/*

NTP MODULE

Copyright (C) 2016-2019 by Xose Pérez <xose dot perez at gmail dot com>

*/

#if NTP_SUPPORT

#include <TimeLib.h>
#include <WiFiClient.h>
#include <Ticker.h>

#include <libs/NtpClientWrap.h>

Ticker _ntp_defer;

bool _ntp_report = false;
bool _ntp_configure = false;
bool _ntp_want_sync = false;

// -----------------------------------------------------------------------------
// NTP
// -----------------------------------------------------------------------------

#if WEB_SUPPORT

bool _ntpWebSocketOnReceive(const char * key, JsonVariant& value) {
    return (strncmp(key, "ntp", 3) == 0);
}

void _ntpWebSocketOnSend(JsonObject& root) {
    root["ntpVisible"] = 1;
    root["ntpStatus"] = (timeStatus() == timeSet);
    root["ntpServer"] = getSetting("ntpServer", NTP_SERVER);
    root["ntpOffset"] = getSetting("ntpOffset", NTP_TIME_OFFSET).toInt();
    root["ntpDST"] = getSetting("ntpDST", NTP_DAY_LIGHT).toInt() == 1;
    root["ntpRegion"] = getSetting("ntpRegion", NTP_DST_REGION).toInt();
}

#endif

time_t _ntpSyncProvider() {
    _ntp_want_sync = true;
    return 0;
}

void _ntpWantSync() {
    _ntp_want_sync = true;
}

int _ntpSyncInterval() {
    return secureRandom(NTP_SYNC_INTERVAL, NTP_SYNC_INTERVAL * 2);
}

int _ntpUpdateInterval() {
    return secureRandom(NTP_UPDATE_INTERVAL, NTP_UPDATE_INTERVAL * 2);
}

void inline _ntpSetSyncInterval(bool shortInterval = false) {
    if (shortInterval) {
        setSyncInterval(_ntpSyncInterval());
    } else {
        setSyncInterval(_ntpUpdateInterval());
    }
}

void _ntpStart() {

    _ntpConfigure();

    // short (initial) and long (after sync) intervals
    NTPw.setInterval(_ntpSyncInterval(), _ntpUpdateInterval());
    DEBUG_MSG_P(PSTR("[NTP] Update intervals: %us / %us\n"),
        NTPw.getShortInterval(), NTPw.getLongInterval());

    // setSyncProvider will immediatly call given function by setting next sync time to the current time.
    // Avoid triggering sync immediatly by canceling sync provider flag and resetting sync interval again
    setSyncProvider(_ntpSyncProvider);
    _ntp_want_sync = false;
    _ntpSetSyncInterval(true);

}

void _ntpConfigure() {

    _ntp_configure = false;

    int offset = getSetting("ntpOffset", NTP_TIME_OFFSET).toInt();
    int sign = offset > 0 ? 1 : -1;
    offset = abs(offset);
    int tz_hours = sign * (offset / 60);
    int tz_minutes = sign * (offset % 60);
    if (NTPw.getTimeZone() != tz_hours || NTPw.getTimeZoneMinutes() != tz_minutes) {
        NTPw.setTimeZone(tz_hours, tz_minutes);
        _ntp_report = true;
    }

    bool daylight = getSetting("ntpDST", NTP_DAY_LIGHT).toInt() == 1;
    if (NTPw.getDayLight() != daylight) {
        NTPw.setDayLight(daylight);
        _ntp_report = true;
    }

    String server = getSetting("ntpServer", NTP_SERVER);
    if (!NTPw.getNtpServerName().equals(server)) {
        NTPw.setNtpServerName(server);
    }

    uint8_t dst_region = getSetting("ntpRegion", NTP_DST_REGION).toInt();
    NTPw.setDSTZone(dst_region);

    // Set short interval to sync again shortly, randomized in time to avoid clogging the server with simultaious requests from multiple devices (i.e. on power surge, when devices start up at the same time)
    setSyncInterval(true);

    // Some remote servers can be slow to respond, increase accordingly
    // TODO does this need upper constrain?
    NTPw.setNTPTimeout(getSetting("ntpTimeout", NTP_TIMEOUT).toInt());

}

void _ntpReport() {

    _ntp_report = false;

    #if WEB_SUPPORT
        wsSend(_ntpWebSocketOnSend);
    #endif

    if (ntpSynced()) {
        time_t t = now();
        DEBUG_MSG_P(PSTR("[NTP] UTC Time  : %s\n"), ntpDateTime(ntpLocal2UTC(t)).c_str());
        DEBUG_MSG_P(PSTR("[NTP] Local Time: %s\n"), ntpDateTime(t).c_str());
    }

