/**
 * @copyright Utilitech AS 2023
 * License: Fair Source
 * 
 */

#include "PriceService.h"
#include <EEPROM.h>
#include "Uptime.h"
#include "TimeLib.h"
#include "DnbCurrParser.h"
#include "FirmwareVersion.h"
#include <LittleFS.h>
#include "AmsStorage.h"
#include "hexutils.h"

#include "GcmParser.h"

#if defined(ESP32)
#include <esp_task_wdt.h>
#endif

PriceService::PriceService(RemoteDebug* Debug) : priceConfig(std::vector<PriceConfig>()) {
    this->buf = (char*) malloc(BufferSize);

    debugger = Debug;

    // Entso-E uses CET/CEST
    TimeChangeRule CEST = {"CEST", Last, Sun, Mar, 2, 120};
	TimeChangeRule CET = {"CET ", Last, Sun, Oct, 3, 60};
	tz = new Timezone(CEST, CET);

    tomorrowFetchMinute = 15 + random(45); // Random between 13:15 and 14:00
}

void PriceService::setup(PriceServiceConfig& config) {
    if(this->config == NULL) {
        this->config = new PriceServiceConfig();
    }
    memcpy(this->config, &config, sizeof(config));
    lastTodayFetch = lastTomorrowFetch = lastCurrencyFetch = 0;
    if(today != NULL) delete today;
    if(tomorrow != NULL) delete tomorrow;
    today = tomorrow = NULL;

    if(http != NULL) {
        delete http;
    }
    http = new HTTPClient();
    http->setFollowRedirects(HTTPC_STRICT_FOLLOW_REDIRECTS);
    http->setReuse(false);
    http->setTimeout(60000);
    http->setUserAgent("ams2mqtt/" + String(FirmwareVersion::VersionString));

    #if defined(AMS2MQTT_PRICE_KEY)
        key = new uint8_t[16] AMS2MQTT_PRICE_KEY;
        hub = true;
    #else
        hub = false;
    #endif
    #if defined(AMS2MQTT_PRICE_AUTHENTICATION)
        auth = new uint8_t[16] AMS2MQTT_PRICE_AUTHENTICATION;
        hub = hub && true;
    #else
        hub = false;
    #endif

    load();
}

char* PriceService::getToken() {
    return this->config->entsoeToken;
}

char* PriceService::getCurrency() {
    return this->config->currency;
}

char* PriceService::getArea() {
    return this->config->area;
}

char* PriceService::getSource() {
    if(this->today != NULL && this->tomorrow != NULL) {
        if(strcmp(this->today->source, this->tomorrow->source) == 0) {
            return this->today->source;
        } else {
            return "MIX";
        }
    } else if(today != NULL) {
        return this->today->source;
    } else if(tomorrow != NULL) {
        return this->tomorrow->source;
    }
    return "";
}

float PriceService::getValueForHour(uint8_t direction, int8_t hour) {
    time_t cur = time(nullptr);
    return getValueForHour(direction, cur, hour);
}

float PriceService::getValueForHour(uint8_t direction, time_t ts, int8_t hour) {
    float ret = getEnergyPriceForHour(direction, ts, hour);
    if(ret == PRICE_NO_VALUE)
        return ret;

    tmElements_t tm;
    breakTime(tz->toLocal(ts + (hour) * SECS_PER_HOUR), tm);
    uint8_t day = 0x01 << (tm.Wday - 2);
    uint32_t hrs = 0x01 << tm.Hour;

    for (uint8_t i = 0; i < priceConfig.size(); i++) {
        PriceConfig pc = priceConfig.at(i);
        if(pc.type == PRICE_TYPE_FIXED) continue;
        uint8_t start_month = pc.start_month == 0 || pc.start_month > 12 ? 1 : pc.start_month;
        uint8_t start_dayofmonth = pc.start_dayofmonth == 0 || pc.start_dayofmonth > 31 ? 1 : pc.start_dayofmonth;
        uint8_t end_month = pc.end_month == 0 || pc.end_month > 12 ? 12 : pc.end_month;
        uint8_t end_dayofmonth = pc.end_dayofmonth == 0 || pc.end_dayofmonth > 31 ? 31 : pc.end_dayofmonth;

