/*
 * Copyright (C) 2013 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_TAG "HealthLoop"
#define KLOG_LEVEL 6

#include <health/HealthLoop.h>

#include <errno.h>
#include <sys/epoll.h>  // epoll_create1(), epoll_ctl(), epoll_wait()
#include <sys/timerfd.h>
#include <unistd.h>  // read()

#include <android-base/logging.h>
#include <batteryservice/BatteryService.h>
#include <cutils/klog.h>  // KLOG_*()
#include <cutils/uevent.h>
#include <healthd/healthd.h>

#include <BpfSyscallWrappers.h>
#include <health/utils.h>

using android::base::ErrnoError;
using android::base::Result;
using android::base::unique_fd;
using namespace android;
using namespace std::chrono_literals;

namespace android {
namespace hardware {
namespace health {

static constexpr uint32_t kUeventMsgLen = 2048;

HealthLoop::HealthLoop() {
    InitHealthdConfig(&healthd_config_);
    awake_poll_interval_ = -1;
    wakealarm_wake_interval_ = healthd_config_.periodic_chores_interval_fast;
}

HealthLoop::~HealthLoop() {
    LOG(FATAL) << "HealthLoop cannot be destroyed";
}

int HealthLoop::RegisterEvent(int fd, BoundFunction func, EventWakeup wakeup) {
    CHECK(!reject_event_register_);

    auto* event_handler = event_handlers_
                                  .emplace_back(std::make_unique<EventHandler>(
                                          EventHandler{this, fd, std::move(func)}))
                                  .get();

    struct epoll_event ev = {
        .events = EPOLLIN | EPOLLERR,
        .data.ptr = reinterpret_cast<void*>(event_handler),
    };

    if (wakeup == EVENT_WAKEUP_FD) ev.events |= EPOLLWAKEUP;

    if (epoll_ctl(epollfd_, EPOLL_CTL_ADD, fd, &ev) == -1) {
        KLOG_ERROR(LOG_TAG, "epoll_ctl failed; errno=%d\n", errno);
        return -1;
    }

    return 0;
}

void HealthLoop::WakeAlarmSetInterval(int interval) {
    struct itimerspec itval;

    if (wakealarm_fd_ == -1) return;

    wakealarm_wake_interval_ = interval;

    if (interval == -1) interval = 0;

    itval.it_interval.tv_sec = interval;
    itval.it_interval.tv_nsec = 0;
    itval.it_value.tv_sec = interval;
    itval.it_value.tv_nsec = 0;

    if (timerfd_settime(wakealarm_fd_, 0, &itval, NULL) == -1)
        KLOG_ERROR(LOG_TAG, "wakealarm_set_interval: timerfd_settime failed\n");
}

void HealthLoop::AdjustWakealarmPeriods(bool charger_online) {
    // Fast wake interval when on charger (watch for overheat);
    // slow wake interval when on battery (watch for drained battery).

    int new_wake_interval = charger_online ? healthd_config_.periodic_chores_interval_fast
                                           : healthd_config_.periodic_chores_interval_slow;

    if (new_wake_interval != wakealarm_wake_interval_) WakeAlarmSetInterval(new_wake_interval);

    // During awake periods poll at fast rate.  If wake alarm is set at fast
    // rate then just use the alarm; if wake alarm is set at slow rate then
    // poll at fast rate while awake and let alarm wake up at slow rate when
    // asleep.

    if (healthd_config_.periodic_chores_interval_fast == -1)
        awake_poll_interval_ = -1;
    else
        awake_poll_interval_ = new_wake_interval == healthd_config_.periodic_chores_interval_fast
                                       ? -1
                                       : healthd_config_.periodic_chores_interval_fast * 1000;
}

void HealthLoop::PeriodicChores() {
    ScheduleBatteryUpdate();
}

// Returns true if and only if the battery statistics should be updated.
bool HealthLoop::RecvUevents() {
    bool update_stats = false;
    for (;;) {
        char msg[kUeventMsgLen + 2];
        int n = uevent_kernel_multicast_recv(uevent_fd_, msg, kUeventMsgLen);
        if (n < 0 && errno == ENOBUFS) {
            update_stats = true;
        }
        if (n <= 0) return update_stats;
        if (n >= kUeventMsgLen) {
            // too long -- discard
            continue;
        }
        if (update_stats) {
            continue;
        }

        msg[n] = '\0';
        msg[n + 1] = '\0';
        for (char* cp = msg; *cp;) {
            if (strcmp(cp, "SUBSYSTEM=power_supply") == 0) {
                update_stats = true;
                break;
            }

            /* advance to after the next \0 */
            while (*cp++) {
            }
        }
    }
}

void HealthLoop::UeventEvent(uint32_t /*epevents*/) {
    if (RecvUevents()) {
        ScheduleBatteryUpdate();
    }
}

