- introduce additional placeholders supported by the template

- introduce placeholder support into `empty_template`
- introduce new placeholders for templates, update README with new placeholders

README.md

@@ -213,7 +213,7 @@ For advanced use cases additional settings can be provided to the action
 
 ### PR Template placeholders
 
-Table of supported placeholders allowed to be used in the `template` configuration.
+Table of supported placeholders allowed to be used in the `pr_template` configuration.
 
 | **Placeholder**  | **Description**                                             |
 |------------------|-------------------------------------------------------------|
@@ -230,26 +230,33 @@ Table of supported placeholders allowed to be used in the `template` configurati
 
 ### Template placeholders
 
-Table of supported placeholders allowed to be used in the `pr_template` configuration.
+Table of supported placeholders allowed to be used in the `template` and `empty_template` (only supports placeholder marked for empty) configuration.
+
+| **Placeholder**            | **Description**                                                                                    | **Empty** |
+|----------------------------|----------------------------------------------------------------------------------------------------|:---------:|
+| `${{CHANGELOG}}`           | The contents of the changelog, matching the labels as specified in the categories configuration    |           |
+| `${{UNCATEGORIZED}}`       | All pull requests not matching a specified label in categories                                     |           |
+| `${{OWNER}}`               | Describes the owner of the repository the changelog was generated for                              | x         |
+| `${{REPO}}`                | The repository name of the repo the changelog was generated for                                    | x         |
+| `${{FROM_TAG}}`            | Defines the 'start' from where the changelog did consider merged pull requests                     | x         |
+| `${{TO_TAG}}`              | Defines until which tag the changelog did consider merged pull requests                            | x         |
+| `${{CATEGORIZED_COUNT}}`   | The count of PRs which were categorized                                                            |           |
+| `${{UNCATEGORIZED_COUNT}}` | The count of PRs and changes which were not categorized. No label overlapping with category labels |           |
 
-| **Placeholder**      | **Description**                                                                                 |
-|----------------------|-------------------------------------------------------------------------------------------------|
-| `${{CHANGELOG}}`     | The contents of the changelog, matching the labels as specified in the categories configuration |
-| `${{UNCATEGORIZED}}` | All pull requests not matching a specified label in categories                                  |
 
 ### Configuration Specification
 
 Table of descriptions for the `configuration.json` options. 
 
 | **Input**                | **Description**                                                                                                                                                                                                                    |
-|--------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|--------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | categories               | An array of `category` specifications, offering a flexible way to group changes into categories                                                                                                                                    |
 | category.title           | The display name of a category in the changelog                                                                                                                                                                                    |
 | category.labels          | An array of labels, to match pull request labels against. If any PR label, matches any category label, the pull request will show up under this category                                                                           |
 | sort                     | The sort order of pull requests. [ASC, DESC]                                                                                                                                                                                       |
 | template                 | Specifies the global template to pick for creating the changelog. See [Template placeholders](#template-placeholders) for possible values                                                                                          |
 | pr_template              | Defines the per pull request template. See [PR Template placeholders](#pr-template-placeholders) for possible values                                                                                                               |
-| empty_template           | Template to pick if no changes are detected. Does not support placeholders                                                                                                                                                        |
+| empty_template           | Template to pick if no changes are detected. See [Template placeholders](#template-placeholders) for possible values                                                                                                               |
 | transformers             | An array of `transform` specifications, offering a flexible API to modify the text per pull request. This is applied on the change text created with `pr_template`. `transformers` are executed per change, in the order specified |
 | transformer.pattern      | A `regex` pattern, extracting values of the change message.                                                                                                                                                                        |
 | transformer.target       | The result pattern, the regex groups will be filled into. Allows for full transformation of a pull request message. Including potentially specified texts                                                                          |

src/releaseNotes.ts

@@ -31,7 +31,11 @@ export class ReleaseNotes {
     }
 
     core.startGroup('📦 Build changelog')
-    const resultChangelog = buildChangelog(mergedPullRequests, configuration)
+    const resultChangelog = buildChangelog(
+      mergedPullRequests,
+      configuration,
+      this.options
+    )
     core.endGroup()
     return resultChangelog
   }

src/releaseNotesBuilder.ts

@@ -6,6 +6,7 @@ import {failOrError} from './utils'
 import {Octokit} from '@octokit/rest'
 import {Tags} from './tags'
 import {ReleaseNotes} from './releaseNotes'
+import {fillAdditionalPlaceholders} from './transform'
 
 export class ReleaseNotesBuilder {
   constructor(
@@ -96,19 +97,23 @@ export class ReleaseNotesBuilder {
       core.endGroup()
     }
 
-    const releaseNotes = new ReleaseNotes(octokit, {
+    const options = {
       owner: this.owner,
       repo: this.repo,
       fromTag: this.fromTag,
       toTag: this.toTag,
       failOnError: this.failOnError,
       configuration: this.configuration
-    })
+    }
+    const releaseNotes = new ReleaseNotes(octokit, options)
 
     return (
       (await releaseNotes.pull()) ||
+      fillAdditionalPlaceholders(
         this.configuration.empty_template ||
-      DefaultConfiguration.empty_template
+          DefaultConfiguration.empty_template,
+        options
+      )
     )
   }
 }

src/transform.ts

@@ -1,5 +1,6 @@
 import {PullRequestInfo, sortPullRequests} from './pullRequests'
 import * as core from '@actions/core'
+import {ReleaseNotesOptions} from './releaseNotes'
 import {
   Category,
   Configuration,
@@ -9,7 +10,8 @@ import {
 
 export function buildChangelog(
   prs: PullRequestInfo[],
-  config: Configuration
+  config: Configuration,
+  options: ReleaseNotesOptions
 ): string {
   // sort to target order
   const sort = config.sort || DefaultConfiguration.sort
@@ -96,10 +98,37 @@ export function buildChangelog(
     '${{UNCATEGORIZED}}',
     changelogUncategorized
   )
+
+  // fill other placeholders
+  transformedChangelog = transformedChangelog.replace(
+    '${{CATEGORIZED_COUNT}}',
+    categorized.size.toString()
+  )
+  transformedChangelog = transformedChangelog.replace(
+    '${{UNCATEGORIZED_COUNT}}',
+    uncategorized.length.toString()
+  )
+  transformedChangelog = fillAdditionalPlaceholders(
+    transformedChangelog,
+    options
+  )
+
   core.info(`ℹ️ Filled template`)
   return transformedChangelog
 }
 
+export function fillAdditionalPlaceholders(
+  text: string,
+  options: ReleaseNotesOptions
+): string {
+  let transformed = text
+  transformed = transformed.replace('${{OWNER}}', options.owner)
+  transformed = transformed.replace('${{REPO}}', options.repo)
+  transformed = transformed.replace('${{FROM_TAG}}', options.fromTag)
+  transformed = transformed.replace('${{TO_TAG}}', options.toTag)
+  return transformed
+}
+
 function haveCommonElements(arr1: string[], arr2: string[]): Boolean {
   return arr1.some(item => arr2.includes(item))
 }