        if((pc.direction & direction) == direction && (pc.days & day) == day && (pc.hours & hrs) == hrs && tm.Month >= start_month && tm.Day >= start_dayofmonth && tm.Month <= end_month && tm.Day <= end_dayofmonth) {
            switch(pc.type) {
                case PRICE_TYPE_ADD:
                    ret += pc.value / 10000.0;
                    break;
                case PRICE_TYPE_SUBTRACT:
                    ret -= pc.value / 10000.0;
                    break;
                case PRICE_TYPE_PCT:
                    ret += ((pc.value / 10000.0) * ret) / 100.0;
                    break;
            }
        }
    }
    return ret;
}

float PriceService::getEnergyPriceForHour(uint8_t direction, time_t ts, int8_t hour) {
    tmElements_t tm;
    breakTime(tz->toLocal(ts + (hour) * SECS_PER_HOUR), tm);
    uint8_t day = 0x01 << (tm.Wday - 2);
    uint32_t hrs = 0x01 << tm.Hour;

    float value = PRICE_NO_VALUE;
    for (uint8_t i = 0; i < priceConfig.size(); i++) {
        PriceConfig pc = priceConfig.at(i);
        if(pc.type != PRICE_TYPE_FIXED) continue;
        uint8_t start_month = pc.start_month == 0 || pc.start_month > 12 ? 1 : pc.start_month;
        uint8_t start_dayofmonth = pc.start_dayofmonth == 0 || pc.start_dayofmonth > 31 ? 1 : pc.start_dayofmonth;
        uint8_t end_month = pc.end_month == 0 || pc.end_month > 12 ? 12 : pc.end_month;
        uint8_t end_dayofmonth = pc.end_dayofmonth == 0 || pc.end_dayofmonth > 31 ? 31 : pc.end_dayofmonth;

        if((pc.direction & direction) == direction && (pc.days & day) == day && (pc.hours & hrs) == hrs && tm.Month >= start_month && tm.Day >= start_dayofmonth && tm.Month <= end_month && tm.Day <= end_dayofmonth) {
            if(value == PRICE_NO_VALUE) {
                value = pc.value / 10000.0;
            } else {
                value += pc.value / 10000.0;
            }
        }
    }
    if(value != PRICE_NO_VALUE) return value;

    int8_t pos = hour;

    breakTime(tz->toLocal(ts), tm);
    while(tm.Hour > 0) {
        ts -= 3600;
        breakTime(tz->toLocal(ts), tm);
        pos++;
    }
    uint8_t hoursToday = 0;
    uint8_t todayDate = tm.Day;
    while(tm.Day == todayDate) {
        ts += 3600;
        breakTime(tz->toLocal(ts), tm);
        hoursToday++;
    }
    if(pos > 49)
        return PRICE_NO_VALUE;

    float multiplier = 1.0;
    if(pos >= hoursToday) {
        if(tomorrow == NULL)
            return PRICE_NO_VALUE;
        if(tomorrow->points[pos-hoursToday] == PRICE_NO_VALUE)
            return PRICE_NO_VALUE;
        value = tomorrow->points[pos-hoursToday] / 10000.0;
        if(strcmp(tomorrow->measurementUnit, "KWH") == 0) {
            // Multiplier is 1
        } else if(strcmp(tomorrow->measurementUnit, "MWH") == 0) {
            multiplier *= 0.001;
        } else {
            return PRICE_NO_VALUE;
        }
        float mult = getCurrencyMultiplier(tomorrow->currency, config->currency, time(nullptr));
        if(mult == 0) return PRICE_NO_VALUE;
        multiplier *= mult;
    } else if(pos >= 0) {
        if(today == NULL)
            return PRICE_NO_VALUE;
        if(today->points[pos] == PRICE_NO_VALUE)
            return PRICE_NO_VALUE;
        value = today->points[pos] / 10000.0;
        if(strcmp(today->measurementUnit, "KWH") == 0) {
            // Multiplier is 1
        } else if(strcmp(today->measurementUnit, "MWH") == 0) {
            multiplier *= 0.001;
        } else {
            return PRICE_NO_VALUE;
        }
        float mult = getCurrencyMultiplier(today->currency, config->currency, time(nullptr));
        if(mult == 0) return PRICE_NO_VALUE;
        multiplier *= mult;
    }
    return value * multiplier;
}

bool PriceService::loop() {
    uint64_t now = millis64();
    if(now < 10000) return false; // Grace period

    time_t t = time(nullptr);
    if(t < FirmwareVersion::BuildEpoch) return false;

