/*
 * Copyright (c) 2016, Google. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 *       copyright notice, this list of conditions and the following
 *       disclaimer in the documentation and/or other materials provided
 *       with the distribution.
 *     * Neither the name of The Linux Foundation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#define LOG_TAG "NanohubHAL"

#include <fcntl.h>
#include <poll.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/inotify.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <hardware/context_hub.h>
#include <hardware/hardware.h>

#include <utils/Log.h>

#include <cinttypes>

#include "nanohub_perdevice.h"
#include "system_comms.h"
#include "nanohubhal.h"

#define NANOHUB_LOCK_DIR        "/data/system/nanohub_lock"
#define NANOHUB_LOCK_FILE       NANOHUB_LOCK_DIR "/lock"
#define NANOHUB_LOCK_DIR_PERMS  (S_IRUSR | S_IWUSR | S_IXUSR)

namespace android {

namespace nanohub {

static int rwrite(int fd, const void *buf, int len)
{
    int ret;

    do {
        ret = write(fd, buf, len);
    } while (ret < 0 && errno == EINTR);

    if (ret != len) {
        return errno ? -errno : -EIO;
    }

    return 0;
}

static int rread(int fd, void *buf, int len)
{
    int ret;

    do {
        ret = read(fd, buf, len);
    } while (ret < 0 && errno == EINTR);

    return ret;
}

static bool init_inotify(pollfd *pfd) {
    bool success = false;

    mkdir(NANOHUB_LOCK_DIR, NANOHUB_LOCK_DIR_PERMS);
    pfd->fd = inotify_init1(IN_NONBLOCK);
    if (pfd->fd < 0) {
        ALOGE("Couldn't initialize inotify: %s", strerror(errno));
    } else if (inotify_add_watch(pfd->fd, NANOHUB_LOCK_DIR, IN_CREATE | IN_DELETE) < 0) {
        ALOGE("Couldn't add inotify watch: %s", strerror(errno));
        close(pfd->fd);
    } else {
        pfd->events = POLLIN;
        success = true;
    }

    return success;
}

static void discard_inotify_evt(pollfd &pfd) {
    if ((pfd.revents & POLLIN)) {
        char buf[sizeof(inotify_event) + NAME_MAX + 1];
        int ret = read(pfd.fd, buf, sizeof(buf));
        ALOGD("Discarded %d bytes of inotify data", ret);
    }
}

static void wait_on_dev_lock(pollfd &pfd) {
    // While the lock file exists, poll on the inotify fd (with timeout)
    discard_inotify_evt(pfd);
    while (access(NANOHUB_LOCK_FILE, F_OK) == 0) {
        ALOGW("Nanohub is locked; blocking read thread");
        int ret = poll(&pfd, 1, 5000);
        if (ret > 0) {
            discard_inotify_evt(pfd);
        }
    }
}

int NanoHub::doSendToDevice(const hub_app_name_t *name, const void *data, uint32_t len)
{
    if (len > MAX_RX_PACKET) {
        return -EINVAL;
    }

    nano_message msg = {
        .hdr = {
            .event_id = APP_FROM_HOST_EVENT_ID,
            .app_name = *name,
            .len = static_cast<uint8_t>(len),
        },
    };

    memcpy(&msg.data[0], data, len);

    return rwrite(mFd, &msg, len + sizeof(msg.hdr));
}

void NanoHub::doSendToApp(const hub_app_name_t *name, uint32_t typ, const void *data, uint32_t len)
{
    hub_message_t msg = {
        .app_name = *name,
        .message_type = typ,
        .message_len = len,
        .message = data,
    };

    mMsgCbkFunc(0, &msg, mMsgCbkData);
}

void* NanoHub::run(void *data)
{
    NanoHub *self = static_cast<NanoHub*>(data);
    return self->doRun();
}

void* NanoHub::doRun()
{
    enum {
        IDX_NANOHUB,
        IDX_CLOSE_PIPE,
        IDX_INOTIFY
    };
    pollfd myFds[3] = {
        [IDX_NANOHUB] = { .fd = mFd, .events = POLLIN, },
        [IDX_CLOSE_PIPE] = { .fd = mThreadClosingPipe[0], .events = POLLIN, },
    };
    pollfd &inotifyFd = myFds[IDX_INOTIFY];
    bool hasInotify = false;
    int numPollFds = 2;

    if (init_inotify(&inotifyFd)) {
        numPollFds++;
        hasInotify = true;
    }

    while (1) {
        int ret = poll(myFds, numPollFds, -1);
        if (ret <= 0) {
            ALOGD("poll is being weird");
            continue;
        }

        if (hasInotify) {
            wait_on_dev_lock(inotifyFd);
        }

        if (myFds[IDX_NANOHUB].revents & POLLIN) { // we have data

            nano_message msg;

