cantata/context/ultimatelyricsprovider.cpp

/*
 * Cantata
 *
 * Copyright (c) 2011-2013 Craig Drummond <craig.p.drummond@gmail.com>
 *
 */
/* This file is part of Clementine.
   Copyright 2010, David Sansome <me@davidsansome.com>

   Clementine 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 3 of the License, or
   (at your option) any later version.

   Clementine 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 Clementine.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "ultimatelyricsprovider.h"
#include "networkaccessmanager.h"
#include "song.h"
#include <QNetworkReply>
#include <QTextCodec>

static const int constRedirectLimit=5;

static QString extract(const QString &source, const QString &begin, const QString &end)
{
    int beginIdx = source.indexOf(begin);
    if (-1==beginIdx) {
        return QString();
    }
    beginIdx += begin.length();

    int endIdx = source.indexOf(end, beginIdx);
    if (-1==endIdx) {
        return QString();
    }

    return source.mid(beginIdx, endIdx - beginIdx - 1);
}

static QString extractXmlTag(const QString &source, const QString &tag)
{
    QRegExp re("<(\\w+).*>"); // ಠ_ಠ
    if (-1==re.indexIn(tag)) {
        return QString();
    }

    return extract(source, tag, "</" + re.cap(1) + ">");
}

static QString exclude(const QString &source, const QString &begin, const QString &end)
{
    int beginIdx = source.indexOf(begin);
    if (-1==beginIdx) {
        return source;
    }

    int endIdx = source.indexOf(end, beginIdx + begin.length());
    if (-1==endIdx) {
        return source;
    }

    return source.left(beginIdx) + source.right(source.length() - endIdx - end.length());
}

static QString excludeXmlTag(const QString &source, const QString &tag)
{
    QRegExp re("<(\\w+).*>"); // ಠ_ಠ
    if (-1==re.indexIn(tag)) {
        return source;
    }

    return exclude(source, tag, "</" + re.cap(1) + ">");
}

static void applyExtractRule(const UltimateLyricsProvider::Rule &rule, QString *content)
{
    foreach (const UltimateLyricsProvider::RuleItem& item, rule) {
        if (item.second.isNull()) {
            *content = extractXmlTag(*content, item.first);
        } else {
            *content = extract(*content, item.first, item.second);
        }
    }
}

static void applyExcludeRule(const UltimateLyricsProvider::Rule &rule, QString *content)
{
    foreach (const UltimateLyricsProvider::RuleItem& item, rule) {
        if (item.second.isNull()) {
            *content = excludeXmlTag(*content, item.first);
        } else {
            *content = exclude(*content, item.first, item.second);
        }
    }
}

static QString firstChar(const QString &text)
{
    return text.isEmpty() ? text : text[0].toLower();
}

static QString titleCase(const QString &text)
{
    if (0==text.length()) {
        return QString();
    }
    if (1==text.length()) {
        return text[0].toUpper();
    }
    return text[0].toUpper() + text.right(text.length() - 1).toLower();
}

UltimateLyricsProvider::UltimateLyricsProvider()
    : enabled(true)
    , relevance(0)
    , redirectCount(0)
{
}

void UltimateLyricsProvider::fetchInfo(int id, const Song &metadata)
{
    #if QT_VERSION < 0x050000
    const QTextCodec *codec = QTextCodec::codecForName(charset.toAscii().constData());
    #else
    const QTextCodec *codec = QTextCodec::codecForName(charset.toLatin1().constData());
    #endif
    if (!codec) {
        emit lyricsReady(id, QString());
        return;
    }

    // strip "featuring <someone else>" from the song.artist
    QString artistFixed=metadata.artist;
    QStringList toStrip;
    toStrip << QLatin1String(" ft. ") << QLatin1String(" feat. ") << QLatin1String(" featuring ");
    foreach (const QString s, toStrip) {
        int strip = artistFixed.toLower().indexOf( " ft. ");
        if (-1!=strip) {
            artistFixed = artistFixed.mid( 0, strip );
        }
    }

    // Fill in fields in the URL
    QString urlText(url);
    doUrlReplace("{artist}", artistFixed.toLower(),      &urlText);
    doUrlReplace("{album}",  metadata.album.toLower(),   &urlText);
    doUrlReplace("{title}",  metadata.title.toLower(),   &urlText);
    doUrlReplace("{Artist}", artistFixed,                &urlText);
    doUrlReplace("{Album}",  metadata.album,             &urlText);
    doUrlReplace("{Title}",  metadata.title,             &urlText);
    doUrlReplace("{Title2}", titleCase(metadata.title),  &urlText);
    doUrlReplace("{a}",      firstChar(artistFixed),     &urlText);

    // Fetch the URL, follow redirects
    redirectCount = 0;
    QNetworkReply *reply = NetworkAccessManager::self()->get(QNetworkRequest(QUrl(urlText)));
    requests[reply] = id;
    connect(reply, SIGNAL(finished()), SLOT(lyricsFetched()));
}

void UltimateLyricsProvider::lyricsFetched()
{
    QNetworkReply *reply = qobject_cast<QNetworkReply*>(sender());
    if (!reply)
        return;

    int id = requests.take(reply);
    reply->deleteLater();

    if (QNetworkReply::NoError!=reply->error()) {
        //emit Finished(id);
        emit lyricsReady(id, QString());
        return;
    }

    // Handle redirects
    QVariant redirect_target = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
    if (redirect_target.isValid()) {
        if (redirectCount >= constRedirectLimit) {
            //emit Finished(id);
            emit lyricsReady(id, QString());
            return;
        }

        QUrl target = redirect_target.toUrl();
        if (target.scheme().isEmpty() || target.host().isEmpty()) {
            QString path = target.path();
            target = reply->url();
            target.setPath(path);
        }

        redirectCount ++;
        QNetworkReply* reply = NetworkAccessManager::self()->get(QNetworkRequest(target));
        requests[reply] = id;
        connect(reply, SIGNAL(finished()), SLOT(lyricsFetched()));
        return;
    }

    #if QT_VERSION < 0x050000
    const QTextCodec *codec = QTextCodec::codecForName(charset.toAscii().constData());
    #else
    const QTextCodec *codec = QTextCodec::codecForName(charset.toLatin1().constData());
    #endif
    const QString original_content = codec->toUnicode(reply->readAll());

    // Check for invalid indicators
    foreach (const QString &indicator, invalidIndicators) {
        if (original_content.contains(indicator)) {
            //emit Finished(id);
            emit lyricsReady(id, QString());
            return;
        }
    }

    QString lyrics;

    // Apply extract rules
    foreach (const Rule& rule, extractRules) {
        QString content = original_content;
        applyExtractRule(rule, &content);

        if (!content.isEmpty()) {
            lyrics = content;
        }
    }

    // Apply exclude rules
    foreach (const Rule& rule, excludeRules) {
        applyExcludeRule(rule, &lyrics);
    }

    lyrics=lyrics.trimmed();
    emit lyricsReady(id, lyrics);
}

void UltimateLyricsProvider::doUrlReplace(const QString &tag, const QString &value, QString *u) const
{
    if (!u->contains(tag)) {
        return;
    }

    // Apply URL character replacement
    QString valueCopy(value);
    foreach (const UltimateLyricsProvider::UrlFormat& format, urlFormats) {
        QRegExp re("[" + QRegExp::escape(format.first) + "]");
        valueCopy.replace(re, format.second);
    }

    u->replace(tag, valueCopy, Qt::CaseInsensitive);
}