * of the function's sample table. Default is hard to represent in
     * ascii, but basically [0 (Size0 1) 0 (Size1 1)...].
     * This attribute is optional.
     *
     * See page 265 in the PDF 1.3 spec.
     * @param theDecode ArrayList objects of Double objects.
     * This is a linear mapping of sample values into the range.
     * The default is just the range.
     *
     * This attribute is optional.
     * Read about it on page 265 of the PDF 1.3 spec.
     * @param theFunctionDataStream The sample values that specify the function are provided in a stream.
     *
     * This is optional, but is almost always used.
     *
     * Page 265 of the PDF 1.3 spec has more.
     * @param theFilter This is a vector of String objects which are the various filters that
     * have are to be applied to the stream to make sense of it. Order matters,
     * so watch out.
     *
     * This is not documented in the Function section of the PDF 1.3 spec,
     * it was deduced from samples that this is sometimes used, even if we may never
     * use it in FOP. It is added for completeness sake.
     * @param theNumber The object number of this PDF object.
     * @param theFunctionType This is the type of function (0,2,3, or 4).
     * It should be 0 as this is the constructor for sampled functions.
     */
    public PDFFunction(int theNumber, int theFunctionType, ArrayList theDomain,
                       ArrayList theRange, ArrayList theSize, int theBitsPerSample,
                       int theOrder, ArrayList theEncode, ArrayList theDecode,
                       StringBuffer theFunctionDataStream, ArrayList theFilter) {
        super(theNumber);

        this.functionType = 0;      // dang well better be 0;
        this.size = theSize;
        this.bitsPerSample = theBitsPerSample;
        this.order = theOrder;      // int
        this.encode = theEncode;    // vector of int
        this.decode = theDecode;    // vector of int
        this.functionDataStream = theFunctionDataStream;
        this.filter = theFilter;    // vector of Strings

        // the domain and range are actually two dimensional arrays.
        // so if there's not an even number of items, bad stuff
        // happens.
        this.domain = theDomain;
        this.range = theRange;
    }

    /**
     * create an complete Function object of Type 2, an Exponential Interpolation function.
     *
     * Use null for an optional object parameter if you choose not to use it.
     * For optional int parameters, pass the default.
     *
     * @param theNumber the object's number
     * @param theDomain ArrayList objects of Double objects.
     * This is the domain of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theRange ArrayList of Doubles that is the Range of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theCZero This is a vector of Double objects which defines the function result
     * when x=0.
     *
     * This attribute is optional.
     * It's described on page 268 of the PDF 1.3 spec.
     * @param theCOne This is a vector of Double objects which defines the function result
     * when x=1.
     *
     * This attribute is optional.
     * It's described on page 268 of the PDF 1.3 spec.
     * @param theInterpolationExponentN This is the inerpolation exponent.
     *
     * This attribute is required.
     * PDF Spec page 268
     * @param theFunctionType The type of the function, which should be 2.
     */
    public PDFFunction(int theNumber, int theFunctionType, ArrayList theDomain,
                       ArrayList theRange, ArrayList theCZero, ArrayList theCOne,
                       double theInterpolationExponentN) {
        super(theNumber);

        this.functionType = 2;    // dang well better be 2;

        this.cZero = theCZero;
        this.cOne = theCOne;
        this.interpolationExponentN = theInterpolationExponentN;


        this.domain = theDomain;
        this.range = theRange;

    }

    /**
     * create an complete Function object of Type 3, a Stitching function.
     *
     * Use null for an optional object parameter if you choose not to use it.
     * For optional int parameters, pass the default.
     *
     * @param theNumber the object's number
     * @param theDomain ArrayList objects of Double objects.
     * This is the domain of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theRange ArrayList objects of Double objects.
     * This is the Range of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theFunctions A ArrayList of the PDFFunction objects that the stitching function stitches.
     *
     * This attributed is required.
     * It is described on page 269 of the PDF spec.
     * @param theBounds This is a vector of Doubles representing the numbers that,
     * in conjunction with Domain define the intervals to which each function from
     * the 'functions' object applies. It must be in order of increasing magnitude,
     * and each must be within Domain.
     *
     * It basically sets how much of the gradient each function handles.
     *
     * This attributed is required.
     * It's described on page 269 of the PDF 1.3 spec.
     * @param theEncode ArrayList objects of Double objects.
     * This is the linear mapping of input values intop the domain
     * of the function's sample table. Default is hard to represent in
     * ascii, but basically [0 (Size0 1) 0 (Size1 1)...].
     * This attribute is required.
     *
     * See page 270 in the PDF 1.3 spec.
     * @param theFunctionType This is the function type. It should be 3,
     * for a stitching function.
     */
    public PDFFunction(int theNumber, int theFunctionType, ArrayList theDomain,
                       ArrayList theRange, ArrayList theFunctions,
                       ArrayList theBounds, ArrayList theEncode) {
        super(theNumber);