            ret = rread(mFd, &msg, sizeof(msg));
            if (ret <= 0) {
                ALOGE("read failed with %d", ret);
                break;
            }
            if (ret < (int)sizeof(msg.hdr)) {
                ALOGE("Only read %d bytes", ret);
                break;
            }

            uint32_t len = msg.hdr.len;

            if (len > sizeof(msg.data)) {
                ALOGE("malformed packet with len %" PRIu32, len);
                break;
            }

            if (ret != (int)(sizeof(msg.hdr) + len)) {
                ALOGE("Expected %zu bytes, read %d bytes", sizeof(msg.hdr) + len, ret);
                break;
            }

            ret = SystemComm::handleRx(&msg);
            if (ret < 0) {
                ALOGE("SystemComm::handleRx() returned %d", ret);
            } else if (ret) {
                doSendToApp(&msg.hdr.app_name, msg.hdr.event_id, &msg.data[0], msg.hdr.len);
            }
        }

        if (myFds[IDX_CLOSE_PIPE].revents & POLLIN) { // we have been asked to die
            ALOGD("thread exiting");
            break;
        }
    }

    close(mFd);
    return NULL;
}

int NanoHub::openHub()
{
    int ret = 0;

    mFd = open(get_devnode_path(), O_RDWR);
    if (mFd < 0) {
        ALOGE("cannot find hub devnode '%s'", get_devnode_path());
        ret = -errno;
        goto fail_open;
    }

    if (pipe(mThreadClosingPipe)) {
        ALOGE("failed to create signal pipe");
        ret = -errno;
        goto fail_pipe;
    }

    if (pthread_create(&mWorkerThread, NULL, &NanoHub::run, this)) {
        ALOGE("failed to spawn worker thread");
        ret = -errno;
        goto fail_thread;
    }

    return 0;

fail_thread:
    close(mThreadClosingPipe[0]);
    close(mThreadClosingPipe[1]);

fail_pipe:
    close(mFd);

fail_open:
    return ret;
}

int NanoHub::closeHub(void)
{
    char zero = 0;

    //signal
    while(write(mThreadClosingPipe[1], &zero, 1) != 1);

    //wait
    (void)pthread_join(mWorkerThread, NULL);

    //cleanup
    ::close(mThreadClosingPipe[0]);
    ::close(mThreadClosingPipe[1]);

    reset();

    return 0;
}

int NanoHub::doSubscribeMessages(uint32_t hub_id, context_hub_callback *cbk, void *cookie)
{
    if (hub_id) {
        return -ENODEV;
    }

    Mutex::Autolock _l(mLock);
    int ret = 0;

    if (!mMsgCbkFunc && !cbk) { //we're off and staying off - do nothing

        ALOGD("staying off");
    } else if (cbk && mMsgCbkFunc) { //new callback but staying on

        ALOGD("staying on");
    } else if (mMsgCbkFunc) {     //we were on but turning off

        ALOGD("turning off");

        ret = closeHub();
    } else if (cbk) {             //we're turning on

        ALOGD("turning on");
        ret = openHub();
    }

    mMsgCbkFunc = cbk;
    mMsgCbkData = cookie;

    return ret;
}

int NanoHub::doSendToNanohub(uint32_t hub_id, const hub_message_t *msg)
{
    if (hub_id) {
        return -ENODEV;
    }

    int ret = 0;
    Mutex::Autolock _l(mLock);

    if (!mMsgCbkFunc) {
        ALOGW("refusing to send a message when nobody around to get a reply!");
        ret = -EIO;
    } else {
        if (!msg || !msg->message) {
            ALOGW("not sending invalid message 1");
            ret = -EINVAL;
        } else if (get_hub_info()->os_app_name == msg->app_name) {
            //messages to the "system" app are special - hal handles them
            ret = SystemComm::handleTx(msg);
        } else if (msg->message_type || msg->message_len > MAX_RX_PACKET) {
            ALOGW("not sending invalid message 2");
            ret = -EINVAL;
        } else {
            ret = doSendToDevice(&msg->app_name, msg->message, msg->message_len);
        }
    }

    return ret;
}

static int hal_get_hubs(context_hub_module_t*, const context_hub_t ** list)
{
    *list = get_hub_info();

    return 1; /* we have one hub */
}

}; // namespace nanohub

}; // namespace android

context_hub_module_t HAL_MODULE_INFO_SYM = {
    .common = {
        .tag = HARDWARE_MODULE_TAG,
        .module_api_version = CONTEXT_HUB_DEVICE_API_VERSION_1_0,
        .hal_api_version = HARDWARE_HAL_API_VERSION,
        .id = CONTEXT_HUB_MODULE_ID,
        .name = "Nanohub HAL",
        .author = "Google",
    },

    .get_hubs = android::nanohub::hal_get_hubs,
    .subscribe_messages = android::nanohub::NanoHub::subscribeMessages,
    .send_message = android::nanohub::NanoHub::sendToNanohub,
};