From 2d2710a7c486ab2dc5c005695df1089d5d1d03a5 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 21 May 2020 13:51:08 +0200
Subject: [PATCH 1/6] packages/cli: move plugin diff prompts to separate file

---
 .../cli/src/commands/plugin/diff/index.ts     | 44 +++------------
 .../cli/src/commands/plugin/diff/prompts.ts   | 53 +++++++++++++++++++
 2 files changed, 59 insertions(+), 38 deletions(-)
 create mode 100644 packages/cli/src/commands/plugin/diff/prompts.ts

diff --git a/packages/cli/src/commands/plugin/diff/index.ts b/packages/cli/src/commands/plugin/diff/index.ts
index 5338594a3b..6300ff64d8 100644
--- a/packages/cli/src/commands/plugin/diff/index.ts
+++ b/packages/cli/src/commands/plugin/diff/index.ts
@@ -14,12 +14,14 @@
  * limitations under the License.
  */
 
-import chalk from 'chalk';
-import inquirer from 'inquirer';
 import { Command } from 'commander';
 import { readTemplateFiles } from './read';
 import { handlers, handleAllFiles } from './handlers';
-import { PromptFunc } from './types';
+import {
+  inquirerPromptFunc,
+  makeCheckPromptFunc,
+  yesPromptFunc,
+} from './prompts';
 
 const fileHandlers = [
   {
@@ -41,46 +43,12 @@ const fileHandlers = [
   },
 ];
 
-const inquirerPromptFunc: PromptFunc = async (msg) => {
-  const { result } = await inquirer.prompt({
-    type: 'confirm',
-    name: 'result',
-    message: chalk.blue(msg),
-  });
-  return result;
-};
-
-const makeCheck = () => {
-  let failed = false;
-
-  const promptFunc: PromptFunc = async (msg) => {
-    failed = true;
-    console.log(chalk.red(`[Check Failed] ${msg}`));
-    return false;
-  };
-
-  const finalize = () => {
-    if (failed) {
-      throw new Error(
-        'Check failed, the plugin is not in sync with the latest template',
-      );
-    }
-  };
-
-  return [promptFunc, finalize] as const;
-};
-
-const yesPromptFunc: PromptFunc = async (msg) => {
-  console.log(`Accepting: "${msg}"`);
-  return true;
-};
-
 export default async (cmd: Command) => {
   let promptFunc = inquirerPromptFunc;
   let finalize = () => {};
 
   if (cmd.check) {
-    [promptFunc, finalize] = makeCheck();
+    [promptFunc, finalize] = makeCheckPromptFunc();
   } else if (cmd.yes) {
     promptFunc = yesPromptFunc;
   }
diff --git a/packages/cli/src/commands/plugin/diff/prompts.ts b/packages/cli/src/commands/plugin/diff/prompts.ts
new file mode 100644
index 0000000000..ac04fc3559
--- /dev/null
+++ b/packages/cli/src/commands/plugin/diff/prompts.ts
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import chalk from 'chalk';
+import inquirer from 'inquirer';
+import { PromptFunc } from './types';
+
+export const inquirerPromptFunc: PromptFunc = async msg => {
+  const { result } = await inquirer.prompt({
+    type: 'confirm',
+    name: 'result',
+    message: chalk.blue(msg),
+  });
+  return result;
+};
+
+export const makeCheckPromptFunc = () => {
+  let failed = false;
+
+  const promptFunc: PromptFunc = async msg => {
+    failed = true;
+    console.log(chalk.red(`[Check Failed] ${msg}`));
+    return false;
+  };
+
+  const finalize = () => {
+    if (failed) {
+      throw new Error(
+        'Check failed, the plugin is not in sync with the latest template',
+      );
+    }
+  };
+
+  return [promptFunc, finalize] as const;
+};
+
+export const yesPromptFunc: PromptFunc = async msg => {
+  console.log(`Accepting: "${msg}"`);
+  return true;
+};

From 18139238a4cedb1a457b3be24fdacb05568949de Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 21 May 2020 15:54:02 +0200
Subject: [PATCH 2/6] packages/cli: move plugin diff modules to separate diff
 lib

