(function (global) {
    'use strict';

    /**
     * Canvas pick / inspect mode without project code.
     * @constructor
     */
    function NodePickController() {
        this.mode = 'game';
        this._cc = null;
        this._selected = null;
        this._onSelect = null;
        this._onMode = null;
        this._boundDown = this._onPointerDown.bind(this);
        this._canvas = null;
        this._overlay = null;
        this._raf = 0;
    }

    /** @param {*} cc */
    NodePickController.prototype.bindEngine = function (cc) {
        this._cc = cc;
        this._canvas = document.getElementById('GameCanvas');
        this._ensureOverlay();
        this.setMode('game');
    };

    /** 挂到 pw-root，用 fixed 定位，避免被预览容器 overflow 裁切 */
    NodePickController.prototype._ensureOverlay = function () {
        var overlay = document.getElementById('pw-pick-overlay');
        var root = document.getElementById('pw-root');
        if (!overlay) {
            overlay = document.createElement('div');
            overlay.id = 'pw-pick-overlay';
            overlay.className = 'pw-pick-overlay';
            overlay.hidden = true;
        }
        if (root && overlay.parentNode !== root) root.appendChild(overlay);
        this._overlay = overlay;
    };

    /** @param {function(*):void} cb */
    NodePickController.prototype.onSelect = function (cb) {
        this._onSelect = cb;
    };

    /** @param {function(string):void} cb */
    NodePickController.prototype.onModeChange = function (cb) {
        this._onMode = cb;
    };

    /** @returns {*} */
    NodePickController.prototype.getSelected = function () {
        return this._selected;
    };

    /**
     * @param {string} mode game|inspect
     */
    NodePickController.prototype.setMode = function (mode) {
        this.mode = mode === 'inspect' ? 'inspect' : 'game';
        var root = document.getElementById('pw-root');
        if (root) root.classList.toggle('pw-inspect', this.mode === 'inspect');
        var gameBtn = document.getElementById('pw-mode-game');
        var inspectBtn = document.getElementById('pw-mode-inspect');
        if (gameBtn) gameBtn.classList.toggle('active', this.mode === 'game');
        if (inspectBtn) inspectBtn.classList.toggle('active', this.mode === 'inspect');

        if (!this._canvas) return;
        if (this.mode === 'inspect') {
            this._canvas.addEventListener('pointerdown', this._boundDown, true);
        } else {
            this._canvas.removeEventListener('pointerdown', this._boundDown, true);
        }
        if (this._selected) this._startOverlayLoop();
        else {
            this._stopOverlayLoop();
            if (this._overlay) this._overlay.hidden = true;
        }
        if (this._onMode) this._onMode(this.mode);
    };

    /** @param {*} node */
    NodePickController.prototype.select = function (node) {
        this._selected = node || null;
        this._ensureOverlay();
        if (this._selected) this._startOverlayLoop();
        else {
            this._stopOverlayLoop();
            if (this._overlay) this._overlay.hidden = true;
        }
        this._updateOverlay();
        if (this._onSelect) this._onSelect(this._selected);
    };

    NodePickController.prototype._onPointerDown = function (ev) {
        if (this.mode !== 'inspect') return;
        ev.preventDefault();
        ev.stopPropagation();
        var node = this._hitTest(ev.clientX, ev.clientY);
        this.select(node);
    };

    NodePickController.prototype._hitTest = function (clientX, clientY) {
        var cc = this._cc;
        var canvas = this._canvas;
        if (!cc || !canvas) return null;
        var scene = cc.director.getScene();
        if (!scene) return null;
        var stack = [];
        this._walk(scene, function (n) { stack.push(n); });
        for (var i = stack.length - 1; i >= 0; i--) {
            var node = stack[i];
            if (!node || !node.activeInHierarchy) continue;
            var uit = node.getComponent && node.getComponent(cc.UITransform);
            if (!uit) continue;
            var box = this._getNodeClientRect(node);
            if (!box) continue;
            if (clientX >= box.left && clientX <= box.right && clientY >= box.top && clientY <= box.bottom) {
                return node;
            }
        }
        return null;
    };

    NodePickController.prototype._walk = function (node, fn) {
        if (!node) return;
        fn(node);
        var children = node.children;
        if (!children) return;
        for (var i = 0; i < children.length; i++) this._walk(children[i], fn);
    };