    #ifndef AMS2MQTT_PRICE_KEY
    if(strlen(getToken()) == 0) {
        return false;
    }
    #endif
    if(!config->enabled)
        return false;
    if(strlen(config->area) == 0)
        return false;
    if(strlen(config->currency) == 0)
        return false;

    tmElements_t tm;
    breakTime(tz->toLocal(t), tm);

    if(currentDay == 0) {
        currentDay = tm.Day;
        currentHour = tm.Hour;
    }
    
    if(currentDay != tm.Day) {
        if(today != NULL) delete today;
        if(tomorrow != NULL) {
            today = tomorrow;
            tomorrow = NULL;
        }
        currentDay = tm.Day;
        currentHour = tm.Hour;
        return today != NULL; // Only trigger MQTT publish if we have todays prices.
    } else if(currentHour != tm.Hour) {
        currentHour = tm.Hour;
        return today != NULL; // Only trigger MQTT publish if we have todays prices.
    }

    bool readyToFetchForTomorrow = tomorrow == NULL && (tm.Hour > 13 || (tm.Hour == 13 && tm.Minute >= tomorrowFetchMinute)) && (lastTomorrowFetch == 0 || now - lastTomorrowFetch > (nextFetchDelayMinutes*60000));

    if(today == NULL && (lastTodayFetch == 0 || now - lastTodayFetch > (nextFetchDelayMinutes*60000))) {
        try {
            lastTodayFetch = now;
            today = fetchPrices(t);
        } catch(const std::exception& e) {
            if(lastError == 0) {
                lastError = 900;
                nextFetchDelayMinutes = 60;
            }
            today = NULL;
        }
        return today != NULL && !readyToFetchForTomorrow; // Only trigger MQTT publish if we have todays prices and we are not immediately ready to fetch price for tomorrow.
    }

    // Prices for next day are published at 13:00 CE(S)T, but to avoid heavy server traffic at that time, we will 
    // fetch with one hour (with some random delay) and retry every 15 minutes
    if(readyToFetchForTomorrow) {
        try {
            lastTomorrowFetch = now;
            tomorrow = fetchPrices(t+SECS_PER_DAY);
        } catch(const std::exception& e) {
            if(lastError == 0) {
                lastError = 900;
                nextFetchDelayMinutes = 60;
            }
            tomorrow = NULL;
        }
        return tomorrow != NULL;
    }

    return false;
}

bool PriceService::retrieve(const char* url, Stream* doc) {
    #if defined(ESP32)
        if(http->begin(url)) {
            #if defined(ESP32)
                esp_task_wdt_reset();
            #elif defined(ESP8266)
                ESP.wdtFeed();
            #endif

            int status = http->GET();

            #if defined(ESP32)
                esp_task_wdt_reset();
            #elif defined(ESP8266)
                ESP.wdtFeed();
            #endif

            if(status == HTTP_CODE_OK) {
                http->writeToStream(doc);
                http->end();
                lastError = 0;
                nextFetchDelayMinutes = 1;
                return true;
            } else {
                lastError = status;
                if(status == 429) {
                    nextFetchDelayMinutes = 15;
                } else if(status == 404) {
                    nextFetchDelayMinutes = 10;
                } else {
                    nextFetchDelayMinutes = 2;
                }
                if(debugger->isActive(RemoteDebug::ERROR)) debugger->printf_P(PSTR("(PriceService) Communication error, returned status: %d\n"), status);
                if(debugger->isActive(RemoteDebug::ERROR)) debugger->printf(http->errorToString(status).c_str());
                if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf(http->getString().c_str());

                http->end();
                return false;
            }
        } else {
            return false;
        }
    #endif
    return false;
}

float PriceService::getCurrencyMultiplier(const char* from, const char* to, time_t t) {
    if(strcmp(from, to) == 0)
        return 1.00;

    uint64_t now = millis64();
    if(now > lastCurrencyFetch && (lastCurrencyFetch == 0 || (now - lastCurrencyFetch) > 60000)) {
        lastCurrencyFetch = now;
        
        DnbCurrParser p;

        #if defined(ESP32)
            esp_task_wdt_reset();
        #elif defined(ESP8266)
            ESP.wdtFeed();
        #endif