---
 .../plugin/{diff/index.ts => diff.ts}         |  7 ++++---
 .../{commands/plugin => lib}/diff/handlers.ts |  6 +++---
 packages/cli/src/lib/diff/index.ts            | 20 +++++++++++++++++++
 .../{commands/plugin => lib}/diff/prompts.ts  |  0
 .../src/{commands/plugin => lib}/diff/read.ts | 12 +++++------
 .../{commands/plugin => lib}/diff/types.ts    |  0
 6 files changed, 32 insertions(+), 13 deletions(-)
 rename packages/cli/src/commands/plugin/{diff/index.ts => diff.ts} (92%)
 rename packages/cli/src/{commands/plugin => lib}/diff/handlers.ts (97%)
 create mode 100644 packages/cli/src/lib/diff/index.ts
 rename packages/cli/src/{commands/plugin => lib}/diff/prompts.ts (100%)
 rename packages/cli/src/{commands/plugin => lib}/diff/read.ts (93%)
 rename packages/cli/src/{commands/plugin => lib}/diff/types.ts (100%)

diff --git a/packages/cli/src/commands/plugin/diff/index.ts b/packages/cli/src/commands/plugin/diff.ts
similarity index 92%
rename from packages/cli/src/commands/plugin/diff/index.ts
rename to packages/cli/src/commands/plugin/diff.ts
index 6300ff64d8..542b94b0ff 100644
--- a/packages/cli/src/commands/plugin/diff/index.ts
+++ b/packages/cli/src/commands/plugin/diff.ts
@@ -15,13 +15,14 @@
  */
 
 import { Command } from 'commander';
-import { readTemplateFiles } from './read';
-import { handlers, handleAllFiles } from './handlers';
 import {
+  readTemplateFiles,
+  handlers,
+  handleAllFiles,
   inquirerPromptFunc,
   makeCheckPromptFunc,
   yesPromptFunc,
-} from './prompts';
+} from '../../lib/diff';
 
 const fileHandlers = [
   {
diff --git a/packages/cli/src/commands/plugin/diff/handlers.ts b/packages/cli/src/lib/diff/handlers.ts
similarity index 97%
rename from packages/cli/src/commands/plugin/diff/handlers.ts
rename to packages/cli/src/lib/diff/handlers.ts
index 87518eab3e..643c018ddc 100644
--- a/packages/cli/src/commands/plugin/diff/handlers.ts
+++ b/packages/cli/src/lib/diff/handlers.ts
@@ -18,7 +18,7 @@ import fs from 'fs-extra';
 import chalk from 'chalk';
 import { dirname } from 'path';
 import { diffLines } from 'diff';
-import { paths } from '../../../lib/paths';
+import { paths } from '../paths';
 import { TemplateFile, PromptFunc, FileHandler } from './types';
 
 export async function writeTargetFile(targetPath: string, contents: string) {
@@ -221,8 +221,8 @@ export async function handleAllFiles(
 ) {
   for (const file of files) {
     const { targetPath } = file;
-    const fileHandler = fileHandlers.find((handler) =>
-      handler.patterns.some((pattern) =>
+    const fileHandler = fileHandlers.find(handler =>
+      handler.patterns.some(pattern =>
         typeof pattern === 'string'
           ? pattern === targetPath
           : pattern.test(targetPath),
diff --git a/packages/cli/src/lib/diff/index.ts b/packages/cli/src/lib/diff/index.ts
new file mode 100644
index 0000000000..04c5ee2e45
--- /dev/null
+++ b/packages/cli/src/lib/diff/index.ts
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export * from './handlers';
+export * from './prompts';
+export * from './read';
+export * from './types';
diff --git a/packages/cli/src/commands/plugin/diff/prompts.ts b/packages/cli/src/lib/diff/prompts.ts
similarity index 100%
rename from packages/cli/src/commands/plugin/diff/prompts.ts
rename to packages/cli/src/lib/diff/prompts.ts
diff --git a/packages/cli/src/commands/plugin/diff/read.ts b/packages/cli/src/lib/diff/read.ts
similarity index 93%
rename from packages/cli/src/commands/plugin/diff/read.ts
rename to packages/cli/src/lib/diff/read.ts
index a05d7166e2..b408da94e9 100644
--- a/packages/cli/src/commands/plugin/diff/read.ts
+++ b/packages/cli/src/lib/diff/read.ts
@@ -18,8 +18,8 @@ import fs from 'fs-extra';
 import { relative as relativePath } from 'path';
 import handlebars from 'handlebars';
 import recursiveReadDir from 'recursive-readdir';
-import { paths } from '../../../lib/paths';
-import { version } from '../../../lib/version';
+import { paths } from '../paths';
+import { version } from '../version';
 import { PluginInfo, TemplateFile } from './types';
 
 // Reads info from the existing plugin
@@ -64,11 +64,9 @@ export async function readTemplate(
   templateDir: string,
   templateVars: any,
 ): Promise<TemplateFile[]> {
-  const templateFilePaths = await recursiveReadDir(templateDir).catch(
-    (error) => {
-      throw new Error(`Failed to read template directory: ${error.message}`);
-    },
-  );
+  const templateFilePaths = await recursiveReadDir(templateDir).catch(error => {
+    throw new Error(`Failed to read template directory: ${error.message}`);
+  });
 
   const templateFiles = new Array<TemplateFile>();
   for (const templateFile of templateFilePaths) {
diff --git a/packages/cli/src/commands/plugin/diff/types.ts b/packages/cli/src/lib/diff/types.ts
similarity index 100%
rename from packages/cli/src/commands/plugin/diff/types.ts
rename to packages/cli/src/lib/diff/types.ts

