// src/screens/portfolio/views/RiskManagementView.cpp
#include "screens/portfolio/views/RiskManagementView.h"

#include "ui/theme/Theme.h"

#include <QEvent>
#include <QGridLayout>
#include <QHBoxLayout>
#include <QHeaderView>
#include <QTabBar>
#include <QVBoxLayout>

#include <algorithm>
#include <cmath>
#include <numeric>

namespace fincept::screens {

namespace {

/// Recursively empties a layout, destroying the widgets it owns.
///
/// `delete panel->layout()` alone does NOT destroy child widgets — they stay
/// parented to the panel, keep their last geometry and keep painting, so every
/// rebuild stacked another full set of metric cards on top of the previous one
/// (a visible artefact and an unbounded leak). Always drain the layout first.
void clear_layout(QLayout* layout) {
    if (!layout)
        return;
    QLayoutItem* item = nullptr;
    while ((item = layout->takeAt(0)) != nullptr) {
        if (auto* w = item->widget()) {
            w->hide();
            w->deleteLater();
        } else if (auto* child = item->layout()) {
            clear_layout(child);
        }
        // `item` IS the nested layout when item->layout() is non-null, so a
        // single delete covers both cases — never delete both.
        delete item;
    }
}

} // namespace

// Pre-defined stress test scenarios
struct StressScenario {
    const char* name;
    const char* description;
    double equity_shock; // percentage shock to equities
    double bond_shock;
    double commodity_shock;
};

static const StressScenario kScenarios[] = {
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "2008 Financial Crisis"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Lehman collapse, credit freeze"), -38.5, 5.2, -33.0},
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "2020 COVID Crash"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Pandemic selloff (Feb-Mar 2020)"), -33.9, 1.2, -20.0},
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Dot-com Bust"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Tech bubble burst (2000-2002)"), -49.1, 8.5, -10.0},
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Interest Rate Shock +3%"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Aggressive Fed tightening"), -15.0, -12.0, -5.0},
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Black Monday 1987"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Single-day market crash"), -22.6, 2.0, -8.0},
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Inflation Surge"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "1970s-style stagflation"), -10.0, -15.0, 25.0},
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Geopolitical Crisis"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Major conflict escalation"), -12.0, 3.0, 15.0},
    {QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Currency Crisis"),
     QT_TRANSLATE_NOOP("fincept::screens::RiskManagementView", "Emerging market contagion"), -18.0, 1.0, 5.0},
};

RiskManagementView::RiskManagementView(QWidget* parent) : QWidget(parent) {
    build_ui();
}

void RiskManagementView::build_ui() {
    auto* layout = new QVBoxLayout(this);
    layout->setContentsMargins(0, 0, 0, 0);

    tabs_ = new QTabWidget;
    tabs_->tabBar()->setElideMode(Qt::ElideNone);
    tabs_->tabBar()->setExpanding(false);
    tabs_->tabBar()->setUsesScrollButtons(false);
    tabs_->setDocumentMode(true);
    tabs_->setStyleSheet(QString("QTabWidget::pane { border:0; background:%1; }"
                                 "QTabBar::tab { background:%2; color:%3; padding:8px 18px; border:0;"
                                 "  border-bottom:2px solid transparent; font-size:10px; font-weight:700;"
                                 "  letter-spacing:1px; }"
                                 "QTabBar::tab:selected { color:%4; border-bottom:2px solid %4; }"
                                 "QTabBar::tab:hover { color:%5; }")
                             .arg(ui::colors::BG_BASE(), ui::colors::BG_SURFACE(), ui::colors::TEXT_SECONDARY(),
                                  ui::colors::AMBER(), ui::colors::TEXT_PRIMARY()));

    // ── Risk Overview tab ────────────────────────────────────────────────────
    overview_panel_ = new QWidget(this);
    overview_panel_->setStyleSheet(QString("background:%1;").arg(ui::colors::BG_BASE()));
    overview_tab_index_ = tabs_->addTab(overview_panel_, tr("RISK OVERVIEW"));