        float currencyMultiplier = 0;
        snprintf_P(buf, BufferSize, PSTR("https://data.norges-bank.no/api/data/EXR/B.%s.NOK.SP?lastNObservations=1"), from);
        if(retrieve(buf, &p)) {
            if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf_P(PSTR("(PriceService)  got exchange rate %.4f\n"), p.getValue());
            currencyMultiplier = p.getValue();
            if(strncmp(to, "NOK", 3) != 0) {
                snprintf_P(buf, BufferSize, PSTR("https://data.norges-bank.no/api/data/EXR/B.%s.NOK.SP?lastNObservations=1"), to);
                if(retrieve(buf, &p)) {
                    if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf_P(PSTR("(PriceService)  got exchange rate %.4f\n"), p.getValue());
                    if(p.getValue() > 0.0) {
                        currencyMultiplier /= p.getValue();
                    } else {
                        currencyMultiplier = 0;
                    }
                } else {
                    currencyMultiplier = 0;
                }
            }
        }
        if(currencyMultiplier != 0) {
            if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf_P(PSTR("(PriceService) Resulting currency multiplier: %.4f\n"), currencyMultiplier);
            tmElements_t tm;
            breakTime(t, tm);
            lastCurrencyFetch = now + (SECS_PER_DAY * 1000) - (((((tm.Hour * 60) + tm.Minute) * 60) + tm.Second) * 1000) + (3600000 * 6) + (tomorrowFetchMinute * 60);
            this->currencyMultiplier = currencyMultiplier;
        } else {
            if(debugger->isActive(RemoteDebug::WARNING)) debugger->printf_P(PSTR("(PriceService) Multiplier ended in success, but without value\n"));
            lastCurrencyFetch = now + (SECS_PER_HOUR * 1000);
            if(this->currencyMultiplier == 1) return 0;
        }
    }
    return currencyMultiplier;
}

PricesContainer* PriceService::fetchPrices(time_t t) {
    if(strlen(getToken()) > 0) {
        tmElements_t tm;
        breakTime(tz->toLocal(t), tm);
        time_t e1 = t - (tm.Hour * 3600) - (tm.Minute * 60) - tm.Second; // Local midnight
        time_t e2 = e1 + SECS_PER_DAY;
        tmElements_t d1, d2;
        breakTime(e1, d1);
        breakTime(e2, d2);

        snprintf_P(buf, BufferSize, PSTR("https://web-api.tp.entsoe.eu/api?securityToken=%s&documentType=A44&periodStart=%04d%02d%02d%02d%02d&periodEnd=%04d%02d%02d%02d%02d&in_Domain=%s&out_Domain=%s"), 
        getToken(), 
        d1.Year+1970, d1.Month, d1.Day, d1.Hour, 00,
        d2.Year+1970, d2.Month, d2.Day, d2.Hour, 00,
        config->area, config->area);

        #if defined(ESP32)
            esp_task_wdt_reset();
        #elif defined(ESP8266)
            ESP.wdtFeed();
        #endif

        if(debugger->isActive(RemoteDebug::INFO)) debugger->printf_P(PSTR("(PriceService) Fetching prices for %02d.%02d.%04d\n"), tm.Day, tm.Month, tm.Year+1970);
        if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf_P(PSTR("(PriceService)  url: %s\n"), buf);
        EntsoeA44Parser a44;
        if(retrieve(buf, &a44) && a44.getPoint(0) != PRICE_NO_VALUE) {
            PricesContainer* ret = new PricesContainer();
            a44.get(ret);
            return ret;
        } else {
            return NULL;
        }
    } else if(hub) {
        tmElements_t tm;
        breakTime(tz->toLocal(t), tm);

        String data;
        snprintf_P(buf, BufferSize, PSTR("http://hub.amsleser.no/hub/price/%s/%d/%d/%d?currency=%s"),
            config->area,
            tm.Year+1970,
            tm.Month,
            tm.Day,
            config->currency
        );
        if(debugger->isActive(RemoteDebug::INFO)) debugger->printf_P(PSTR("(PriceService) Fetching prices for %02d.%02d.%04d\n"), tm.Day, tm.Month, tm.Year+1970);
        if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf_P(PSTR("(PriceService)  url: %s\n"), buf);
        #if defined(ESP8266)
        WiFiClient client;
        client.setTimeout(5000);
        if(http->begin(client, buf)) {
        #elif defined(ESP32)
        if(http->begin(buf)) {
        #endif
            int status = http->GET();

            #if defined(ESP32)
                esp_task_wdt_reset();
            #elif defined(ESP8266)
                ESP.wdtFeed();
            #endif

            if(status == HTTP_CODE_OK) {
                data = http->getString();
                http->end();
                
                uint8_t* content = (uint8_t*) (data.c_str());

