#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/gpio.h"

#include "display.h"

#define PIN 20
#define MAX_TRANSITIONS 100

void prepare_sensor() {
    gpio_set_dir(PIN, GPIO_OUT);

    gpio_put(PIN, true);
    sleep_ms(1000);
}

void ask_sensor() {
    gpio_put(PIN, false);
    sleep_ms(20);

    gpio_set_dir(PIN, GPIO_IN);
    gpio_pull_up(PIN);
}

uint64_t read_bytes(uint32_t *transitions, uint8_t transitions_count) {
    uint64_t output = 0;
    uint32_t start_time = transitions[2];
    int bits = 0;

    for (int i=3; i<transitions_count; i++) {
        if (i % 2 == 0) { // low state
            // bit is 1 if delay before low state is more than 30 ms
            output <<= 1;
            output |= (transitions[i] - start_time > 50);
            bits++;
        }
        start_time = transitions[i];
    }

    printf("Bits: %d\n", bits);

    return output;
}

bool read_to_variables(uint64_t data, float *humidity, float *temperature) {
    uint8_t temp_dec = (data >> 8) & 0xFF;
    uint8_t temp_int = (data >> 16) & 0xFF;
    uint8_t hum_dec = (data >> 24) & 0xFF;
    uint8_t hum_int = (data >> 32) & 0xFF;

    *temperature = temp_int + (temp_dec / 255.0);
    *humidity = hum_int + (hum_dec / 255.0);

    uint8_t calculated_checksum = hum_int + hum_dec + temp_int + temp_dec;
    uint8_t checksum = data & 0xFF;

    return checksum == calculated_checksum;
} 

int main() {

    stdio_init_all();

    initialize_display();
    display_digit(11);
    int disp = 11;

    printf("Initializing sensor...\n");
    gpio_init(PIN);
    prepare_sensor();

    while (true) {
        printf("\n");

        uint32_t transitions[MAX_TRANSITIONS];
        uint8_t transitions_count = 0;
        bool state = true;

        ask_sensor();

        uint32_t start = time_us_32();
        uint32_t time_now = start;
        
        while (time_now - start < 100000) {
            time_now = time_us_32();
            bool new_state = gpio_get(PIN);
            if (new_state != state) {
                transitions[transitions_count++] = time_now;
                state = new_state;
            }
        }

        if (transitions_count > 0) {
            printf("Transitions: %d\n", transitions_count);
            printf("Time taken: %dus\n", transitions[transitions_count - 1] - start);

            for (int i=0; i<transitions_count; i++) {
                printf("#%d to %s after %dus\n", i, (i % 2 == 0 ? "low" : "high"), transitions[i] - start);
                start = transitions[i];
            }
            
            uint64_t output = read_bytes(transitions, transitions_count);

            float temperature, humidity;
            bool valid = read_to_variables(output, &temperature, &humidity);
        
            printf("Temperature: %f\n", temperature);
            printf("Humidity: %f\n", humidity);
            printf("Valid: %s\n", valid ? "yes" : "no");

            int d = humidity / 10;
            if (d > 10) d = 10;
            display_animate(disp, d);
            disp = d;
        } else {
            display_animate(disp, 10);
            disp = 10;
            printf("Error reading\n");
        }

        prepare_sensor();
        sleep_ms(1000);
    }

    return 0;
}