ci: add tag release workflow

.gitea/workflows/release.yml

@@ -0,0 +1,111 @@
+name: Release
+
+"on":
+  push:
+    tags:
+      - "**"
+
+permissions:
+  contents: read
+  releases: write
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Build changelog
+        id: changelog
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          current_tag="${GITHUB_REF_NAME}"
+          previous_tag=""
+
+          if previous_tag="$(git describe --tags --abbrev=0 "${current_tag}^" 2>/dev/null)"; then
+            range="${previous_tag}..${current_tag}"
+            {
+              printf '## Changelog\n\n'
+              printf 'Changes since `%s`.\n\n' "${previous_tag}"
+              git log --reverse --pretty=format:'- %h %s' "${range}"
+              printf '\n'
+            } >CHANGELOG.md
+          else
+            {
+              printf '## Changelog\n\n'
+              printf 'Initial release.\n\n'
+              git log --reverse --pretty=format:'- %h %s' "${current_tag}"
+              printf '\n'
+            } >CHANGELOG.md
+          fi
+
+      - name: Create or update release
+        env:
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          current_tag="${GITHUB_REF_NAME}"
+          api_url="${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/releases"
+          release_by_tag_url="${api_url}/tags/${current_tag}"
+
+          json_escape() {
+            sed ':a;N;$!ba;s/\\/\\\\/g;s/"/\\"/g;s/\t/\\t/g;s/\r//g;s/\n/\\n/g'
+          }
+
+          body="$(json_escape < CHANGELOG.md)"
+          payload="$(printf '{"tag_name":"%s","name":"%s","body":"%s","draft":false,"prerelease":false}' \
+            "${current_tag}" \
+            "${current_tag}" \
+            "${body}")"
+
+          http_code="$(
+            curl --silent --show-error --output release.json --write-out '%{http_code}' \
+              --header "Authorization: token ${GITEA_TOKEN}" \
+              --header 'Accept: application/json' \
+              "${release_by_tag_url}"
+          )"
+
+          case "${http_code}" in
+            200)
+              release_id="$(
+                tr '{,' '\n' < release.json |
+                  sed -n 's/^[[:space:]]*"id":[[:space:]]*\([0-9][0-9]*\)$/\1/p' |
+                  head -n1
+              )"
+
+              if [ -z "${release_id}" ]; then
+                echo "failed to parse release id from existing release response" >&2
+                exit 1
+              fi
+
+              curl --silent --show-error --fail \
+                --request PATCH \
+                --header "Authorization: token ${GITEA_TOKEN}" \
+                --header 'Accept: application/json' \
+                --header 'Content-Type: application/json' \
+                --data "${payload}" \
+                "${api_url}/${release_id}" >/dev/null
+              ;;
+            404)
+              curl --silent --show-error --fail \
+                --request POST \
+                --header "Authorization: token ${GITEA_TOKEN}" \
+                --header 'Accept: application/json' \
+                --header 'Content-Type: application/json' \
+                --data "${payload}" \
+                "${api_url}" >/dev/null
+              ;;
+            *)
+              echo "unexpected status code while looking up release: ${http_code}" >&2
+              cat release.json >&2
+              exit 1
+              ;;
+          esac