PDF4QT/Pdf4QtLib/sources/pdfstructuretree.h

//    Copyright (C) 2019-2020 Jakub Melka
//
//    This file is part of Pdf4Qt.
//
//    Pdf4Qt is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Lesser General Public License as published by
//    the Free Software Foundation, either version 3 of the License, or
//    (at your option) any later version.
//
//    Pdf4Qt 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 Lesser General Public License for more details.
//
//    You should have received a copy of the GNU Lesser General Public License
//    along with Pdf4Qt.  If not, see <https://www.gnu.org/licenses/>.

#ifndef PDFSTRUCTURETREE_H
#define PDFSTRUCTURETREE_H

#include "pdfobject.h"
#include "pdfobjectutils.h"
#include "pdffile.h"
#include "pdfexception.h"

namespace pdf
{
class PDFDocument;
class PDFObjectStorage;
struct PDFStructureTreeAttributeDefinition;

class PDFStructureItem;
class PDFStructureTree;
class PDFStructureElement;
class PDFStructureMarkedContentReference;
class PDFStructureObjectReference;

class Pdf4QtLIBSHARED_EXPORT PDFStructureTreeAbstractVisitor
{
public:
    inline PDFStructureTreeAbstractVisitor() = default;
    virtual ~PDFStructureTreeAbstractVisitor() = default;

    virtual void visitStructureTree(const PDFStructureTree* structureTree);
    virtual void visitStructureElement(const PDFStructureElement* structureElement);
    virtual void visitStructureMarkedContentReference(const PDFStructureMarkedContentReference* structureMarkedContentReference);
    virtual void visitStructureObjectReference(const PDFStructureObjectReference* structureObjectReference);

protected:
    void acceptChildren(const PDFStructureItem* item);
};

class  Pdf4QtLIBSHARED_EXPORT PDFStructureTreeAttribute
{
public:

    enum class Owner
    {
        Invalid,

        /// Defined for user owner
        UserProperties,

        /// Defined for NSO (namespace owner)
        NSO,

        Layout,
        List,
        PrintField,
        Table,

        Artifact,

        XML_1_00,
        HTML_3_20,
        HTML_4_01,
        HTML_5_00,
        OEB_1_00,
        RTF_1_05,
        CSS_1_00,
        CSS_2_00,
        CSS_3_00,
        RDFa_1_10,
        ARIA_1_1,
    };

    explicit PDFStructureTreeAttribute();
    explicit PDFStructureTreeAttribute(const PDFStructureTreeAttributeDefinition* definition,
                                       Owner owner,
                                       PDFInteger revision,
                                       PDFObjectReference namespaceReference,
                                       PDFObject value);

    enum Attribute
    {
        User,

        // Standard layout attributes
        Placement,
        WritingMode,
        BackgroundColor,
        BorderColor,
        BorderStyle,
        BorderThickness,
        Color,
        Padding,

        // Block element attributes
        SpaceBefore,
        SpaceAfter,
        StartIndent,
        EndIndent,
        TextIndent,
        TextAlign,
        BBox,
        Width,
        Height,
        BlockAlign,
        InlineAlign,
        TBorderStyle,
        TPadding,
        LineHeight,
        BaselineShift,
        TextPosition,
        TextDecorationType,
        TextDecorationColor,
        TextDecorationThickness,
        ColumnCount,
        ColumnWidths,
        ColumnGap,
        GlyphOrientationVertical,
        RubyAlign,
        RubyPosition,

        // List attributes
        ListNumbering,
        ContinuedList,
        ContinuedFrom,

        // PrintField attributes
        Role,
        Checked,
        Desc,

        // Table attributes
        RowSpan,
        ColSpan,
        Headers,
        Scope,
        Short,

        // Artifact attributes
        Type,
        Subtype,

        LastAttribute
    };

    /// Returns attribute type
    Attribute getType() const;

    /// Returns attribute type name
    QString getTypeName(const PDFObjectStorage* storage) const;

    /// Returns attribute owner
    Owner getOwner() const { return m_owner; }

    /// Returns owner name
    QString getOwnerName() const;

    /// Returns true, if attribute is inheritable
    bool isInheritable() const;

    /// Returns attribute revision number
    PDFInteger getRevision() const { return m_revision; }

    /// Sets attribute revision number
    void setRevision(PDFInteger revision) { m_revision = revision; }

