#include "denote_metadata.h"

#include <QFileInfo>
#include <QRegularExpression>

namespace Denote {

QDateTime Metadata::creationDate() const
{
    if (identifier.isEmpty())
        return {};
    return QDateTime::fromString(identifier, QStringLiteral("yyyyMMdd'T'HHmmss"));
}

Metadata parseFilename(const QString &path)
{
    Metadata meta;
    meta.path = path;

    const QString fname = QFileInfo(path).fileName();

    // Identifier: leading YYYYMMDDTHHMMSS
    static const QRegularExpression reId(QStringLiteral("^(\\d{8}T\\d{6})"));
    auto m = reId.match(fname);
    if (m.hasMatch())
        meta.identifier = m.captured(1);

    // Signature: ==sig-- (between identifier and title)
    static const QRegularExpression reSig(QStringLiteral("==([^-]+?)--"));
    m = reSig.match(fname);
    if (m.hasMatch())
        meta.signature = m.captured(1);

    // Title: --title (first -- delimited segment, before __ or .)
    static const QRegularExpression reTitle(QStringLiteral("--([^_\\.]+)"));
    m = reTitle.match(fname);
    if (m.hasMatch()) {
        QString raw = m.captured(1);
        raw.replace(QLatin1Char('-'), QLatin1Char(' '));
        meta.title = raw;
    }

    // Tags: __tag1_tag2 (before extension or end)
    static const QRegularExpression reTags(QStringLiteral("__(.+?)(?:\\.|$)"));
    m = reTags.match(fname);
    if (m.hasMatch()) {
        meta.tags = m.captured(1).split(QLatin1Char('_'), Qt::SkipEmptyParts);
    }

    return meta;
}

QString generateIdentifier()
{
    return QDateTime::currentDateTime().toString(QStringLiteral("yyyyMMdd'T'HHmmss"));
}

QString slugifyTitle(const QString &title)
{
    QString slug = title.toLower();
    slug.replace(QLatin1Char(' '), QLatin1Char('-'));
    slug.replace(QLatin1Char('_'), QLatin1Char('-'));

    // Remove anything that isn't a-z, 0-9, or hyphen
    static const QRegularExpression reClean(QStringLiteral("[^a-z0-9-]"));
    slug.remove(reClean);

    return slug;
}

bool isValidTag(const QString &tag)
{
    if (tag.isEmpty())
        return false;
    for (const QChar &ch : tag) {
        if (!ch.isLetterOrNumber())
            return false;
        if (ch.isLetter() && ch.isUpper())
            return false;
    }
    return true;
}

QString buildFilename(const QString &title,
                      const QStringList &tags,
                      const QString &signature,
                      const QString &ext)
{
    QString result = generateIdentifier();

    // Signature
    if (!signature.isEmpty()) {
        QString sig = signature.toLower();
        sig.replace(QLatin1Char(' '), QStringLiteral("=="));
        sig.replace(QLatin1Char('_'), QStringLiteral("=="));
        // Remove special chars
        static const QRegularExpression reSigClean(
            QStringLiteral("[{}!@#$%^&*()+\'\"?,.\\\\|;:~`\u2018\u2019\u201c\u201d/-]"));
        sig.remove(reSigClean);
        // Normalize consecutive equals
        static const QRegularExpression reEq(QStringLiteral("={3,}"));
        sig.replace(reEq, QStringLiteral("=="));
        // Trim trailing =
        while (sig.endsWith(QLatin1Char('=')))
            sig.chop(1);
        result += QStringLiteral("==") + sig;
    }

    // Title
    result += QStringLiteral("--") + slugifyTitle(title);

    // Tags
    if (!tags.isEmpty()) {
        result += QStringLiteral("__") + tags.join(QLatin1Char('_'));
    }

    // Extension
    result += ext;

    return result;
}

} // namespace Denote