    // ── Stress Test tab ──────────────────────────────────────────────────────
    auto* stress_w = new QWidget(this);
    auto* stress_layout = new QVBoxLayout(stress_w);
    stress_layout->setContentsMargins(12, 8, 12, 8);

    stress_title_ = new QLabel(tr("PORTFOLIO STRESS TESTING"));
    stress_title_->setStyleSheet(
        QString("color:%1; font-size:12px; font-weight:700; letter-spacing:1px;").arg(ui::colors::AMBER()));
    stress_layout->addWidget(stress_title_);

    stress_note_ = new QLabel(tr("Estimated impact of historical and hypothetical market scenarios"));
    stress_note_->setStyleSheet(QString("color:%1; font-size:9px;").arg(ui::colors::TEXT_TERTIARY()));
    stress_layout->addWidget(stress_note_);

    stress_table_ = new QTableWidget;
    stress_table_->setColumnCount(5);
    stress_table_->setHorizontalHeaderLabels(
        {tr("SCENARIO"), tr("DESCRIPTION"), tr("EQUITY SHOCK"), tr("PORTFOLIO IMPACT"), tr("P&L IMPACT")});
    stress_table_->setSelectionMode(QAbstractItemView::NoSelection);
    stress_table_->setEditTriggers(QAbstractItemView::NoEditTriggers);
    stress_table_->setShowGrid(false);
    stress_table_->verticalHeader()->setVisible(false);
    stress_table_->horizontalHeader()->setStretchLastSection(true);
    stress_table_->setColumnWidth(0, 180);
    stress_table_->setColumnWidth(1, 240);
    stress_table_->setColumnWidth(2, 100);
    stress_table_->setColumnWidth(3, 120);
    stress_table_->setStyleSheet(QString("QTableWidget { background:%1; color:%2; border:none; font-size:11px; }"
                                         "QTableWidget::item { padding:4px 8px; border-bottom:1px solid %3; }"
                                         "QHeaderView::section { background:%4; color:%5; border:none;"
                                         "  border-bottom:2px solid %6; padding:4px 8px; font-size:9px;"
                                         "  font-weight:700; letter-spacing:0.5px; }")
                                     .arg(ui::colors::BG_BASE(), ui::colors::TEXT_PRIMARY(), ui::colors::BORDER_DIM(),
                                          ui::colors::BG_SURFACE(), ui::colors::TEXT_SECONDARY(), ui::colors::AMBER()));
    stress_layout->addWidget(stress_table_, 1);
    stress_tab_index_ = tabs_->addTab(stress_w, tr("STRESS TEST"));

    // ── Risk Contribution tab ────────────────────────────────────────────────
    auto* contrib_w = new QWidget(this);
    auto* contrib_layout = new QVBoxLayout(contrib_w);
    contrib_layout->setContentsMargins(12, 8, 12, 8);

    contrib_title_ = new QLabel(tr("RISK CONTRIBUTION BY HOLDING"));
    contrib_title_->setStyleSheet(
        QString("color:%1; font-size:12px; font-weight:700; letter-spacing:1px;").arg(ui::colors::AMBER()));
    contrib_layout->addWidget(contrib_title_);