    /// Returns namespace for this attribute (or empty reference, if it doesn't exists)
    PDFObjectReference getNamespace() const { return m_namespace; }

    /// Returns attribute value
    const PDFObject& getValue() const { return m_value; }

    /// Returns default attribute value. If default attribute value
    /// cannot be determined, empty object is returned.
    PDFObject getDefaultValue() const;

    /// Returns true, if attribute is user defined
    bool isUser() const { return getType() == Attribute::User; }

    /// Returns user property name. This function should be called only for
    /// user properties. If error occurs, then empty string is returned.
    /// \param storage Storage (for resolving of indirect objects)
    QString getUserPropertyName(const PDFObjectStorage* storage) const;

    /// Returns user property value. This function should be called only for
    /// user properties. If error occurs, then empty object is returned.
    /// \param storage Storage (for resolving of indirect objects)
    PDFObject getUserPropertyValue(const PDFObjectStorage* storage) const;

    /// Returns user property formatted value. This function should be called only for
    /// user properties. If error occurs, then empty string is returned.
    /// \param storage Storage (for resolving of indirect objects)
    QString getUserPropertyFormattedValue(const PDFObjectStorage* storage) const;

    /// Returns true, if user property is hidden. This function should be called only for
    /// user properties. If error occurs, then empty string is returned.
    /// \param storage Storage (for resolving of indirect objects)
    bool getUserPropertyIsHidden(const PDFObjectStorage* storage) const;

    /// Parses attributes and adds them into \p attributes array. Invalid
    /// attributes are not added. New attributes are appended to the end
    /// of the array.
    /// \param storage Storage
    /// \param object Container of attributes
    /// \param attributes[in,out] Attributes
    static void parseAttributes(const PDFObjectStorage* storage, PDFObject object, std::vector<PDFStructureTreeAttribute>& attributes);

private:
    /// Parses single attribute dictionary and appends new attributes to the end of the list.
    /// \param storage Storage
    /// \param object Container of attributes
    /// \param attributes[in,out] Attributes
    static void parseAttributeDictionary(const PDFObjectStorage* storage, PDFObject object, std::vector<PDFStructureTreeAttribute>& attributes);

    const PDFStructureTreeAttributeDefinition* m_definition = nullptr;

    /// Attribute owner
    Owner m_owner = Owner::Invalid;

    /// Revision number
    PDFInteger m_revision = 0;

    /// Namespace
    PDFObjectReference m_namespace;

    /// Value of attribute. In case of standard attribute, attribute
    /// value is directly stored here. In case of user attribute,
    /// then user attribute dictionary is stored here.
    PDFObject m_value;
};

class PDFStructureTree;
class PDFStructureItem;
class PDFStructureElement;
class PDFStructureObjectReference;
class PDFStructureMarkedContentReference;

using PDFStructureItemPointer = QSharedPointer<PDFStructureItem>;

/// Root class for all structure tree items
class Pdf4QtLIBSHARED_EXPORT PDFStructureItem
{
public:
    explicit inline PDFStructureItem(PDFStructureItem* parent, PDFStructureTree* root) :
        m_parent(parent),
        m_root(root)
    {

    }

    virtual ~PDFStructureItem() = default;

    enum Type
    {
        Invalid,

        // Document level types - chapter 14.8.4.3 of PDF 2.0 specification
        Document, DocumentFragment,

        // Grouping types - chapter 14.8.4.4 of PDF 2.0 specification
        Part, Div, Aside,

        // Block level structure types - chapter 14.8.4.5 of PDF 2.0 specification
        P, H1, H2, H3, H4, H5, H6, H7, H, Title, FENote,

        // Subblock level structure types - chapter 14.8.4.6 of PDF 2.0 specification
        Sub,

        // Inline structure types - chapter 14.8.4.7 of PDF 2.0 specification
        Lbl, Span, Em, Strong, Link, Annot, Form, Ruby, RB, RT, RP, Warichu, WR, WP,

        // Other structure types - chapter 14.8.4.7 of PDF 2.0 specification
        L, LI, LBody, Table, TR, TH, TD, THead, TBody, TFoot, Caption, Figure, Formula, Artifact,

        // PDF 1.7 backward compatibility types
        Sect, Art, BlockQuote, TOC, TOCI, Index, NonStruct, Private, Quote, Note, Reference, BibEntry, Code,

