From 4e14ab1c592edbb806f9b448c0dbd8cf4e1ef5dc Mon Sep 17 00:00:00 2001
From: Semen <tenischev.semen@gmail.com>
Date: Thu, 30 Apr 2020 15:35:17 +0300
Subject: [PATCH] feat: add hooks before (#315)
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* feat: add hooks before

* Rephrasing of description.

* Apply suggestions from code review

fix typos

Co-authored-by: Fran Méndez <fmvilas@gmail.com>

Co-authored-by: Semen Tenishchev <semen.tenishchev@t-systems.com>
Co-authored-by: Fran Méndez <fmvilas@gmail.com>
---
 docs/authoring.md | 31 ++++++++++++++++++++++++++++++-
 lib/generator.js  |  1 +
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/docs/authoring.md b/docs/authoring.md
index c0aca779a..db909bfad 100644
--- a/docs/authoring.md
+++ b/docs/authoring.md
@@ -76,8 +76,16 @@ In case you have more than one template and want to reuse filters, you can put t
 
 ## Hooks
 
-Hooks are functions called by the generator on a specific moment in the generation process. For now there is one hook supported called `generate:after` that is called at the very end of the generation. The generator will parse all the files in the `.hooks` directory.
+Hooks are functions called by the generator on a specific moment in the generation process.
+The following types of hooks are currently supported:
 
+|Hook name|Description|
+|---|---|
+| `generate:before` | Called after registration of all filters and before generator starts processing of the template.|
+| `generate:after` | Called at the very end of the generation. |
+
+The generator will parse all the files in the `.hooks` directory.
+#### Examples
 Below you have an example Hook that after generation creates an AsyncAPI file.
 
 ```js
@@ -100,6 +108,27 @@ module.exports = register => {
   });
 };
 ```
+And here an example Hook that before generation switches `publish` and `subscribe` operations for each channel.
+
+```js
+module.exports = register => {
+  register('generate:before', generator => {
+    const asyncapi = generator.asyncapi;
+    for (let [key, value] of Object.entries(asyncapi.channels())) {
+      let publish = value._json.publish;
+      value._json.publish = value._json.subscribe;
+      value._json.subscribe = publish;
+      if (!value._json.subscribe) {
+        delete value._json.subscribe;
+      }
+      if (!value._json.publish) {
+        delete value._json.publish;
+      }
+    }
+  });
+};
+```
+
 
 ## Partials
 
diff --git a/lib/generator.js b/lib/generator.js
index 45ef3ddfd..5052928d6 100644
--- a/lib/generator.js
+++ b/lib/generator.js
@@ -147,6 +147,7 @@ class Generator {
       await this.loadTemplateConfig();
       this.registerHooks();
       await registerFilters(this.nunjucks, this.templateConfig, this.templateDir, FILTERS_DIRNAME);
+      await this.launchHook('generate:before');
 
       if (this.entrypoint) {
         const entrypointPath = path.resolve(this.templateContentDir, this.entrypoint);