#include <pico/stdlib.h>
#include <pico/time.h>

// Pin definitions
#define RED_PIN 15
#define YELLOW_PIN 6
#define GREEN_PIN 4

// Timing constants (in milliseconds)
#define RED_DURATION 5000    // 5 seconds
#define YELLOW_DURATION 2000 // 2 seconds
#define GREEN_DURATION 5000  // 5 seconds

// States for the traffic light
enum TrafficState { RED, YELLOW, GREEN };
enum TrafficState currentState = RED;

// Timing variables
uint64_t lastStateChange = 0;

// Function to check if enough time has passed (non-blocking)
bool has_time_passed(uint64_t last_time, uint32_t interval_ms) {
    return (time_us_64() / 1000) - last_time >= interval_ms;
}

void setup() {
    // Initialize pins
    gpio_init(RED_PIN);
    gpio_init(YELLOW_PIN);
    gpio_init(GREEN_PIN);
    gpio_set_dir(RED_PIN, GPIO_OUT);
    gpio_set_dir(YELLOW_PIN, GPIO_OUT);
    gpio_set_dir(GREEN_PIN, GPIO_OUT);

    // Initial state: Red ON, others OFF
    gpio_put(RED_PIN, 1);
    gpio_put(YELLOW_PIN, 0);
    gpio_put(GREEN_PIN, 0);
}

int main() {
    setup();

    while (true) {
        uint64_t currentTime = time_us_64() / 1000; // Convert to milliseconds

        // Check if it's time to change state
        switch (currentState) {
            case RED:
                if (has_time_passed(lastStateChange, RED_DURATION)) {
                    // Switch to Yellow
                    gpio_put(RED_PIN, 0);
                    gpio_put(YELLOW_PIN, 1);
                    gpio_put(GREEN_PIN, 0);
                    currentState = YELLOW;
                    lastStateChange = currentTime;
                }
                break;

            case YELLOW:
                if (has_time_passed(lastStateChange, YELLOW_DURATION)) {
                    // Switch to Green
                    gpio_put(RED_PIN, 0);
                    gpio_put(YELLOW_PIN, 0);
                    gpio_put(GREEN_PIN, 1);
                    currentState = GREEN;
                    lastStateChange = currentTime;
                }
                break;

            case GREEN:
                if (has_time_passed(lastStateChange, GREEN_DURATION)) {
                    // Switch to Red
                    gpio_put(RED_PIN, 1);
                    gpio_put(YELLOW_PIN, 0);
                    gpio_put(GREEN_PIN, 0);
                    currentState = RED;
                    lastStateChange = currentTime;
                }
                break;
        }
    }

    return 0;
}