/*
 * Copyright 2017 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.
 */

// #define LOG_NDEBUG 0
#define LOG_TAG "audio_utils_PowerLog"
#include <log/log.h>

#include <algorithm>
#include <iomanip>
#include <math.h>
#include <sstream>
#include <stdint.h>
#include <unistd.h>

#include <audio_utils/clock.h>
#include <audio_utils/power.h>
#include <audio_utils/PowerLog.h>

namespace android {

// TODO move to separate file
template <typename T, size_t N>
constexpr size_t array_size(const T(&)[N])
{
    return N;
}

PowerLog::PowerLog(uint32_t sampleRate,
        uint32_t channelCount,
        audio_format_t format,
        size_t entries,
        size_t framesPerEntry)
    : mCurrentTime(0)
    , mCurrentEnergy(0)
    , mCurrentFrames(0)
    , mIdx(0)
    , mConsecutiveZeroes(0)
    , mSampleRate(sampleRate)
    , mChannelCount(channelCount)
    , mFormat(format)
    , mFramesPerEntry(framesPerEntry)
    , mEntries(entries)
{
    (void)mSampleRate; // currently unused, for future use
    LOG_ALWAYS_FATAL_IF(!audio_utils_is_compute_power_format_supported(format),
            "unsupported format: %#x", format);
}

void PowerLog::log(const void *buffer, size_t frames, int64_t nowNs)
{
    std::lock_guard<std::mutex> guard(mLock);

    const size_t bytes_per_sample = audio_bytes_per_sample(mFormat);
    while (frames > 0) {
        // check partial computation
        size_t required = mFramesPerEntry - mCurrentFrames;
        size_t process = std::min(required, frames);

        if (mCurrentTime == 0) {
            mCurrentTime = nowNs;
        }
        mCurrentEnergy +=
                audio_utils_compute_energy_mono(buffer, mFormat, process * mChannelCount);
        mCurrentFrames += process;

        ALOGV("nowNs:%lld, required:%zu, process:%zu, mCurrentEnergy:%f, mCurrentFrames:%zu",
                (long long)nowNs, required, process, mCurrentEnergy, mCurrentFrames);
        if (process < required) {
            return;
        }

        // We store the data as normalized energy per sample. The energy sequence is
        // zero terminated. Consecutive zeroes are ignored.
        if (mCurrentEnergy == 0.f) {
            if (mConsecutiveZeroes++ == 0) {
                mEntries[mIdx++] = std::make_pair(nowNs, 0.f);
                // zero terminate the signal sequence.
            }
        } else {
            mConsecutiveZeroes = 0;
            mEntries[mIdx++] = std::make_pair(mCurrentTime, mCurrentEnergy);
            ALOGV("writing %lld %f", (long long)mCurrentTime, mCurrentEnergy);
        }
        if (mIdx >= mEntries.size()) {
            mIdx -= mEntries.size();
        }
        mCurrentTime = 0;
        mCurrentEnergy = 0;
        mCurrentFrames = 0;
        frames -= process;
        buffer = (const uint8_t *)buffer + mCurrentFrames * mChannelCount * bytes_per_sample;
    }
}

std::string PowerLog::dumpToString(const char *prefix, size_t lines, int64_t limitNs) const
{
    std::lock_guard<std::mutex> guard(mLock);

    const size_t maxColumns = 10;
    const size_t numberOfEntries = mEntries.size();
    if (lines == 0) lines = SIZE_MAX;