    contrib_table_ = new QTableWidget;
    contrib_table_->setColumnCount(6);
    contrib_table_->setHorizontalHeaderLabels(
        {tr("SYMBOL"), tr("WEIGHT"), tr("VOL PROXY"), tr("RISK CONTRIB"), tr("VAR CONTRIB"), tr("CONCENTRATION")});
    contrib_table_->setSelectionMode(QAbstractItemView::NoSelection);
    contrib_table_->setEditTriggers(QAbstractItemView::NoEditTriggers);
    contrib_table_->setShowGrid(false);
    contrib_table_->verticalHeader()->setVisible(false);
    contrib_table_->horizontalHeader()->setStretchLastSection(true);
    contrib_table_->setStyleSheet(QString("QTableWidget { background:%1; color:%2; border:none; font-size:11px; }"
                                          "QTableWidget::item { padding:4px 8px; border-bottom:1px solid %3; }"
                                          "QHeaderView::section { background:%4; color:%5; border:none;"
                                          "  border-bottom:2px solid %6; padding:4px 8px; font-size:9px;"
                                          "  font-weight:700; letter-spacing:0.5px; }")
                                      .arg(ui::colors::BG_BASE(), ui::colors::TEXT_PRIMARY(), ui::colors::BORDER_DIM(),
                                           ui::colors::BG_SURFACE(), ui::colors::TEXT_SECONDARY(),
                                           ui::colors::AMBER()));
    contrib_layout->addWidget(contrib_table_, 1);
    contrib_tab_index_ = tabs_->addTab(contrib_w, tr("RISK CONTRIBUTION"));

    layout->addWidget(tabs_);
}

void RiskManagementView::set_data(const portfolio::PortfolioSummary& summary, const QString& currency) {
    summary_ = summary;
    currency_ = currency;
    has_data_ = true;
    update_overview();
    update_stress_test();
    update_contribution();
}

void RiskManagementView::changeEvent(QEvent* event) {
    if (event->type() == QEvent::LanguageChange)
        retranslateUi();
    QWidget::changeEvent(event);
}

void RiskManagementView::retranslateUi() {
    if (tabs_) {
        if (overview_tab_index_ >= 0)
            tabs_->setTabText(overview_tab_index_, tr("RISK OVERVIEW"));
        if (stress_tab_index_ >= 0)
            tabs_->setTabText(stress_tab_index_, tr("STRESS TEST"));
        if (contrib_tab_index_ >= 0)
            tabs_->setTabText(contrib_tab_index_, tr("RISK CONTRIBUTION"));
    }
    if (stress_title_)
        stress_title_->setText(tr("PORTFOLIO STRESS TESTING"));
    if (stress_note_)
        stress_note_->setText(tr("Estimated impact of historical and hypothetical market scenarios"));
    if (contrib_title_)
        contrib_title_->setText(tr("RISK CONTRIBUTION BY HOLDING"));

    if (stress_table_)
        stress_table_->setHorizontalHeaderLabels(
            {tr("SCENARIO"), tr("DESCRIPTION"), tr("EQUITY SHOCK"), tr("PORTFOLIO IMPACT"), tr("P&L IMPACT")});
    if (contrib_table_)
        contrib_table_->setHorizontalHeaderLabels(
            {tr("SYMBOL"), tr("WEIGHT"), tr("VOL PROXY"), tr("RISK CONTRIB"), tr("VAR CONTRIB"), tr("CONCENTRATION")});

    // re-render dynamic content so tr() row labels (scenario names, ratings) pick up new locale
    if (has_data_) {
        update_overview();
        update_stress_test();
        update_contribution();
    }
}

void RiskManagementView::set_metrics(const portfolio::ComputedMetrics& metrics) {
    metrics_ = metrics;
    update_stress_test(); // rescale with real beta
}

void RiskManagementView::update_overview() {
    if (auto* old = overview_panel_->layout()) {
        clear_layout(old);
        delete old;
    }

    auto* layout = new QVBoxLayout(overview_panel_);
    layout->setContentsMargins(16, 12, 16, 12);
    layout->setSpacing(12);

    auto* title = new QLabel(tr("PORTFOLIO RISK OVERVIEW"));
    title->setStyleSheet(
        QString("color:%1; font-size:12px; font-weight:700; letter-spacing:1px;").arg(ui::colors::AMBER()));
    layout->addWidget(title);

    // Compute basic risk metrics
    double total_mv = summary_.total_market_value;

