/*
  Copyright (c) 2015-2016 Montel Laurent <montel@kde.org>

  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License, version 2, as
  published by the Free Software Foundation.

  This program 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
  General Public License for more details.

  You should have received a copy of the GNU General Public License along
  with this program; if not, write to the Free Software Foundation, Inc.,
  51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
#ifndef SEARCHRULE_H
#define SEARCHRULE_H

#include "mailcommon_export.h"
#include <AkonadiCore/SearchQuery>

#include <AkonadiCore/Item>

class KConfigGroup;
namespace MailCommon
{
/**
 * @short This class represents one search pattern rule.
 * Incoming mail is sent through the list of mail filter
 * rules before it is placed in the associated mail folder (usually "inbox").
 * This class represents one mail filter rule. It is also used to represent
 * a search rule as used by the search dialog and folders.
 */
class MAILCOMMON_EXPORT SearchRule
{
public:
    /**
     * Defines a pointer to a search rule.
     */
    typedef std::shared_ptr<SearchRule> Ptr;

    /**
     * Describes operators for comparison of field and contents.
     *
     * If you change the order or contents of the enum: do not forget
     * to change funcConfigNames[], sFilterFuncList and matches()
     * in SearchRule, too.
     * Also, it is assumed that these functions come in pairs of logical
     * opposites (ie. "=" <-> "!=", ">" <-> "<=", etc.).
     */
    enum Function {
        FuncNone = -1,
        FuncContains = 0,
        FuncContainsNot,
        FuncEquals,
        FuncNotEqual,
        FuncRegExp,
        FuncNotRegExp,
        FuncIsGreater,
        FuncIsLessOrEqual,
        FuncIsLess,
        FuncIsGreaterOrEqual,
        FuncIsInAddressbook,
        FuncIsNotInAddressbook,
        FuncIsInCategory,
        FuncIsNotInCategory,
        FuncHasAttachment,
        FuncHasNoAttachment,
        FuncStartWith,
        FuncNotStartWith,
        FuncEndWith,
        FuncNotEndWith
    };

    enum RequiredPart {
        Envelope = 0,
        Header,
        CompleteMessage
    };

    /**
     * Creates new new search rule.
     *
     * @param field The field to search in.
     * @param function The function to use for searching.
     * @param contents The contents to search for.
     */
    explicit SearchRule(const QByteArray &field = QByteArray(), Function function = FuncContains,
                        const QString &contents = QString());

    /**
     * Creates a new search rule from an @p other rule.
     */
    SearchRule(const SearchRule &other);

    /**
     * Initializes this rule with an @p other rule.
     */
    const SearchRule &operator=(const SearchRule &other);

    /**
     * Creates a new search rule of a certain type by instantiating the
     * appropriate subclass depending on the @p field.
     *
     * @param field The field to search in.
     * @param function The function to use for searching.
     * @param contents The contents to search for.
     */
    static SearchRule::Ptr createInstance(const QByteArray &field = 0,
                                          Function function = FuncContains,
                                          const QString &contents = QString());

    /**
     * Creates a new search rule of a certain type by instantiating the
     * appropriate subclass depending on the @p field.
     *
     * @param field The field to search in.
     * @param function The name of the function to use for searching.
     * @param contents The contents to search for.
     */
    static SearchRule::Ptr createInstance(const QByteArray &field,
                                          const char *function,
                                          const QString &contents);

    /**
     * Creates a new search rule by cloning an @p other rule.
     */
    static SearchRule::Ptr createInstance(const SearchRule &other);

    /**
     * Creates a new search rule by deseralizing its structure from a data @p stream.
     */
    static SearchRule::Ptr createInstance(QDataStream &stream);

    /**
     * Creates a new search rule from a given config @p group.
     *
     * @param group The config group to read the structure from.
     * @param index The identifier that is used to distinguish
     *              rules within a single config group.
     *
     * @note This function does no validation of the data obtained
     *       from the config file. You should call isEmpty yourself
     *       if you need valid rules.
     */
    static SearchRule::Ptr createInstanceFromConfig(const KConfigGroup &group, int index);

    /**
     * Destroys the search rule.
     */
    virtual ~SearchRule();

    /**
     * Tries to match the rule against the KMime::Message in the
     * given @p item.
     *
     * @return true if the rule matched, false otherwise.
     *
     * @note Must be implemented by subclasses.
     */
    virtual bool matches(const Akonadi::Item &item) const = 0;

    /**
     * Determines whether the rule is worth considering.
     * It isn't if either the field is not set or the contents is empty.
     * The calling code should make sure that it's rule list contains
     * only non-empty rules, as matches doesn't check this.
     */
    virtual bool isEmpty() const = 0;

    /**
     * Returns the required part from the item that is needed for the search to
     * operate. See @ref RequiredPart */
    virtual SearchRule::RequiredPart requiredPart() const = 0;

    /**
     * Saves the object into a given config @p group.
     *
     * @param index The identifier that is used to distinguish
     *              rules within a single config group.
     *
     * @note This function will happily write itself even when it's
     *       not valid, assuming higher layers to Do The Right Thing(TM).
     */
    void writeConfig(KConfigGroup &group, int index) const;

    void generateSieveScript(QStringList &requires, QString &code);

    /**
     * Sets the filter @p function of the rule.
     */
    void setFunction(Function function);

    /**
     * Returns the filter function of the rule.
     */
    Function function() const;

    /**
     * Sets the message header field @p name.
     *
     * @note Make sure the name contains no trailing ':'.
     */
    void setField(const QByteArray &name);

    /**
     * Returns the message header field name (without the trailing ':').
     *
     * There are also six pseudo-headers:
     * @li \<message\>: Try to match against the whole message.
     * @li \<body\>: Try to match against the body of the message.
     * @li \<any header\>: Try to match against any header field.
     * @li \<recipients\>: Try to match against both To: and Cc: header fields.
     * @li \<size\>: Try to match against size of message (numerical).
     * @li \<age in days\>: Try to match against age of message (numerical).
     * @li \<status\>: Try to match against status of message (status).
     * @li \<tag\>: Try to match against message tags.
     */
    QByteArray field() const;

    /**
     * Set the @p contents of the rule.
     *
     * This can be either a substring to search for in
     * or a regexp pattern to match against the header.
     */
    void setContents(const QString &contents);

    /**
     * Returns the contents of the rule.
     */
    QString contents() const;

    /**
     * Returns the rule as string for debugging purpose
     */
    const QString asString() const;

    /**
     * Adds query terms to the given term group.
     */
    virtual void addQueryTerms(Akonadi::SearchTerm &groupTerm, bool &emptyIsNotAnError) const
    {
        Q_UNUSED(groupTerm);
        Q_UNUSED(emptyIsNotAnError);
    }

    QDataStream &operator>>(QDataStream &) const;
    virtual QString informationAboutNotValidRules() const
    {
        return QString();
    }

protected:
    /**
     * Helper that returns whether the rule has a negated function.
     */
    bool isNegated() const;

    /**
     * Converts the rule function into the corresponding Akonadi query operator.
     */
    Akonadi::SearchTerm::Condition akonadiComparator() const;

protected:
    QString quote(const QString &content) const;
private:
    static Function configValueToFunc(const char *);
    static QString functionToString(Function);
    QString conditionToString(Function function);

    QByteArray mField;
    Function mFunction;
    QString  mContents;
};
}

#endif // SEARCHRULE_H
