#include <qpdf/QPDFAnnotationObjectHelper.hh>

#include <qpdf/QPDFMatrix.hh>

#include <qpdf/QPDFObjectHandle_private.hh>

#include <qpdf/QTC.hh>

#include <qpdf/QUtil.hh>

using namespace qpdf;

QPDFAnnotationObjectHelper::QPDFAnnotationObjectHelper(QPDFObjectHandle oh) :

    QPDFObjectHelper(oh)

{

}

std::string

QPDFAnnotationObjectHelper::getSubtype()

{

    return oh().getKey("/Subtype").getName();

}

QPDFObjectHandle::Rectangle

QPDFAnnotationObjectHelper::getRect()

{

    return oh().getKey("/Rect").getArrayAsRectangle();

}

QPDFObjectHandle

QPDFAnnotationObjectHelper::getAppearanceDictionary()

{

    return oh().getKey("/AP");

}

std::string

QPDFAnnotationObjectHelper::getAppearanceState()

{

    Name AS = get("/AS");

    return AS ? AS.value() : "";

}

int

QPDFAnnotationObjectHelper::getFlags()

{

    Integer flags_obj = get("/F");

    return flags_obj ? flags_obj : 0;

}

QPDFObjectHandle

QPDFAnnotationObjectHelper::getAppearanceStream(std::string const& which, std::string const& state)

{

    QPDFObjectHandle ap = getAppearanceDictionary();

    std::string desired_state = state.empty() ? getAppearanceState() : state;

    if (ap.isDictionary()) {

        QPDFObjectHandle ap_sub = ap.getKey(which);

        if (ap_sub.isStream()) {

            // According to the spec, Appearance State is supposed to refer to a subkey of the

            // appearance stream when /AP is a dictionary, but files have been seen in the wild

            // where Appearance State is `/N` and `/AP` is a stream. Therefore, if `which` points to

            // a stream, disregard state and just use the stream. See qpdf issue #949 for details.

            return ap_sub;

        }

        if (ap_sub.isDictionary() && !desired_state.empty()) {

            QPDFObjectHandle ap_sub_val = ap_sub.getKey(desired_state);

            if (ap_sub_val.isStream()) {

                return ap_sub_val;

            }

        }

    }

    return Null::temp();

}

std::string

QPDFAnnotationObjectHelper::getPageContentForAppearance(

    std::string const& name, int rotate, int required_flags, int forbidden_flags)

{

    if (!getAppearanceStream("/N").isStream()) {

        return "";

    }

    // The appearance matrix computed by this method is the transformation matrix that needs to be

    // in effect when drawing this annotation's appearance stream on the page. The algorithm for

    // computing the appearance matrix described in section 12.5.5 of the ISO-32000 PDF spec is

    // similar but not identical to what we are doing here.

    // When rendering an appearance stream associated with an annotation, there are four relevant

    // components:

    //

    // * The appearance stream's bounding box (/BBox)

    // * The appearance stream's matrix (/Matrix)

    // * The annotation's rectangle (/Rect)

    // * In the case of form fields with the NoRotate flag, the page's rotation

    // When rendering a form xobject in isolation, just drawn with a /Do operator, there is no form

    // field, so page rotation is not relevant, and there is no annotation, so /Rect is not

    // relevant, so only /BBox and /Matrix are relevant. The effect of these are as follows:

    // * /BBox is treated as a clipping region

    // * /Matrix is applied as a transformation prior to rendering the appearance stream.

    // There is no relationship between /BBox and /Matrix in this case.

    // When rendering a form xobject in the context of an annotation, things are a little different.

    // In particular, a matrix is established such that /BBox, when transformed by /Matrix, would

    // fit completely inside of /Rect. /BBox is no longer a clipping region. To illustrate the

    // difference, consider a /Matrix of [2 0 0 2 0 0], which is scaling by a factor of two along

    // both axes. If the appearance stream drew a rectangle equal to /BBox, in the case of the form

    // xobject in isolation, this matrix would cause only the lower-left quadrant of the rectangle

    // to be visible since the scaling would cause the rest of it to fall outside of the clipping

    // region. In the case of the form xobject displayed in the context of an annotation, such a

    // matrix would have no effect at all because it would be applied to the bounding box first, and

    // then when the resulting enclosing quadrilateral was transformed to fit into /Rect, the effect

    // of the scaling would be undone.

    // Our job is to create a transformation matrix that compensates for these differences so that

    // the appearance stream of an annotation can be drawn as a regular form xobject.

    // To do this, we perform the following steps, which overlap significantly with the algorithm

    // in 12.5.5:

    // 1. Transform the four corners of /BBox by applying /Matrix to them, creating an arbitrarily

    //    transformed quadrilateral.

