/*
  Copyright 2018-2019, Barcelona Supercomputing Center (BSC), Spain
  Copyright 2015-2019, Johannes Gutenberg Universitaet Mainz, Germany

  This software was partially supported by the
  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).

  This software was partially supported by the
  ADA-FS project under the SPPEXA project funded by the DFG.

  SPDX-License-Identifier: MIT
*/


#include <daemon/main.hpp>
#include "version.hpp"
#include <global/log_util.hpp>
#include <global/env_util.hpp>
#include <global/rpc/rpc_types.hpp>
#include <global/rpc/rpc_utils.hpp>
#include <daemon/env.hpp>
#include <daemon/handler/rpc_defs.hpp>
#include <daemon/ops/metadentry.hpp>
#include <daemon/backend/metadata/db.hpp>
#include <daemon/backend/data/chunk_storage.hpp>
#include <daemon/util.hpp>

#include <boost/filesystem.hpp>
#include <boost/program_options.hpp>
#include <boost/tokenizer.hpp>

#include <iostream>
#include <fstream>
#include <csignal>
#include <unistd.h>
#include <condition_variable>

using namespace std;
namespace po = boost::program_options;
namespace bfs = boost::filesystem;

static condition_variable shutdown_please;
static mutex mtx;

void init_environment() {
    // Initialize metadata db
    std::string metadata_path = GKFS_DATA->metadir() + "/rocksdb"s;
    GKFS_DATA->spdlogger()->debug("{}() Initializing metadata DB: '{}'", __func__, metadata_path);
    try {
        GKFS_DATA->mdb(std::make_shared<MetadataDB>(metadata_path));
    } catch (const std::exception& e) {
        GKFS_DATA->spdlogger()->error("{}() Failed to initialize metadata DB: {}", __func__, e.what());
        throw;
    }

    // Initialize data backend
    std::string chunk_storage_path = GKFS_DATA->rootdir() + "/data/chunks"s;
    GKFS_DATA->spdlogger()->debug("{}() Initializing storage backend: '{}'", __func__, chunk_storage_path);
    bfs::create_directories(chunk_storage_path);
    try {
        GKFS_DATA->storage(std::make_shared<ChunkStorage>(chunk_storage_path, gkfs_config::rpc::chunksize));
    } catch (const std::exception& e) {
        GKFS_DATA->spdlogger()->error("{}() Failed to initialize storage backend: {}", __func__, e.what());
        throw;
    }

    // Init margo for RPC
    GKFS_DATA->spdlogger()->debug("{}() Initializing RPC server: '{}'",
                                  __func__, GKFS_DATA->bind_addr());
    try {
        init_rpc_server(GKFS_DATA->bind_addr());
    } catch (const std::exception& e) {
        GKFS_DATA->spdlogger()->error("{}() Failed to initialize RPC server: {}", __func__, e.what());
        throw;
    }

    // Init Argobots ESs to drive IO
    try {
        GKFS_DATA->spdlogger()->debug("{}() Initializing I/O pool", __func__);
        init_io_tasklet_pool();
    } catch (const std::exception& e) {
        GKFS_DATA->spdlogger()->error("{}() Failed to initialize Argobots pool for I/O: {}", __func__, e.what());
        throw;
    }

    // TODO set metadata configurations. these have to go into a user configurable file that is parsed here
    GKFS_DATA->atime_state(gkfs_config::metadata::use_atime);
    GKFS_DATA->mtime_state(gkfs_config::metadata::use_mtime);
    GKFS_DATA->ctime_state(gkfs_config::metadata::use_ctime);
    GKFS_DATA->link_cnt_state(gkfs_config::metadata::use_link_cnt);
    GKFS_DATA->blocks_state(gkfs_config::metadata::use_blocks);
    // Create metadentry for root directory
    Metadata root_md{S_IFDIR | S_IRWXU | S_IRWXG | S_IRWXO};
    try {
        gkfs::metadentry::create("/", root_md);
    } catch (const std::exception& e) {
        throw runtime_error("Failed to write root metadentry to KV store: "s + e.what());
    }
    // setup hostfile to let clients know that a daemon is running on this host
    if (!GKFS_DATA->hosts_file().empty()) {
        gkfs::util::populate_hosts_file();
    }
    GKFS_DATA->spdlogger()->info("Startup successful. Daemon is ready.");
}