From 12c669e904f7686845bd21d8d6866b03f8d1b0b8 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 21 May 2020 18:57:33 +0200
Subject: [PATCH 3/6] packages/cli: split diff template read into two steps and
 tweak handlers api

---
 packages/cli/src/commands/plugin/diff.ts |  4 +-
 packages/cli/src/lib/diff/handlers.ts    | 82 +++++++++++-------------
 packages/cli/src/lib/diff/read.ts        | 81 ++++++++++++++++-------
 packages/cli/src/lib/diff/types.ts       | 33 ++++------
 4 files changed, 107 insertions(+), 93 deletions(-)

diff --git a/packages/cli/src/commands/plugin/diff.ts b/packages/cli/src/commands/plugin/diff.ts
index 542b94b0ff..ba3e99527f 100644
--- a/packages/cli/src/commands/plugin/diff.ts
+++ b/packages/cli/src/commands/plugin/diff.ts
@@ -16,7 +16,7 @@
 
 import { Command } from 'commander';
 import {
-  readTemplateFiles,
+  diffTemplateFiles,
   handlers,
   handleAllFiles,
   inquirerPromptFunc,
@@ -54,7 +54,7 @@ export default async (cmd: Command) => {
     promptFunc = yesPromptFunc;
   }
 
-  const templateFiles = await readTemplateFiles('default-plugin');
+  const templateFiles = await diffTemplateFiles('default-plugin');
   await handleAllFiles(fileHandlers, templateFiles, promptFunc);
   await finalize();
 };
diff --git a/packages/cli/src/lib/diff/handlers.ts b/packages/cli/src/lib/diff/handlers.ts
index 643c018ddc..9e46dd92cf 100644
--- a/packages/cli/src/lib/diff/handlers.ts
+++ b/packages/cli/src/lib/diff/handlers.ts
@@ -14,36 +14,30 @@
  * limitations under the License.
  */
 
-import fs from 'fs-extra';
 import chalk from 'chalk';
-import { dirname } from 'path';
 import { diffLines } from 'diff';
-import { paths } from '../paths';
-import { TemplateFile, PromptFunc, FileHandler } from './types';
-
-export async function writeTargetFile(targetPath: string, contents: string) {
-  const path = paths.resolveTarget(targetPath);
-  await fs.ensureDir(dirname(path));
-  await fs.writeFile(path, contents, 'utf8');
-}
+import { FileDiff, PromptFunc, FileHandler, WriteFileFunc } from './types';
 
 class PackageJsonHandler {
-  static async handler(file: TemplateFile, prompt: PromptFunc) {
+  static async handler(
+    { path, write, missing, targetContents, templateContents }: FileDiff,
+    prompt: PromptFunc,
+  ) {
     console.log('Checking package.json');
 
-    if (!file.targetExists) {
-      throw new Error(`${file.targetPath} doesn't exist`);
+    if (missing) {
+      throw new Error(`${path} doesn't exist`);
     }
 
-    const pkg = JSON.parse(file.templateContents);
-    const targetPkg = JSON.parse(file.targetContents);
+    const pkg = JSON.parse(templateContents);
+    const targetPkg = JSON.parse(targetContents);
 
-    const handler = new PackageJsonHandler(file, prompt, pkg, targetPkg);
+    const handler = new PackageJsonHandler(write, prompt, pkg, targetPkg);
     await handler.handle();
   }
 
   constructor(
-    private readonly file: TemplateFile,
+    private readonly writeFunc: WriteFileFunc,
     private readonly prompt: PromptFunc,
     private readonly pkg: any,
     private readonly targetPkg: any,
@@ -144,31 +138,29 @@ class PackageJsonHandler {
   }
 
   private async write() {
-    await fs.writeFile(
-      paths.resolveTarget(this.file.targetPath),
-      `${JSON.stringify(this.targetPkg, null, 2)}\n`,
-    );
+    await this.writeFunc(`${JSON.stringify(this.targetPkg, null, 2)}\n`);
   }
 }
 
 // Make sure the file is an exact match of the template
-async function exactMatchHandler(file: TemplateFile, prompt: PromptFunc) {
-  console.log(`Checking ${file.targetPath}`);
+async function exactMatchHandler(
+  { path, write, missing, targetContents, templateContents }: FileDiff,
+  prompt: PromptFunc,
+) {
+  console.log(`Checking ${path}`);
+  const coloredPath = chalk.cyan(path);
 
