#include "mainwindow.h"

#include "imageprep.h"
#include "photoitemwidget.h"
#include "uploadclient.h"

#include <QDateTime>
#include <QFileDialog>
#include <QFileInfo>
#include <QFormLayout>
#include <QFuture>
#include <QFutureWatcher>
#include <QLabel>
#include <QLineEdit>
#include <QPushButton>
#include <QScrollArea>
#include <QSpinBox>
#include <QStackedWidget>
#include <QStandardPaths>
#include <QUuid>
#include <QVBoxLayout>
#include <QtConcurrent>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    setWindowTitle(QStringLiteral("Photo Gallery Uploader"));

    m_stack = new QStackedWidget(this);
    m_stack->addWidget(buildSettingsPage()); // index 0
    m_stack->addWidget(buildPostPage());     // index 1
    setCentralWidget(m_stack);

    if (m_settings.isConfigured())
        showPost();
    else
        showSettings();
}

QWidget *MainWindow::buildSettingsPage()
{
    auto *page = new QWidget;
    auto *layout = new QVBoxLayout(page);
    layout->setContentsMargins(24, 24, 24, 24);

    auto *form = new QFormLayout;
    m_baseUrl = new QLineEdit;
    m_baseUrl->setPlaceholderText(QStringLiteral("https://photos.example.com"));
    m_username = new QLineEdit;
    m_password = new QLineEdit;
    m_password->setEchoMode(QLineEdit::Password);
    m_concurrency = new QSpinBox;
    m_concurrency->setRange(1, Settings::kMaxConcurrency);
    form->addRow(QStringLiteral("Base URL"), m_baseUrl);
    form->addRow(QStringLiteral("Username"), m_username);
    form->addRow(QStringLiteral("Password"), m_password);
    form->addRow(QStringLiteral("Simultaneous uploads"), m_concurrency);
    layout->addLayout(form);

    m_saveButton = new QPushButton(QStringLiteral("Save && test connection"));
    connect(m_saveButton, &QPushButton::clicked, this, &MainWindow::saveAndTest);
    layout->addWidget(m_saveButton);

    m_settingsStatus = new QLabel;
    m_settingsStatus->setWordWrap(true);
    layout->addWidget(m_settingsStatus);

    m_settingsBack = new QPushButton(QStringLiteral("Back"));
    connect(m_settingsBack, &QPushButton::clicked, this, &MainWindow::showPost);
    layout->addWidget(m_settingsBack);

    layout->addWidget(new QLabel(QStringLiteral(
        "The password is stored in your system keychain, never in plain text. "
        "https is required — Basic auth would otherwise send it in the clear.")));
    layout->addStretch();
    return page;
}

QWidget *MainWindow::buildPostPage()
{
    auto *page = new QWidget;
    auto *outer = new QVBoxLayout(page);
    outer->setContentsMargins(24, 24, 24, 24);

    auto *choose = new QPushButton(QStringLiteral("Choose photos…"));
    connect(choose, &QPushButton::clicked, this, &MainWindow::chooseImages);
    outer->addWidget(choose);

    // Scrollable list of per-photo cards.
    auto *scroll = new QScrollArea;
    scroll->setWidgetResizable(true);
    auto *container = new QWidget;
    m_itemsLayout = new QVBoxLayout(container);
    m_itemsLayout->setAlignment(Qt::AlignTop);
    m_emptyHint = new QLabel(QStringLiteral("No photos selected"));
    m_emptyHint->setAlignment(Qt::AlignCenter);
    m_itemsLayout->addWidget(m_emptyHint);
    scroll->setWidget(container);
    outer->addWidget(scroll, 1);

    m_postButton = new QPushButton(QStringLiteral("Post"));
    m_postButton->setEnabled(false);
    connect(m_postButton, &QPushButton::clicked, this, &MainWindow::submit);
    outer->addWidget(m_postButton);

    m_postSummary = new QLabel;
    m_postSummary->setWordWrap(true);
    outer->addWidget(m_postSummary);

    m_lastPost = new QLabel;
    m_lastPost->setOpenExternalLinks(true);
    m_lastPost->setWordWrap(true);
    outer->addWidget(m_lastPost);

    auto *settingsButton = new QPushButton(QStringLiteral("Settings"));
    connect(settingsButton, &QPushButton::clicked, this, &MainWindow::showSettings);
    outer->addWidget(settingsButton);

