#include "opdsparser.h"

#include <QStringList>
#include <QVariantMap>
#include <QXmlStreamReader>

static QString elementText(QXmlStreamReader &reader)
{
    return reader.readElementText(QXmlStreamReader::IncludeChildElements).trimmed();
}

static QVariantMap parseEntry(QXmlStreamReader &reader)
{
    QVariantMap entry;
    QStringList authors;
    QVariantList formats;
    QString title;
    QString summary;
    QString id;
    QString coverHref;
    QString thumbHref;
    QString navHref;

    while (!reader.atEnd()) {
        reader.readNext();
        if (reader.tokenType() == QXmlStreamReader::EndElement
                && reader.name() == QLatin1String("entry"))
            break;
        if (reader.tokenType() != QXmlStreamReader::StartElement)
            continue;

        const QStringRef name = reader.name();
        if (name == QLatin1String("title")) {
            title = elementText(reader);
        } else if (name == QLatin1String("id")) {
            id = elementText(reader);
        } else if (name == QLatin1String("name")) {
            const QString author = elementText(reader);
            if (!author.isEmpty())
                authors.append(author);
        } else if (name == QLatin1String("content") || name == QLatin1String("summary")) {
            if (summary.isEmpty())
                summary = elementText(reader);
        } else if (name == QLatin1String("link")) {
            const QXmlStreamAttributes attrs = reader.attributes();
            const QString rel = attrs.value(QLatin1String("rel")).toString();
            const QString href = attrs.value(QLatin1String("href")).toString();
            const QString type = attrs.value(QLatin1String("type")).toString();

            if (rel == QLatin1String("http://opds-spec.org/image")) {
                coverHref = href;
            } else if (rel == QLatin1String("http://opds-spec.org/image/thumbnail")) {
                thumbHref = href;
            } else if (rel == QLatin1String("http://opds-spec.org/acquisition")) {
                QVariantMap format;
                format.insert(QStringLiteral("format"), attrs.value(QLatin1String("title")).toString());
                format.insert(QStringLiteral("mime"), type);
                format.insert(QStringLiteral("size"), attrs.value(QLatin1String("length")).toString().toLongLong());
                format.insert(QStringLiteral("url"), href);
                formats.append(format);
            } else if (rel == QLatin1String("subsection")) {
                if (navHref.isEmpty())
                    navHref = href;
            } else if (navHref.isEmpty() && type.contains(QLatin1String("opds-catalog"))) {
                // calibre-web: i link di navigazione dell'indice non hanno rel="subsection"
                navHref = href;
            }
        }
    }

    entry.insert(QStringLiteral("title"), title);
    entry.insert(QStringLiteral("authors"), authors.join(QStringLiteral(", ")));
    entry.insert(QStringLiteral("summary"), summary);
    entry.insert(QStringLiteral("coverUrl"), !coverHref.isEmpty() ? coverHref : thumbHref);
    entry.insert(QStringLiteral("formats"), formats);
    entry.insert(QStringLiteral("id"), id);
    entry.insert(QStringLiteral("isNavigation"), !navHref.isEmpty());
    entry.insert(QStringLiteral("linkUrl"), navHref);
    return entry;
}

bool OpdsParser::parse(const QByteArray &xml,
                       QVariantList *entries,
                       QString *nextUrl,
                       QString *feedTitle,
                       QString *errorMessage)
{
    QXmlStreamReader reader(xml);
    QVariantList result;
    QString next;
    QString title;

    while (!reader.atEnd()) {
        reader.readNext();
        if (reader.tokenType() != QXmlStreamReader::StartElement)
            continue;

        const QStringRef name = reader.name();
        if (name == QLatin1String("entry")) {
            result.append(parseEntry(reader));
        } else if (name == QLatin1String("link")) {
            const QXmlStreamAttributes attrs = reader.attributes();
            if (attrs.value(QLatin1String("rel")).toString() == QLatin1String("next"))
                next = attrs.value(QLatin1String("href")).toString();
        } else if (name == QLatin1String("title") && title.isEmpty()) {
            title = elementText(reader);
        }
    }

    if (reader.hasError() && result.isEmpty()) {
        if (errorMessage)
            *errorMessage = reader.errorString();
        return false;
    }

    if (entries)
        *entries = result;
    if (nextUrl)
        *nextUrl = next;
    if (feedTitle)
        *feedTitle = title;
    return true;
}