#ifndef BLINK_APP_H
#define BLINK_APP_H

#include <hal.h>

/*
 * BlinkApp -- Testable blink logic, decoupled from hardware.
 *
 * Blinks an LED and reads a button. When the button is pressed,
 * the blink rate doubles (toggles between normal and fast mode).
 *
 * All hardware access goes through the injected Hal pointer. This
 * class has no dependency on Arduino.h and compiles on any host.
 */
class BlinkApp {
public:
    static constexpr uint8_t DEFAULT_LED_PIN    = LED_BUILTIN;  // pin 13
    static constexpr uint8_t DEFAULT_BUTTON_PIN = 2;
    static constexpr unsigned long SLOW_INTERVAL_MS = 500;
    static constexpr unsigned long FAST_INTERVAL_MS = 125;

    BlinkApp(Hal* hal,
             uint8_t led_pin = DEFAULT_LED_PIN,
             uint8_t button_pin = DEFAULT_BUTTON_PIN)
        : hal_(hal)
        , led_pin_(led_pin)
        , button_pin_(button_pin)
        , led_state_(LOW)
        , fast_mode_(false)
        , last_toggle_ms_(0)
        , last_button_state_(HIGH)  // pulled up, so HIGH = not pressed
    {}

    // Call once from setup()
    void begin() {
        hal_->pinMode(led_pin_, OUTPUT);
        hal_->pinMode(button_pin_, INPUT_PULLUP);
        hal_->serialBegin(115200);
        hal_->serialPrintln("BlinkApp started");
        last_toggle_ms_ = hal_->millis();
    }

    // Call repeatedly from loop()
    void update() {
        handleButton();
        handleBlink();
    }

    // -- Accessors for testing ----------------------------------------------
    bool ledState() const       { return led_state_ == HIGH; }
    bool fastMode() const       { return fast_mode_; }
    unsigned long interval() const {
        return fast_mode_ ? FAST_INTERVAL_MS : SLOW_INTERVAL_MS;
    }

private:
    void handleButton() {
        uint8_t reading = hal_->digitalRead(button_pin_);

        // Detect falling edge (HIGH -> LOW = button press with INPUT_PULLUP)
        if (last_button_state_ == HIGH && reading == LOW) {
            fast_mode_ = !fast_mode_;
            hal_->serialPrintln(fast_mode_ ? "FAST" : "SLOW");
        }
        last_button_state_ = reading;
    }

    void handleBlink() {
        unsigned long now = hal_->millis();
        unsigned long target = fast_mode_ ? FAST_INTERVAL_MS : SLOW_INTERVAL_MS;

        if (now - last_toggle_ms_ >= target) {
            led_state_ = (led_state_ == HIGH) ? LOW : HIGH;
            hal_->digitalWrite(led_pin_, led_state_);
            last_toggle_ms_ = now;
        }
    }

    Hal* hal_;
    uint8_t led_pin_;
    uint8_t button_pin_;
    uint8_t led_state_;
    bool fast_mode_;
    unsigned long last_toggle_ms_;
    uint8_t last_button_state_;
};

#endif // BLINK_APP_H