CLI: Add support for templates fetched from npm

Summary:
This PR allows anyone to publish templates for React Native.

It's possible for people to publish modules for React Native, we should also support custom templates. A suggestion from a Cordova mantainer where they did the same thing suggests this is useful:
https://github.com/mkonicek/AppTemplateFeedback/issues/1

I published a sample template [react-native-template-demo](https://www.npmjs.com/package/react-native-template-demo).

(GitHub: https://github.com/mkonicek/react-native-template-demo)

With this PR anyone can then use that template:

`react-native init MyApp --template demo`

The convention is: if someone publishes an npm package called `react-native-template-foo`, people can use it by running `react-native init MyApp --template foo`.

Use a template called `react-native-template-demo` from npm:

`react-native init MyApp --template demo`

Use a local template:

`react-native init MyApp --template file:///path_to/react-native-template-dem
Closes https://github.com/facebook/react-native/pull/12548

Differential Revision: D4620567

Pulled By: mkonicek

fbshipit-source-id: bb40d457a7fec28edb577f08137e73241072de3a

local-cli/generator/copyProjectTemplateAndReplace.js

@@ -21,6 +21,12 @@ const walk = require('../util/walk');
  * @param srcPath e.g. '/Users/martin/AwesomeApp/node_modules/react-native/local-cli/templates/HelloWorld'
  * @param destPath e.g. '/Users/martin/AwesomeApp'
  * @param newProjectName e.g. 'AwesomeApp'
+ * @param options e.g. {
+ *          upgrade: true,
+ *          force: false,
+ *          displayName: 'Hello World',
+ *          ignorePaths: ['template/file/to/ignore.md'],
+ *        }
  */
 function copyProjectTemplateAndReplace(srcPath, destPath, newProjectName, options) {
   if (!srcPath) { throw new Error('Need a path to copy from'); }
@@ -45,6 +51,20 @@ function copyProjectTemplateAndReplace(srcPath, destPath, newProjectName, option
       .replace(/HelloWorld/g, newProjectName)
       .replace(/helloworld/g, newProjectName.toLowerCase());
 
+    // Templates may contain files that we don't want to copy.
+    // Examples:
+    // - Dummy package.json file included in the template only for publishing to npm
+    // - Docs specific to the template (.md files)
+    if (options.ignorePaths) {
+      if (!Array.isArray(options.ignorePaths)) {
+        throw new Error('options.ignorePaths must be an array');
+      }
+      if (options.ignorePaths.some(ignorePath => ignorePath === relativeFilePath)) {
+        // Skip copying this file
+        return;
+      }
+    }
+
     let contentChangedCallback = null;
     if (options.upgrade && (!options.force)) {
       contentChangedCallback = (_, contentChanged) => {

local-cli/generator/templates.js

@@ -13,7 +13,10 @@ const execSync = require('child_process').execSync;
 const fs = require('fs');
 const path = require('path');
 
-const availableTemplates = {
+/**
+ * Templates released as part of react-native in local-cli/templates.
+ */
+const builtInTemplates = {
   navigation: 'HelloNavigation',
 };
 
@@ -22,9 +25,9 @@ function listTemplatesAndExit(newProjectName, options) {
     // Just listing templates using 'react-native init --template'.
     // Not creating a new app.
     // Print available templates and exit.
-    const templateKeys = Object.keys(availableTemplates);
+    const templateKeys = Object.keys(builtInTemplates);
     if (templateKeys.length === 0) {
-      // Just a guard, should never happen as long availableTemplates
+      // Just a guard, should never happen as long builtInTemplates
       // above is defined correctly :)
       console.log(
         'There are no templates available besides ' +
@@ -47,12 +50,13 @@ function listTemplatesAndExit(newProjectName, options) {
 }
 