-  const { targetPath, templateContents } = file;
-  const coloredPath = chalk.cyan(targetPath);
-
-  if (!file.targetExists) {
+  if (missing) {
     if (await prompt(`Missing ${coloredPath}, do you want to add it?`)) {
-      await writeTargetFile(targetPath, templateContents);
+      await write(templateContents);
     }
     return;
   }
-  if (file.targetContents === templateContents) {
+  if (targetContents === templateContents) {
     return;
   }
 
-  const diffs = diffLines(file.targetContents, templateContents);
+  const diffs = diffLines(targetContents, templateContents);
   for (const diff of diffs) {
     if (diff.added) {
       process.stdout.write(chalk.green(`+${diff.value}`));
@@ -184,27 +176,29 @@ async function exactMatchHandler(file: TemplateFile, prompt: PromptFunc) {
       `Outdated ${coloredPath}, do you want to apply the above patch?`,
     )
   ) {
-    await writeTargetFile(targetPath, templateContents);
+    await write(templateContents);
   }
 }
 
 // Adds the file if it is missing, but doesn't check existing files
-async function existsHandler(file: TemplateFile, prompt: PromptFunc) {
-  console.log(`Making sure ${file.targetPath} exists`);
+async function existsHandler(
+  { path, write, missing, templateContents }: FileDiff,
+  prompt: PromptFunc,
+) {
+  console.log(`Making sure ${path} exists`);
 
-  const { targetPath, templateContents } = file;
-  const coloredPath = chalk.cyan(targetPath);
+  const coloredPath = chalk.cyan(path);
 
-  if (!file.targetExists) {
+  if (missing) {
     if (await prompt(`Missing ${coloredPath}, do you want to add it?`)) {
-      await writeTargetFile(targetPath, templateContents);
+      await write(templateContents);
     }
     return;
   }
 }
 
-async function skipHandler(file: TemplateFile) {
-  console.log(`Skipping ${file.targetPath}`);
+async function skipHandler({ path }: FileDiff) {
+  console.log(`Skipping ${path}`);
 }
 
 export const handlers = {
@@ -216,22 +210,20 @@ export const handlers = {
 
 export async function handleAllFiles(
   fileHandlers: FileHandler[],
-  files: TemplateFile[],
+  files: FileDiff[],
   promptFunc: PromptFunc,
 ) {
   for (const file of files) {
-    const { targetPath } = file;
+    const { path } = file;
     const fileHandler = fileHandlers.find(handler =>
       handler.patterns.some(pattern =>
-        typeof pattern === 'string'
-          ? pattern === targetPath
-          : pattern.test(targetPath),
+        typeof pattern === 'string' ? pattern === path : pattern.test(path),
       ),
     );
     if (fileHandler) {
       await fileHandler.handler(file, promptFunc);
     } else {
-      throw new Error(`No template file handler found for ${targetPath}`);
+      throw new Error(`No template file handler found for ${path}`);
     }
   }
 }
diff --git a/packages/cli/src/lib/diff/read.ts b/packages/cli/src/lib/diff/read.ts
index b408da94e9..a0bb6364ca 100644
--- a/packages/cli/src/lib/diff/read.ts
+++ b/packages/cli/src/lib/diff/read.ts
@@ -15,15 +15,29 @@
  */
 
 import fs from 'fs-extra';
-import { relative as relativePath } from 'path';
+import {
+  dirname,
+  resolve as resolvePath,
+  relative as relativePath,
+} from 'path';
 import handlebars from 'handlebars';
 import recursiveReadDir from 'recursive-readdir';
 import { paths } from '../paths';
 import { version } from '../version';
-import { PluginInfo, TemplateFile } from './types';
+import { FileDiff } from './types';
+
+export type PluginInfo = {
+  id: string;
+  name: string;
+};
+
+export type TemplatedFile = {
+  path: string;
+  contents: string;
+};
 
 // Reads info from the existing plugin
-export async function readPluginInfo(): Promise<PluginInfo> {
+async function readPluginInfo(): Promise<PluginInfo> {
   let name: string;
   try {
     const pkg = require(paths.resolveTarget('package.json'));
@@ -47,7 +61,7 @@ export async function readPluginInfo(): Promise<PluginInfo> {
   return { id, name };
 }
 
-export async function readTemplateFile(
+async function readTemplateFile(
   templateFile: string,
   templateVars: any,
 ): Promise<string> {
@@ -60,51 +74,70 @@ export async function readTemplateFile(
   return handlebars.compile(contents)(templateVars);
 }
 
-export async function readTemplate(
+async function readTemplate(
   templateDir: string,
   templateVars: any,
-): Promise<TemplateFile[]> {
+): Promise<TemplatedFile[]> {
   const templateFilePaths = await recursiveReadDir(templateDir).catch(error => {
     throw new Error(`Failed to read template directory: ${error.message}`);
   });
 
