/*
* Copyright (C) 2015 The Lemon Man
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* 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.
*/

namespace Gedit {
namespace FindInFilesPlugin {

class RegexFind : Object, IMatcher {
    private Regex re;

    public RegexFind (string pattern, bool ignore_case) throws Error {
        var flags = RegexCompileFlags.OPTIMIZE;

        if (ignore_case)
            flags |= RegexCompileFlags.CASELESS;

        re = new Regex (pattern, flags);
    }

    public bool has_match (uint8 *text, size_t text_length, size_t pos, ref Range match) {
        MatchInfo info;
        int casted_pos;

        // Prevent an integer overflow when downcasting from size_t to int
        if (pos > int.MAX) {
            casted_pos = 0;
            text += pos;
        } else {
            casted_pos = (int)pos;
        }

        // Avoid strdup-ing the whole buffer
        unowned string str = (string)text;

        // Pass the text length as str isn't null terminated
        try {
            if (!re.match_full (str, (ssize_t)text_length, casted_pos, 0, out info))
                return false;
        }
        catch (RegexError err) {
            warning (err.message);
            return false;
        }

        info.fetch_pos (0, out match.from, out match.to);

        return true;
    }
}

class BoyerMooreHorspool : Object, IMatcher {
    private string pattern;
    private int bad_char_shift[256];

    private bool ignore_case;

    public BoyerMooreHorspool (string pattern_, bool ignore_case_) {
        pattern = pattern_;
        ignore_case = ignore_case_;

        for (int i = 0; i < 256; i++) {
            bad_char_shift[i] = pattern.length;
        }

        for (int i = 0; i < pattern.length - 1; i++) {
            if (ignore_case) {
                bad_char_shift[Posix.toupper(pattern[i])] = pattern.length - 1 - i;
                bad_char_shift[Posix.tolower(pattern[i])] = pattern.length - 1 - i;
            } else {
                bad_char_shift[pattern[i]] = pattern.length - 1 - i;
            }
        }
    }

    public bool has_match (uint8 *text, size_t text_length, size_t pos, ref Range match) {
        uint i = 0;

        text += pos;
        text_length -= pos;

        if (text_length < pattern.length)
            return false;

        while (i <= text_length - pattern.length) {
            for (int j = pattern.length - 1; j >= 0; j--) {
                // Check for a match backwards
                if (ignore_case) {
                    if (Posix.tolower(text[i + j]) != Posix.tolower(pattern[j]))
                        break;
                } else {
                    if (text[i + j] != pattern[j])
                        break;
                }

                // The whole needle has been matched!
                if (j == 0) {
                    match.from = pos + i;
                    match.to = match.from + pattern.length;
                    return true;
                }
            }

            // Jump ahead in the buffer
            i += bad_char_shift[text[i + pattern.length - 1]];
        }

        return false;
    }
}

} // namespace FindInFilesPlugin
} // namespace Gedit