#ifndef CONFIGOBJECT_HH
#define CONFIGOBJECT_HH

#include <QObject>
#include <QString>
#include <QHash>
#include <QVector>
#include <QMetaProperty>

#include <yaml-cpp/yaml.h>

#include "errorstack.hh"

// Forward declaration
class Config;
class ConfigObject;
class ConfigExtension;

/** Helper function to test property type. */
template <class T>
bool propIsInstance(const QMetaProperty &prop) {
  if (QMetaType::UnknownType == prop.typeId())
    return false;
  QMetaType type = prop.metaType();
  if (! (QMetaType::PointerToQObject & type.flags()))
    return false;
  return type.metaObject()->inherits(&T::staticMetaObject);
}


/** Base class for all configuration objects (channels, zones, contacts, etc).
 *
 * @ingroup conf */
class ConfigItem : public QObject
{
  Q_OBJECT

public:
  /** Parse context for config objects. During serialization, each config object gets an
   * ID assigned. When reading the config, these IDs must be matched back to the corresponding
   * objects. This is done using this context. */
  class Context
  {
  public:
    /** Empty constructor. */
    Context();
    /** Destructor. */
    virtual ~Context();

    /** Returns the read version string. */
    const QString &version() const;
    /** Sets the version string. */
    void setVersion(const QString &ver);

    /** Returns @c true, if the context contains the given object. */
    virtual bool contains(ConfigObject *obj) const;
    /** Returns @c true, if the context contains the given ID. */
    virtual bool contains(const QString &id) const;

    /** Returns ID of the given object. */
    virtual QString getId(ConfigObject *obj) const;
    /** Returns the object for the given ID. */
    virtual ConfigObject *getObj(const QString &id) const;

    /** Associates the given object with the given ID. */
    virtual bool add(const QString &id, ConfigObject *);

    /** Returns @c true if the property of the class has the specified tag associated. */
    static bool hasTag(const QString &className, const QString &property, const QString &tag);
    /** Returns @c true if the property of the class has the specified object as a tag associated. */
    static bool hasTag(const QString &className, const QString &property, ConfigObject *obj);
    /** Returns the object associated with the tag for the property of the class. */
    static ConfigObject *getTag(const QString &className, const QString &property, const QString &tag);
    /** Returns the tag associated with the object for the property of the class. */
    static QString getTag(const QString &className, const QString &property, ConfigObject *obj);
    /** Associates the given object with the tag for the property of the given class. */
    static void setTag(const QString &className, const QString &property, const QString &tag, ConfigObject *obj);

  protected:
    /** The version string. */
    QString _version;
    /** ID->OBJ look-up table. */
    QHash<QString, ConfigObject *> _objects;
    /** OBJ->ID look-up table. */
    QHash<ConfigObject*, QString> _ids;
    /** Maps tags to singleton objects. */
    static QHash<QString, QHash<QString, ConfigObject *>> _tagObjects;
    /** Maps singleton objects to tags. */
    static QHash<QString, QHash<ConfigObject *, QString>> _tagNames;
  };

protected:
  /** Hidden constructor.
   * @param parent Specifies the QObject parent. */
  explicit ConfigItem(QObject *parent = nullptr);

public:
  /** Copies the given item into this one.
   * @returns @c true if copying was successful and false otherwise. The two items must be of the
   *          same type (obviously). */
  virtual bool copy(const ConfigItem &other);

  /** Clones this item. */
  virtual ConfigItem *clone() const = 0;

  /** Compares the items.
   *
   * This method returns 0 if the two items are equivalent and -1, 1 otherwise. The established
   * order is somewhat arbitrary.
   *
   * @returns 0 if the two items are equivalent, -1 or 1 otherwise.*/
  virtual int compare(const ConfigItem &other) const;

public:
  /** Recursively labels the config object.
   * Does not assign a label if the @c idBase passed to the constructor is empty. */
  virtual bool label(Context &context, const ErrorStack &err=ErrorStack());
  /** Recursively serializes the configuration to YAML nodes.
   * The complete configuration must be labeled first. */
  virtual YAML::Node serialize(const Context &context, const ErrorStack &err=ErrorStack());

  /** Allocates an instance for the given property on the given YAML node.
   * This is usually done automatically based on the meta-type of the property. To be able to
   * instantiate the item, its default constructor must be Q_INVOKABLE. */
  virtual ConfigItem *allocateChild(QMetaProperty &prop, const YAML::Node &node,
                                    const Context &ctx, const ErrorStack &err=ErrorStack());
  /** Parses the given YAML node, updates the given object and updates the given context (IDs). */
  virtual bool parse(const YAML::Node &node, Context &ctx, const ErrorStack &err=ErrorStack());
  /** Links the given object to the rest of the codeplug using the given context. */
  virtual bool link(const YAML::Node &node, const Context &ctx, const ErrorStack &err=ErrorStack());

  /** Clears the config object. */
  virtual void clear();

  /** Returns the config, the item belongs to or @c nullptr if not part of a config. */
  virtual const Config *config() const;
  /** Searches the config tree to find all instances of the given type names. */
  virtual void findItemsOfTypes(const QStringList &typeNames, QSet<ConfigItem*> &items) const;

