ci: embed build & push script in workflow (#154)

This is to make it possible to build previous versions via the
workflow_dispatch event.

.github/workflows/docker-image-push.yml

@@ -58,4 +58,32 @@ jobs:
       - name: Build Docker image
         env:
           PLATFORMS: linux/amd64,linux/arm64/v8,linux/arm/v7
-        run: ./scripts/build-and-push.sh
+        run: |
+          set -euo pipefail
+
+          VERSION="$(git describe --exact-match --tags HEAD)"
+          TAG="$VERSION"
+          MAJOR_TAG="$(sed -nre 's/^([0-9]+).*/\1/p' <<< "$VERSION")"
+          DOCKERHUB_IMAGE="thelounge/thelounge"
+          GITHUB_IMAGE="ghcr.io/thelounge/thelounge"
+          TAGS=(
+              "--tag" "${DOCKERHUB_IMAGE}:${TAG}"
+              "--tag" "${GITHUB_IMAGE}:${TAG}"
+          )
+
+          # If not a pre-release push :latest & MAJOR_TAG
+          if grep -qE "^[0-9]*\.[0-9]*\.[0-9]*$" <<< "${VERSION}"; then
+              TAGS+=(
+                  "--tag" "${DOCKERHUB_IMAGE}:latest"
+                  "--tag" "${DOCKERHUB_IMAGE}:${MAJOR_TAG}"
+                  "--tag" "${GITHUB_IMAGE}:latest"
+                  "--tag" "${GITHUB_IMAGE}:${MAJOR_TAG}"
+              )
+          fi
+
+          docker buildx build \
+              --push \
+              --platform "${PLATFORMS}" \
+              "${TAGS[@]}" \
+              --file Dockerfile \
+              .