        // Last type identifier
        LastType,
    };

    virtual PDFStructureTree* asStructureTree() { return nullptr; }
    virtual const PDFStructureTree* asStructureTree() const { return nullptr; }

    virtual PDFStructureElement* asStructureElement() { return nullptr; }
    virtual const PDFStructureElement* asStructureElement() const { return nullptr; }

    virtual PDFStructureMarkedContentReference* asStructureMarkedContentReference() { return nullptr; }
    virtual const PDFStructureMarkedContentReference* asStructureMarkedContentReference() const { return nullptr; }

    virtual PDFStructureObjectReference* asStructureObjectReference() { return nullptr; }
    virtual const PDFStructureObjectReference* asStructureObjectReference() const { return nullptr; }

    virtual void accept(PDFStructureTreeAbstractVisitor* visitor) const = 0;

    const PDFStructureItem* getParent() const { return m_parent; }
    PDFStructureItem* getParent() { return m_parent; }
    const PDFStructureTree* getTree() const { return m_root; }
    PDFStructureTree* getTree() { return m_root; }
    PDFObjectReference getSelfReference() const { return m_selfReference; }
    std::size_t getChildCount() const { return m_children.size(); }
    const PDFStructureItem* getChild(size_t i) const { return m_children.at(i).get(); }

    /// Parses structure tree item from the object. If error occurs,
    /// null pointer is returned.
    /// \param storage Storage
    /// \param object Structure tree item object
    /// \param context Parsing context
    /// \param parent Parent item
    static PDFStructureItemPointer parse(const PDFObjectStorage* storage, PDFObject object, PDFMarkedObjectsContext* context, PDFStructureItem* parent);

    /// Get structure tree type from name
    /// \param name Name
    static Type getTypeFromName(const QByteArray& name);

protected:
    /// Parses kids of the item. Invalid items aren't added
    /// to the kid list.
    /// \param storage Storage
    /// \param parentItem Parent item, where children are inserted
    /// \param dictionary Dictionary
    /// \param context Context
    static void parseKids(const PDFObjectStorage* storage,
                          PDFStructureItem* parentItem,
                          const PDFDictionary* dictionary,
                          PDFMarkedObjectsContext* context);

    PDFStructureItem* m_parent;
    PDFStructureTree* m_root;
    PDFObjectReference m_selfReference;
    std::vector<PDFStructureItemPointer> m_children;
};

/// Structure tree namespace
class Pdf4QtLIBSHARED_EXPORT PDFStructureTreeNamespace
{
public:
    explicit inline PDFStructureTreeNamespace() = default;

    const PDFObjectReference& getSelfReference() const { return m_selfReference; }
    const QString& getNamespace() const { return m_namespace; }
    const PDFFileSpecification& getSchema() const { return m_schema; }
    const PDFObject& getRoleMapNS() const { return m_roleMapNS; }

    static PDFStructureTreeNamespace parse(const PDFObjectStorage* storage, PDFObject object);

private:
    PDFObjectReference m_selfReference;
    QString m_namespace;
    PDFFileSpecification m_schema;
    PDFObject m_roleMapNS;
};

using PDFStructureTreeNamespaces = std::vector<PDFStructureTreeNamespace>;

/// Structure tree, contains structure element hierarchy
class Pdf4QtLIBSHARED_EXPORT PDFStructureTree : public PDFStructureItem
{
public:
    explicit inline PDFStructureTree() : PDFStructureItem(nullptr, this) { }

    virtual PDFStructureTree* asStructureTree() override { return this; }
    virtual const PDFStructureTree* asStructureTree() const override { return this; }

    virtual void accept(PDFStructureTreeAbstractVisitor* visitor) const override { visitor->visitStructureTree(this); }

    /// Returns parents from parent tree for given entry. If entry
    /// is not found, then empty vector is returned.
    /// \param id Id
    std::vector<PDFObjectReference> getParents(PDFInteger id) const;

    /// Returns parent key for structural entry with given id,
    /// and index. Id is, typically, structural tree parent key in page,
    /// index is index into the marked content references array.
    /// \param id Structural tree parent id
    /// \param index Index into the subarray
    PDFObjectReference getParent(PDFInteger id, PDFInteger index) const;

    /// Returns type from role. Role can be an entry in RoleMap dictionary,
    /// or one of the standard roles.
    /// \param role Role
    Type getTypeFromRole(const QByteArray& role) const;