    // 2. Find the minimum upright rectangle that encompasses the resulting quadrilateral. This is

    //    the "transformed appearance box", T.

    // 3. Compute matrix A that maps the lower left and upper right corners of T to the annotation's

    //    /Rect. This can be done by scaling so that the sizes match and translating so that the

    //    scaled T exactly overlaps /Rect.

    // If the annotation's /F flag has bit 4 set, this means that annotation is to be rotated about

    // its upper left corner to counteract any rotation of the page so it remains upright. To

    // achieve this effect, we do the following extra steps:

    // 1. Perform the rotation on /BBox box prior to transforming it with /Matrix (by replacing

    //    matrix with concatenation of matrix onto the rotation)

    // 2. Rotate the destination rectangle by the specified amount

    // 3. Apply the rotation to A as computed above to get the final appearance matrix.

    QPDFObjectHandle rect_obj = oh().getKey("/Rect");

    QPDFObjectHandle as = getAppearanceStream("/N").getDict();

    QPDFObjectHandle bbox_obj = as.getKey("/BBox");

    QPDFObjectHandle matrix_obj = as.getKey("/Matrix");

    int flags = getFlags();

    if (flags & forbidden_flags) {

        QTC::TC("qpdf", "QPDFAnnotationObjectHelper forbidden flags");

        return "";

    }

    if ((flags & required_flags) != required_flags) {

        QTC::TC("qpdf", "QPDFAnnotationObjectHelper missing required flags");

        return "";

    }

    if (!(bbox_obj.isRectangle() && rect_obj.isRectangle())) {

        return "";

    }

    QPDFMatrix matrix;

    if (matrix_obj.isMatrix()) {

        QTC::TC("qpdf", "QPDFAnnotationObjectHelper explicit matrix");

        matrix = QPDFMatrix(matrix_obj.getArrayAsMatrix());

    } else {

        QTC::TC("qpdf", "QPDFAnnotationObjectHelper default matrix");

    }

    QPDFObjectHandle::Rectangle rect = rect_obj.getArrayAsRectangle();

    bool do_rotate = (rotate && (flags & an_no_rotate));

    if (do_rotate) {

        // If the annotation flags include the NoRotate bit and the page is rotated, we have to

        // rotate the annotation about its upper left corner by the same amount in the opposite

        // direction so that it will remain upright in absolute coordinates. Since the semantics of

        // /Rotate for a page are to rotate the page, while the effect of rotating using a

        // transformation matrix is to rotate the coordinate system, the opposite directionality is

        // explicit in the code.

        QPDFMatrix mr;

        mr.rotatex90(rotate);

        mr.concat(matrix);

        matrix = mr;

        double rect_w = rect.urx - rect.llx;

        double rect_h = rect.ury - rect.lly;

        switch (rotate) {

        case 90:

            QTC::TC("qpdf", "QPDFAnnotationObjectHelper rotate 90");

            rect = QPDFObjectHandle::Rectangle(

                rect.llx, rect.ury, rect.llx + rect_h, rect.ury + rect_w);

            break;

        case 180:

            QTC::TC("qpdf", "QPDFAnnotationObjectHelper rotate 180");

            rect = QPDFObjectHandle::Rectangle(

                rect.llx - rect_w, rect.ury, rect.llx, rect.ury + rect_h);

            break;

        case 270:

            QTC::TC("qpdf", "QPDFAnnotationObjectHelper rotate 270");

            rect = QPDFObjectHandle::Rectangle(

                rect.llx - rect_h, rect.ury - rect_w, rect.llx, rect.ury);

            break;

        default:

            // ignore

            break;

        }

    }

    // Transform bounding box by matrix to get T

    QPDFObjectHandle::Rectangle bbox = bbox_obj.getArrayAsRectangle();

    QPDFObjectHandle::Rectangle T = matrix.transformRectangle(bbox);

    if ((T.urx == T.llx) || (T.ury == T.lly)) {

        // avoid division by zero

        return "";

    }

    // Compute a matrix to transform the appearance box to the rectangle

    QPDFMatrix AA;

    AA.translate(rect.llx, rect.lly);

    AA.scale((rect.urx - rect.llx) / (T.urx - T.llx), (rect.ury - rect.lly) / (T.ury - T.lly));

    AA.translate(-T.llx, -T.lly);

    if (do_rotate) {

        AA.rotatex90(rotate);

    }

    as.replaceKey("/Subtype", QPDFObjectHandle::newName("/Form"));

    return ("q\n" + AA.unparse() + " cm\n" + name + " Do\n" + "Q\n");

}