  /** Returns @c true if this object is of class @c Object. */
  template <class Object>
  bool is() const {
    return nullptr != qobject_cast<const Object*>(this);
  }

  /** Casts this object to the given type. */
  template <class Object>
  const Object *as() const {
    return qobject_cast<const Object*>(this);
  }

  /** Casts this object to the given type. */
  template <class Object>
  Object *as() {
    return qobject_cast<Object *>(this);
  }

  /** Returns @c true if there is a class info "description" for this instance. */
  bool hasDescription() const;
  /** Returns @c true if there is a class info "longDescription" for this instance. */
  bool hasLongDescription() const;
  /** Returns @c true if there is a class info "[PropertyName]Description" for the given property. */
  bool hasDescription(const QMetaProperty &prop) const;
  /** Returns @c true if there is a class info "[PropertyName]LongDescription" for the given property. */
  bool hasLongDescription(const QMetaProperty &prop) const;
  /** Returns the description of this instance if set by a class info. */
  QString description() const;
  /** Returns the long description of this instance if set by a class info. */
  QString longDescription() const;
  /** Returns the description of property if set by a class info. */
  QString description(const QMetaProperty &prop) const;
  /** Returns the long description of property if set by a class info. */
  QString longDescription(const QMetaProperty &prop) const;

protected:
  /** Recursively serializes the configuration to YAML nodes.
   * The complete configuration must be labeled first. */
  virtual bool populate(YAML::Node &node, const Context &context, const ErrorStack &err=ErrorStack());

signals:
  /** Gets emitted once the config object is modified.
   * The instance passed is the modified item, this event is passed up the config tree. */
  void modified(ConfigItem *obj);
  /** Gets emitted before clearing the item. */
  void beginClear();
  /** Gets emitted after clearing the item. */
  void endClear();
};


/** Base class of all labeled and named objects.
 * @ingroup config */
class ConfigObject: public ConfigItem
{
  Q_OBJECT

  /** The name of the object. */
  Q_PROPERTY(QString name READ name WRITE setName)

  /** Specifies the prefix for every ID assigned to every object during serialization. */
  Q_CLASSINFO("IdPrefix", "obj")

protected:
  /** Hidden constructor.
   * @param parent Specifies the QObject parent. */
  ConfigObject(QObject *parent = nullptr);

  /** Hidden constructor.
   * @param name Name of the object.
   * @param parent Specifies the QObject parent. */
  ConfigObject(const QString &name, QObject *parent = nullptr);

public:
  /** Returns the name of the object. */
  virtual const QString &name() const;
  /** Sets the name of the object. */
  virtual void setName(const QString &name);

public:
  /** Returns the ID prefix for this object. */
  QString idPrefix() const;
  bool label(Context &context, const ErrorStack &err=ErrorStack());
  bool parse(const YAML::Node &node, Context &ctx, const ErrorStack &err=ErrorStack());

protected:
  virtual bool populate(YAML::Node &node, const Context &context, const ErrorStack &err=ErrorStack());

  /** Helper to find the @c IdPrefix class info in the class hierarchy. */
  static QString findIdPrefix(const QMetaObject* meta);

protected:
  /** Holds the name of the object. */
  QString _name;
};


/** Base class of all device/vendor specific configuration extensions.
 * This class already implements the serialization of all @c QMetaObject
 * properties. */
class ConfigExtension : public ConfigItem
{
  Q_OBJECT

protected:
  /** Hidden constructor. */
  explicit ConfigExtension(QObject *parent=nullptr);
};


/** Generic list class for config objects.
 * @ingroup config */
class AbstractConfigObjectList: public QObject
{
  Q_OBJECT

protected:
  /** Hidden constructor. */
  explicit AbstractConfigObjectList(const QMetaObject &elementTypes=ConfigObject::staticMetaObject, QObject *parent = nullptr);
  /** Hidden constructor from initializer list. */
  AbstractConfigObjectList(const std::initializer_list<QMetaObject> &elementTypes, QObject *parent=nullptr);

public:
  /** Copies all elements from @c other to this list. */
  virtual bool copy(const AbstractConfigObjectList &other);

  /** Recursively labels the config object. */
  virtual bool label(ConfigItem::Context &context, const ErrorStack &err=ErrorStack()) = 0;
  /** Recursively serializes the configuration to YAML nodes.
   * The complete configuration must be labeled first. */
  virtual YAML::Node serialize(const ConfigItem::Context &context, const ErrorStack &err=ErrorStack()) = 0;

  /** Returns the number of elements in the list. */
  virtual int count() const;
  /** Returns the index of the given object within the list. */
  virtual int indexOf(ConfigObject *obj) const;
  /** Clears the list. */
  virtual void clear();

  /** Returns the config object, this list belongs to. */
  virtual const Config *config() const;
  /** Searches the config tree to find all instances of the given type names. */
  virtual void findItemsOfTypes(const QStringList &typeNames, QSet<ConfigItem*> &items) const;
  /** Searches the list for objects with the given name. */
  virtual QList<ConfigObject *> findItemsByName(const QString name) const;