    return page;
}

void MainWindow::showSettings()
{
    m_baseUrl->setText(m_settings.baseUrl());
    m_username->setText(m_settings.username());
    m_password->setText(m_settings.readPassword());
    m_concurrency->setValue(m_settings.concurrency());
    m_settingsStatus->clear();
    m_settingsBack->setVisible(m_settings.isConfigured());
    m_stack->setCurrentIndex(0);
}

void MainWindow::showPost()
{
    const Settings::LastPost last = m_settings.lastPost();
    if (last.valid()) {
        m_lastPost->setText(QStringLiteral("Last post: <a href=\"%1\">%2</a>")
                                .arg(last.url, last.caption.isEmpty() ? last.slug : last.caption));
    } else {
        m_lastPost->clear();
    }
    m_stack->setCurrentIndex(1);
}

void MainWindow::saveAndTest()
{
    // Concurrency is not a credential; persist it regardless of URL validity.
    m_settings.setConcurrency(m_concurrency->value());

    const QString urlError = Settings::validateBaseUrl(m_baseUrl->text());
    if (!urlError.isEmpty()) {
        m_settingsStatus->setText(urlError);
        return;
    }
    if (m_username->text().trimmed().isEmpty() || m_password->text().isEmpty()) {
        m_settingsStatus->setText(QStringLiteral("Username and password are required"));
        return;
    }

    m_settings.setBaseUrl(m_baseUrl->text());
    m_settings.setUsername(m_username->text());
    m_settings.writePassword(m_password->text());
    m_baseUrl->setText(m_settings.baseUrl());

    m_saveButton->setEnabled(false);
    m_settingsStatus->setText(QStringLiteral("Testing…"));

    auto *client = new UploadClient(m_settings.baseUrl(), m_settings.username(),
                                    m_settings.readPassword(), this);
    connect(client, &UploadClient::testFinished, this, [this, client](const QString &error) {
        m_saveButton->setEnabled(true);
        m_settingsBack->setVisible(m_settings.isConfigured());
        m_settingsStatus->setText(error.isEmpty()
                                      ? QStringLiteral("Saved — server reachable and credentials accepted")
                                      : error);
        client->deleteLater();
    });
    client->testConnection();
}

void MainWindow::chooseImages()
{
    const QStringList paths = QFileDialog::getOpenFileNames(
        this, QStringLiteral("Choose photos"), QString(),
        QStringLiteral("Images (*.jpg *.jpeg *.png *.heic *.heif *.webp *.tif *.tiff *.bmp);;All files (*)"));
    for (const QString &path : paths)
        addItem(path);
    refreshPosting();
}

void MainWindow::addItem(const QString &path)
{
    m_emptyHint->hide();
    auto *item = new PhotoItemWidget(path);
    connect(item, &PhotoItemWidget::removeRequested, this, &MainWindow::removeItem);
    m_items.append(item);
    m_itemsLayout->addWidget(item);
}

void MainWindow::removeItem(PhotoItemWidget *item)
{
    m_items.removeOne(item);
    m_queue.removeOne(item); // may be waiting for a slot — drop it before deleting
    item->deleteLater();
    if (m_items.isEmpty())
        m_emptyHint->show();
    refreshPosting();
}

void MainWindow::clearItems()
{
    for (PhotoItemWidget *item : std::as_const(m_items))
        item->deleteLater();
    m_items.clear();
    m_queue.clear();
    m_emptyHint->show();
    m_postSummary->clear();
    refreshPosting();
}

void MainWindow::submit()
{
    if (m_items.isEmpty())
        return;
    if (!m_settings.isConfigured()) {
        m_postSummary->setText(QStringLiteral("Set the server URL and credentials first"));
        return;
    }

    // Capture the batch's credentials once, then feed the queue through a
    // concurrency cap rather than firing every photo at the server at once.
    m_batchCacheDir = QStandardPaths::writableLocation(QStandardPaths::TempLocation);
    m_batchBaseUrl = m_settings.baseUrl();
    m_batchUsername = m_settings.username();
    m_batchPassword = m_settings.readPassword();

    m_queue.clear();
    for (PhotoItemWidget *item : std::as_const(m_items)) {
        if (item->status() != PhotoItemWidget::Status::Success)
            m_queue.append(item); // re-posting retries only failures
    }
    if (m_queue.isEmpty())
        return;

