/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once
#include <sys/types.h>
#include <tuple>
#include <unistd.h>
#include <memory>
#include <drm/msm_drm.h>
#include <drm/msm_drm_pp.h>
#include <xf86drm.h>
#include <xf86drmMode.h>
#include <array>
#include <deque>
#include <mutex>
#include <utils/Timers.h>

namespace histogram {

struct TimeKeeper {
    virtual nsecs_t current_time() const = 0;
    virtual ~TimeKeeper() = default;
protected:
    TimeKeeper() = default;
    TimeKeeper& operator=(TimeKeeper const&) = delete;
    TimeKeeper(TimeKeeper const&) = delete;
};

struct DefaultTimeKeeper final : TimeKeeper
{
    nsecs_t current_time() const final;
};

class Ringbuffer
{
public:
    static std::unique_ptr<Ringbuffer> create(size_t ringbuffer_size, std::unique_ptr<TimeKeeper> tk);
    void insert(drm_msm_hist const& frame);
    bool resize(size_t ringbuffer_size);

    using Sample = std::tuple<uint64_t /* numFrames */, std::array<uint64_t, HIST_V_SIZE> /* bins */>;
    Sample collect_cumulative() const;
    Sample collect_ringbuffer_all() const;
    Sample collect_after(nsecs_t timestamp) const;
    Sample collect_max(uint32_t max_frames) const;
    Sample collect_max_after(nsecs_t timestamp, uint32_t max_frames) const;
    ~Ringbuffer() = default;

private:
    Ringbuffer(size_t ringbuffer_size, std::unique_ptr<TimeKeeper> tk);
    Ringbuffer(Ringbuffer const&) = delete;
    Ringbuffer& operator=(Ringbuffer const&) = delete;

    Sample collect_max(uint32_t max_frames, std::unique_lock<std::mutex> const&) const;
    Sample collect_max_after(nsecs_t timestamp, uint32_t max_frames, std::unique_lock<std::mutex> const&) const;
    void update_cumulative(nsecs_t now, uint64_t& count, std::array<uint64_t, HIST_V_SIZE>& bins) const;

    std::mutex mutable mutex;
    struct HistogramEntry {
        drm_msm_hist histogram;
        nsecs_t start_timestamp;
        nsecs_t end_timestamp;
    };
    std::deque<HistogramEntry> ringbuffer;
    size_t rb_max_size;
    std::unique_ptr<TimeKeeper> const timekeeper;

    uint64_t cumulative_frame_count;
    std::array<uint64_t, HIST_V_SIZE> cumulative_bins;
};

}