    // Use 30-day realized volatility from ComputedMetrics when available;
    // fall back to single-day cross-sectional proxy otherwise.
    double ann_vol = 0;
    if (metrics_.volatility.has_value()) {
        ann_vol = *metrics_.volatility; // already annualised %
    } else {
        double avg_vol = 0;
        int vol_count = 0;
        for (const auto& h : summary_.holdings) {
            if (std::abs(h.day_change_percent) > 0.001) {
                avg_vol += std::abs(h.day_change_percent);
                ++vol_count;
            }
        }
        if (vol_count > 0)
            avg_vol /= vol_count;
        ann_vol = avg_vol * std::sqrt(252.0);
    }
    const double avg_vol = ann_vol / std::sqrt(252.0); // daily % for VaR formula

    // Concentration
    auto sorted = summary_.holdings;
    std::sort(sorted.begin(), sorted.end(), [](const auto& a, const auto& b) { return a.weight > b.weight; });
    double conc_top1 = sorted.isEmpty() ? 0 : sorted[0].weight;
    double conc_top3 = 0;
    for (qsizetype i = 0; i < std::min(qsizetype{3}, sorted.size()); ++i)
        conc_top3 += sorted[i].weight;
    double conc_top5 = 0;
    for (qsizetype i = 0; i < std::min(qsizetype{5}, sorted.size()); ++i)
        conc_top5 += sorted[i].weight;

    // VaR/CVaR — parametric normal: CVaR/VaR = phi(1.645)/0.05 ≈ 1.546
    double var95 = total_mv * avg_vol * 1.645 / 100.0;
    double cvar95 = var95 * 1.546;

    // Metric cards grid
    auto* grid = new QGridLayout;
    grid->setSpacing(8);

    auto add_card = [&](int r, int c, const QString& label, const QString& value, const char* color,
                        const QString& sub = {}) {
        auto* card = new QWidget(this);
        card->setStyleSheet(
            QString("background:%1; border:1px solid %2;").arg(ui::colors::BG_RAISED(), ui::colors::BORDER_DIM()));
        auto* cl = new QVBoxLayout(card);
        cl->setContentsMargins(12, 8, 12, 8);
        cl->setSpacing(2);

        auto* lbl = new QLabel(label);
        lbl->setStyleSheet(QString("color:%1; font-size:8px; font-weight:700; letter-spacing:0.5px;")
                               .arg(ui::colors::TEXT_TERTIARY()));
        cl->addWidget(lbl);

        auto* val = new QLabel(value);
        val->setStyleSheet(QString("color:%1; font-size:16px; font-weight:700;").arg(color));
        cl->addWidget(val);

        if (!sub.isEmpty()) {
            auto* s = new QLabel(sub);
            s->setStyleSheet(QString("color:%1; font-size:8px;").arg(ui::colors::TEXT_TERTIARY()));
            cl->addWidget(s);
        }

        grid->addWidget(card, r, c);
    };

    auto fmt = [](double v, int dp = 2) { return QString::number(v, 'f', dp); };

    add_card(0, 0, tr("PORTFOLIO VALUE"), QString("%1 %2").arg(currency_, fmt(total_mv)), ui::colors::WARNING,
             tr("Total market value"));
    // Be honest about which of the two sources produced the number — the card
    // previously always claimed "day-change proxy" even when the real 30-day
    // realized volatility from ComputedMetrics was used.
    add_card(0, 1, tr("ANNUALIZED VOLATILITY"), QString("%1%").arg(fmt(ann_vol, 1)), ui::colors::AMBER,
             metrics_.volatility.has_value() ? tr("30-day realized") : tr("Based on day-change proxy"));
    add_card(0, 2, tr("VALUE AT RISK (95%)"), QString("%1 %2").arg(currency_, fmt(var95)), ui::colors::NEGATIVE,
             tr("1-day parametric"));
    add_card(0, 3, tr("CONDITIONAL VaR"), QString("%1 %2").arg(currency_, fmt(cvar95)), ui::colors::NEGATIVE,
             tr("Expected shortfall"));

