/*
 * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
 * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
 * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
 * Code distributed by Google as part of the polymer project is also
 * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 */

(function(scope) {

  // imports

  var log = window.WebComponents ? WebComponents.flags.log : {};
  var hasShadowDOMPolyfill = window.ShadowDOMPolyfill;

  // magic words
  
  var STYLE_SCOPE_ATTRIBUTE = 'element';
  var STYLE_CONTROLLER_SCOPE = 'controller';
  
  var styles = {
    STYLE_SCOPE_ATTRIBUTE: STYLE_SCOPE_ATTRIBUTE,
    /**
     * Installs external stylesheets and <style> elements with the attribute 
     * polymer-scope='controller' into the scope of element. This is intended
     * to be a called during custom element construction.
    */
    installControllerStyles: function() {
      // apply controller styles, but only if they are not yet applied
      var scope = this.findStyleScope();
      if (scope && !this.scopeHasNamedStyle(scope, this.localName)) {
        // allow inherited controller styles
        var proto = getPrototypeOf(this), cssText = '';
        while (proto && proto.element) {
          cssText += proto.element.cssTextForScope(STYLE_CONTROLLER_SCOPE);
          proto = getPrototypeOf(proto);
        }
        if (cssText) {
          this.installScopeCssText(cssText, scope);
        }
      }
    },
    installScopeStyle: function(style, name, scope) {
      var scope = scope || this.findStyleScope(), name = name || '';
      if (scope && !this.scopeHasNamedStyle(scope, this.localName + name)) {
        var cssText = '';
        if (style instanceof Array) {
          for (var i=0, l=style.length, s; (i<l) && (s=style[i]); i++) {
            cssText += s.textContent + '\n\n';
          }
        } else {
          cssText = style.textContent;
        }
        this.installScopeCssText(cssText, scope, name);
      }
    },
    installScopeCssText: function(cssText, scope, name) {
      scope = scope || this.findStyleScope();
      name = name || '';
      if (!scope) {
        return;
      }
      if (hasShadowDOMPolyfill) {
        cssText = shimCssText(cssText, scope.host);
      }
      var style = this.element.cssTextToScopeStyle(cssText,
          STYLE_CONTROLLER_SCOPE);
      Polymer.applyStyleToScope(style, scope);
      // cache that this style has been applied
      this.styleCacheForScope(scope)[this.localName + name] = true;
    },
    findStyleScope: function(node) {
      // find the shadow root that contains this element
      var n = node || this;
      while (n.parentNode) {
        n = n.parentNode;
      }
      return n;
    },
    scopeHasNamedStyle: function(scope, name) {
      var cache = this.styleCacheForScope(scope);
      return cache[name];
    },
    styleCacheForScope: function(scope) {
      if (hasShadowDOMPolyfill) {
        var scopeName = scope.host ? scope.host.localName : scope.localName;
        return polyfillScopeStyleCache[scopeName] || (polyfillScopeStyleCache[scopeName] = {});
      } else {
        return scope._scopeStyles = (scope._scopeStyles || {});
      }
    }
  };

  var polyfillScopeStyleCache = {};
  
  // NOTE: use raw prototype traversal so that we ensure correct traversal
  // on platforms where the protoype chain is simulated via __proto__ (IE10)
  function getPrototypeOf(prototype) {
    return prototype.__proto__;
  }

  function shimCssText(cssText, host) {
    var name = '', is = false;
    if (host) {
      name = host.localName;
      is = host.hasAttribute('is');
    }
    var selector = WebComponents.ShadowCSS.makeScopeSelector(name, is);
    return WebComponents.ShadowCSS.shimCssText(cssText, selector);
  }

  // exports

  scope.api.instance.styles = styles;
  
})(Polymer);