    NodePickController.prototype._startOverlayLoop = function () {
        var self = this;
        this._stopOverlayLoop();
        var tick = function () {
            self._updateOverlay();
            self._raf = requestAnimationFrame(tick);
        };
        this._raf = requestAnimationFrame(tick);
    };

    NodePickController.prototype._stopOverlayLoop = function () {
        if (this._raf) cancelAnimationFrame(this._raf);
        this._raf = 0;
    };

    /**
     * UI 节点包围盒 → 浏览器 client 坐标。
     * 使用可见区域中心原点映射（与竖屏 UI Canvas 一致），避免 worldToScreen 在自定义帧尺寸下偏移。
     * @param {*} node
     */
    NodePickController.prototype._getNodeClientRect = function (node) {
        var cc = this._cc;
        var canvas = this._canvas;
        if (!cc || !canvas || !node || !node.isValid) return null;
        var uit = node.getComponent && node.getComponent(cc.UITransform);
        if (!uit) return null;

        var canvasRect = canvas.getBoundingClientRect();
        if (canvasRect.width < 2 || canvasRect.height < 2) return null;

        var corners = null;
        if (typeof uit.getBoundingBoxToWorld === 'function') {
            var box = uit.getBoundingBoxToWorld();
            if (box && box.width >= 0 && box.height >= 0) {
                corners = [
                    { x: box.x, y: box.y },
                    { x: box.x + box.width, y: box.y },
                    { x: box.x + box.width, y: box.y + box.height },
                    { x: box.x, y: box.y + box.height },
                ];
            }
        }
        if (!corners) corners = this._localCornersToWorld(uit);
        if (!corners) return null;

        var vs = cc.view && typeof cc.view.getVisibleSize === 'function'
            ? cc.view.getVisibleSize()
            : { width: canvasRect.width, height: canvasRect.height };
        var vw = Math.max(1, vs.width);
        var vh = Math.max(1, vs.height);

        var xs = [];
        var ys = [];
        for (var i = 0; i < corners.length; i++) {
            // UI 世界坐标：原点在可见区域中心，Y 向上
            var nx = corners[i].x / vw + 0.5;
            var ny = 0.5 - corners[i].y / vh;
            xs.push(canvasRect.left + nx * canvasRect.width);
            ys.push(canvasRect.top + ny * canvasRect.height);
        }

        var left = Math.min.apply(null, xs);
        var right = Math.max.apply(null, xs);
        var top = Math.min.apply(null, ys);
        var bottom = Math.max.apply(null, ys);
        return {
            left: left,
            top: top,
            right: right,
            bottom: bottom,
            width: Math.max(2, right - left),
            height: Math.max(2, bottom - top),
        };
    };

    NodePickController.prototype._localCornersToWorld = function (uit) {
        var cc = this._cc;
        var w = uit.width;
        var h = uit.height;
        var ax = uit.anchorX != null ? uit.anchorX : (uit.anchorPoint ? uit.anchorPoint.x : 0.5);
        var ay = uit.anchorY != null ? uit.anchorY : (uit.anchorPoint ? uit.anchorPoint.y : 0.5);
        var locals = [
            { x: -ax * w, y: -ay * h },
            { x: (1 - ax) * w, y: -ay * h },
            { x: (1 - ax) * w, y: (1 - ay) * h },
            { x: -ax * w, y: (1 - ay) * h },
        ];
        if (typeof uit.convertToWorldSpaceAR !== 'function' || !cc.Vec3) return null;
        var out = [];
        for (var i = 0; i < 4; i++) {
            out.push(uit.convertToWorldSpaceAR(new cc.Vec3(locals[i].x, locals[i].y, 0)));
        }
        return out;
    };

    NodePickController.prototype._updateOverlay = function () {
        var overlay = this._overlay;
        var node = this._selected;
        var cc = this._cc;
        if (!overlay) return;
        if (!node || !node.isValid || !cc) {
            overlay.hidden = true;
            return;
        }
        var box = this._getNodeClientRect(node);
        if (!box) {
            overlay.hidden = true;
            return;
        }
        overlay.hidden = false;
        overlay.style.position = 'fixed';
        overlay.style.left = box.left + 'px';
        overlay.style.top = box.top + 'px';
        overlay.style.width = box.width + 'px';
        overlay.style.height = box.height + 'px';
    };

    global.PWNodePick = NodePickController;
})(window);