[FIX] gmail: use rollup to avoid ES6 imports

Google App Scripts do not support ES6 imports
which causes issues when trying to push the typescript files directly.
They recommend using
rollup to package every file into a single file to get rid of imports.

We introduce roll-up as a new compilation step and update the README
accordingly.

The setting for sourcemap is moved from tsconfig to rollup.config.js
as using tsc sourcemap with rollup does not work.

task-3329768

Author: reth-odoo

gmail/.claspignore

@@ -4,3 +4,10 @@ node_modules
 node_modules/**
 node_modules/**/.*/**
 node_modules/**/.*
+
+# ignore all files…
+**/**
+
+# include appscript and build result
+!appsscript.json
+!build/*.js

gmail/.gitignore

@@ -34,6 +34,9 @@ bower_components
 .DS_Store
 Thumbs.db
 
+# Ignore final built js file
+build/
+
 # Ignore built ts files
 dist/**/*
 

gmail/README.md

@@ -5,36 +5,78 @@ and also to link your Gmail contacts to your Odoo partners, to create leads from
 ![Odoo Gmail Extension](./assets/img/readme.png)
 
 # Development
-## Installation
+## Requirements
 First you need npm,
 > apt-get install -y npm
 
-We use [clasp](https://github.com/google/clasp) to push the project on the Google platform
-> npm install -g @google/clasp
+Install the dependencies
+> npm install
+
+## Prettier
+You should auto-format the code using the prettier configuration,
+> `npx prettier --config .prettierrc 'src/**/*.ts' --write`
+
+## Compiling
+
+We use [rollup.js](https://github.com/rollup/rollup) to package all of the source files into a single one.
+This is necessary as App Scripts do not support ES6 import/export statements yet.
+
+Once you have applied the necessary changes, run the following command:
+> npx rollup -c
+
+This will simultaneously compile and package the typescript sourcecode inside `build/main.js`
+
+Now all you need to do is upload the script to your account and deploy it!
+
+## Uploading method 1: Manually copying the file
+If you do not plan on updating this script regularly, perhaps you will prefer using Google's GUI.
+
+- Head to [the App Scripts manager](https://script.google.com/) and create a project
+- Go to the project settings and enable appscript.json editing: `Show "appsscript.json" manifest file in editor`
+- Copy the contents of your local `appscript.json` to the remote one in the project editor
+- Create a file `main.gs` and remove the existing `Code.gs` if any.
+- Copy the contents of your local `build/main.js` to the `main.gs` file in the project editor
 
-Project dependencies
-> npm install --dev @types/google-apps-script
+## Uploading method 2: Using Clasp
+You may want to use the Google's CLI tool [clasp](https://github.com/google/clasp) to manage, compile and update your app script.
+
+First install
+> npm install -g @google/clasp
 
-## Clasp
 Login to your account to be able to push on your Gmail project,
-> clasp login --no-localhost
+> clasp login
 
-Open your Gmail project
-> clasp open
+Note: the `--no-localhost` option we previously recommended was [deprecated by google](https://developers.google.com/identity/protocols/oauth2/resources/oob-migration)
 
-Enable the Gmail API
-> clasp apis enable gmail
+### If you already have a project
+Update `.clasp.json` to use your own script id and project.
+If you do not have a specific project, use `Default`.
 
-Automatically push the project when a changed is detected
-> clasp push --watch
+### If you do not have a project yet
+Remove `.clasp.json`
 
-## Prettier
-You should auto-format the code using the prettier configuration,
-> `npx prettier --config .prettierrc 'src/**/*.ts' --write`
+Create a project
+> clasp create
+
+For the project type, select "api".
+
+### Push your project
+Push the project
+> clasp push
+
+
+# Deployment
+Finally, you can enable the add-on for your account.
+
+Head to [the App Scripts manager](https://script.google.com/).
+- Select your project and click "Deploy".
+- For testing on your account just select "Test deployments". "Google Workspace Add-on" should be automatically selected as the type.
+- Click "Install" and the add-on should appear in the addons tab of Gmail.
+
+You're done!
 
-## Install the add-on on your Gmail account
-1. Share the google project to your Gmail account
-2. Then go to "Publish" -> "Deploy from manifest" and click on "Install the add-on"
+For final deployments you will need to create a Google Cloud Project with the GMail API and link it to this script.
+Refer to Google's documentation for more information.
 
 # Documentation
 `GmailApp` object,

gmail/package.json

@@ -1,8 +1,11 @@
 {
-  "dependencies": {
-    "@types/google-apps-script": "^1.0.31"
-  },
   "devDependencies": {
-    "prettier": "^2.2.1"
-  }
+    "@rollup/plugin-node-resolve": "^15.0.2",
+    "@rollup/plugin-typescript": "^11.1.1",
+    "@types/google-apps-script": "^1.0.64",
+    "prettier": "^2.2.1",
+    "rollup": "^3.22.0",
+    "tslib": "^2.5.3"
+  },
+  "type": "module"
 }

gmail/rollup.config.js

@@ -0,0 +1,37 @@
+import typescript from "@rollup/plugin-typescript";
+import { nodeResolve } from "@rollup/plugin-node-resolve";
+
+const extensions = [".ts"];
+
+/**
+ * Prevent tree-shaking the entry-point
+ * by not shaking any module that isn't imported by anyone.
+ * @returns side-effects or nothing
+ */
+function preventEntrypointShakingPlugin() {
+    return {
+        name: "no-treeshaking",
+        resolveId(id, importer) {
+            if (!importer) {
+                return { id, moduleSideEffects: "no-treeshake" };
+            }
+            return null;
+        },
+    };
+}
+
+export default {
+    input: "./src/main.ts",
+    output: {
+        dir: "./build",
+        format: "esm",
+        sourcemap: true,
+    },
+    plugins: [
+        preventEntrypointShakingPlugin(),
+        nodeResolve({
+            extensions,
+        }),
+        typescript(),
+    ],
+};

gmail/tsconfig.json

@@ -2,7 +2,6 @@
   "compilerOptions": {
     "outDir": "./build",
     "baseUrl": ".",
-    "sourceMap": true,
     "strictNullChecks": false,
     "noImplicitThis": true,
     "noEmitOnError": true,