/*
 * qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
 * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
 *
 * 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.
 */

#pragma once

#include <QString>

/// Where the cursor sits in a query, and therefore what should be offered.
///
/// A plain value type produced by a pure function so the parsing rules can be
/// tested without a widget or a database.
struct CompletionContext
{
    enum Kind {
        None,    ///< Complete nothing: inside a quoted literal, for instance.
        Prefix,  ///< Complete a query keyword: tag:, date:, and, or, not.
        Value,   ///< Complete a value for `prefix`.
    };

    Kind kind = None;

    /// For Value, the keyword left of ':', lowercased. Empty for Prefix.
    QString prefix;

    /// The text being matched against the candidates.
    QString stem;

    /// The exact span an accepted completion overwrites. Covers only the text
    /// being completed, so accepting never disturbs neighbouring text.
    int replaceFrom = 0;
    int replaceLength = 0;
};

/// Decides what the cursor position implies about completion.
///
/// `cursor` is an offset into `text`, as QLineEdit::cursorPosition() returns.
CompletionContext completionContext(const QString &text, int cursor);