#include "screens/polymarket/PolymarketOrderBook.h"

#include "ui/theme/Theme.h"
#include "ui/theme/ThemeManager.h"

#include <QMouseEvent>
#include <QPainter>
#include <QVBoxLayout>

#include <algorithm>

namespace fincept::screens::polymarket {

using namespace fincept::ui;
using namespace fincept::services::prediction;

PolymarketOrderBook::PolymarketOrderBook(QWidget* parent) : QWidget(parent) {
    setMinimumHeight(200);
    setAccessibleName(tr("Order book"));
    setToolTip(tr("Click a price level to load it into the trade ticket."));

    connect(&ui::ThemeManager::instance(), &ui::ThemeManager::theme_changed, this, [this](const ui::ThemeTokens&) {
        cache_dirty_ = true;
        update();
    });

    repaint_timer_ = new QTimer(this);
    repaint_timer_->setInterval(50); // 20fps max
    connect(repaint_timer_, &QTimer::timeout, this, [this]() {
        if (cache_dirty_) {
            rebuild_cache();
            update();
        }
    });
}

void PolymarketOrderBook::set_data(const PredictionOrderBook& book) {
    QMutexLocker lock(&mutex_);
    bids_ = book.bids;
    asks_ = book.asks;

    // Calculate spread
    double best_bid = bids_.isEmpty() ? 0 : bids_[0].price;
    double best_ask = asks_.isEmpty() ? 0 : asks_[0].price;
    spread_ = (best_bid > 0 && best_ask > 0) ? (best_ask - best_bid) : 0;

    cache_dirty_ = true;
}

void PolymarketOrderBook::clear() {
    QMutexLocker lock(&mutex_);
    bids_.clear();
    asks_.clear();
    spread_ = 0;
    cache_dirty_ = true;
    update();
}

void PolymarketOrderBook::showEvent(QShowEvent* e) {
    QWidget::showEvent(e);
    repaint_timer_->start();
}

void PolymarketOrderBook::hideEvent(QHideEvent* e) {
    QWidget::hideEvent(e);
    repaint_timer_->stop();
}

void PolymarketOrderBook::resizeEvent(QResizeEvent* e) {
    QWidget::resizeEvent(e);
    cache_dirty_ = true;
}

void PolymarketOrderBook::paintEvent(QPaintEvent*) {
    if (cache_dirty_)
        rebuild_cache();
    QPainter p(this);
    p.drawPixmap(0, 0, cache_);
}

void PolymarketOrderBook::mousePressEvent(QMouseEvent* event) {
    int y = event->pos().y();
    if (y < HEADER_HEIGHT)
        return;

    // Resolve which price level was clicked using the SAME visible-row counts the
    // painter used, otherwise a click lands on a different level than the one
    // drawn (which, for a trading order book, fills the order form with a wrong
    // price). Compute under the lock, then emit outside it so a slot that calls
    // back into set_data()/clear() can't deadlock on mutex_.
    double clicked_price = 0.0;
    bool has_click = false;
    {
        QMutexLocker lock(&mutex_);
        int row_idx = (y - HEADER_HEIGHT) / ROW_HEIGHT;
        int ask_rows = 0, bid_rows = 0;
        visible_row_counts(ask_rows, bid_rows);

        if (row_idx < ask_rows) {
            // Asks are painted highest-first (reversed), so the top row is the
            // last ask index and the row just above the spread is asks_[0].
            int ask_i = ask_rows - 1 - row_idx;
            if (ask_i >= 0 && ask_i < asks_.size()) {
                clicked_price = asks_[ask_i].price;
                has_click = true;
            }
        } else {
            int bid_idx = row_idx - ask_rows - 1; // -1 for the spread row
            if (bid_idx >= 0 && bid_idx < bid_rows && bid_idx < bids_.size()) {
                clicked_price = bids_[bid_idx].price;
                has_click = true;
            }
        }
    }
    if (has_click)
        emit price_clicked(clicked_price);
}

void PolymarketOrderBook::visible_row_counts(int& ask_rows, int& bid_rows) const {
    const int h = height();
    const int max_rows = (h - HEADER_HEIGHT) / ROW_HEIGHT;
    ask_rows = qMin(asks_.size(), qMax(1, max_rows / 2 - 1));
    bid_rows = qMin(bids_.size(), qMax(1, max_rows / 2 - 1));
}

void PolymarketOrderBook::rebuild_cache() {
    QMutexLocker lock(&mutex_);
    cache_dirty_ = false;

    int w = width();
    int h = height();
    if (w <= 0 || h <= 0)
        return;

    cache_ = QPixmap(w, h);
    cache_.fill(QColor(colors::BG_BASE()));
    QPainter p(&cache_);
    p.setRenderHint(QPainter::Antialiasing, false);

    QFont header_font(fonts::DATA_FAMILY, 8);
    header_font.setWeight(QFont::Bold);
    QFont data_font(fonts::DATA_FAMILY, 9);