}

#if BROKER_SUPPORT

void inline _ntpBroker() {
    static unsigned char last_minute = 60;
    if (ntpSynced() && (minute() != last_minute)) {
        last_minute = minute();
        brokerPublish(BROKER_MSG_TYPE_DATETIME, MQTT_TOPIC_DATETIME, ntpDateTime().c_str());
    }
}

#endif

void _ntpLoop() {

    // Disable ntp sync when softAP is active. This will not crash, but instead spam debug-log with pointless sync failures.
    if (!wifiConnected()) return;

    if (_ntp_configure) _ntpConfigure();

    // NTPClientLib will trigger callback with sync status
    // see: NTPw.onNTPSyncEvent([](NTPSyncEvent_t error){ ... }) below
    if (_ntp_want_sync) {
        _ntp_want_sync = false;
        NTPw.getTime();
    }

    // Print current time whenever configuration changes or after successful sync
    if (_ntp_report) _ntpReport();

    #if BROKER_SUPPORT
        _ntpBroker();
    #endif

}

// TODO: remove me!
void _ntpBackwards() {
    moveSetting("ntpServer1", "ntpServer");
    delSetting("ntpServer2");
    delSetting("ntpServer3");
    int offset = getSetting("ntpOffset", NTP_TIME_OFFSET).toInt();
    if (-30 < offset && offset < 30) {
        offset *= 60;
        setSetting("ntpOffset", offset);
    }
}

// -----------------------------------------------------------------------------

bool ntpSynced() {
    #if NTP_WAIT_FOR_SYNC
        // Has synced at least once
        return (NTPw.getFirstSync() > 0);
    #else
        // TODO: runtime setting?
        return true;
    #endif
}

String ntpDateTime(time_t t) {
    char buffer[20];
    snprintf_P(buffer, sizeof(buffer),
        PSTR("%04d-%02d-%02d %02d:%02d:%02d"),
        year(t), month(t), day(t), hour(t), minute(t), second(t)
    );
    return String(buffer);
}

String ntpDateTime() {
    if (ntpSynced()) return ntpDateTime(now());
    return String();
}

// XXX: returns garbage during DST switch
time_t ntpLocal2UTC(time_t local) {
    int offset = getSetting("ntpOffset", NTP_TIME_OFFSET).toInt();
    if (NTPw.isSummerTime()) offset += 60;
    return local - offset * 60;
}

// -----------------------------------------------------------------------------

void ntpSetup() {

    _ntpBackwards();

    #if TERMINAL_SUPPORT
        terminalRegisterCommand(F("NTP"), [](Embedis* e) {
            if (ntpSynced()) {
                _ntpReport();
                terminalOK();
            } else {
                DEBUG_MSG_P(PSTR("[NTP] Not synced\n"));
            }
        });

        terminalRegisterCommand(F("NTP.SYNC"), [](Embedis* e) {
            _ntpWantSync();
            terminalOK();
        });
    #endif

    NTPw.onNTPSyncEvent([](NTPSyncEvent_t error) {
        if (error) {
            #if WEB_SUPPORT
                wsSend_P(PSTR("{\"ntpStatus\": false}"));
            #endif
            if (error == noResponse) {
                DEBUG_MSG_P(PSTR("[NTP] Error: NTP server not reachable\n"));
            } else if (error == invalidAddress) {
                DEBUG_MSG_P(PSTR("[NTP] Error: Invalid NTP server address\n"));
            }
        } else {
            _ntp_report = true;
            setTime(NTPw.getLastNTPSync());
        }
    });

    wifiRegister([](justwifi_messages_t code, char * parameter) {
        if (code == MESSAGE_CONNECTED) {
            if (!ntpSynced()) {
                _ntp_defer.once_ms(secureRandom(NTP_START_DELAY, NTP_START_DELAY * 15), _ntpWantSync);
            }
        }
    });

    #if WEB_SUPPORT
        wsOnSendRegister(_ntpWebSocketOnSend);
        wsOnReceiveRegister(_ntpWebSocketOnReceive);
    #endif

    // Main callbacks
    espurnaRegisterLoop(_ntpLoop);
    espurnaRegisterReload([]() { _ntp_configure = true; });

    // Sets up NTP instance, installs ours sync provider
    _ntpStart();

}

#endif // NTP_SUPPORT