Add golangci-lint (#17)

.github/workflows/.golangci.yml

@@ -0,0 +1,17 @@
+run:
+  go: '1.19'
+
+linters:
+  disable-all: true
+  enable:
+    - gofumpt
+
+issues:
+  # Show only new issues: if there are unstaged changes or untracked files,
+  # only those changes are analyzed, else only changes in HEAD~ are analyzed.
+  # It's a super-useful option for integration of golangci-lint into existing large codebase.
+  # It's not practical to fix all existing issues at the moment of integration:
+  # much better don't allow issues in new code.
+  #
+  # Default: false
+  new: true

.github/workflows/golangci-lint.yml

@@ -0,0 +1,35 @@
+name: golangci-lint
+on:
+  push:
+
+permissions:
+  contents: read
+  # Optional: allow read access to pull request. Use with `only-new-issues` option.
+  # pull-requests: read
+
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # Fetch all history for all branches and tags
+      - uses: actions/setup-go@v5
+        with:
+          go-version: stable
+      - name: Find base branch
+        id: find_base_branch
+        run: |
+          BASE_BRANCH=$(git for-each-ref --format='%(upstream:short)' "$(git symbolic-ref -q HEAD)")
+          if [ -z "$BASE_BRANCH" ]; then
+            echo "BASE_BRANCH=origin/main" >> $GITHUB_ENV  # Default to main if no upstream is set
+          else
+            echo "BASE_BRANCH=$BASE_BRANCH" >> $GITHUB_ENV
+          fi
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v6
+        with:
+          version: v1.59
+          args: --config .github/workflows/.golangci.yml --new-from-rev ${{ env.BASE_BRANCH }}