/**
 *
 */
#include <time.h>
#include <WiFi.h>
#include <Arduino.h>
#include <ESP_SSLClient.h>
#include "config.h"
#include "certs.h"
#include "credentials.h"


enum door_state {
    /*
     */
    CLOSED = '0',
    OPEN = '1'
};
door_state new_door_state = CLOSED;
door_state current_door_state = CLOSED;
WiFiClient basic_client;
ESP_SSLClient ssl_client;


void display_info() {
    /*
     * ausgabe einiger infos tum device. ich verstehe allerdings die
     * for-schleife nicht.
     */
    uint32_t chipId = 0;

    for (int i = 0; i < 17; i = i + 8) {
        chipId |= ((ESP.getEfuseMac() >> (40 - i)) & 0xff) << i;
    }
    Serial.printf("\nESP32 Chip model = %s Rev %d\n", ESP.getChipModel(),
                  ESP.getChipRevision());
    Serial.printf("This chip has %d cores\n", ESP.getChipCores());
    Serial.print("Chip ID: ");
    Serial.println(chipId);
    Serial.print(" ");
}

void init_wifi() {
    /*
     */
    int counter = 0;
    Serial.print("Connecting to wifi ");
    Serial.print(WIFI_SSID);
    WiFi.mode(WIFI_STA);
    WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
    while (WiFi.status() != WL_CONNECTED)
    {
        delay(500);
        Serial.print(".");
        counter++;
        if (counter >= 180) {
            Serial.println(" Failed");
            ESP.restart();
        }
    }
    Serial.println(" Connected");
    Serial.print("IP: ");
    Serial.println(WiFi.localIP());
    Serial.print("Strength: ");
    Serial.println(WiFi.RSSI());
}

void set_clock() {
    /*
     * We need time for certificate authorization
     */
    Serial.print("Fetch time from ");
    Serial.println(NTP_URL);
    configTime(GTM_OFFSET_SEC, DAYLIGHT_OFFSET_SEC, NTP_URL);
    printLocalTime();
}

void printLocalTime() {
    /*
     */
    struct tm timeinfo;
    if (!getLocalTime(&timeinfo)) {
        Serial.println("Failed to obtain time");
        return;
    }
    Serial.printf("%s\n", asctime(&timeinfo));
}

void set_ssl() {
    /*
     */
    // ssl_client.setTimeout(120); 
    // ssl_client.setSessionTimeout(0); 
    ssl_client.setDebugLevel(SSL_DEBUG_LEVEL);
    ssl_client.setClient(&basic_client, false);
    ssl_client.setSSLVersion(BR_TLS12, BR_TLS12);
    ssl_client.setCACert(CA_CERTS);
    ssl_client.setCertificate(CLIENT_CERT);
    ssl_client.setPrivateKey(CLIENT_KEY);

}

door_state read_door_state() {
    /* 
     *  die initialisierung des reed-switch-pins mit pullup bewirkt, dass am pin
     *  3,3 volt anliegen. die verbindung des pins mit GND sorgt dafür,
     *  dass die spannung "abfließen" kann. dadurch hat der pin dann den
     *  status 'low'. die option geht leider nur mit der bibliothek für den
     *  esp8862.
     *  geschlossene tür -> reed geschlossen -> low
     *  geöffnete tür -> reed offen -> high
     */
    if (digitalRead(REED_PIN) == HIGH) {
        return OPEN;
    }
    return CLOSED;
}

bool send_status(door_state state) {
    /*
     * param 1: door_state
     * returns: boolean
     *
     * needs error handling
     */
    int32_t response = 0;
    int counter = 0;

    // connect to server
    Serial.print("Connecting to server ");
    Serial.print(SERVER_URL);
    Serial.print(" ... ");
    if (ssl_client.connect(SERVER_URL, SERVER_PORT)) {
        Serial.println(" ok");
        Serial.print("Upgrade to HTTPS...");
        if (!ssl_client.connectSSL())
        {
            Serial.println(" failed\r\n");
            return false;
        }
        Serial.println(" ok");
        // send new status
        Serial.print("Send new status ... ");
        response = ssl_client.write(current_door_state);
        ssl_client.flush();
        Serial.print("Bytes written: ");
        Serial.println(response);

        Serial.print("Read response...");
        Serial.print((char)ssl_client.read());
        Serial.println();
    } else {
        Serial.println(" failed\n");
        ssl_client.stop();
        return false;
    }
    ssl_client.stop();
    return true;
}

void setup() {
    /*
     */
    Serial.begin(115200);
    Serial.println("------------- setup -------------");
    display_info();
    init_wifi();
    set_clock();
    set_ssl();
    Serial.println("-------- setup finished ---------");
}

void loop() {
    /*
     */
    new_door_state = read_door_state();
    if (new_door_state != current_door_state) {
        Serial.print("Status has changed to ");
        Serial.println(new_door_state);
        if (send_status(new_door_state)) {
            current_door_state = new_door_state;
            Serial.println("Door status send successful");
        } else {
            Serial.println("Failed to send new door status");
        }
    }
    delay(FREQUENCY);
}