/**
 * Destroys the margo, argobots, and mercury environments
 */
void destroy_enviroment() {
    GKFS_DATA->spdlogger()->debug("{}() Removing mount directory", __func__);
    boost::system::error_code ecode;
    bfs::remove_all(GKFS_DATA->mountdir(), ecode);
    GKFS_DATA->spdlogger()->debug("{}() Freeing I/O executions streams", __func__);
    for (unsigned int i = 0; i < RPC_DATA->io_streams().size(); i++) {
        ABT_xstream_join(RPC_DATA->io_streams().at(i));
        ABT_xstream_free(&RPC_DATA->io_streams().at(i));
    }

    if (!GKFS_DATA->hosts_file().empty()) {
        GKFS_DATA->spdlogger()->debug("{}() Removing hosts file", __func__);
        try {
            gkfs::util::destroy_hosts_file();
        } catch (const bfs::filesystem_error& e) {
            GKFS_DATA->spdlogger()->debug("{}() hosts file not found", __func__);
        }
    }

    if (RPC_DATA->server_rpc_mid() != nullptr) {
        GKFS_DATA->spdlogger()->debug("{}() Finalizing margo RPC server", __func__);
        margo_finalize(RPC_DATA->server_rpc_mid());
    }

    GKFS_DATA->spdlogger()->info("{}() Closing metadata DB", __func__);
    GKFS_DATA->close_mdb();
}

void init_io_tasklet_pool() {
    assert(gkfs_config::rpc::daemon_io_xstreams >= 0);
    unsigned int xstreams_num = gkfs_config::rpc::daemon_io_xstreams;

    //retrieve the pool of the just created scheduler
    ABT_pool pool;
    auto ret = ABT_pool_create_basic(ABT_POOL_FIFO_WAIT, ABT_POOL_ACCESS_MPMC, ABT_TRUE, &pool);
    if (ret != ABT_SUCCESS) {
        throw runtime_error("Failed to create I/O tasks pool");
    }

    //create all subsequent xstream and the associated scheduler, all tapping into the same pool
    vector<ABT_xstream> xstreams(xstreams_num);
    for (unsigned int i = 0; i < xstreams_num; ++i) {
        ret = ABT_xstream_create_basic(ABT_SCHED_BASIC_WAIT, 1, &pool,
                ABT_SCHED_CONFIG_NULL, &xstreams[i]);
        if (ret != ABT_SUCCESS) {
            throw runtime_error("Failed to create task execution streams for I/O operations");
        }
    }

    RPC_DATA->io_streams(xstreams);
    RPC_DATA->io_pool(pool);
}

void init_rpc_server(const string & protocol_port) {
    hg_addr_t addr_self;
    hg_size_t addr_self_cstring_sz = 128;
    char addr_self_cstring[128];
    // IMPORTANT: this struct needs to be zeroed before use
    struct hg_init_info hg_options = {};
#if USE_SHM
    hg_options.auto_sm = HG_TRUE;
#else
    hg_options.auto_sm = HG_FALSE;
#endif
    hg_options.stats = HG_FALSE;
    hg_options.na_class = nullptr;
    // Start Margo (this will also initialize Argobots and Mercury internally)
    auto mid = margo_init_opt(protocol_port.c_str(),
                              MARGO_SERVER_MODE,
                              &hg_options,
                              HG_TRUE,
                              gkfs_config::rpc::daemon_handler_xstreams);
    if (mid == MARGO_INSTANCE_NULL) {
        throw runtime_error("Failed to initialize the Margo RPC server");
    }
    // Figure out what address this server is listening on (must be freed when finished)
    auto hret = margo_addr_self(mid, &addr_self);
    if (hret != HG_SUCCESS) {
        margo_finalize(mid);
        throw runtime_error("Failed to retrieve server RPC address");
    }
    // Convert the address to a cstring (with \0 terminator).
    hret = margo_addr_to_string(mid, addr_self_cstring, &addr_self_cstring_sz, addr_self);
    if (hret != HG_SUCCESS) {
        margo_addr_free(mid, addr_self);
        margo_finalize(mid);
        throw runtime_error("Failed to convert server RPC address to string");
    }
    margo_addr_free(mid, addr_self);

    std::string addr_self_str(addr_self_cstring);
    RPC_DATA->self_addr_str(addr_self_str);

