#include "apiclient.h"

#include "opdsparser.h"
#include "settings.h"

#include <QCryptographicHash>
#include <QDebug>
#include <QDir>
#include <QFile>
#include <QFileInfo>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QSslError>
#include <QStandardPaths>
#include <QTimer>
#include <QUrl>

ApiClient::ApiClient(Settings *settings, QObject *parent)
    : QObject(parent)
    , m_settings(settings)
{
    m_cacheDir = QStandardPaths::writableLocation(QStandardPaths::CacheLocation)
            + QStringLiteral("/covers");
    QDir().mkpath(m_cacheDir);
}

QString ApiClient::resolveUrl(const QString &relative) const
{
    if (relative.isEmpty())
        return QString();
    if (relative.startsWith(QLatin1String("http://"))
            || relative.startsWith(QLatin1String("https://")))
        return relative;
    // risoluzione RFC 3986: gestisce i path assoluti del server (es. /calibre/opds/books)
    // senza raddoppiare il sottopath già presente nel baseUrl
    QUrl base(m_settings->baseUrl());
    return base.resolved(QUrl(relative)).toString();
}

void ApiClient::applyAuth(QNetworkRequest &request)
{
    const QString auth = m_settings->authHeader();
    if (!auth.isEmpty())
        request.setRawHeader("Authorization", auth.toUtf8());
}

QNetworkReply *ApiClient::startGet(const QUrl &url)
{
    QNetworkRequest request(url);
    request.setRawHeader("Accept",
                         "application/atom+xml, application/xml, text/xml;q=0.9, */*;q=0.8");
    request.setRawHeader("User-Agent", "harbour-calibreweb/0.1");
    applyAuth(request);

    QNetworkReply *reply = m_nam.get(request);
    if (m_settings->ignoreSslErrors()) {
        connect(reply, &QNetworkReply::sslErrors, reply,
                static_cast<void (QNetworkReply::*)(const QList<QSslError> &)>(
                        &QNetworkReply::ignoreSslErrors));
    }

    // timeout di sicurezza (30 s): senza, una richiesta verso un host irraggiungibile
    // resta appesa all'infinito
    QTimer *timer = new QTimer(reply);
    timer->setSingleShot(true);
    timer->setInterval(30000);
    connect(timer, &QTimer::timeout, reply, &QNetworkReply::abort);
    timer->start();
    return reply;
}

void ApiClient::getFeed(const QString &url)
{
    // i link dei feed OPDS sono spesso relativi (/opds/new): risolvi contro il server
    const QString resolved = resolveUrl(url);
    qDebug() << "getFeed request:" << resolved;
    QNetworkReply *reply = startGet(QUrl(resolved));
    connect(reply, &QNetworkReply::finished, this, [this, reply]() {
        reply->deleteLater();
        const int status = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
        if (reply->error() != QNetworkReply::NoError || status >= 400) {
            QString message;
            if (reply->error() == QNetworkReply::OperationCanceledError)
                message = QStringLiteral("Timeout: il server non risponde (30 s)");
            else if (status == 401)
                message = QStringLiteral(
                        "Autenticazione richiesta (401). Controlla utente e password.");
            else if (status == 404)
                message = QStringLiteral("Endpoint non trovato (404). Controlla l'indirizzo.");
            else
                message = reply->errorString();
            qDebug() << "getFeed ERROR status:" << status
                     << "error:" << reply->error() << "-" << message;
            emit feedError(message);
            return;
        }

        const QByteArray body = reply->readAll();
        QVariantList entries;
        QString nextUrl;
        QString feedTitle;
        QString parseError;
        if (OpdsParser::parse(body, &entries, &nextUrl, &feedTitle, &parseError)) {
            qDebug() << "getFeed OK status:" << status
                     << "entries:" << entries.size();
            emit feedReady(entries, resolveUrl(nextUrl), feedTitle);
        } else {
            // risposta 2xx ma non XML: quasi sempre una pagina HTML (redirect/login/URL errato)
            const QByteArray contentType = reply->header(
                    QNetworkRequest::ContentTypeHeader).toByteArray();
            QString message;
            if (contentType.contains("html") || body.trimmed().startsWith("<!DOCTYPE")
                    || body.trimmed().startsWith("<html")) {
                message = QStringLiteral(
                        "Il server ha risposto con una pagina HTML, non OPDS. "
                        "Controlla l'indirizzo (es. sottopath /calibre) e che il browse anonimo "
                        "o le credenziali siano corretti.");
            } else {
                message = parseError.isEmpty()
                        ? QStringLiteral("Risposta non valida dal server")
                        : parseError;
            }
            qDebug() << "getFeed parse error:" << parseError
                     << "content-type:" << contentType;
            emit feedError(message);
        }
    });
}

void ApiClient::fetchImage(const QString &url, const QString &id)
{
    if (url.isEmpty()) {
        emit imageReady(id, QString());
        return;
    }

    const QString resolved = resolveUrl(url);
    const QUrl imageUrl(resolved);

    QString fileName = QString::fromLatin1(
            QCryptographicHash::hash(imageUrl.path().toUtf8(), QCryptographicHash::Md5).toHex());
    const QString suffix = QFileInfo(imageUrl.path()).suffix();
    if (!suffix.isEmpty() && suffix.length() <= 5)
        fileName += QLatin1Char('.') + suffix;
    const QString localPath = m_cacheDir + QLatin1Char('/') + fileName;

    if (QFile::exists(localPath)) {
        emit imageReady(id, localPath);
        return;
    }

    QNetworkReply *reply = startGet(imageUrl);
    connect(reply, &QNetworkReply::finished, this, [this, reply, id, localPath]() {
        reply->deleteLater();
        const int status = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
        if (reply->error() != QNetworkReply::NoError || status >= 400) {
            emit imageReady(id, QString());
            return;
        }
        QFile file(localPath);
        if (file.open(QIODevice::WriteOnly)) {
            file.write(reply->readAll());
            file.close();
            emit imageReady(id, localPath);
        } else {
            emit imageReady(id, QString());
        }
    });
}