// Copyright (C) 2026 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0

#pragma once

#include "sampletrace.h"

#include <tracing/timelinemodel.h>

namespace Profiler::Internal {

// CPU usage of a sampled recording in the timeline: a "Total" graph row with
// the number of running threads per sampling tick, plus one row per thread
// marking when that thread was on-CPU. Graph rendering works through
// relativeHeight(), like the QML profiler's MemoryUsageModel.
//
// Item times are nanoseconds (the timeline's display unit); the sample data
// is microseconds.
class CpuUsageModel : public Timeline::TimelineModel
{
    Q_OBJECT

public:
    explicit CpuUsageModel(Timeline::TimelineModelAggregator *parent);

    // The model keeps the pointer; pass nullptr to clear.
    void setTraceData(const SampleTraceData *data);

    qint64 traceEndNs() const { return m_traceEndNs; }

    int expandedRow(int index) const override;
    int collapsedRow(int index) const override;
    QRgb color(int index) const override;
    float relativeHeight(int index) const override;
    qint64 rowMaxValue(int rowNumber) const override;
    Timeline::RowLabels labels() const override;
    Timeline::ItemDetails details(int index) const override;
    Timeline::OrderedItemDetails orderedDetails(int index) const override;
    void navigateToDetail(int itemIndex, int detailRow) override;

    bool rendersAsDensity() const override;
    bool fillDensityColumns(int row, qint64 startTime, qint64 endTime,
                            QList<float> &out) const override;
    QRgb rowColor(int row) const override;

    void clear() override;

private:
    void load();
    void ensureDensityCache(qint64 startNs, qint64 endNs, int columns) const;

    struct Item
    {
        int running = 0;      // running threads at this tick
        int threadRow = -1;   // -1: total item; otherwise index into m_threads
        quint64 tid = 0;
        int sampleIndex = -1; // thread items: index into m_data->samples (the stack)
        int tickIndex = -1;   // index into m_ticks (used by the total item)
    };

    // Retained sample grid for per-column density aggregation. Sorted ascending
    // by startNs; one entry per sampling tick.
    struct TickRow
    {
        qint64 startNs = 0;
        int running = 0;        // running threads at this tick
        QList<int> runningRows; // thread row indices (FirstThreadRow + idx) on-CPU
    };

    const SampleTraceData *m_data = nullptr;
    QList<Item> m_items;      // parallel to TimelineModel item indices
    QList<quint64> m_threads; // per-thread row order (first appearance)
    QList<QRgb> m_rowColors; // index = expanded row; constant colour per row
    QList<TickRow> m_ticks;
    int m_maxRunning = 1;     // peak concurrent on-CPU threads; the total row's full scale
    qint64 m_traceEndNs = 0;

    // Per-column density accumulators, rebuilt once per (start, end, columns)
    // view and shared across all rows of a repaint. See ensureDensityCache().
    mutable qint64 m_cacheStartNs = 0;
    mutable qint64 m_cacheEndNs = -1;
    mutable int m_cacheColumns = 0;
    mutable bool m_cacheValid = false;
    mutable QList<int> m_cacheCovered;       // [col] ticks in the column
    mutable QList<int> m_cacheRunSum;        // [col] sum of running threads
    mutable QList<QList<int>> m_cacheActive; // [threadIndex][col] on-CPU ticks
};

} // namespace Profiler::Internal