    GKFS_DATA->spdlogger()->info("{}() Accepting RPCs on address {}", __func__, addr_self_cstring);

    // Put context and class into RPC_data object
    RPC_DATA->server_rpc_mid(mid);

    // register RPCs
    register_server_rpcs(mid);
}

/**
 * Registers RPC handlers to Margo instance
 * @param hg_class
 */
void register_server_rpcs(margo_instance_id mid) {
    MARGO_REGISTER(mid, gkfs::hg_tag::fs_config, void, rpc_config_out_t, rpc_srv_fs_config);
    MARGO_REGISTER(mid, gkfs::hg_tag::create, rpc_mk_node_in_t, rpc_err_out_t, rpc_srv_mk_node);
    MARGO_REGISTER(mid, gkfs::hg_tag::stat, rpc_path_only_in_t, rpc_stat_out_t, rpc_srv_stat);
    MARGO_REGISTER(mid, gkfs::hg_tag::decr_size, rpc_trunc_in_t, rpc_err_out_t, rpc_srv_decr_size);
    MARGO_REGISTER(mid, gkfs::hg_tag::remove, rpc_rm_node_in_t, rpc_err_out_t, rpc_srv_rm_node);
    MARGO_REGISTER(mid, gkfs::hg_tag::update_metadentry, rpc_update_metadentry_in_t, rpc_err_out_t,
                   rpc_srv_update_metadentry);
    MARGO_REGISTER(mid, gkfs::hg_tag::get_metadentry_size, rpc_path_only_in_t, rpc_get_metadentry_size_out_t,
                   rpc_srv_get_metadentry_size);
    MARGO_REGISTER(mid, gkfs::hg_tag::update_metadentry_size, rpc_update_metadentry_size_in_t,
                   rpc_update_metadentry_size_out_t, rpc_srv_update_metadentry_size);
    MARGO_REGISTER(mid, gkfs::hg_tag::get_dirents, rpc_get_dirents_in_t, rpc_get_dirents_out_t,
                   rpc_srv_get_dirents);
#ifdef HAS_SYMLINKS
    MARGO_REGISTER(mid, gkfs::hg_tag::mk_symlink, rpc_mk_symlink_in_t, rpc_err_out_t, rpc_srv_mk_symlink);
#endif
    MARGO_REGISTER(mid, gkfs::hg_tag::write_data, rpc_write_data_in_t, rpc_data_out_t, rpc_srv_write_data);
    MARGO_REGISTER(mid, gkfs::hg_tag::read_data, rpc_read_data_in_t, rpc_data_out_t, rpc_srv_read_data);
    MARGO_REGISTER(mid, gkfs::hg_tag::trunc_data, rpc_trunc_in_t, rpc_err_out_t, rpc_srv_trunc_data);
    MARGO_REGISTER(mid, gkfs::hg_tag::chunk_stat, rpc_chunk_stat_in_t, rpc_chunk_stat_out_t, rpc_srv_chunk_stat);
}

void shutdown_handler(int dummy) {
    GKFS_DATA->spdlogger()->info("{}() Received signal: '{}'", __func__, strsignal(dummy));
    shutdown_please.notify_all();
}

void initialize_loggers() {
    std::string path = gkfs_config::logging::daemon_log_path;
    // Try to get log path from env variable
    std::string env_path_key = DAEMON_ENV_PREFIX;
    env_path_key += "DAEMON_LOG_PATH";
    char* env_path = getenv(env_path_key.c_str());
    if (env_path != nullptr) {
        path = env_path;
    }

    spdlog::level::level_enum level = get_spdlog_level(gkfs_config::logging::daemon_log_level);
    // Try to get log path from env variable
    std::string env_level_key = DAEMON_ENV_PREFIX;
    env_level_key += "LOG_LEVEL";
    char* env_level = getenv(env_level_key.c_str());
    if (env_level != nullptr) {
        level = get_spdlog_level(env_level);
    }

    auto logger_names = std::vector<std::string>{
        "main",
        "MetadataDB",
        "ChunkStorage",
    };