-  const templateFiles = new Array<TemplateFile>();
+  const templatedFiles = new Array<TemplatedFile>();
   for (const templateFile of templateFilePaths) {
-    // Target file inside the target dir without template extension
-    const targetFile = templateFile
-      .replace(templateDir, paths.targetDir)
-      .replace(/\.hbs$/, '');
-    const targetPath = relativePath(paths.targetDir, targetFile);
+    const path = relativePath(templateDir, templateFile).replace(/\.hbs$/, '');
+    const contents = await readTemplateFile(templateFile, templateVars);
 
-    const templateContents = await readTemplateFile(templateFile, templateVars);
+    templatedFiles.push({ path, contents });
+  }
+
+  return templatedFiles;
+}
+
+async function diffTemplatedFiles(
+  targetDir: string,
+  templatedFiles: TemplatedFile[],
+): Promise<FileDiff[]> {
+  const fileDiffs = new Array<FileDiff>();
+  for (const { path, contents: templateContents } of templatedFiles) {
+    const targetPath = resolvePath(targetDir, path);
+    const targetExists = await fs.pathExists(targetPath);
+
+    const write = async (contents: string) => {
+      await fs.ensureDir(dirname(targetPath));
+      await fs.writeFile(targetPath, contents, 'utf8');
+    };
 
-    const targetExists = await fs.pathExists(targetFile);
     if (targetExists) {
-      const targetContents = await fs.readFile(targetFile, 'utf8');
-      templateFiles.push({
-        targetPath,
-        targetExists,
+      const targetContents = await fs.readFile(targetPath, 'utf8');
+      fileDiffs.push({
+        path,
+        write,
+        missing: false,
         targetContents,
         templateContents,
       });
     } else {
-      templateFiles.push({
-        targetPath,
-        targetExists,
+      fileDiffs.push({
+        path,
+        write,
+        missing: true,
+        targetContents: '',
         templateContents,
       });
     }
   }
 
-  return templateFiles;
+  return fileDiffs;
 }
 
 // Read all template files for a given template, along with all matching files in the target dir
-export async function readTemplateFiles(template: string) {
+export async function diffTemplateFiles(template: string) {
   const pluginInfo = await readPluginInfo();
   const templateVars = { version, ...pluginInfo };
 
   const templateDir = paths.resolveOwn('templates', template);
 
-  return await readTemplate(templateDir, templateVars);
+  const templatedFiles = await readTemplate(templateDir, templateVars);
+  const fileDiffs = await diffTemplatedFiles(paths.targetDir, templatedFiles);
+  return fileDiffs;
 }
diff --git a/packages/cli/src/lib/diff/types.ts b/packages/cli/src/lib/diff/types.ts
index 7a04cf8d2e..6c50d9fcf9 100644
--- a/packages/cli/src/lib/diff/types.ts
+++ b/packages/cli/src/lib/diff/types.ts
@@ -14,35 +14,24 @@
  * limitations under the License.
  */
 
-export type PluginInfo = {
-  id: string;
-  name: string;
-};
+export type WriteFileFunc = (contents: string) => Promise<void>;
 
-export type TemplateFile = {
+export type FileDiff = {
   // Relative path within the target directory
-  targetPath: string;
+  path: string;
+  // Wether the target file exists in the target directory.
+  missing: boolean;
+  // Contents of the file in the target directory, or an empty string if the file is missing.
+  targetContents: string;
   // Contents of the compiled template file
   templateContents: string;
-} & (
-  | {
-      // Whether the template file exists in the target directory
-      targetExists: true;
-      // Contents of the file in the target directory, if it exists
-      targetContents: string;
-    }
-  | {
-      // Whether the template file exists in the target directory
-      targetExists: false;
-    }
-);
+  // Write new contents to the target file
+  write: WriteFileFunc;
+};
 
 export type PromptFunc = (msg: string) => Promise<boolean>;
 
-export type HandlerFunc = (
-  file: TemplateFile,
-  prompt: PromptFunc,
-) => Promise<void>;
+export type HandlerFunc = (file: FileDiff, prompt: PromptFunc) => Promise<void>;
 
 export type FileHandler = {
   patterns: Array<string | RegExp>;

From f0107283f856441e8fae0111d975c3fdd671e6e1 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 21 May 2020 19:31:14 +0200
Subject: [PATCH 4/6] packages/cli: move reading of plugin template data to
 plugin diff

