wasm.yml

name: wasm

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

# gh-pages is a single branch, so let one deployment finish before the next
# starts rather than having two pushes race each other for it.
concurrency:
  group: gh-pages
  cancel-in-progress: false

env:
  # Each Qt minor release targets one specific Emscripten version, and mixing
  # them does not work: see "Qt for WebAssembly" in the Qt documentation.
  QT_VERSION: 6.10.2
  EMSDK_VERSION: 4.0.7

jobs:
  build:
    name: wasm
    runs-on: ubuntu-24.04
    permissions:
      contents: write # to push the built site to gh-pages
    steps:
    - uses: actions/checkout@v7

    # Cross-compiling needs two Qt installations: the wasm one to link
    # against, and a host one of the same version for moc, uic and rcc, which
    # have to run on the build machine.
    - name: Install Qt (host tools)
      uses: jurplel/install-qt-action@v4
      with:
        version: ${{ env.QT_VERSION }}
        host: linux
        target: desktop
        arch: linux_gcc_64
        cache: true
        dir: ${{ runner.temp }}/qt-host

    # Take note of where that landed before the wasm install overwrites
    # QT_ROOT_DIR with its own: QT_HOST_PATH is how the wasm build is told
    # which moc, uic and rcc to run, and those have to be the host ones.
    - name: Remember the host Qt
      run: echo "QT_HOST_PATH=$QT_ROOT_DIR" >> "$GITHUB_ENV"

    - name: Install Qt (WebAssembly)
      uses: jurplel/install-qt-action@v4
      with:
        version: ${{ env.QT_VERSION }}
        host: all_os
        target: wasm
        arch: wasm_singlethread
        cache: true
        dir: ${{ runner.temp }}/qt-wasm

    - name: Cache the Emscripten SDK
      id: emsdk-cache
      uses: actions/cache@v6
      with:
        path: emsdk
        key: emsdk-${{ env.EMSDK_VERSION }}-${{ runner.os }}

    - name: Install the Emscripten SDK
      if: steps.emsdk-cache.outputs.cache-hit != 'true'
      run: |
        git clone --depth 1 https://github.com/emscripten-core/emsdk.git
        ./emsdk/emsdk install "$EMSDK_VERSION"

    # Also on a cache hit: activate is what writes the config the compiler
    # reads, and it records absolute paths.
    - name: Activate the Emscripten SDK
      run: ./emsdk/emsdk activate "$EMSDK_VERSION"

    - name: Build and install libqgcodeeditor
      run: |
        source ./emsdk/emsdk_env.sh
        # No .deb to install from here, so build the editor widget into a
        # staging prefix. Static, so it ends up inside the .wasm rather than
        # beside it.
        git clone --depth 1 https://github.com/QGCoder/libqgcodeeditor
        emcmake cmake -S libqgcodeeditor -B libqgcodeeditor/build -G Ninja \
            -DCMAKE_BUILD_TYPE=Release \
            -DCMAKE_TOOLCHAIN_FILE="$QT_ROOT_DIR/lib/cmake/Qt6/qt.toolchain.cmake" \
            -DQT_HOST_PATH="$QT_HOST_PATH" \
            -DCMAKE_INSTALL_PREFIX="$PWD/qgcodeeditor-prefix" \
            -DBUILD_STATIC_LIB=ON \
            -DBUILD_EXAMPLES=OFF \
            -DBUILD_DESIGNER_PLUGIN=OFF
        cmake --build libqgcodeeditor/build -j"$(nproc)"
        cmake --install libqgcodeeditor/build

    - name: Build qgcoder
      run: |
        source ./emsdk/emsdk_env.sh
        # CMAKE_FIND_ROOT_PATH, not CMAKE_PREFIX_PATH: the Emscripten toolchain
        # sets CMAKE_FIND_ROOT_PATH_MODE_LIBRARY to ONLY, so find_library()
        # looks under the find roots and nowhere else - a prefix path alone is
        # searched for packages but not for the library itself.
        emcmake cmake -B build -G Ninja \
            -DCMAKE_BUILD_TYPE=Release \
            -DCMAKE_TOOLCHAIN_FILE="$QT_ROOT_DIR/lib/cmake/Qt6/qt.toolchain.cmake" \
            -DQT_HOST_PATH="$QT_HOST_PATH" \
            -DCMAKE_FIND_ROOT_PATH="$PWD/qgcodeeditor-prefix"
        cmake --build build -j"$(nproc)"

    - name: Assemble the site
      run: |
        cmake --install build --prefix "$PWD/dist"
        mkdir -p site
        cp dist/bin/qgcoder.html dist/bin/qgcoder.js \
           dist/bin/qgcoder.wasm dist/bin/qtloader.js dist/bin/qtlogo.svg site/
        # GitHub Pages serves index.html for a directory, and the Qt shell page
        # refers to its own files by relative name, so a copy under both names
        # works either way round.
        cp site/qgcoder.html site/index.html
        # without this, Pages runs the directory through Jekyll, which drops
        # files whose names begin with an underscore
        touch site/.nojekyll
        ls -lh site

    - uses: actions/upload-artifact@v7
      with:
        name: wasm
        if-no-files-found: error
        path: site

    # Only what lands on main gets published; a pull request is built to check
    # that it still compiles and no further.
    - name: Publish to gh-pages
      if: github.event_name == 'push' && github.ref == 'refs/heads/main'
      env:
        GIT_AUTHOR_NAME: Github Actions
        GIT_AUTHOR_EMAIL: jakob.flierl@gmail.com
        GIT_COMMITTER_NAME: Github Actions
        GIT_COMMITTER_EMAIL: jakob.flierl@gmail.com
      run: |
        # A fresh orphan commit every time: the site is a build artifact, and
        # keeping a history of one would mean carrying every .wasm ever built -
        # about 15 MB apiece - in the repository for good.
        cd site
        git init -q -b gh-pages
        git add -A
        git commit -q -m "Deploy ${GITHUB_SHA} to gh-pages"
        git push -q --force \
            "https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/${GITHUB_REPOSITORY}.git" \
            gh-pages