name: docs site build and push
on:
  push:
    branches:
      - main
  # Build-only (no push) on PRs that touch the build/deploy pipeline, so
  # Dockerfile / workflow changes are validated before they reach main.
  pull_request:
    paths:
      - 'docker/**'
      - '.dockerignore'
      - '.github/workflows/build_n_push.yml'
      - 'next.config.mjs'
      - 'package.json'
      - 'package-lock.json'
  workflow_dispatch:

permissions:
  contents: read

# Serialise non-PR runs while allowing superseded PR validation to be canceled.
# Builds publish only an immutable SHA tag; the mutable ref tag is promoted
# separately after the build and a final ref check.
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ github.event_name == 'pull_request' }}

jobs:
  docs_build_n_push:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          # Full history so gen:last-updated / gen:sitemap can read real
          # per-file commit dates (a shallow clone would yield wrong dates).
          fetch-depth: 0

      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Restore Next.js build cache
        uses: actions/cache@v4
        with:
          path: .next/cache
          key: ${{ runner.os }}-nextjs-${{ hashFiles('package-lock.json') }}-${{ hashFiles('src/**', 'mdx/**', 'next.config.mjs') }}
          restore-keys: |
            ${{ runner.os }}-nextjs-${{ hashFiles('package-lock.json') }}-

      - name: Build
        run: npm run build

      - name: Docker meta
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: netbirdio/docs.netbird.io

      - name: Login to DockerHub
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USER }}
          password: ${{ secrets.DOCKER_TOKEN }}

      # Non-PR runs publish an immutable image first. A canceled or stale run
      # can leave this tag behind, but it cannot change :main (or another
      # mutable ref tag).
      - name: Docker build and publish immutable image
        uses: docker/build-push-action@v6
        with:
          context: .
          file: docker/Dockerfile
          push: ${{ github.event_name != 'pull_request' }}
          # Keep a single-arch manifest (no attestation index) so the server's
          # `docker compose pull` stays happy.
          provenance: false
          tags: netbirdio/docs.netbird.io:${{ github.sha }}
          labels: ${{ steps.meta.outputs.labels }}

      # Promotion is a single remote manifest-tag update after the expensive
      # build. Combined with serialisation and the final ref comparison, an
      # older run cannot replace the mutable tag after a newer run publishes.
      - name: Promote current image to ref tag
        if: github.event_name != 'pull_request'
        env:
          SOURCE_IMAGE: netbirdio/docs.netbird.io:${{ github.sha }}
          TARGET_TAGS: ${{ steps.meta.outputs.tags }}
        run: |
          remote_sha="$(git ls-remote origin "${GITHUB_REF}" | awk 'NR == 1 { print $1 }')"
          if [ -z "$remote_sha" ]; then
            echo "Could not resolve ${GITHUB_REF} on origin" >&2
            exit 1
          fi

          if [ "$GITHUB_SHA" != "$remote_sha" ]; then
            echo "Skipping tag promotion: ${GITHUB_SHA} is stale; ${GITHUB_REF} is now ${remote_sha}"
            exit 0
          fi

          if [ -z "$TARGET_TAGS" ]; then
            echo "Docker metadata produced no target tags" >&2
            exit 1
          fi

          while IFS= read -r target_tag; do
            if [ -n "$target_tag" ]; then
              docker buildx imagetools create \
                --prefer-index=false \
                --tag "$target_tag" \
                "$SOURCE_IMAGE"
            fi
          done <<< "$TARGET_TAGS"