    add_card(1, 0, tr("TOP HOLDING CONC."), QString("%1%").arg(fmt(conc_top1, 1)),
             conc_top1 > 30 ? ui::colors::NEGATIVE : ui::colors::POSITIVE, tr("Largest position"));
    add_card(1, 1, tr("TOP 3 CONCENTRATION"), QString("%1%").arg(fmt(conc_top3, 1)),
             conc_top3 > 60 ? ui::colors::NEGATIVE : ui::colors::WARNING, tr("Sum of top 3"));
    add_card(1, 2, tr("TOP 5 CONCENTRATION"), QString("%1%").arg(fmt(conc_top5, 1)), ui::colors::CYAN,
             tr("Sum of top 5"));
    add_card(1, 3, tr("DIVERSIFICATION"), tr("%n holdings", "", summary_.total_positions),
             summary_.total_positions >= 10 ? ui::colors::POSITIVE : ui::colors::WARNING,
             summary_.total_positions >= 10 ? tr("Well diversified") : tr("Consider adding more"));

    layout->addLayout(grid);
    layout->addStretch();
}

void RiskManagementView::update_stress_test() {
    double total_mv = summary_.total_market_value;

    // ── Compute actual asset-class weights from holdings ──────────────────────
    // Classify each holding into equity / bond / commodity / crypto for the
    // stress scenarios below. This is an asset-class heuristic distinct from
    // the GICS-style sector used by SectorResolver / AnalyticsSectorsView.
    double equity_wt = 0, bond_wt = 0, commodity_wt = 0, crypto_wt = 0;
    for (const auto& h : summary_.holdings) {
        const QString s = h.symbol.toUpper();
        bool is_crypto = s.endsWith("-USD") || s.endsWith("-USDT");
        bool is_bond = s == "TLT" || s == "AGG" || s == "BND" || s == "IEF" || s == "SHY" || s == "LQD" || s == "HYG" ||
                       s == "EMB" || s.contains("BOND") || s.contains("TREAS");
        bool is_comm = s == "GLD" || s == "IAU" || s == "SLV" || s == "USO" || s.contains("OIL") || s.contains("GOLD");

        if (is_crypto)
            crypto_wt += h.weight;
        else if (is_bond)
            bond_wt += h.weight;
        else if (is_comm)
            commodity_wt += h.weight;
        else
            equity_wt += h.weight;
    }
    // Normalise to fractions
    equity_wt /= 100.0;
    bond_wt /= 100.0;
    commodity_wt /= 100.0;
    crypto_wt /= 100.0;

    int n = sizeof(kScenarios) / sizeof(kScenarios[0]);
    stress_table_->setRowCount(n);

    for (int r = 0; r < n; ++r) {
        const auto& s = kScenarios[r];
        stress_table_->setRowHeight(r, 32);

        auto set_cell = [&](int col, const QString& text, const char* color = nullptr,
                            Qt::Alignment align = Qt::AlignLeft | Qt::AlignVCenter) {
            auto* item = new QTableWidgetItem(text);
            item->setTextAlignment(align);
            if (color)
                item->setForeground(QColor(color));
            stress_table_->setItem(r, col, item);
        };

        // Weighted impact using actual portfolio composition
        double impact_pct = s.equity_shock * equity_wt + s.bond_shock * bond_wt + s.commodity_shock * commodity_wt +
                            s.equity_shock * 1.5 * crypto_wt; // crypto amplified

        // Scale by portfolio beta vs SPY (if available from OLS).
        // Beta > 1 means portfolio amplifies market moves; beta < 1 dampens.
        // SPY equity_shock is the base market scenario, so multiply equity
        // component by beta. Bond/commodity/crypto retain their own sensitivities.
        if (metrics_.beta.has_value()) {
            const double beta = std::max(0.0, *metrics_.beta); // clamp negative beta to 0
            const double equity_impact = s.equity_shock * equity_wt * beta;
            const double other_impact =
                s.bond_shock * bond_wt + s.commodity_shock * commodity_wt + s.equity_shock * 1.5 * crypto_wt;
            impact_pct = equity_impact + other_impact;
        }

