#include "ControlsPanel.h"

#include <QFrame>
#include <QHBoxLayout>
#include <QLabel>
#include <QMouseEvent>
#include <QTimer>
#include <QVBoxLayout>

#include "ControlActionText.h"
#include "GameWorldView.h"
#include "selection/SelectionNames.h"

namespace
{

const int kMarginPx      = 8;   // between the band's edge and the panel
const int kCardMarginPx  = 8;   // inside the panel, around its content
const int kRefreshMs     = 50;  // see the class comment on why this polls

// Separates the heading's name from its detail, e.g. "BUILD MODE * Assembler".
const QChar kHeadingSeparator(0x00B7);  // U+00B7 MIDDLE DOT

// One row: the chips for the bindings, then what the action is called. Built as a plain
// widget rather than a class of its own -- it holds no state and answers no questions.
QWidget* makeRow(ControlAction action, const ControlContext& context, QWidget* parent)
{
    QWidget*     row    = new QWidget(parent);
    QHBoxLayout* layout = new QHBoxLayout(row);
    layout->setContentsMargins(0, 2, 0, 2);
    layout->setSpacing(4);

    // Every badge is rendered from the binding the resolver matches, so a chip cannot
    // claim a key that does nothing (REQ-UI-CONTROLS-ACCURACY).
    const std::vector<ControlBinding> bindings = getControlActionBindings(action, context);
    for (const ControlBinding& binding : bindings)
    {
        QLabel* badge = new QLabel(getControlBindingBadge(binding), row);
        badge->setObjectName(QStringLiteral("controlBadge"));
        layout->addWidget(badge);
    }

    QLabel* label = new QLabel(getControlActionLabel(action, context), row);
    label->setObjectName(action == ControlAction::ExitMode
                             ? QStringLiteral("controlLabelExit")
                             : QStringLiteral("controlLabel"));
    layout->addSpacing(4);
    layout->addWidget(label);
    layout->addStretch(1);
    return row;
}

}  // namespace

ControlsPanel::ControlsPanel(const GameWorldView* view, QWidget* parent)
    : QWidget(parent)
    , m_view(view)
{
    // Floats over the rendered world, so it brings its own background to stay legible
    // over any world content (REQ-UI-CONTROLS-PANEL). Palette colors match the build
    // button bar's and the selection panel's chrome; like them this is widget chrome
    // rather than world rendering, so it is deliberately not a visuals.toml color. The
    // class scoped selector keeps the border on the panel rather than cascading onto
    // its children.
    setAttribute(Qt::WA_StyledBackground, true);
    setStyleSheet(QStringLiteral(
        "ControlsPanel { background-color: palette(window);"
        " border: 1px solid palette(mid); border-radius: 4px; }"
        "QLabel#controlHeading { font-weight: bold; letter-spacing: 1px;"
        " color: palette(text); }"
        "QLabel#controlBadge { border: 1px solid palette(mid); border-radius: 3px;"
        " padding: 1px 5px; font-family: monospace; color: palette(text); }"
        "QLabel#controlLabel { color: palette(text); }"
        // The row that leaves the mode reads differently from the ones that act within
        // it (REQ-UI-CONTROLS-CARD).
        "QLabel#controlLabelExit { color: palette(bright-text); }"
        "QLabel#controlCaption { color: palette(mid); font-size: 10px;"
        " letter-spacing: 1px; }"));

    QVBoxLayout* outerLayout = new QVBoxLayout(this);
    outerLayout->setContentsMargins(kCardMarginPx, kCardMarginPx,
                                    kCardMarginPx, kCardMarginPx);
    outerLayout->setSpacing(4);

    m_heading = new QLabel(this);
    m_heading->setObjectName(QStringLiteral("controlHeading"));
    m_heading->setCursor(Qt::PointingHandCursor);
    outerLayout->addWidget(m_heading);

    m_rows       = new QWidget(this);
    m_rowsLayout = new QVBoxLayout(m_rows);
    m_rowsLayout->setContentsMargins(0, 0, 0, 0);
    m_rowsLayout->setSpacing(0);
    outerLayout->addWidget(m_rows);

