ci: update git-cliff commands and add MR handling

.gitlab-ci.yml

@@ -10,7 +10,7 @@ build:
   script:
   - env | sort
 
-prepare_release:
+changelog:
   stage: prepare
   image:
     name: orhunp/git-cliff:latest
@@ -19,9 +19,33 @@ prepare_release:
     GIT_STRATEGY: clone # clone entire repo instead of reusing workspace
     GIT_DEPTH: 0 # avoid shallow clone to give cliff all the info it needs
   script:
-  - git-cliff --current > CHANGELOG.md
+  - 'git-cliff --bump --unreleased > CHANGES.md'
+  - 'git-cliff --bump > CHANGELOG.md'
+  - 'git-cliff --bumped-version 2>/dev/null > VERSION'
   artifacts:
     paths:
+    - CHANGES.md
     - CHANGELOG.md
+    - VERSION
+  rules:
+  - if: $CI_DEFAULT_BRANCH == $CI_COMMIT_BRANCH
+
+handle_mr:
+  stage: prepare
+  image: alpine:latest
+  needs:
+  - changelog
+  variables:
+    GIT_STRATEGY: clone # clone entire repo instead of reusing workspace
+    GIT_DEPTH: 0 # avoid shallow clone to give cliff all the info it needs
+  before_script:
+  - 'apk add --no-cache git jq curl'
+  - 'git config --global user.email "${GIT_USER_EMAIL:-$GITLAB_USER_EMAIL}"'
+  - 'git config --global user.name "${GIT_USER_NAME:-$GITLAB_USER_NAME}"'
+  script:
+  - 'git checkout -b next-release'
+  - 'git add CHANGELOG.md'
+  - 'git commit -m "ci: prepare release $(git-cliff --bumped-version 2>/dev/null)"'
+  - 'git push origin next-release --force'
   rules:
   - if: $CI_DEFAULT_BRANCH == $CI_COMMIT_BRANCH