feat: adds custom tags values to generate changelog (#26)

* feat: adds the option to pass from and to tags to generate changelog instead of just using latest and latest-1

* docs: adds advanced usage example

* fix: fixes message when to-tag is found

* fix: fixes variable value when to-tag is found

* fix: fixes shell linting errors

README.md

@@ -57,5 +57,23 @@ If your `package.json` isn't available in root, you can pass the directory of th
           package-dir: 'root/to/my/package.json'
 ```
 
+If your use case does not need to generate changelog from latest and latest-1 tags, you can pass the custom flags. An example is when your release tag on git is generated after the changelog so you must use something like _git log v1..HEAD_ --oneline:
+
+```yaml
+      - name: Changelog
+        uses: scottbrenner/generate-changelog-action@master
+        id: Changelog
+        with:
+          package-dir: 'root/to/my/package.json'
+          from-tag: v1.0
+          to-tag: HEAD
+```
+
 For more information, see [actions/create-release: Usage](https://github.com/actions/create-release#usage) and [lob/generate-changelog: Usage](https://github.com/lob/generate-changelog#usage)
 
+
+| Property                  | Default       | Description                                                                                                                   |
+| ------------------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------- |
+| package-dir               | package.json  | The path for the package.json if it is not in root                                                                            |
+| from-tag                  | "last tag"    | The tag to generate changelog from. If not set, fallbacks to git last tag -1. Ex.: v1.0                                       |
+| to-tag                    | "current tag" | The tag to generate changelog up to. If not set, fallbacks to git last tag.   Ex.: v2.0                                       |

action.yml

@@ -9,11 +9,22 @@ inputs:
     description: 'The path for the package.json if it is not in root'
     required: false
     default: 'package.json'
+  from-tag:
+    description: 'The tag to generate changelog from'
+    required: false
+    default: ''
+  to-tag:
+    description: 'The tag to generate changelog up to'
+    required: false
+    default: ''        
 runs:
   using: 'docker'
   image: 'Dockerfile'
   args:
     - ${{ inputs.package-dir }}
+  env:
+    FROM_TAG: ${{ inputs.from-tag }}
+    TO_TAG: ${{ inputs.to-tag }}
 branding:
   icon: 'edit'
   color: 'gray-dark'

entrypoint.sh

@@ -5,8 +5,22 @@ if [ "$1" ] && [ "$1" != "package.json" ]; then
   cp "$1" package.json
 fi
 
-previous_tag=$(git tag --sort version:refname | tail -n 2 | head -n 1)
-new_tag=$(git tag --sort version:refname | tail -n 1)
+if [ -z "$FROM_TAG" ]; then
+  echo "No from-tag passed. Fallbacking to git previous tag."
+  previous_tag=$(git tag --sort version:refname | tail -n 2 | head -n 1)
+else
+  echo "From-tag detected. Using it's value."
+  previous_tag=$FROM_TAG
+fi
+
+if [ -z "$TO_TAG"   ]; then
+  echo "No to-tag passed. Fallbacking to git previous tag."
+  new_tag=$(git tag --sort version:refname | tail -n 1)
+else
+  echo "To-tag detected. Using it's value."
+  new_tag=$TO_TAG
+fi
+
 changelog=$(generate-changelog -t "$previous_tag..$new_tag" --file -)
 
 changelog="${changelog//'%'/'%25'}"