Support reading data from stdin (#24)

Sometimes the data payload is too large as command line args. This PR
adds support for parsing data from stdin.

README.md

@@ -13,19 +13,40 @@ A collection of email templates used by [WATcloud](https://cloud.watonomous.ca/)
 
 ## Development
 
+### Emails
+
 ```sh
 npm ci
 npm run dev
 ```
 
 Open [localhost:3000](http://localhost:3000) with your browser to see email previews.
 
-Run the following to use the CLI:
+### CLI
 
 ```sh
+npm run build
 node ./dist/cli/index.js
 ```
 
+#### Packaging the CLI
+
+```sh
+npm run build
+npm version --no-git-tag-version 0.0.0-dev
+npm pack --pack-destination .
+```
+
+A `watonomous-watcloud-emails-0.0.0-dev.tgz` file will be created in the current directory.
+Use it as follows:
+
+```sh
+npx watonomous-watcloud-emails-0.0.0-dev.tgz --help
+# or
+npm install -g watonomous-watcloud-emails-0.0.0-dev.tgz
+watcloud-emails --help
+```
+
 ## Releasing
 
 Releases are manually created from the [Releases page](https://github.com/WATonomous/watcloud-emails/releases).

cli/index.ts

@@ -32,7 +32,12 @@ program
     .action(async (template_name, options) => {
         let data = {};
         if (options.data) {
-            data = JSON.parse(options.data);
+            if (options.data === '-') {
+                // Read from stdin
+                data = JSON.parse(fs.readFileSync(0, 'utf-8'));
+            } else {
+                data = JSON.parse(options.data);
+            }
         }
 
         const template = await getTemplate(template_name, [data]);
@@ -57,7 +62,12 @@ program
     .action(async (template_name, options) => {
         let data = [];
         if (options.data) {
-            data = JSON.parse(options.data);
+            if (options.data === '-') {
+                // Read from stdin
+                data = JSON.parse(fs.readFileSync(0, 'utf-8'));
+            } else {
+                data = JSON.parse(options.data);
+            }
         }
 
         const template = await getTemplate(template_name, data);