    // Polling rather than subscribing; see the class comment.
    m_refreshTimer = new QTimer(this);
    connect(m_refreshTimer, &QTimer::timeout, this, &ControlsPanel::refresh);
    m_refreshTimer->start(kRefreshMs);

    refresh();
}

void ControlsPanel::anchorTo(const QRect& bandRect)
{
    m_bandRect = bandRect;
    refit();
}

void ControlsPanel::mousePressEvent(QMouseEvent* event)
{
    // Only the heading toggles; a click anywhere else is swallowed so it never reaches
    // the world beneath (REQ-UI-CONTROLS-PANEL).
    if (m_heading->geometry().contains(event->pos()))
    {
        m_collapsed = !m_collapsed;
        m_rows->setVisible(!m_collapsed);
        refit();
    }
    event->accept();
}

void ControlsPanel::refresh()
{
    if (!m_view) { return; }

    const ControlContext context = m_view->getControlContext();

    const QString                    heading = getHeadingText(context);
    const std::vector<ControlAction> contextActions = getContextActions(context);
    const std::vector<ControlAction> alwaysActions  = getAlwaysAvailableActions(context);

    if (heading == m_shownHeading && contextActions == m_shownContextActions
        && alwaysActions == m_shownAlwaysActions)
    {
        return;
    }

    m_shownHeading        = heading;
    m_shownContextActions = contextActions;
    m_shownAlwaysActions  = alwaysActions;
    rebuild(context);
}

void ControlsPanel::rebuild(const ControlContext& context)
{
    m_heading->setText(m_shownHeading);

    // Rows are rebuilt wholesale rather than reconciled: a context change replaces
    // nearly all of them, and the panel redraws only when something actually changed.
    while (QLayoutItem* item = m_rowsLayout->takeAt(0))
    {
        delete item->widget();
        delete item;
    }

    for (ControlAction action : m_shownContextActions)
    {
        m_rowsLayout->addWidget(makeRow(action, context, m_rows));
    }

    // The always-available block sits under a divider in every context, the General one
    // included, so the card is read the same way wherever the player is
    // (REQ-UI-CONTROLS-CARD).
    if (!m_shownAlwaysActions.empty())
    {
        QFrame* divider = new QFrame(m_rows);
        divider->setFrameShape(QFrame::HLine);
        divider->setFrameShadow(QFrame::Plain);
        m_rowsLayout->addSpacing(6);
        m_rowsLayout->addWidget(divider);

        QLabel* caption = new QLabel(tr("ALWAYS AVAILABLE"), m_rows);
        caption->setObjectName(QStringLiteral("controlCaption"));
        m_rowsLayout->addWidget(caption);
    }

    for (ControlAction action : m_shownAlwaysActions)
    {
        m_rowsLayout->addWidget(makeRow(action, context, m_rows));
    }

    m_rows->setVisible(!m_collapsed);
    refit();
}

QString ControlsPanel::getHeadingText(const ControlContext& context) const
{
    const ControlContextKind kind = getControlContextKind(context);
    const QString            name = getControlContextName(kind);

    QString detail;
    switch (kind)
    {
    case ControlContextKind::Build:
        detail = getBuildingTypeName(context.builderType);
        break;
    case ControlContextKind::Blueprint:
    {
        // The temporary blueprint is never named (REQ-UI-BLUEPRINT-TEMP), so it is
        // labelled by what it is rather than left blank.
        const QString blueprintName = m_view->getActiveBlueprintName();
        detail = blueprintName.isEmpty() ? tr("Temporary") : blueprintName;
        break;
    }
    case ControlContextKind::Selection:
        detail = context.selection == ControlSelection::Buildings
                     ? tr("%n building(s)", "", context.selectionCount)
                     : tr("%n object(s)", "", context.selectionCount);
        break;
    case ControlContextKind::General:
    case ControlContextKind::Deconstruct:
        break;
    }

    if (detail.isEmpty()) { return name; }
    return name + QStringLiteral(" ") + kHeadingSeparator + QStringLiteral(" ") + detail;
}

void ControlsPanel::refit()
{
    if (m_bandRect.isNull()) { return; }

    // The layout drops hidden widgets from its size hint, but only once it has been
    // re-run: collapsing hides the rows before Qt would get around to it on its own.
    layout()->activate();

    const QRect band = m_bandRect.adjusted(kMarginPx, kMarginPx, -kMarginPx, -kMarginPx);
    if (band.width() <= 0 || band.height() <= 0) { return; }

    const QSize hint     = sizeHint();
    const int   widthPx  = qMin(hint.width(), band.width());
    const int   heightPx = qMin(hint.height(), band.height());

    // Left edge of the band, sitting on its bottom edge, so the panel grows upward as
    // rows are added (REQ-UI-CONTROLS-PANEL).
    setGeometry(band.left(), band.bottom() - heightPx + 1, widthPx, heightPx);
}