    setup_loggers(logger_names, level, path);
}

int main(int argc, const char* argv[]) {

    // Parse input
    po::options_description desc("Allowed options");
    desc.add_options()
            ("help,h", "Help message")
            ("mountdir,m", po::value<string>()->required(), "User Fuse mountdir")
            ("rootdir,r", po::value<string>()->required(), "data directory")
            ("metadir,i", po::value<string>(), "metadata directory, if not set rootdir is used for metadata ")
            ("listen,l", po::value<string>(), "Address or interface to bind the daemon on. Default: local hostname")
            ("hosts-file,H", po::value<string>(),
                             "Shared file used by deamons to register their "
                             "enpoints. (default './gkfs_hosts.txt')")
            ("version,h", "print version and exit");
    po::variables_map vm;
    po::store(po::parse_command_line(argc, argv, desc), vm);

    if (vm.count("help")) {
        cout << desc << "\n";
        return 1;
    }

    if (vm.count("version")) {
        cout << GKFS_VERSION_STRING << endl;
#ifndef NDEBUG
        cout << "Debug: ON" << endl;
#else
        cout << "Debug: OFF" << endl;
#endif
        cout << "RPC protocol: " << RPC_PROTOCOL << endl;
#if USE_SHM
        cout << "Shared-memory comm: ON" << endl;
#else
        cout << "Shared-memory comm: OFF" << endl;
#endif
#if CREATE_CHECK_PARENTS
        cout << "Create check parents: ON" << endl;
#else
        cout << "Create check parents: OFF" << endl;
#endif
        cout << "Chunk size: " << gkfs_config::rpc::chunksize << " bytes" << endl;
        return 0;
    }

    try {
        po::notify(vm);
    } catch (po::required_option& e) {
        std::cerr << "Error: " << e.what() << "\n";
        return 1;
    }

    initialize_loggers();
    GKFS_DATA->spdlogger(spdlog::get("main"));


    string addr;
    if (vm.count("listen")) {
        addr = vm["listen"].as<string>();
    } else {
        addr = get_my_hostname(true);
    }

    GKFS_DATA->bind_addr(fmt::format("{}://{}", RPC_PROTOCOL, addr));

    string hosts_file;
    if (vm.count("hosts-file")) {
        hosts_file = vm["hosts-file"].as<string>();
    } else {
        hosts_file =
                gkfs::env::get_var(gkfs::env::HOSTS_FILE, gkfs_config::hostfile_path);
    }
    GKFS_DATA->hosts_file(hosts_file);

    GKFS_DATA->spdlogger()->info("{}() Initializing environment", __func__);

    assert(vm.count("mountdir"));
    auto mountdir = vm["mountdir"].as<string>();
    // Create mountdir. We use this dir to get some information on the underlying fs with statfs in gkfs_statfs
    bfs::create_directories(mountdir);
    GKFS_DATA->mountdir(bfs::canonical(mountdir).native());

    assert(vm.count("rootdir"));
    auto rootdir = vm["rootdir"].as<string>();
    auto rootdir_path = bfs::path(rootdir) / fmt::format_int(getpid()).str();
    GKFS_DATA->spdlogger()->debug("{}() Root directory: '{}'",
                                  __func__, rootdir_path.native());
    bfs::create_directories(rootdir_path);
    GKFS_DATA->rootdir(rootdir_path.native());

    if (vm.count("metadir")) {
        auto metadir = vm["metadir"].as<string>();
        bfs::create_directories(metadir);
        GKFS_DATA->metadir(bfs::canonical(metadir).native());
    } else {
        // use rootdir as metadata dir
        GKFS_DATA->metadir(GKFS_DATA->rootdir());
    }

    try {
        init_environment();
    } catch (const std::exception& e) {
        auto emsg = fmt::format("Failed to initialize environment: {}", e.what());
        GKFS_DATA->spdlogger()->error(emsg);
        cerr << emsg << endl;
        destroy_enviroment();
        exit(EXIT_FAILURE);
    }

    signal(SIGINT, shutdown_handler);
    signal(SIGTERM, shutdown_handler);
    signal(SIGKILL, shutdown_handler);

    unique_lock<mutex> lk(mtx);
    // Wait for shutdown signal to initiate shutdown protocols
    shutdown_please.wait(lk);
    GKFS_DATA->spdlogger()->info("{}() Shutting down...", __func__);
    destroy_enviroment();
    GKFS_DATA->spdlogger()->info("{}() Complete. Exiting...", __func__);
    return 0;
}