        // Signed currency delta. The column used to hard-code a leading "-"
        // even for scenarios the portfolio profits from (e.g. Inflation Surge
        // on a commodity-heavy book), reporting a gain as a loss.
        const double delta = total_mv * impact_pct / 100.0;

        set_cell(0, tr(s.name), ui::colors::TEXT_PRIMARY);
        set_cell(1, tr(s.description), ui::colors::TEXT_SECONDARY);
        set_cell(2, QString("%1%").arg(QString::number(s.equity_shock, 'f', 1)),
                 s.equity_shock < 0 ? ui::colors::NEGATIVE : ui::colors::POSITIVE, Qt::AlignRight | Qt::AlignVCenter);
        set_cell(3, QString("%1%2%").arg(impact_pct < 0 ? "" : "+").arg(QString::number(impact_pct, 'f', 1)),
                 impact_pct < 0 ? ui::colors::NEGATIVE : ui::colors::POSITIVE, Qt::AlignRight | Qt::AlignVCenter);
        set_cell(4,
                 QString("%1%2 %3")
                     .arg(delta < 0 ? "-" : "+")
                     .arg(currency_)
                     .arg(QString::number(std::abs(delta), 'f', 0)),
                 delta < 0 ? ui::colors::NEGATIVE : ui::colors::POSITIVE, Qt::AlignRight | Qt::AlignVCenter);
    }
}

void RiskManagementView::update_contribution() {
    auto sorted = summary_.holdings;
    std::sort(sorted.begin(), sorted.end(), [](const auto& a, const auto& b) { return a.weight > b.weight; });

    contrib_table_->setRowCount(sorted.size());

    // Total portfolio vol proxy
    double total_vol = 0;
    for (const auto& h : sorted)
        total_vol += std::abs(h.day_change_percent) * h.weight / 100.0;

    for (int r = 0; r < sorted.size(); ++r) {
        const auto& h = sorted[r];
        contrib_table_->setRowHeight(r, 28);

        auto set_cell = [&](int col, const QString& text, const char* color = nullptr,
                            Qt::Alignment align = Qt::AlignRight | Qt::AlignVCenter) {
            auto* item = new QTableWidgetItem(text);
            item->setTextAlignment(col == 0 ? (Qt::AlignLeft | Qt::AlignVCenter) : align);
            if (color)
                item->setForeground(QColor(color));
            contrib_table_->setItem(r, col, item);
        };

        double vol_proxy = std::abs(h.day_change_percent);
        double risk_contrib = vol_proxy * h.weight / 100.0;
        double risk_pct = total_vol > 0 ? (risk_contrib / total_vol) * 100.0 : 0;
        double var_contrib = summary_.total_market_value * vol_proxy * 1.645 / 100.0 * h.weight / 100.0;

        set_cell(0, h.symbol, ui::colors::CYAN);
        set_cell(1, QString("%1%").arg(QString::number(h.weight, 'f', 1)));
        set_cell(2, QString("%1%").arg(QString::number(vol_proxy, 'f', 2)),
                 vol_proxy > 3 ? ui::colors::NEGATIVE : ui::colors::TEXT_PRIMARY);
        set_cell(3, QString("%1%").arg(QString::number(risk_pct, 'f', 1)),
                 risk_pct > 20 ? ui::colors::NEGATIVE : ui::colors::TEXT_PRIMARY);
        set_cell(4, QString("%1 %2").arg(currency_, QString::number(var_contrib, 'f', 2)));

        // Concentration rating
        const char* conc_color = h.weight > 20   ? ui::colors::NEGATIVE
                                 : h.weight > 10 ? ui::colors::WARNING
                                                 : ui::colors::POSITIVE;
        QString conc_text = h.weight > 20 ? tr("HIGH") : h.weight > 10 ? tr("MEDIUM") : tr("LOW");
        set_cell(5, conc_text, conc_color);
    }
}

} // namespace fincept::screens