---
 packages/cli/src/commands/plugin/diff.ts | 39 +++++++++++++++++++++++-
 packages/cli/src/lib/diff/read.ts        | 38 ++---------------------
 2 files changed, 40 insertions(+), 37 deletions(-)

diff --git a/packages/cli/src/commands/plugin/diff.ts b/packages/cli/src/commands/plugin/diff.ts
index ba3e99527f..66db692ab4 100644
--- a/packages/cli/src/commands/plugin/diff.ts
+++ b/packages/cli/src/commands/plugin/diff.ts
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import fs from 'fs-extra';
 import { Command } from 'commander';
 import {
   diffTemplateFiles,
@@ -23,6 +24,13 @@ import {
   makeCheckPromptFunc,
   yesPromptFunc,
 } from '../../lib/diff';
+import { paths } from '../../lib/paths';
+import { version } from '../../lib/version';
+
+export type PluginData = {
+  id: string;
+  name: string;
+};
 
 const fileHandlers = [
   {
@@ -54,7 +62,36 @@ export default async (cmd: Command) => {
     promptFunc = yesPromptFunc;
   }
 
-  const templateFiles = await diffTemplateFiles('default-plugin');
+  const data = await readPluginData();
+  const templateFiles = await diffTemplateFiles('default-plugin', {
+    version,
+    ...data,
+  });
   await handleAllFiles(fileHandlers, templateFiles, promptFunc);
   await finalize();
 };
+
+// Reads templating data from the existing plugin
+async function readPluginData(): Promise<PluginData> {
+  let name: string;
+  try {
+    const pkg = require(paths.resolveTarget('package.json'));
+    name = pkg.name;
+  } catch (error) {
+    throw new Error(`Failed to read target package, ${error}`);
+  }
+
+  const pluginTsContents = await fs.readFile(
+    paths.resolveTarget('src/plugin.ts'),
+    'utf8',
+  );
+  // TODO: replace with some proper parsing logic or plugin metadata file
+  const pluginIdMatch = pluginTsContents.match(/id: ['"`](.+?)['"`]/);
+  if (!pluginIdMatch) {
+    throw new Error(`Failed to parse plugin.ts, no plugin ID found`);
+  }
+
+  const id = pluginIdMatch[1];
+
+  return { id, name };
+}
diff --git a/packages/cli/src/lib/diff/read.ts b/packages/cli/src/lib/diff/read.ts
index a0bb6364ca..75e1b86d24 100644
--- a/packages/cli/src/lib/diff/read.ts
+++ b/packages/cli/src/lib/diff/read.ts
@@ -23,44 +23,13 @@ import {
 import handlebars from 'handlebars';
 import recursiveReadDir from 'recursive-readdir';
 import { paths } from '../paths';
-import { version } from '../version';
 import { FileDiff } from './types';
 
-export type PluginInfo = {
-  id: string;
-  name: string;
-};
-
 export type TemplatedFile = {
   path: string;
   contents: string;
 };
 
-// Reads info from the existing plugin
-async function readPluginInfo(): Promise<PluginInfo> {
-  let name: string;
-  try {
-    const pkg = require(paths.resolveTarget('package.json'));
-    name = pkg.name;
-  } catch (error) {
-    throw new Error(`Failed to read target package, ${error}`);
-  }
-
-  const pluginTsContents = await fs.readFile(
-    paths.resolveTarget('src/plugin.ts'),
-    'utf8',
-  );
-  // TODO: replace with some proper parsing logic or plugin metadata file
-  const pluginIdMatch = pluginTsContents.match(/id: ['"`](.+?)['"`]/);
-  if (!pluginIdMatch) {
-    throw new Error(`Failed to parse plugin.ts, no plugin ID found`);
-  }
-
-  const id = pluginIdMatch[1];
-
-  return { id, name };
-}
-
 async function readTemplateFile(
   templateFile: string,
   templateVars: any,
@@ -131,13 +100,10 @@ async function diffTemplatedFiles(
 }
 
 // Read all template files for a given template, along with all matching files in the target dir
-export async function diffTemplateFiles(template: string) {
-  const pluginInfo = await readPluginInfo();
-  const templateVars = { version, ...pluginInfo };
-
+export async function diffTemplateFiles(template: string, templateData: any) {
   const templateDir = paths.resolveOwn('templates', template);
 
-  const templatedFiles = await readTemplate(templateDir, templateVars);
+  const templatedFiles = await readTemplate(templateDir, templateData);
   const fileDiffs = await diffTemplatedFiles(paths.targetDir, templatedFiles);
   return fileDiffs;
 }

From f38ae61f5ba3f5ecc5f8f0daa9834b925ef608cc Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 21 May 2020 19:42:46 +0200
Subject: [PATCH 5/6] packages/cli: added app:diff + fixes to template and diff
 lib