 /**
+ * @param destPath Create the new project at this path.
  * @param newProjectName For example 'AwesomeApp'.
- * @param templateKey Template to use, for example 'navigation'.
+ * @param template Template to use, for example 'navigation'.
  * @param yarnVersion Version of yarn available on the system, or null if
  *                    yarn is not available. For example '0.18.1'.
  */
-function createProjectFromTemplate(destPath, newProjectName, templateKey, yarnVersion) {
+function createProjectFromTemplate(destPath, newProjectName, template, yarnVersion) {
   // Expand the basic 'HelloWorld' template
   copyProjectTemplateAndReplace(
     path.resolve('node_modules', 'react-native', 'local-cli', 'templates', 'HelloWorld'),
@@ -60,7 +64,11 @@ function createProjectFromTemplate(destPath, newProjectName, templateKey, yarnVe
     newProjectName
   );
 
-  if (templateKey !== undefined) {
+  if (template === undefined) {
+    // No specific template, use just the HelloWorld template above
+    return;
+  }
+
   // Keep the files from the 'HelloWorld' template, and overwrite some of them
   // with the specified project template.
   // The 'HelloWorld' template contains the native files (these are used by
@@ -69,29 +77,113 @@ function createProjectFromTemplate(destPath, newProjectName, templateKey, yarnVe
   // This way we don't have to duplicate the native files in every template.
   // If we duplicated them we'd make RN larger and risk that people would
   // forget to maintain all the copies so they would go out of sync.
-    const templateName = availableTemplates[templateKey];
+  const builtInTemplateName = builtInTemplates[template];
-    if (templateName) {
+  if (builtInTemplateName) {
-      copyProjectTemplateAndReplace(
+    // template is e.g. 'navigation',
-        path.resolve(
+    // use the built-in local-cli/templates/HelloNavigation folder
-          'node_modules', 'react-native', 'local-cli', 'templates', templateName
+    createFromBuiltInTemplate(builtInTemplateName, destPath, newProjectName, yarnVersion);
-        ),
-        destPath,
-        newProjectName
-      );
   } else {
-      throw new Error('Uknown template: ' + templateKey);
+    // template is e.g. 'ignite',
+    // use the template react-native-template-ignite from npm
+    createFromRemoteTemplate(template, destPath, newProjectName, yarnVersion);
+  }
+}
+
+// (We might want to get rid of built-in templates in the future -
+// publish them to npm and install from there.)
+function createFromBuiltInTemplate(templateName, destPath, newProjectName, yarnVersion) {
+  const templatePath = path.resolve(
+    'node_modules', 'react-native', 'local-cli', 'templates', templateName
+  );
+  copyProjectTemplateAndReplace(
+    templatePath,
+    destPath,
+    newProjectName,
+  );
+  installTemplateDependencies(templatePath, yarnVersion);
+}
+
+/**
+ * The following formats are supported for the template:
+ * - 'demo' -> Fetch the package react-native-template-demo from npm
+ * - git://..., http://..., file://... or any other URL supported by npm
+ */
+function createFromRemoteTemplate(template, destPath, newProjectName, yarnVersion) {
+  let installPackage;
+  let templateName;
+  if (template.includes('://')) {
+     // URL, e.g. git://, file://
+     installPackage = template;
+     templateName = template.substr(template.lastIndexOf('/') + 1);
+  } else {
+    // e.g 'demo'
+    installPackage = 'react-native-template-' + template;
+    templateName = installPackage;
   }
 
-    // Add dependencies:
+  // Check if the template exists
+  console.log(`Fetching template ${installPackage}...`);
+  try {
+    if (yarnVersion) {
+      execSync(`yarn add ${installPackage} --ignore-scripts`, {stdio: 'inherit'});
+    } else {
+      execSync(`npm install ${installPackage} --save --save-exact --ignore-scripts`, {stdio: 'inherit'});
+    }
+    const templatePath = path.resolve(
+      'node_modules', templateName
+    );
+    copyProjectTemplateAndReplace(
+      templatePath,
+      destPath,
+      newProjectName,
+      {
+        // Every template contains a dummy package.json file included
+        // only for publishing the template to npm.
+        // We want to ignore this dummy file, otherwise it would overwrite
+        // our project's package.json file.
+        ignorePaths: ['package.json', 'dependencies.json'],
+      }
+    );
+    installTemplateDependencies(templatePath, yarnVersion);
+  } finally {
+    // Clean up the temp files
+    try {
+      if (yarnVersion) {
+        execSync(`yarn remove ${templateName} --ignore-scripts`);
+      } else {
+        execSync(`npm uninstall ${templateName} --ignore-scripts`);
+      }
+    } catch (err) {
+      // Not critical but we still want people to know and report
+      // if this the clean up fails.
+      console.warn(
+        `Failed to clean up template temp files in node_modules/${templateName}. ` +
+        'This is not a critical error, you can work on your app.'
+      );
+    }
+  }
+}
 