    // Header
    p.fillRect(0, 0, w, HEADER_HEIGHT, QColor(colors::BG_RAISED()));
    p.setPen(QColor(colors::BORDER_DIM()));
    p.drawLine(0, HEADER_HEIGHT - 1, w, HEADER_HEIGHT - 1);
    p.setFont(header_font);
    p.setPen(QColor(colors::TEXT_SECONDARY()));
    int col_w = w / 3;
    p.drawText(8, 0, col_w, HEADER_HEIGHT, Qt::AlignLeft | Qt::AlignVCenter, tr("PRICE"));
    p.drawText(col_w, 0, col_w, HEADER_HEIGHT, Qt::AlignRight | Qt::AlignVCenter, tr("SIZE"));
    p.drawText(2 * col_w, 0, col_w - 8, HEADER_HEIGHT, Qt::AlignRight | Qt::AlignVCenter, tr("TOTAL"));

    // Separator
    p.setPen(QColor(colors::BORDER_DIM()));
    p.drawLine(0, HEADER_HEIGHT - 1, w, HEADER_HEIGHT - 1);

    int ask_rows = 0, bid_rows = 0;
    visible_row_counts(ask_rows, bid_rows);

    // Find max cumulative size for depth bars
    double max_depth = 0;
    double cum = 0;
    for (int i = 0; i < ask_rows; ++i) {
        cum += asks_[i].size;
        max_depth = qMax(max_depth, cum);
    }
    cum = 0;
    for (int i = 0; i < bid_rows; ++i) {
        cum += bids_[i].size;
        max_depth = qMax(max_depth, cum);
    }
    if (max_depth == 0)
        max_depth = 1;

    p.setFont(data_font);
    int y = HEADER_HEIGHT;

    // Asks (highest first → reversed)
    cum = 0;
    for (int i = ask_rows - 1; i >= 0; --i) {
        cum += asks_[i].size;
        double depth_pct = cum / max_depth;
        int bar_w = static_cast<int>(w * depth_pct);

        p.fillRect(w - bar_w, y, bar_w, ROW_HEIGHT, QColor(220, 38, 38, 25));

        p.setPen(QColor(colors::NEGATIVE()));
        p.drawText(4, y, col_w, ROW_HEIGHT, Qt::AlignLeft | Qt::AlignVCenter, QString::number(asks_[i].price, 'f', 2));
        p.setPen(QColor(colors::TEXT_SECONDARY()));
        p.drawText(col_w, y, col_w, ROW_HEIGHT, Qt::AlignRight | Qt::AlignVCenter,
                   QString::number(asks_[i].size, 'f', 1));
        p.drawText(2 * col_w, y, col_w - 4, ROW_HEIGHT, Qt::AlignRight | Qt::AlignVCenter,
                   QString::number(cum, 'f', 1));

        p.setPen(QColor(colors::BORDER_DIM()));
        p.drawLine(0, y + ROW_HEIGHT - 1, w, y + ROW_HEIGHT - 1);
        y += ROW_HEIGHT;
    }

    // Spread row
    p.fillRect(0, y, w, ROW_HEIGHT, QColor(colors::BG_RAISED()));
    p.setPen(QColor(colors::AMBER()));
    p.setFont(header_font);
    p.drawText(4, y, w - 8, ROW_HEIGHT, Qt::AlignCenter, tr("SPREAD %1").arg(QString::number(spread_, 'f', 4)));
    y += ROW_HEIGHT;

    // Bids (highest first)
    p.setFont(data_font);
    cum = 0;
    for (int i = 0; i < bid_rows; ++i) {
        cum += bids_[i].size;
        double depth_pct = cum / max_depth;
        int bar_w = static_cast<int>(w * depth_pct);

        p.fillRect(w - bar_w, y, bar_w, ROW_HEIGHT, QColor(22, 163, 74, 25));

        p.setPen(QColor(colors::POSITIVE()));
        p.drawText(4, y, col_w, ROW_HEIGHT, Qt::AlignLeft | Qt::AlignVCenter, QString::number(bids_[i].price, 'f', 2));
        p.setPen(QColor(colors::TEXT_SECONDARY()));
        p.drawText(col_w, y, col_w, ROW_HEIGHT, Qt::AlignRight | Qt::AlignVCenter,
                   QString::number(bids_[i].size, 'f', 1));
        p.drawText(2 * col_w, y, col_w - 4, ROW_HEIGHT, Qt::AlignRight | Qt::AlignVCenter,
                   QString::number(cum, 'f', 1));

        p.setPen(QColor(colors::BORDER_DIM()));
        p.drawLine(0, y + ROW_HEIGHT - 1, w, y + ROW_HEIGHT - 1);
        y += ROW_HEIGHT;
    }

    if (bids_.isEmpty() && asks_.isEmpty()) {
        p.setPen(QColor(colors::TEXT_DIM()));
        p.drawText(rect(), Qt::AlignCenter, tr("No order book data"));
    }
}

void PolymarketOrderBook::changeEvent(QEvent* event) {
    if (event->type() == QEvent::LanguageChange) {
        // Painted text reads tr() at paint time; invalidate the cached pixmap
        // so the next repaint re-evaluates the new language.
        cache_dirty_ = true;
        update();
    }
    QWidget::changeEvent(event);
}

} // namespace fincept::screens::polymarket