    /// Returns class attributes for given class. If class is not found,
    /// then empty attributes are returned.
    /// \param className Class name
    const std::vector<PDFStructureTreeAttribute>& getClassAttributes(const QByteArray& className) const;

    /// Returns a list of namespaces
    const PDFStructureTreeNamespaces& getNamespaces() const { return m_namespaces; }

    /// Returns a list of pronunciation lexicons
    const std::vector<PDFFileSpecification>& getPronunciationLexicons() const { return m_pronunciationLexicons; }

    /// Returns a list of associated files
    const std::vector<PDFFileSpecification>& getAssociatedFiles() const { return m_associatedFiles; }

    /// Returns true, if structure tree is valid
    bool isValid() const { return getChildCount() > 0; }

    /// Parses structure tree from the object. If error occurs, empty structure
    /// tree is returned.
    /// \param storage Storage
    /// \param object Structure tree root object
    static PDFStructureTree parse(const PDFObjectStorage* storage, PDFObject object);

    struct ParentTreeEntry
    {
        PDFInteger id = 0;
        PDFObjectReference reference;

        bool operator<(const ParentTreeEntry& other) const
        {
            return id < other.id;
        }
    };

    /// Returns given page tree entry. If index is invalid,
    /// empty parent tree entry is returned.
    /// \param index Index
    ParentTreeEntry getParentTreeEntry(PDFInteger index) const;

private:
    using ParentTreeEntries = std::vector<ParentTreeEntry>;

    std::map<QByteArray, PDFObjectReference> m_idTreeMap;
    ParentTreeEntries m_parentTreeEntries;
    PDFInteger m_parentNextKey = 0;
    std::map<QByteArray, Type> m_roleMap;
    std::map<QByteArray, std::vector<PDFStructureTreeAttribute>> m_classMap;
    PDFStructureTreeNamespaces m_namespaces;
    std::vector<PDFFileSpecification> m_pronunciationLexicons;
    std::vector<PDFFileSpecification> m_associatedFiles;
};

/// Structure element
class Pdf4QtLIBSHARED_EXPORT PDFStructureElement : public PDFStructureItem
{
public:
    explicit inline PDFStructureElement(PDFStructureItem* parent, PDFStructureTree* root) :
        PDFStructureItem(parent, root)
    {

    }

    enum StringValue
    {
        Title,
        Language,
        AlternativeDescription,
        ExpandedForm,
        ActualText,
        Phoneme,
        LastStringValue
    };

    virtual PDFStructureElement* asStructureElement() override { return this; }
    virtual const PDFStructureElement* asStructureElement() const override { return this; }
    virtual void accept(PDFStructureTreeAbstractVisitor* visitor) const override { visitor->visitStructureElement(this); }

    const QByteArray& getTypeName() const { return m_typeName; }
    Type getStandardType() const { return m_standardType; }
    const QByteArray& getId() const { return m_id; }
    const std::vector<PDFObjectReference>& getReferences() const { return m_references; }
    const PDFObjectReference& getPageReference() const { return m_pageReference; }
    const std::vector<PDFStructureTreeAttribute>& getAttributes() const { return m_attributes; }
    PDFInteger getRevision() const { return m_revision; }
    const QString& getText(StringValue stringValue) const { return m_texts.at(stringValue); }
    const std::vector<PDFFileSpecification>& getAssociatedFiles() const { return m_associatedFiles; }
    const PDFObjectReference& getNamespace() const { return m_namespace; }
    const QByteArray& getPhoneticAlphabet() const { return m_phoneticAlphabet; }

    enum class RevisionPolicy
    {
        Ignore,
        Match
    };

    using Attribute = PDFStructureTreeAttribute::Attribute;
    using AttributeOwner = PDFStructureTreeAttribute::Owner;

    /// Finds attribute matching given owner and revision policy. If attribute with given
    /// owner is not found, then any matching attribute is returned. If none is found,
    /// then nullptr is returned.
    /// \param attribute Attribute
    /// \param owner Owner
    /// \param policy Revision number policy
    const PDFStructureTreeAttribute* findAttribute(Attribute attribute, AttributeOwner owner, RevisionPolicy policy) const;