+function installTemplateDependencies(templatePath, yarnVersion) {
   // dependencies.json is a special file that lists additional dependencies
   // that are required by this template
   const dependenciesJsonPath = path.resolve(
-      'node_modules', 'react-native', 'local-cli', 'templates', templateName, 'dependencies.json'
+    templatePath, 'dependencies.json'
   );
-    if (fs.existsSync(dependenciesJsonPath)) {
   console.log('Adding dependencies for the project...');
-      const dependencies = JSON.parse(fs.readFileSync(dependenciesJsonPath));
+  if (!fs.existsSync(dependenciesJsonPath)) {
+    console.log('No additional dependencies.');
+    return;
+  }
+
+  let dependencies;
+  try {
+    dependencies = JSON.parse(fs.readFileSync(dependenciesJsonPath));
+  } catch (err) {
+    throw new Error(
+      'Could not parse the template\'s dependencies.json: ' + err.message
+    );
+  }
   for (let depName in dependencies) {
     const depVersion = dependencies[depName];
     const depToInstall = depName + '@' + depVersion;
@@ -102,8 +194,8 @@ function createProjectFromTemplate(destPath, newProjectName, templateKey, yarnVe
       execSync(`npm install ${depToInstall} --save --save-exact`, {stdio: 'inherit'});
     }
   }
-    }
+  console.log('Linking native dependencies into the project\'s build files...');
-  }
+  execSync('react-native link', {stdio: 'inherit'});
 }
 
 module.exports = {

local-cli/link/link.js

@@ -5,6 +5,8 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
  */
 
 const log = require('npmlog');
@@ -29,6 +31,8 @@ const pollParams = require('./pollParams');
 const commandStub = require('./commandStub');
 const promisify = require('./promisify');
 
+import type {ConfigT} from '../core';
+
 log.heading = 'rnpm-link';
 
 const dedupeAssets = (assets) => uniq(assets, asset => path.basename(asset));
@@ -125,18 +129,20 @@ const linkAssets = (project, assets) => {
 };
 
 /**
- * Updates project and links all dependencies to it
+ * Updates project and links all dependencies to it.
  *
- * If optional argument [packageName] is provided, it's the only one that's checked
+ * @param args If optional argument [packageName] is provided,
+ *             only that package is processed.
+ * @param config CLI config, see local-cli/core/index.js
  */
-function link(args, config) {
+function link(args: Array<string>, config: ConfigT) {
   var project;
   try {
     project = config.getProjectConfig();
   } catch (err) {
     log.error(
       'ERRPACKAGEJSON',
-      'No package found. Are you sure it\'s a React Native project?'
+      'No package found. Are you sure this is a React Native project?'
     );
     return Promise.reject(err);
   }
@@ -169,8 +175,8 @@ function link(args, config) {
 
   return promiseWaterfall(tasks).catch(err => {
     log.error(
-      `It seems something went wrong while linking. Error: ${err.message} \n`
+      `Something went wrong while linking. Error: ${err.message} \n` +
-      + 'Please file an issue here: https://github.com/facebook/react-native/issues'
+      'Please file an issue here: https://github.com/facebook/react-native/issues'
     );
     throw err;
   });
@@ -178,6 +184,6 @@ function link(args, config) {
 
 module.exports = {
   func: link,
-  description: 'links all native dependencies',
+  description: 'links all native dependencies (updates native build files)',
   name: 'link [packageName]',
 };