                DataParserContext ctx = {0,0,0,0};
                ctx.length = data.length();
                GCMParser gcm(key, auth);
                int8_t gcmRet = gcm.parse(content, ctx);
                if(gcmRet > 0) {
                    PricesContainer* ret = new PricesContainer();
                    for(uint8_t i = 0; i < 25; i++) {
                        ret->points[i] = PRICE_NO_VALUE;
                    }
                    memcpy(ret, content+gcmRet, sizeof(*ret));
                    for(uint8_t i = 0; i < 25; i++) {
                        ret->points[i] = ntohl(ret->points[i]);
                    }
                    lastError = 0;
                    nextFetchDelayMinutes = 1;
                    return ret;
                } else {
                    lastError = gcmRet;
                    nextFetchDelayMinutes = 60;
                    if(debugger->isActive(RemoteDebug::ERROR)) debugger->printf_P(PSTR("(PriceService) Error code while decrypting prices: %d\n"), gcmRet);
                }
            } else {
                lastError = status;
                if(status == 429) {
                    nextFetchDelayMinutes = 60;
                } else if(status == 404) {
                    nextFetchDelayMinutes = 15;
                } else {
                    nextFetchDelayMinutes = 5;
                }
                if(debugger->isActive(RemoteDebug::ERROR)) debugger->printf_P(PSTR("(PriceService) Communication error, returned status: %d\n"), status);
                if(debugger->isActive(RemoteDebug::ERROR)) {
                    debugger->printf(http->errorToString(status).c_str());
                    debugger->println();
                }
                if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf(http->getString().c_str());

                http->end();
            }
        }
    }
    return NULL;
}

void PriceService::debugPrint(byte *buffer, int start, int length) {
	for (int i = start; i < start + length; i++) {
		if (buffer[i] < 0x10)
			debugger->print(F("0"));
		debugger->print(buffer[i], HEX);
		debugger->print(F(" "));
		if ((i - start + 1) % 16 == 0)
			debugger->println(F(""));
		else if ((i - start + 1) % 4 == 0)
			debugger->print(F(" "));

		yield(); // Let other get some resources too
	}
	debugger->println(F(""));
}

int16_t PriceService::getLastError() {
    return lastError;
}

std::vector<PriceConfig>& PriceService::getPriceConfig() {
    return this->priceConfig;
}

void PriceService::setPriceConfig(uint8_t index, PriceConfig &priceConfig) {
    stripNonAscii((uint8_t*) priceConfig.name, 32);

    if(this->priceConfig.capacity() != index+1)
        this->priceConfig.resize(index+1);
    if(this->priceConfig.size() > index)    
        this->priceConfig[index] = priceConfig;
    else   
        this->priceConfig.push_back(priceConfig);
}

void PriceService::cropPriceConfig(uint8_t size) {
    this->priceConfig.resize(size);
    this->priceConfig.shrink_to_fit();

}

bool PriceService::save() {
    if(!LittleFS.begin()) {
        if(debugger->isActive(RemoteDebug::ERROR)) debugger->printf_P(PSTR("(PriceService) Unable to load LittleFS\n"));
        return false;
    }

    if(debugger->isActive(RemoteDebug::INFO)) debugger->printf_P(PSTR("(PriceService) Saving price config\n"));

    PriceConfig pc;
    File file = LittleFS.open(FILE_PRICE_CONF, "w");
    uint8_t count = priceConfig.size();
    uint16_t bytes = 1 + (count * sizeof(pc));
    char buf[bytes];
    buf[0] = count;
    for(uint8_t i = 0; i < count; i++) {
        pc = priceConfig.at(i);
        memcpy(buf + 1 + (i * sizeof(pc)), &pc, sizeof(pc));
    }
    for(unsigned long i = 0; i < bytes; i++) {
        file.write(buf[i]);
    }
    file.close();

    return true;
}

bool PriceService::load() {
    if(!LittleFS.begin()) {
        if(debugger->isActive(RemoteDebug::ERROR)) debugger->printf_P(PSTR("(PriceService) Unable to load LittleFS\n"));
        return false;
    }
    if(!LittleFS.exists(FILE_PRICE_CONF)) {
        if(debugger->isActive(RemoteDebug::DEBUG)) debugger->printf_P(PSTR("(PriceService) No price config file\n"));
        return false;
    }
    if(debugger->isActive(RemoteDebug::INFO)) debugger->printf_P(PSTR("(PriceService) Loading price config\n"));

    this->priceConfig.clear();

    PriceConfig pc;
    File file = LittleFS.open(FILE_PRICE_CONF, "r");
    uint8_t count = file.read();
    for(uint8_t i = 0; i < count; i++) {
        file.readBytes((char*) &pc, sizeof(pc));
        this->priceConfig.push_back(pc);
    }
    file.close();

    return true;
}