// Attach a BPF filter to the @uevent_fd file descriptor. This fails in recovery mode because BPF is
// not supported in recovery mode. This fails for kernel versions 5.4 and before because the BPF
// program is rejected by the BPF verifier of older kernels.
Result<void> HealthLoop::AttachFilter(int uevent_fd) {
    static const char prg[] =
            "/sys/fs/bpf/vendor/prog_filterPowerSupplyEvents_skfilter_power_supply";
    int filter_fd(bpf::retrieveProgram(prg));
    if (filter_fd < 0) {
        return ErrnoError() << "failed to load BPF program " << prg;
    }
    if (setsockopt(uevent_fd, SOL_SOCKET, SO_ATTACH_BPF, &filter_fd, sizeof(filter_fd)) < 0) {
        close(filter_fd);
        return ErrnoError() << "failed to attach BPF program";
    }
    close(filter_fd);
    return {};
}

void HealthLoop::UeventInit(void) {
    uevent_fd_.reset(uevent_create_socket(kUeventMsgLen, true));

    if (uevent_fd_ < 0) {
        KLOG_ERROR(LOG_TAG, "uevent_init: uevent_open_socket failed\n");
        return;
    }

    fcntl(uevent_fd_, F_SETFL, O_NONBLOCK);

    Result<void> attach_result = AttachFilter(uevent_fd_);
    if (!attach_result.ok()) {
        std::string error_msg = attach_result.error().message();
        error_msg +=
                ". This is expected in recovery mode and also for kernel versions before 5.10.";
        KLOG_WARNING(LOG_TAG, "%s\n", error_msg.c_str());
    } else {
        KLOG_INFO(LOG_TAG, "Successfully attached the BPF filter to the uevent socket\n");
    }

    if (RegisterEvent(uevent_fd_, &HealthLoop::UeventEvent, EVENT_WAKEUP_FD))
        KLOG_ERROR(LOG_TAG, "register for uevent events failed\n");

    if (uevent_bind(uevent_fd_.get()) < 0) {
        uevent_fd_.reset();
        KLOG_ERROR(LOG_TAG, "uevent_init: binding socket failed\n");
        return;
    }
}

void HealthLoop::WakeAlarmEvent(uint32_t /*epevents*/) {
    // No need to lock because wakealarm_fd_ is guaranteed to be initialized.

    unsigned long long wakeups;

    if (read(wakealarm_fd_, &wakeups, sizeof(wakeups)) == -1) {
        KLOG_ERROR(LOG_TAG, "wakealarm_event: read wakealarm fd failed\n");
        return;
    }

    PeriodicChores();
}

void HealthLoop::WakeAlarmInit(void) {
    wakealarm_fd_.reset(timerfd_create(CLOCK_BOOTTIME_ALARM, TFD_NONBLOCK));
    if (wakealarm_fd_ == -1) {
        KLOG_ERROR(LOG_TAG, "wakealarm_init: timerfd_create failed\n");
        return;
    }

    if (RegisterEvent(wakealarm_fd_, &HealthLoop::WakeAlarmEvent, EVENT_WAKEUP_FD))
        KLOG_ERROR(LOG_TAG, "Registration of wakealarm event failed\n");

    WakeAlarmSetInterval(healthd_config_.periodic_chores_interval_fast);
}

void HealthLoop::MainLoop(void) {
    int nevents = 0;
    while (1) {
        reject_event_register_ = true;
        size_t eventct = event_handlers_.size();
        struct epoll_event events[eventct];
        int timeout = awake_poll_interval_;

        int mode_timeout;

        /* Don't wait for first timer timeout to run periodic chores */
        if (!nevents) PeriodicChores();

        Heartbeat();

        mode_timeout = PrepareToWait();
        if (timeout < 0 || (mode_timeout > 0 && mode_timeout < timeout)) timeout = mode_timeout;
        nevents = epoll_wait(epollfd_, events, eventct, timeout);
        if (nevents == -1) {
            if (errno == EINTR) continue;
            KLOG_ERROR(LOG_TAG, "healthd_mainloop: epoll_wait failed\n");
            break;
        }

        for (int n = 0; n < nevents; ++n) {
            if (events[n].data.ptr) {
                auto* event_handler = reinterpret_cast<EventHandler*>(events[n].data.ptr);
                event_handler->func(event_handler->object, events[n].events);
            }
        }
    }

    return;
}

int HealthLoop::InitInternal() {
    epollfd_.reset(epoll_create1(EPOLL_CLOEXEC));
    if (epollfd_ == -1) {
        KLOG_ERROR(LOG_TAG, "epoll_create1 failed; errno=%d\n", errno);
        return -1;
    }

    // Call subclass's init for any additional init steps.
    // Note that healthd_config_ is initialized before wakealarm_fd_; see
    // AdjustUeventWakealarmPeriods().
    Init(&healthd_config_);

    WakeAlarmInit();
    UeventInit();

    return 0;
}

int HealthLoop::StartLoop() {
    int ret;

    klog_set_level(KLOG_LEVEL);

    ret = InitInternal();
    if (ret) {
        KLOG_ERROR(LOG_TAG, "Initialization failed, exiting\n");
        return 2;
    }

    MainLoop();
    KLOG_ERROR(LOG_TAG, "Main loop terminated, exiting\n");
    return 3;
}

}  // namespace health
}  // namespace hardware
}  // namespace android