    m_postSummary->clear();
    pumpQueue();
    refreshPosting();
}

int MainWindow::inFlightCount() const
{
    int n = 0;
    for (PhotoItemWidget *item : std::as_const(m_items)) {
        const PhotoItemWidget::Status s = item->status();
        if (s == PhotoItemWidget::Status::Preparing || s == PhotoItemWidget::Status::Uploading)
            ++n;
    }
    return n;
}

void MainWindow::pumpQueue()
{
    const int cap = m_settings.concurrency();
    while (inFlightCount() < cap && !m_queue.isEmpty())
        startItem(m_queue.takeFirst());
}

void MainWindow::startItem(PhotoItemWidget *item)
{
    item->setStatus(PhotoItemWidget::Status::Preparing);

    // Slug from wall-clock time plus a per-item suffix so a batch posted in the
    // same second cannot collide (server derives the stored name from the
    // uploaded filename). The real capture date rides in the date field.
    const QString slug = QDateTime::currentDateTime().toString(QStringLiteral("yyyy-MM-dd-HHmmss"))
        + QLatin1Char('-') + QUuid::createUuid().toString(QUuid::Id128).left(6);
    const QString source = item->sourcePath();
    const QString cacheDir = m_batchCacheDir;
    const QString baseUrl = m_batchBaseUrl;
    const QString username = m_batchUsername;
    const QString password = m_batchPassword;

    auto *watcher = new QFutureWatcher<ImagePrep::Prepared>(this);
    connect(watcher, &QFutureWatcher<ImagePrep::Prepared>::finished, this,
            [this, watcher, item, baseUrl, username, password]() {
                const ImagePrep::Prepared prepared = watcher->result();
                watcher->deleteLater();

                if (!prepared.ok()) {
                    item->setStatus(PhotoItemWidget::Status::Error, prepared.error);
                    pumpQueue(); // free the slot for the next photo
                    refreshPosting();
                    return;
                }

                item->setStatus(PhotoItemWidget::Status::Uploading);
                const QString caption = item->caption();

                auto *client = new UploadClient(baseUrl, username, password, this);
                connect(client, &UploadClient::uploadFinished, this,
                        [this, client, item, prepared, caption](UploadClient::Result result,
                                                                const QString &slug, const QString &url,
                                                                const QString &message) {
                            QFile::remove(prepared.filePath); // no retry queue on the desktop
                            if (result == UploadClient::Result::Success) {
                                m_settings.setLastPost({slug, url, caption, QDateTime::currentDateTime()});
                                item->setStatus(PhotoItemWidget::Status::Success, {}, url);
                            } else {
                                item->setStatus(PhotoItemWidget::Status::Error, message);
                            }
                            client->deleteLater();
                            pumpQueue(); // free the slot for the next photo
                            refreshPosting();
                        });
                client->upload(prepared.filePath, QFileInfo(prepared.filePath).fileName(),
                               caption, item->date());
            });
    watcher->setFuture(QtConcurrent::run([source, cacheDir, slug]() {
        return ImagePrep::prepare(source, cacheDir, slug);
    }));
}

void MainWindow::refreshPosting()
{
    int pending = 0;
    int inFlight = 0;
    int succeeded = 0;
    int failed = 0;
    for (PhotoItemWidget *item : std::as_const(m_items)) {
        switch (item->status()) {
        case PhotoItemWidget::Status::Pending:
            ++pending;
            break;
        case PhotoItemWidget::Status::Preparing:
        case PhotoItemWidget::Status::Uploading:
            ++inFlight;
            break;
        case PhotoItemWidget::Status::Success:
            ++succeeded;
            break;
        case PhotoItemWidget::Status::Error:
            ++failed;
            ++pending; // a failure is re-postable
            break;
        }
    }

    const bool posting = inFlight > 0;
    m_postButton->setEnabled(!m_items.isEmpty() && !posting && pending > 0);
    m_postButton->setText(posting ? QStringLiteral("Posting… (%1/%2)").arg(succeeded).arg(m_items.size())
                          : pending == 1 ? QStringLiteral("Post 1 photo")
                          : pending > 1  ? QStringLiteral("Post %1 photos").arg(pending)
                                         : QStringLiteral("All posted"));

    if (!posting && (succeeded + failed) > 0) {
        QString summary = QStringLiteral("%1 posted").arg(succeeded);
        if (failed > 0)
            summary += QStringLiteral(", %1 failed").arg(failed);
        m_postSummary->setText(summary);
    }
}