feat: add plugin to support android/ios styleUrls (#47)

When given an url "./style.css" and the resource "style.css" does not
exist in the current directory, the plugin will change the url to
"style.android|ios.css". The target platform should be provided in the
options of the plugin.

Closes #36

Author: sis0k0

Diff for: index.js

@@ -2,6 +2,8 @@ var sources = require("webpack-sources");
 var fs = require("fs");
 var path = require("path");
 
+exports.StyleUrlResolvePlugin = require('./resource-resolver-plugins/StyleUrlResolvePlugin');
+
 //HACK: changes the JSONP chunk eval function to `global["nativescriptJsonp"]`
 // applied to tns-java-classes.js only
 exports.NativeScriptJsonpPlugin = function(options) {

Diff for: resource-resolver-plugins/StyleUrlResolvePlugin.js

@@ -0,0 +1,96 @@
+const ts = require("typescript");
+const fs = require("fs");
+const path = require("path");
+
+const StyleUrlResolvePlugin = (function() {
+    function StyleUrlResolvePlugin(options) {
+        if (!options || !options.platform) {
+            throw new Error(`Target platform must be specified!`);
+        }
+
+        this.platform = options.platform;
+    }
+
+    StyleUrlResolvePlugin.prototype.apply = function (compiler) {
+        compiler.plugin("make", (compilation, callback) => {
+            const aotPlugin = getAotPlugin(compilation);
+            aotPlugin._program.getSourceFiles()
+                .forEach(sf => this.usePlatformStyleUrl(sf));
+
+            callback();
+        })
+    };
+
+    function getAotPlugin(compilation) {
+        let maybeAotPlugin = compilation._ngToolsWebpackPluginInstance;
+        if (!maybeAotPlugin) {
+            throw new Error(`This plugin must be used with the AotPlugin!`);
+        }
+
+        return maybeAotPlugin;
+    }
+
+    StyleUrlResolvePlugin.prototype.usePlatformStyleUrl = function(sourceFile) {
+        this.setCurrentDirectory(sourceFile);
+        ts.forEachChild(sourceFile, node => this.traverseDecorators(node));
+    }
+
+    StyleUrlResolvePlugin.prototype.setCurrentDirectory = function(sourceFile) {
+        this.currentDirectory = path.resolve(sourceFile.path, "..");
+    }
+
+    StyleUrlResolvePlugin.prototype.traverseDecorators = function(node) {
+        if (node.kind !== ts.SyntaxKind.ClassDeclaration || !node.decorators) {
+            return;
+        }
+
+        node.decorators.forEach(decorator => {
+            this.traverseDecoratorArguments(decorator.expression.arguments);
+        });
+    }
+
+    StyleUrlResolvePlugin.prototype.traverseDecoratorArguments = function(args) {
+        args.forEach(arg => this.traverseProperties(arg.properties));
+    }
+
+    StyleUrlResolvePlugin.prototype.traverseProperties = function(properties) {
+        properties.filter(isStyleUrls)
+            .forEach(prop => this.traversePropertyElements(prop));
+    }
+
+    function isStyleUrls(property) {
+        return property.name.text === "styleUrls";
+    }
+
+    StyleUrlResolvePlugin.prototype.traversePropertyElements = function(property) {
+        property.initializer.elements
+            .filter(el => this.notPlatformUrl(el.text))
+            .filter(el => this.noMultiplatformFile(el.text))
+            .forEach(el => this.replaceStyleUrlsValue(el));
+    }
+
+    StyleUrlResolvePlugin.prototype.notPlatformUrl = function(styleUrl) {
+        let extensionStartIndex = styleUrl.lastIndexOf(".");
+        let extension = styleUrl.slice(extensionStartIndex);
+
+        return !styleUrl.endsWith(`.${this.platform}${extension}`);
+    }
+
+    StyleUrlResolvePlugin.prototype.noMultiplatformFile = function(styleUrl) {
+        let stylePath = path.resolve(this.currentDirectory, styleUrl);
+
+        return !fs.existsSync(stylePath);
+    }
+
+    StyleUrlResolvePlugin.prototype.replaceStyleUrlsValue = function(element) {
+        const extensionStartIndex = element.text.lastIndexOf(".");
+        const prefix = element.text.slice(0, extensionStartIndex);
+        const currentExtension = element.text.slice(extensionStartIndex);
+
+        element.text = `${prefix}.${this.platform}${currentExtension}`;
+    }
+
+    return StyleUrlResolvePlugin;
+})();
+
+module.exports = StyleUrlResolvePlugin;

Diff for: webpack.common.js.angular.template

@@ -51,6 +51,7 @@ module.exports = function (platform, destinationApp) {
             entryModule: path.resolve(__dirname, "app/app.module#AppModule"),
             typeChecking: false
         }),
+        new nsWebpack.StyleUrlResolvePlugin({platform}),
     ];
 
     if (process.env.npm_config_uglify) {