    /// Parses structure element from the object. If error occurs, nullptr is returned.
    /// \param storage Storage
    /// \param object Structure element object
    /// \param context Visited elements context
    /// \param parent Parent structure tree item
    /// \param root Structure tree root
    static PDFStructureItemPointer parseElement(const PDFObjectStorage* storage,
                                                PDFObject object,
                                                PDFMarkedObjectsContext* context,
                                                PDFStructureItem* parent,
                                                PDFStructureTree* root);

private:
    /// Finds attribute matching given owner and revision policy. If attribute with given
    /// owner is not found, then any matching attribute is returned. If none is found,
    /// then nullptr is returned.
    /// \param attribute Attribute
    /// \param owner Owner
    /// \param policy Revision number policy
    /// \param definition Definition
    const PDFStructureTreeAttribute* findAttributeImpl(Attribute attribute,
                                                       AttributeOwner owner,
                                                       RevisionPolicy policy,
                                                       const PDFStructureTreeAttributeDefinition* definition) const;

    QByteArray m_typeName;
    Type m_standardType;
    QByteArray m_id;
    std::vector<PDFObjectReference> m_references;
    PDFObjectReference m_pageReference;
    std::vector<PDFStructureTreeAttribute> m_attributes;
    PDFInteger m_revision = 0;
    std::array<QString, LastStringValue> m_texts;
    std::vector<PDFFileSpecification> m_associatedFiles;
    PDFObjectReference m_namespace;
    QByteArray m_phoneticAlphabet;
};

/// Structure marked content reference
class Pdf4QtLIBSHARED_EXPORT PDFStructureMarkedContentReference : public PDFStructureItem
{
public:
    explicit inline PDFStructureMarkedContentReference(PDFStructureItem* parent, PDFStructureTree* root) :
        PDFStructureItem(parent, root)
    {

    }

    virtual PDFStructureMarkedContentReference* asStructureMarkedContentReference() override { return this; }
    virtual const PDFStructureMarkedContentReference* asStructureMarkedContentReference() const override { return this; }
    virtual void accept(PDFStructureTreeAbstractVisitor* visitor) const override { visitor->visitStructureMarkedContentReference(this); }

    const PDFObjectReference& getPageReference() const { return m_pageReference; }
    const PDFObjectReference& getContentStreamReference() const { return m_contentStreamReference; }
    const PDFObjectReference& getContentStreamOwnerReference() const { return m_contentStreamOwnerReference; }
    PDFInteger getMarkedContentIdentifier() const { return m_markedContentIdentifier; }

    /// Parses structure marked content reference from the object. If error occurs, nullptr is returned.
    /// \param storage Storage
    /// \param object Structure marked content reference
    /// \param context Visited items context
    /// \param parent Parent structure tree item
    /// \param root Structure tree root
    static PDFStructureItemPointer parseMarkedContentReference(const PDFObjectStorage* storage,
                                                               PDFObject object,
                                                               PDFMarkedObjectsContext* context,
                                                               PDFStructureItem* parent,
                                                               PDFStructureTree* root);

private:
    PDFObjectReference m_pageReference;
    PDFObjectReference m_contentStreamReference;
    PDFObjectReference m_contentStreamOwnerReference;
    PDFInteger m_markedContentIdentifier = 0;
};

/// Structure object reference
class Pdf4QtLIBSHARED_EXPORT PDFStructureObjectReference : public PDFStructureItem
{
public:
    explicit inline PDFStructureObjectReference(PDFStructureItem* parent, PDFStructureTree* root) :
        PDFStructureItem(parent, root)
    {

    }

    virtual PDFStructureObjectReference* asStructureObjectReference() override { return this; }
    virtual const PDFStructureObjectReference* asStructureObjectReference() const override { return this; }
    virtual void accept(PDFStructureTreeAbstractVisitor* visitor) const override { visitor->visitStructureObjectReference(this); }

    const PDFObjectReference& getPageReference() const { return m_pageReference; }
    const PDFObjectReference& getObjectReference() const { return m_objectReference; }

    /// Parses structure object reference from the object. If error occurs, nullptr is returned.
    /// \param storage Storage
    /// \param object Structure marked content reference
    /// \param context Visited items context
    /// \param parent Parent structure tree item
    /// \param root Structure tree root
    static PDFStructureItemPointer parseObjectReference(const PDFObjectStorage* storage,
                                                        PDFObject object,
                                                        PDFMarkedObjectsContext* context,
                                                        PDFStructureItem* parent,
                                                        PDFStructureTree* root);

private:
    PDFObjectReference m_pageReference;
    PDFObjectReference m_objectReference;
};

}   // namespace pdf

#endif // PDFSTRUCTURETREE_H