---
 packages/cli/src/commands/app/diff.ts         | 74 +++++++++++++++++++
 packages/cli/src/index.ts                     |  9 ++-
 packages/cli/src/lib/diff/handlers.ts         | 31 +++++++-
 .../default-app/packages/app/tsconfig.json    | 20 -----
 .../default-app/plugins/welcome/tsconfig.json |  5 --
 .../templates/default-app/prettier.config.js  |  1 -
 6 files changed, 111 insertions(+), 29 deletions(-)
 create mode 100644 packages/cli/src/commands/app/diff.ts
 delete mode 100644 packages/cli/templates/default-app/packages/app/tsconfig.json
 delete mode 100644 packages/cli/templates/default-app/plugins/welcome/tsconfig.json
 delete mode 100644 packages/cli/templates/default-app/prettier.config.js

diff --git a/packages/cli/src/commands/app/diff.ts b/packages/cli/src/commands/app/diff.ts
new file mode 100644
index 0000000000..a667407f23
--- /dev/null
+++ b/packages/cli/src/commands/app/diff.ts
@@ -0,0 +1,74 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Command } from 'commander';
+import {
+  diffTemplateFiles,
+  handlers,
+  handleAllFiles,
+  inquirerPromptFunc,
+  makeCheckPromptFunc,
+  yesPromptFunc,
+} from '../../lib/diff';
+import { version } from '../../lib/version';
+
+const fileHandlers = [
+  {
+    patterns: ['packages/app/package.json'],
+    handler: handlers.appPackageJson,
+  },
+  {
+    patterns: [/tsconfig\.json$/],
+    handler: handlers.exactMatch,
+  },
+  {
+    patterns: [
+      /README\.md$/,
+      /\.eslintrc\.js$/,
+      // make sure files in 1st level of src/ and dev/ exist
+      /^packages\/app\/(src|dev)\/[^/]+$/,
+    ],
+    handler: handlers.exists,
+  },
+  {
+    patterns: [
+      'lerna.json',
+      /^src\//,
+      /^patches\//,
+      /^packages\/app\/public\//,
+      /^packages\/app\/cypress/,
+      // Let plugin:diff take care of the plugins
+      /^plugins/,
+      /package\.json$/,
+    ],
+    handler: handlers.skip,
+  },
+];
+
+export default async (cmd: Command) => {
+  let promptFunc = inquirerPromptFunc;
+  let finalize = () => {};
+
+  if (cmd.check) {
+    [promptFunc, finalize] = makeCheckPromptFunc();
+  } else if (cmd.yes) {
+    promptFunc = yesPromptFunc;
+  }
+
+  const templateFiles = await diffTemplateFiles('default-app', { version });
+  await handleAllFiles(fileHandlers, templateFiles, promptFunc);
+  await finalize();
+};
diff --git a/packages/cli/src/index.ts b/packages/cli/src/index.ts
index f02bf6524f..bdd0d3e1f2 100644
--- a/packages/cli/src/index.ts
+++ b/packages/cli/src/index.ts
@@ -39,6 +39,13 @@ const main = (argv: string[]) => {
     .option('--check', 'Enable type checking and linting')
     .action(actionHandler(() => require('./commands/app/serve')));
 
+  program
+    .command('app:diff')
+    .option('--check', 'Fail if changes are required')
+    .option('--yes', 'Apply all changes')
+    .description('Diff an existing app with the creation template')
+    .action(actionHandler(() => require('./commands/app/diff')));
+
   program
     .command('create-plugin')
     .description('Creates a new plugin in the current repository')
@@ -157,7 +164,7 @@ function actionHandler<T extends readonly any[]>(
   };
 }
 
-process.on('unhandledRejection', (rejection) => {
+process.on('unhandledRejection', rejection => {
   if (rejection instanceof Error) {
     exitWithError(rejection);
   } else {
diff --git a/packages/cli/src/lib/diff/handlers.ts b/packages/cli/src/lib/diff/handlers.ts
index 9e46dd92cf..c4efacb198 100644
--- a/packages/cli/src/lib/diff/handlers.ts
+++ b/packages/cli/src/lib/diff/handlers.ts
@@ -22,6 +22,7 @@ class PackageJsonHandler {
   static async handler(
     { path, write, missing, targetContents, templateContents }: FileDiff,
     prompt: PromptFunc,
+    variant?: string,
   ) {
     console.log('Checking package.json');
 
@@ -32,19 +33,33 @@ class PackageJsonHandler {
     const pkg = JSON.parse(templateContents);
     const targetPkg = JSON.parse(targetContents);
 
-    const handler = new PackageJsonHandler(write, prompt, pkg, targetPkg);
+    const handler = new PackageJsonHandler(
+      write,
+      prompt,
+      pkg,
+      targetPkg,
+      variant,
+    );
     await handler.handle();
   }
 
