#include <SoftwareSerial.h>

#include <linux/printk.h>
#include <linux/time64.h>

#define BTPWR 5
#define BTRX 6
#define BTTX 7
#define RELAY 10

String command;
SoftwareSerial bt(BTRX, BTTX);

int relay_state = LOW;

unsigned long last_start[HIGH + 1];

static inline unsigned long minutes(int m)
{
    return m * MSEC_PER_MIN;
}

unsigned long duration[HIGH + 1] = {
    [LOW]  = minutes(55),
    [HIGH] = minutes(5),
};

void setup(void)
{
    Serial.begin(9600);
    pr_debug("tacqua:\r\n"
         "duration[off]: %ld\r\n"
         "duration[on] : %ld\r\n",
         duration[LOW] / MSEC_PER_MIN,
         duration[HIGH] / MSEC_PER_MIN);

    pinMode(RELAY, OUTPUT);
    /*
     * Use BTPWR as a 5v, 40mA power source for the Bluetooth module.
     */
    pinMode(BTPWR, OUTPUT);
    digitalWrite(BTPWR, OUTPUT);

    bt.begin(9600);
    /* bt.write("AT+NAMETACQUA"); */
}

static int bt_print_tstamp(void)
{
    return spr_info(bt, "%ld: ", millis() / MSEC_PER_MIN);
}

static const char *str_state(int s)
{
    return s ? "On" : "Off";
}

static void switch_relay(int new_state)
{
    if (new_state != relay_state) {
        pr_debug("Switching to: %s\r\n", str_state(new_state));
        bt_print_tstamp();
        bt.println(str_state(new_state));
        relay_state = new_state;
        digitalWrite(RELAY, relay_state);
        last_start[relay_state] = millis();
    }
}

static void show_settings(void)
{
    bt_print_tstamp();

    if (duration[HIGH] == 0) {
        spr_info(bt, "timer Off, relay %s\r\n", str_state(relay_state));
        return;
    }

    spr_info(bt, "last[%s]: %ld\r\n", "On", last_start[HIGH] / MSEC_PER_MIN);
    bt_print_tstamp();
    spr_info(bt, "duration[%s]: %ld\r\n", "On ", duration[HIGH] / MSEC_PER_MIN);
    bt_print_tstamp();
    spr_info(bt, "last[%s]: %ld\r\n", "Off", last_start[LOW] / MSEC_PER_MIN);
    bt_print_tstamp();
    spr_info(bt, "duration[%s]: %ld\r\n", "Off", duration[LOW] / MSEC_PER_MIN);
}

static void do_command(void)
{
    if (command == "0") {
        switch_relay(LOW);
        duration[HIGH] = 0;
    } else if (command == "1") {
        switch_relay(HIGH);
        duration[HIGH] = 0;
    } else {
        char *endptr;
        unsigned long d = strtol(command.c_str(), &endptr, 10);

        if (d != 0) {
            duration[HIGH] = minutes(d);
            pr_debug("duration[%s]: %ld\r\n", "HIGH", duration[HIGH]);
            if (*endptr == ',') {
                d = strtol(endptr + 1, NULL, 10);

                if (d != 0) {
                    duration[LOW] = minutes(d);
                    pr_debug("duration[%s]: %ld\r\n", "LOW", duration[LOW]);
                }
            }

            switch_relay(HIGH);
        } else {
            show_settings();
        }
    }
}

void loop(void)
{
    int c;
    unsigned long now, delta;

    while (bt.available()) {
        c = bt.read();
        if (c == '\r')
            break;
        command += char(c);
    }

    if (c == '\r' && command != "") {
        pr_debug("command: %s\r\n", command.c_str());
        do_command();
        command = "";
    }

    delay(1 * 1000);

    /*
     * Check if timer is on
     */
    if (duration[HIGH] == 0)
        return;

    now = millis();
    delta = now - last_start[relay_state];
    if (delta >= duration[relay_state]) {
        pr_debug("%ld: \r\n", now);
        switch_relay(!relay_state);
    }
}