#include "memberlistmodel.h"
#include "../db/db_manager.h"
#include <QPainter>
#include <QFont>
#include <QTimer>

MemberListModel::MemberListModel(DbManager* db, QObject* parent)
    : QAbstractListModel(parent), m_db(db) {}

int MemberListModel::rowCount(const QModelIndex& parent) const {
    (void)parent;
    return m_totalCount;
}

QVariant MemberListModel::data(const QModelIndex& index, int role) const {
    if (!index.isValid() || index.row() < 0 || index.row() >= m_totalCount)
        return {};

    auto it = m_cache.find(index.row());
    if (it != m_cache.end()) {
        if (role == Qt::DisplayRole) return it->name;
        if (role == Qt::DecorationRole) return QVariant::fromValue(QIcon(it->avatar));
        if (role == Qt::ToolTipRole)
            return QString(it->online ? "online" : "offline") + " | 0x" +
                   QString("%1").arg(it->nodeId, 16, 16, QChar('0'));
        return {};
    }

    if (role == Qt::DisplayRole) {
        scheduleBatch(index.row());
        return QStringLiteral("\u2026");
    }
    return {};
}

void MemberListModel::setChannel(const QString& channelId) {
    beginResetModel();
    m_channelId = channelId;
    m_totalCount = m_db ? m_db->getChannelMemberCount(channelId) : 0;
    m_cache.clear();
    m_pendingFrom = -1;
    endResetModel();
    if (m_totalCount > 0) scheduleBatch(0);
}

void MemberListModel::refresh() { if (!m_channelId.isEmpty()) setChannel(m_channelId); }

void MemberListModel::scheduleBatch(int centerRow) const {
    if (m_pendingFrom >= 0) return;
    int from = centerRow - BATCH / 2;
    if (from < 0) from = 0;
    int maxFrom = m_totalCount - BATCH;
    if (from > maxFrom) from = maxFrom > 0 ? maxFrom : 0;
    const_cast<MemberListModel*>(this)->m_pendingFrom = from;
    const_cast<MemberListModel*>(this)->m_pendingCount = BATCH;
    QTimer::singleShot(0, const_cast<MemberListModel*>(this), &MemberListModel::loadPendingBatch);
}

void MemberListModel::loadPendingBatch() {
    if (m_pendingFrom < 0) return;
    int from = m_pendingFrom, count = m_pendingCount;
    m_pendingFrom = -1;
    loadBatch(from, count);
}

void MemberListModel::loadBatch(int from, int count) {
    if (!m_db || m_channelId.isEmpty()) return;
    int maxFrom = m_totalCount - count;
    if (from > maxFrom) from = maxFrom > 0 ? maxFrom : 0;

    auto members = m_db->getChannelMembers(m_channelId, from, count);
    for (int i = 0; i < members.size(); i++) {
        int row = from + i;
        MemberListItem& item = m_cache[row];
        item.nodeId = members[i].nodeId;
        item.online = members[i].online;
        QString shortId = QString("%1").arg(members[i].nodeId, 8, 16, QChar('0')).right(4).toUpper();
        item.name = members[i].name.isEmpty() ? shortId : members[i].name;
        QColor c = members[i].online ? QColor("#4CAF50") : QColor("#9E9E9E");
        item.avatar = makeAvatar(c, item.name[0]);
    }
    evictDistant(from + BATCH / 2);

    int last = from + (int)members.size() - 1;
    if (last >= from) emit dataChanged(index(from), index(last));
}

void MemberListModel::evictDistant(int centerRow) {
    if (m_cache.size() <= MAX_CACHE) return;
    int half = MAX_CACHE / 2;
    QList<int> toRemove;
    for (auto it = m_cache.begin(); it != m_cache.end(); ++it)
        if (qAbs(it.key() - centerRow) > half)
            toRemove.append(it.key());
    for (int k : toRemove) m_cache.remove(k);
}

QPixmap MemberListModel::makeAvatar(QColor color, QChar letter) const {
    QPixmap pm(24, 24);
    pm.fill(Qt::transparent);
    QPainter p(&pm);
    p.setRenderHint(QPainter::Antialiasing);
    p.setBrush(color);
    p.setPen(Qt::NoPen);
    p.drawEllipse(2, 2, 20, 20);
    p.setPen(Qt::white);
    QFont f; f.setBold(true); f.setPixelSize(12);
    p.setFont(f);
    p.drawText(QRect(0, 0, 24, 24), Qt::AlignCenter, QString(letter));
    p.end();
    return pm;
}