+  static async appHandler(file: FileDiff, prompt: PromptFunc) {
+    return PackageJsonHandler.handler(file, prompt, 'app');
+  }
+
   constructor(
     private readonly writeFunc: WriteFileFunc,
     private readonly prompt: PromptFunc,
     private readonly pkg: any,
     private readonly targetPkg: any,
+    private readonly variant?: string,
   ) {}
 
   async handle() {
     await this.syncField('main');
+    if (this.variant !== 'app') {
+      await this.syncField('main:src');
+    }
     await this.syncField('types');
     await this.syncField('files');
     await this.syncScripts();
@@ -78,7 +93,7 @@ class PackageJsonHandler {
         targetObj[fieldName] = newValue;
         await this.write();
       }
-    } else {
+    } else if (fieldName in obj) {
       if (
         await this.prompt(
           `package.json is missing field ${fullFieldName}, set to ${coloredNewValue}?`,
@@ -95,6 +110,10 @@ class PackageJsonHandler {
     const targetScripts = (this.targetPkg.scripts =
       this.targetPkg.scripts || {});
 
+    if (!pkgScripts) {
+      return;
+    }
+
     for (const key of Object.keys(pkgScripts)) {
       await this.syncField(key, pkgScripts, targetScripts, 'scripts');
     }
@@ -132,7 +151,14 @@ class PackageJsonHandler {
     const targetDeps = (this.targetPkg[fieldName] =
       this.targetPkg[fieldName] || {});
 
+    if (!pkgDeps) {
+      return;
+    }
+
     for (const key of Object.keys(pkgDeps)) {
+      if (this.variant === 'app' && key.startsWith('plugin-')) {
+        continue;
+      }
       await this.syncField(key, pkgDeps, targetDeps, fieldName);
     }
   }
@@ -206,6 +232,7 @@ export const handlers = {
   exists: existsHandler,
   exactMatch: exactMatchHandler,
   packageJson: PackageJsonHandler.handler,
+  appPackageJson: PackageJsonHandler.appHandler,
 };
 
 export async function handleAllFiles(
diff --git a/packages/cli/templates/default-app/packages/app/tsconfig.json b/packages/cli/templates/default-app/packages/app/tsconfig.json
deleted file mode 100644
index 0457810645..0000000000
--- a/packages/cli/templates/default-app/packages/app/tsconfig.json
+++ /dev/null
@@ -1,20 +0,0 @@
-{
-  "extends": "@spotify/web-scripts/config/tsconfig.json",
-  "compilerOptions": {
-    "target": "es5",
-    "lib": ["dom", "dom.iterable", "esnext"],
-    "allowJs": true,
-    "skipLibCheck": true,
-    "esModuleInterop": true,
-    "allowSyntheticDefaultImports": true,
-    "strict": true,
-    "forceConsistentCasingInFileNames": true,
-    "module": "esnext",
-    "moduleResolution": "node",
-    "resolveJsonModule": true,
-    "isolatedModules": true,
-    "jsx": "react",
-    "incremental": false
-  },
-  "include": ["src"]
-}
diff --git a/packages/cli/templates/default-app/plugins/welcome/tsconfig.json b/packages/cli/templates/default-app/plugins/welcome/tsconfig.json
deleted file mode 100644
index 5a3931ffce..0000000000
--- a/packages/cli/templates/default-app/plugins/welcome/tsconfig.json
+++ /dev/null
@@ -1,5 +0,0 @@
-{
-  "extends": "../../tsconfig.json",
-  "include": ["src"],
-  "compilerOptions": {}
-}
diff --git a/packages/cli/templates/default-app/prettier.config.js b/packages/cli/templates/default-app/prettier.config.js
deleted file mode 100644
index 93df970dd6..0000000000
--- a/packages/cli/templates/default-app/prettier.config.js
+++ /dev/null
@@ -1 +0,0 @@
-module.exports = require('@spotify/web-scripts/config/prettier.config.js');

From 6c2a9d471ae67220c89e85e674108a99950f0175 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 21 May 2020 19:45:12 +0200
Subject: [PATCH 6/6] packages/cli: update prettier config in plugin template

---
 packages/cli/templates/default-app/package.json.hbs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/packages/cli/templates/default-app/package.json.hbs b/packages/cli/templates/default-app/package.json.hbs
index 589e20e298..4fda7ff2d7 100644
--- a/packages/cli/templates/default-app/package.json.hbs
+++ b/packages/cli/templates/default-app/package.json.hbs
@@ -28,8 +28,19 @@
   },
   "devDependencies": {
     "@backstage/cli": "^{{version}}",
+    "@spotify/prettier-config": "^7.0.0",
     "lerna": "^3.20.2",
     "patch-package": "^6.2.2",
     "prettier": "^1.19.1"
+  },
+  "prettier": "@spotify/prettier-config",
+  "lint-staged": {
+    "*.{js,jsx,ts,tsx}": [
+      "eslint --fix",
+      "prettier --write"
+    ],
+    "*.{json,md}": [
+      "prettier --write"
+    ]
   }
 }