// Contrast management module
// Uses the Observer pattern to notify the main camera module of contrast changes

const ContrastManager = {
    // Private state
    _currentContrast: 1.0, // Default contrast (no change)
    _observers: new Set(),
    _slider: null,

    // Initialize the contrast manager
    init() {
        this._setupEventListeners();
    },

    // Private methods
    _setupEventListeners() {
        this._slider = document.getElementById('contrast-slider');
        this._slider.addEventListener('input', (e) => {
            this._currentContrast = parseFloat(e.target.value);
            document.getElementById('contrast-value').textContent = this._currentContrast;
            this._notifyObservers();
        });
    },

    _notifyObservers() {
        this._observers.forEach(observer => observer(this._currentContrast));
    },

    // Public methods
    subscribe(observer) {
        this._observers.add(observer);
        return () => this._observers.delete(observer);
    },

    getCurrentContrast() {
        return this._currentContrast;
    },

    // Apply contrast to an image
    applyContrast(imageData, contrast) {
        if (!contrast || contrast === 1.0) return imageData;

        const { data } = imageData;
        const factor = (259 * (contrast + 255)) / (255 * (259 - contrast));

        for (let i = 0; i < data.length; i += 4) {
            // Apply contrast to each color channel
            for (let c = 0; c < 3; c++) {
                const pixel = data[i + c];
                data[i + c] = factor * (pixel - 128) + 128;
            }
        }

        return imageData;
    },

    // Add reset method
    reset() {
        this._currentContrast = 1.0;
        this._slider.value = 0; // Reset slider to middle position
        this._notifyObservers();
    }
};