        this.functionType = 3;    // dang well better be 3;

        this.functions = theFunctions;
        this.bounds = theBounds;
        this.encode = theEncode;
        this.domain = theDomain;
        this.range = theRange;

    }

    /**
     * create an complete Function object of Type 4, a postscript calculator function.
     *
     * Use null for an optional object parameter if you choose not to use it.
     * For optional int parameters, pass the default.
     *
     * @param theDomain ArrayList object of Double objects.
     * This is the domain of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theRange ArrayList object of Double objects.
     * This is the Range of the function.
     * See page 264 of the PDF 1.3 Spec.
     * @param theFunctionDataStream This is a stream of arithmetic, boolean, and stack operators and boolean constants.
     * I end up enclosing it in the '{' and '}' braces for you, so don't do it
     * yourself.
     *
     * This attribute is required.
     * It's described on page 269 of the PDF 1.3 spec.
     * @param theNumber The object number of this PDF object.
     * @param theFunctionType The type of function which should be 4, as this is
     * a Postscript calculator function
     */
    public PDFFunction(int theNumber, int theFunctionType, ArrayList theDomain,
                       ArrayList theRange, StringBuffer theFunctionDataStream) {
        super(theNumber);

        this.functionType = 4;    // dang well better be 4;
        this.functionDataStream = theFunctionDataStream;

        this.domain = theDomain;

        this.range = theRange;

    }


    /**
     * represent as PDF. Whatever the FunctionType is, the correct
     * representation spits out. The sets of required and optional
     * attributes are different for each type, but if a required
     * attribute's object was constructed as null, then no error
     * is raised. Instead, the malformed PDF that was requested
     * by the construction is dutifully output.
     * This policy should be reviewed.
     *
     * @return the PDF string.
     */
    public byte[] toPDF() {
        int vectorSize = 0;
        int numberOfFunctions = 0;
        int tempInt = 0;
        StringBuffer p = new StringBuffer();
        p.append(this.number + " " + this.generation
                 + " obj\n<< \n/FunctionType " + this.functionType + " \n");

        // FunctionType 0
        if (this.functionType == 0) {
            if (this.domain != null) {
                // DOMAIN
                p.append("/Domain [ ");
                vectorSize = this.domain.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.domain.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            } else {
                p.append("/Domain [ 0 1 ] \n");
            }

            // SIZE
            if (this.size != null) {
                p.append("/Size [ ");
                vectorSize = this.size.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.size.get(tempInt))
                             + " ");
                }
                p.append("] \n");
            }
            // ENCODE
            if (this.encode != null) {
                p.append("/Encode [ ");
                vectorSize = this.encode.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.encode.get(tempInt))
                             + " ");
                }
                p.append("] \n");
            } else {
                p.append("/Encode [ ");
                vectorSize = this.functions.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append("0 1 ");
                }
                p.append("] \n");

            }

            // BITSPERSAMPLE
            p.append("/BitsPerSample " + this.bitsPerSample);

            // ORDER (optional)
            if (this.order == 1 || this.order == 3) {
                p.append(" \n/Order " + this.order + " \n");
            }

            // RANGE
            if (this.range != null) {
                p.append("/Range [ ");
                vectorSize = this.range.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.range.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            }

            // DECODE
            if (this.decode != null) {
                p.append("/Decode [ ");
                vectorSize = this.decode.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.decode.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            }

            // LENGTH
            if (this.functionDataStream != null) {
                p.append("/Length " + (this.functionDataStream.length() + 1)
                         + " \n");
            }

            // FILTER?
            if (this.filter != null) {           // if there's a filter
                vectorSize = this.filter.size();
                p.append("/Filter ");
                if (vectorSize == 1) {
                    p.append("/" + ((String)this.filter.get(0))
                             + " \n");
                } else {
                    p.append("[ ");
                    for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                        p.append("/" + ((String)this.filter.get(0))
                                 + " ");
                    }
                    p.append("] \n");
                }
            }
            p.append(">> \n");

