name: Continuous build

on:
  push:
    branches: [master]
  workflow_dispatch:

# The `continuous` tag is recreated on every run, so two runs must not overlap: the loser of the
# race would leave its assets attached to the other one's commit. Newer wins — a build of an older
# commit has nothing left to say once a newer one is underway.
concurrency:
  group: continuous
  cancel-in-progress: true

permissions:
  contents: write

jobs:
  build:
    runs-on: ubuntu-latest
    # Dominated by the node-worker build below, which is long enough that the default limit is not
    # obviously sufficient.
    timeout-minutes: 180

    steps:
      # Into a subdirectory rather than the workspace root: `node-worker` is a `link:../node-worker`
      # dependency, so it has to end up *beside* this checkout, and actions/checkout cannot write
      # outside the workspace.
      - name: Check out the app
        uses: actions/checkout@v5
        with:
          path: app

      - name: Check out node-worker
        uses: actions/checkout@v5
        with:
          repository: heyputer/node-worker
          path: node-worker
          # GITHUB_TOKEN can read a public repository, which is all this needs. The secret is the
          # fallback for as long as node-worker is still private: GITHUB_TOKEN is scoped to this
          # repository alone and cannot read another private one.
          token: ${{ secrets.NODE_WORKER_TOKEN || github.token }}

      # An Emscripten toolchain, a full Node checkout and the object files from a wasm link of Node
      # do not comfortably fit alongside everything the runner image ships with. These two are the
      # largest trees this build will never touch.
      - name: Reclaim runner disk
        run: sudo rm -rf /usr/share/dotnet /usr/local/lib/android

      # Pinned rather than read from a `packageManager` field, which this repo does not set. Both
      # lockfiles are lockfileVersion 9, so one pnpm serves both checkouts.
      - name: Set up pnpm
        uses: pnpm/action-setup@v4
        with:
          version: 11.3.0

      - name: Set up Node
        uses: actions/setup-node@v5
        with:
          node-version: 24

      # node-worker's build also compiles a Rust crate to wasm, via
      # src/worker/node-rust/wasm/build.sh. That script wants cargo and a wasm-bindgen CLI whose
      # version matches the crate's exactly — it checks, and refuses to run on a mismatch.
      #
      # Ahead of the node-worker build rather than folded into it, because build.sh runs at the
      # *end* of prepare-node.js: a toolchain problem would otherwise surface an hour in, after the
      # emsdk and Node work is already done and paid for.
      - name: Set up Rust for the rewriter wasm build
        run: |
          # Read the version out of build.sh's own check rather than restating it here, so this
          # cannot drift from whatever the sibling repo demands at the commit being built.
          build_sh=node-worker/src/worker/node-rust/wasm/build.sh
          version="$(sed -n 's/^WBG="wasm-bindgen \([0-9.]*\)"$/\1/p' "$build_sh")"
          if [ -z "$version" ]; then
            echo "::error::could not read the required wasm-bindgen version out of $build_sh"
            exit 1
          fi
          echo "build.sh wants wasm-bindgen $version"

          # nightly with rust-src, because build.sh builds std from source (`-Z build-std`) and
          # passes unstable rustc flags. The crate's rust-toolchain.toml asks for exactly this;
          # installing it up front beats leaving rustup to fetch it lazily mid-build.
          rustup toolchain install nightly --profile minimal \
            --component rust-src --target wasm32-unknown-unknown

          # The prebuilt binary: `cargo install wasm-bindgen-cli` would compile it from source for
          # several minutes to reach the same place.
          tarball="wasm-bindgen-$version-x86_64-unknown-linux-musl"
          base="https://github.com/wasm-bindgen/wasm-bindgen/releases/download/$version"
          curl -sSfL -O "$base/$tarball.tar.gz" -O "$base/$tarball.tar.gz.sha256sum"
          # Compared by hand rather than with `sha256sum -c`, whose input names a path that only
          # ever existed on the machine that cut the release.
          expected="$(awk '{print $1}' "$tarball.tar.gz.sha256sum")"
          actual="$(sha256sum "$tarball.tar.gz" | awk '{print $1}')"
          if [ "$expected" != "$actual" ]; then
            echo "::error::wasm-bindgen $version checksum mismatch: expected $expected, got $actual"
            exit 1
          fi

          mkdir -p "$HOME/.local/bin"
          tar -xzf "$tarball.tar.gz" --strip-components=1 \
            -C "$HOME/.local/bin" "$tarball/wasm-bindgen"
          echo "$HOME/.local/bin" >> "$GITHUB_PATH"

      # `$GITHUB_PATH` only takes effect in later steps, so this is the first point at which the
      # two binaries build.sh looks for can be confirmed to resolve. Cheap, and it fails here
      # instead of at the very end of a long build.
      - name: Check cargo and wasm-bindgen resolve
        run: |
          cargo --version
          wasm-bindgen --version

      # The long pole by a wide margin: clones emsdk and the Node v25.9.0 source, builds OpenSSL's
      # libcrypto with emcc, links Node itself to wasm, and finally builds the Rust rewriter above.
      # Deliberately uncached — see the note at the end of this file.
      - name: Build node-worker
        working-directory: node-worker
        run: |
          pnpm install --frozen-lockfile
          pnpm build

      - name: Install
        working-directory: app
        run: pnpm install --frozen-lockfile

      # `prebuild` bakes the project templates first, fetching create-vite and its dependency tree
      # from the npm registry, so this needs network as well as CPU.
      - name: Build
        working-directory: app
        run: pnpm build

      # `-C app dist` rather than `-C app/dist .`, so every entry in the archive is prefixed
      # `dist/`. Asserted rather than assumed: getting this wrong produces an archive that looks
      # fine until it is unpacked over somebody's web root.
      - name: Package dist
        run: |
          tar -czf dist.tar.gz -C app dist
          tar -tzf dist.tar.gz | grep -qx 'dist/index.html'

      # Deleted and recreated rather than edited, because the tag has to move to this commit and
      # `gh release edit --target` will not move a tag that already exists. `--repo` throughout
      # because the workspace root is not itself a git checkout.
      - name: Publish the continuous release
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          # Read from the checkout rather than from `github.event`, which has no commit message on
          # a workflow_dispatch run, and passed to printf as an argument so nothing in it is
          # interpreted as shell.
          subject="$(git -C app log -1 --pretty=%s)"
          {
            printf 'Built from `%s` — %s\n\n' "$GITHUB_SHA" "$subject"
            printf '`dist.tar.gz` unpacks to `dist/`.\n\n'
            printf 'The build uses a relative base, so it can be served from any path — `/`,\n'
            printf '`/labs/node/`, anywhere — provided the URL it is served at ends in a slash.\n'
          } > notes.md

          gh release delete continuous --repo "$GITHUB_REPOSITORY" --cleanup-tag --yes || true
          gh release create continuous dist.tar.gz \
            --repo "$GITHUB_REPOSITORY" \
            --target "$GITHUB_SHA" \
            --prerelease \
            --title "Continuous build" \
            --notes-file notes.md

# On caching: nothing here is cached, so every run pays for the full node-worker build. The
# alternative is caching `node-worker/{dist,emsdk,node_core}` keyed on that repo's commit SHA,
# which would turn most runs into a cache restore. Worth revisiting if the wait starts to hurt.