  /** Returns @c true, if the list contains the given object. */
  virtual bool has(ConfigObject *obj) const;
  /** Returns the list element at the given index or @c nullptr if out of bounds. */
  virtual ConfigObject *get(int idx) const;
  /** Adds an element to the list. */
  virtual int add(ConfigObject *obj, int row=-1, bool unique=true);
  /** Replaces an element in the list. */
  virtual int replace(ConfigObject *obj, int row, bool unique=true);
  /** Removes an element from the list. */
  virtual bool take(ConfigObject *obj);
  /** Removes an element from the list (and deletes it if owned). */
  virtual bool del(ConfigObject *obj);

  /** Moves an object at index @c idx one step up. */
  virtual bool moveUp(int idx);
  /** Moves objects at [first, last] one step up. */
  virtual bool moveUp(int first, int last);
  /** Moves an object at index @c idx one step down. */
  virtual bool moveDown(int idx);
  /** Moves objects [first, last] one step down. */
  virtual bool moveDown(int first, int last);
  /** Moves the given source range to the destination index.
   * The destination index is given before the movement. That is, if elements 0 & 1 are moved to
   * indices 1 & 2, call @c move(0,2, 2) */
  virtual bool move(int source, int count, int destination);

  /** Returns the element type for this list. */
  const QList<QMetaObject> &elementTypes() const;
  /** Returns a list of all class names. */
  QStringList classNames() const;

signals:
  /** Gets emitted if an element was added to the list. */
  void elementAdded(int idx);
  /** Gets emitted if one of the lists elements gets modified. */
  void elementModified(int idx);
  /** Gets emitted if one of the lists elements gets deleted. */
  void elementRemoved(int idx);

private slots:
  /** Internal used callback to handle modified elements. */
  void onElementModified(ConfigItem *obj);
  /** Internal used callback to handle deleted elements. */
  void onElementDeleted(QObject *obj);

protected:
  /** Holds the static QMetaObject of the element type. */
  QList<QMetaObject> _elementTypes;
  /** Holds the list items. */
  QVector<ConfigObject *> _items;
};


/** List class for config objects.
 * This list owns the config objects it contains. See @c ConfigObjectRefList for a list of weak
 * references.
 * @ingroup config */
class ConfigObjectList: public AbstractConfigObjectList
{
  Q_OBJECT

protected:
  /** Hidden constructor. */
  explicit ConfigObjectList(const QMetaObject &elementTypes=ConfigItem::staticMetaObject, QObject *parent = nullptr);
  /** Hidden constructor from initializer list. */
  ConfigObjectList(const std::initializer_list<QMetaObject> &elementTypes, QObject *parent=nullptr);

public:
  int add(ConfigObject *obj, int row=-1, bool unique=true);
  bool take(ConfigObject *obj);
  bool del(ConfigObject *obj);
  void clear();
  bool copy(const AbstractConfigObjectList &other);

  /** Compares the object lists.
   *
   * This method returns 0 if the two lists are equivalent and -1, 1 otherwise. The established
   * order is somewhat arbitrary.
   *
   * @returns 0 if the two lists are equivalent, -1 or 1 otherwise.*/
  virtual int compare(const ConfigObjectList &other) const;

  /** Allocates a member objects for the given YAML node. */
  virtual ConfigItem *allocateChild(const YAML::Node &node, ConfigItem::Context &ctx, const ErrorStack &err=ErrorStack()) = 0;
  /** Parses the list from the YAML node. */
  virtual bool parse(const YAML::Node &node, ConfigItem::Context &ctx, const ErrorStack &err=ErrorStack());
  /** Links the list from the given YAML node. */
  virtual bool link(const YAML::Node &node, const ConfigItem::Context &ctx, const ErrorStack &err=ErrorStack());

  bool label(ConfigItem::Context &context, const ErrorStack &err=ErrorStack());
  YAML::Node serialize(const ConfigItem::Context &context, const ErrorStack &err=ErrorStack());
};


/** List class for config objects.
 * This list only references the config objects, see @c ConfigObjectList for a list that owns the
 * config objects.
 * @ingroup config */
class ConfigObjectRefList: public AbstractConfigObjectList
{
  Q_OBJECT

protected:
  /** Hidden constructor. */
  explicit ConfigObjectRefList(const QMetaObject &elementTypes=ConfigObject::staticMetaObject, QObject *parent = nullptr);
  /** Hidden constructor from initializer list. */
  ConfigObjectRefList(const std::initializer_list<QMetaObject> &elementTypes, QObject *parent=nullptr);

public:
  bool label(ConfigItem::Context &context, const ErrorStack &err=ErrorStack());
  YAML::Node serialize(const ConfigItem::Context &context, const ErrorStack &err=ErrorStack());

  /** Compares the object ref lists.
   *
   * This method returns 0 if the two lists are equivalent and -1, 1 otherwise. The established
   * order is somewhat arbitrary.
   *
   * @returns 0 if the two lists are equivalent, -1 or 1 otherwise.*/
  virtual int compare(const ConfigObjectRefList &other) const;
};


#endif // CONFIGOBJECT_HH