    // compute where to start logging
    enum {
        AT_END,
        IN_SIGNAL,
    } state = IN_SIGNAL;
    size_t count = 1;
    size_t column = 0;
    size_t nonzeros = 0;
    ssize_t offset; // TODO doesn't dump if # entries exceeds SSIZE_MAX
    for (offset = 0; offset < (ssize_t)numberOfEntries && count < lines; ++offset) {
        const size_t idx = (mIdx + numberOfEntries - offset - 1) % numberOfEntries; // reverse direction
        const int64_t time = mEntries[idx].first;
        const float energy = mEntries[idx].second;

        if (state == AT_END) {
            if (energy == 0.f) {
                ALOGV("two zeroes detected");
                break; // normally single zero terminated - two zeroes means no more data.
            }
            state = IN_SIGNAL;
        } else { // IN_SIGNAL
            if (energy == 0.f) {
                if (column != 0) {
                    column = 0;
                    ++count;
                }
                state = AT_END;
                continue;
            }
        }
        if (column == 0 && time < limitNs) {
            break;
        }
        ++nonzeros;
        if (++column == maxColumns) {
            column = 0;
            // TODO ideally we would peek the previous entry to see if it is 0
            // to ensure we properly put in a starting signal bracket.
            // We don't do that because it would complicate the logic here.
            ++count;
        }
    }
    if (offset > 0) {
        --offset;
    }
    // We accumulate the log info into a string, and write to the fd once.
    std::stringstream ss;
    ss << std::fixed << std::setprecision(1);
    // ss << std::scientific;
    if (nonzeros == 0) {
        ss << prefix << "Signal power history: (none)\n";
    } else {
        ss << prefix << "Signal power history:\n";

        size_t column = 0;
        bool first = true;
        bool start = false;
        float cumulative = 0.f;
        for (; offset >= 0; --offset) {
            const size_t idx = (mIdx + numberOfEntries - offset - 1) % numberOfEntries;
            const int64_t time = mEntries[idx].first;
            const float energy = mEntries[idx].second;

            if (energy == 0.f) {
                if (!first) {
                    ss << " ] sum(" << audio_utils_power_from_energy(cumulative) << ")";
                }
                cumulative = 0.f;
                column = 0;
                start = true;
                continue;
            }
            if (column == 0) {
                // print time if at start of column
                if (!first) {
                    ss << "\n";
                }
                ss << prefix << " " << audio_utils_time_string_from_ns(time).time
                        << (start ? ": [ ": ":   ");
                first = false;
                start = false;
            }  else {
                ss << " ";
            }
            if (++column >= maxColumns) {
                column = 0;
            }

            cumulative += energy;
            // convert energy to power and print
            const float power =
                    audio_utils_power_from_energy(energy / (mChannelCount * mFramesPerEntry));
            ss << std::setw(6) << power;
            ALOGV("state: %d %lld %f", state, (long long)time, power);
        }
        ss << "\n";
    }
    return ss.str();
}

status_t PowerLog::dump(int fd, const char *prefix, size_t lines, int64_t limitNs) const
{
    // Since dumpToString and write are thread safe, this function
    // is conceptually thread-safe but simultaneous calls to dump
    // by different threads to the same file descriptor may not write
    // the two logs in time order.
    const std::string s = dumpToString(prefix, lines, limitNs);
    if (s.size() > 0 && write(fd, s.c_str(), s.size()) < 0) {
        return -errno;
    }
    return NO_ERROR;
}

} // namespace android

using namespace android;

power_log_t *power_log_create(uint32_t sample_rate,
        uint32_t channel_count, audio_format_t format, size_t entries, size_t frames_per_entry)
{
    if (!audio_utils_is_compute_power_format_supported(format)) {
        return nullptr;
    }
    return reinterpret_cast<power_log_t *>
            (new(std::nothrow)
                    PowerLog(sample_rate, channel_count, format, entries, frames_per_entry));
}

void power_log_log(power_log_t *power_log,
        const void *buffer, size_t frames, int64_t now_ns)
{
    if (power_log == nullptr) {
        return;
    }
    reinterpret_cast<PowerLog *>(power_log)->log(buffer, frames, now_ns);
}

int power_log_dump(
        power_log_t *power_log, int fd, const char *prefix, size_t lines, int64_t limit_ns)
{
    if (power_log == nullptr) {
        return BAD_VALUE;
    }
    return reinterpret_cast<PowerLog *>(power_log)->dump(fd, prefix, lines, limit_ns);
}

void power_log_destroy(power_log_t *power_log)
{
    delete reinterpret_cast<PowerLog *>(power_log);
}