import Toybox.Application;
import Toybox.Graphics;
import Toybox.Lang;
import Toybox.Math;
import Toybox.Timer;
import Toybox.WatchUi;

// Rotating 10-icon ring modelled after the watch Controls menu.
// Selection point is fixed at the 3 o'clock position (START/STOP
// button height). UP/DOWN input rotates the ring with a smooth
// animation.
class MenuView extends WatchUi.View {

    const STORAGE_KEY = "menu_idx";
    const ANIM_DURATION_MS = 200;
    const ANIM_TICK_MS = 16;  // ~60fps

    private var _items as Array<Dictionary>;
    private var _selectedIndex as Number = 0;
    private var _bitmaps as Dictionary = {};

    // Animation state.
    private var _animTimer as Timer.Timer;
    private var _animFrom as Number = 0;   // previous index
    private var _animProgress as Float = 1.0;  // 0.0 → 1.0, 1.0 = done
    private var _animStartMs as Number = 0;

    function initialize() {
        View.initialize();
        _items = Config.menuItems();
        _animTimer = new Timer.Timer();
        var stored = Application.Storage.getValue(STORAGE_KEY);
        if (stored instanceof Number && stored >= 0 && stored < _items.size()) {
            _selectedIndex = stored;
        }
        _animFrom = _selectedIndex;
    }

    function onLayout(dc as Dc) as Void {
        for (var i = 0; i < _items.size(); i++) {
            var iconId = _items[i][:icon];
            _bitmaps[iconId] = WatchUi.loadResource(iconId) as BitmapResource;
        }
    }

    function rotateNext() as Void {
        _startAnim(_selectedIndex);
        _selectedIndex = (_selectedIndex + 1) % _items.size();
        Application.Storage.setValue(STORAGE_KEY, _selectedIndex);
    }

    function rotatePrev() as Void {
        _startAnim(_selectedIndex);
        _selectedIndex = (_selectedIndex - 1 + _items.size()) % _items.size();
        Application.Storage.setValue(STORAGE_KEY, _selectedIndex);
    }

    private function _startAnim(fromIndex as Number) as Void {
        _animFrom = fromIndex;
        _animProgress = 0.0;
        _animStartMs = System.getTimer();
        _animTimer.start(method(:_animTick), ANIM_TICK_MS, true);
    }

    function _animTick() as Void {
        var elapsed = System.getTimer() - _animStartMs;
        _animProgress = elapsed.toFloat() / ANIM_DURATION_MS.toFloat();
        if (_animProgress >= 1.0) {
            _animProgress = 1.0;
            _animTimer.stop();
        }
        WatchUi.requestUpdate();
    }

    function selectedItem() as Dictionary {
        return _items[_selectedIndex];
    }

    function selectedIndex() as Number {
        return _selectedIndex;
    }

    private var _iconPositions as Array = [];

    // Returns the index of the icon closest to (tapX, tapY), or -1.
    function itemIndexAt(tapX as Number, tapY as Number) as Number {
        var bestIdx = -1;
        var bestDist = 999999;
        for (var i = 0; i < _iconPositions.size(); i++) {
            var pos = _iconPositions[i] as Array;
            var ix = pos[0] as Number;
            var iy = pos[1] as Number;
            var size = pos[2] as Number;
            var dx = tapX - ix;
            var dy = tapY - iy;
            var dist = dx * dx + dy * dy;
            var maxDist = (size / 2) * (size / 2);
            if (dist < maxDist && dist < bestDist) {
                bestDist = dist;
                bestIdx = i;
            }
        }
        return bestIdx;
    }

    // Rotate to a specific index with animation.
    function rotateTo(index as Number) as Void {
        if (index == _selectedIndex) { return; }
        _startAnim(_selectedIndex);
        _selectedIndex = index;
        Application.Storage.setValue(STORAGE_KEY, _selectedIndex);
    }

    function onUpdate(dc as Dc) as Void {
        dc.setColor(Config.COLOR_FG, Config.COLOR_BG);
        dc.clear();

        var cx = LayoutMetrics.centerX(dc);
        var cy = LayoutMetrics.centerY(dc);
        var radius = LayoutMetrics.ringRadius(dc);
        var baseSize = LayoutMetrics.iconSize(dc);
        var selSize = LayoutMetrics.selectedIconSize(dc);
        var n = _items.size();
        var selectionAngle = Config.SELECTION_ANGLE_DEG * Math.PI / 180.0;
        var step = 2.0 * Math.PI / n;

        // Ease-out for smooth deceleration.
        var t = _animProgress;
        var ease = 1.0 - (1.0 - t) * (1.0 - t);

        // Interpolate the rotation offset between old and new index.
        var fromOffset = _animFrom.toFloat();
        var toOffset = _selectedIndex.toFloat();
        // Handle wrap-around (e.g. 9→0 or 0→9).
        var diff = toOffset - fromOffset;
        if (diff > n / 2.0) { diff = diff - n; }
        if (diff < -n / 2.0) { diff = diff + n; }
        var currentOffset = fromOffset + diff * ease;

        _iconPositions = new [n];
        for (var i = 0; i < n; i++) {
            var angle = selectionAngle + (i.toFloat() - currentOffset) * step;
            var x = (cx + radius * Math.cos(angle)).toNumber();
            var y = (cy + radius * Math.sin(angle)).toNumber();

            // Smoothly scale selected icon.
            var isSelected = (i == _selectedIndex);
            var wasSelected = (i == _animFrom);
            var targetSize = baseSize;
            if (isSelected && wasSelected) {
                targetSize = selSize;
            } else if (isSelected) {
                targetSize = (baseSize + (selSize - baseSize) * ease).toNumber();
            } else if (wasSelected) {
                targetSize = (selSize - (selSize - baseSize) * ease).toNumber();
            }

            _iconPositions[i] = [x, y, targetSize];

            // Colored circle behind icon.
            var color = _items[i][:color] as Number;
            dc.setColor(color, Config.COLOR_BG);
            dc.fillCircle(x, y, targetSize / 2);

            var iconId = _items[i][:icon];
            var bmp = _bitmaps[iconId] as BitmapResource;
            if (bmp != null) {
                _drawScaledIcon(dc, bmp, x, y, targetSize);
            }

            // Accent ring on selected item (also animated).
            if (isSelected && ease > 0.5) {
                dc.setPenWidth(LayoutMetrics.accentPenWidth(dc));
                dc.setColor(Config.COLOR_ACCENT, Config.COLOR_BG);
                dc.drawCircle(x, y, targetSize / 2 + 5);
            }
        }

        // Only show label when animation is done to avoid flicker.
        if (_animProgress >= 1.0) {
            var lines = _items[_selectedIndex][:lines] as Array<String>;
            dc.setColor(Config.COLOR_FG, Config.COLOR_BG);
            TextUtils.drawCentered(dc, lines, cx, cy, Graphics.FONT_TINY);
        }
    }

    private function _drawScaledIcon(dc as Dc, bmp as BitmapResource,
                                     cx as Number, cy as Number,
                                     targetSize as Number) as Void {
        var bmpW = bmp.getWidth();
        var bmpH = bmp.getHeight();
        var scale = targetSize.toFloat() / bmpW.toFloat();
        var tf = new Graphics.AffineTransform();
        tf.translate(cx.toFloat(), cy.toFloat());
        tf.scale(scale, scale);
        tf.translate(-bmpW.toFloat() / 2.0, -bmpH.toFloat() / 2.0);
        dc.drawBitmap2(0, 0, bmp, { :transform => tf });
    }
}