            // stream representing the function
            if (this.functionDataStream != null) {
                p.append("stream\n" + this.functionDataStream
                         + "\nendstream\n");
            }

            p.append("endobj\n");

        }                                        // end of if FunctionType 0
         else if (this.functionType == 2) {
            // DOMAIN
            if (this.domain != null) {
                p.append("/Domain [ ");
                vectorSize = this.domain.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.domain.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            } else {
                p.append("/Domain [ 0 1 ] \n");
            }


            // RANGE
            if (this.range != null) {
                p.append("/Range [ ");
                vectorSize = this.range.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.range.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            }

            // FunctionType, C0, C1, N are required in PDF

            // C0
            if (this.cZero != null) {
                p.append("/C0 [ ");
                vectorSize = this.cZero.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.cZero.get(tempInt))
                             + " ");
                }
                p.append("] \n");
            }

            // C1
            if (this.cOne != null) {
                p.append("/C1 [ ");
                vectorSize = this.cOne.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.cOne.get(tempInt))
                             + " ");
                }
                p.append("] \n");
            }

            // N: The interpolation Exponent
            p.append("/N "
                     + PDFNumber.doubleOut(new Double(this.interpolationExponentN))
                     + " \n");

            p.append(">> \nendobj\n");

        } else if (this.functionType
                   == 3) {                       // fix this up when my eyes uncross
            // DOMAIN
            if (this.domain != null) {
                p.append("/Domain [ ");
                vectorSize = this.domain.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.domain.get(tempInt))
                             + " ");
                }
                p.append("] \n");
            } else {
                p.append("/Domain [ 0 1 ] \n");
            }

            // RANGE
            if (this.range != null) {
                p.append("/Range [ ");
                vectorSize = this.range.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.range.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            }

            // FUNCTIONS
            if (this.functions != null) {
                p.append("/Functions [ ");
                numberOfFunctions = this.functions.size();
                for (tempInt = 0; tempInt < numberOfFunctions; tempInt++) {
                    p.append(((PDFFunction)this.functions.get(tempInt)).referencePDF()
                             + " ");

                }
                p.append("] \n");
            }


            // ENCODE
            if (this.encode != null) {
                p.append("/Encode [ ");
                vectorSize = this.encode.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.encode.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            } else {
                p.append("/Encode [ ");
                vectorSize = this.functions.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append("0 1 ");
                }
                p.append("] \n");

            }


            // BOUNDS, required, but can be empty
            p.append("/Bounds [ ");
            if (this.bounds != null) {

                vectorSize = this.bounds.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.bounds.get(tempInt))
                             + " ");
                }

            } else {
                if (this.functions != null) {
                    // if there are n functions,
                    // there must be n-1 bounds.
                    // so let each function handle an equal portion
                    // of the whole. e.g. if there are 4, then [ 0.25 0.25 0.25 ]

                    String functionsFraction = PDFNumber.doubleOut(new Double(1.0
                            / ((double)numberOfFunctions)));

                    for (tempInt = 0; tempInt + 1 < numberOfFunctions;
                            tempInt++) {

                        p.append(functionsFraction + " ");
                    }
                    functionsFraction = null;    // clean reference.

                }

            }
            p.append("] \n");


            p.append(">> \nendobj\n");
        } else if (this.functionType
                   == 4) {                       // fix this up when my eyes uncross
            // DOMAIN
            if (this.domain != null) {
                p.append("/Domain [ ");
                vectorSize = this.domain.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.domain.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            } else {
                p.append("/Domain [ 0 1 ] \n");
            }

            // RANGE
            if (this.range != null) {
                p.append("/Range [ ");
                vectorSize = this.range.size();
                for (tempInt = 0; tempInt < vectorSize; tempInt++) {
                    p.append(PDFNumber.doubleOut((Double)this.range.get(tempInt))
                             + " ");
                }

                p.append("] \n");
            }

            // LENGTH
            if (this.functionDataStream != null) {
                p.append("/Length " + (this.functionDataStream.length() + 1)
                         + " \n");
            }

            p.append(">> \n");

            // stream representing the function
            if (this.functionDataStream != null) {
                p.append("stream\n{ " + this.functionDataStream
                         + " } \nendstream\n");
            }

            p.append("endobj\n");

        }

        return (p.toString().getBytes());

    }

}