name: Binary size difference

on:
  pull_request:

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

jobs:
  sizediff:
    runs-on: ubuntu-24.04
    permissions:
      pull-requests: write
    steps:
      # Prepare, install tools
      - name: Add GOBIN to $PATH
        run: |
          echo "$HOME/go/bin" >> $GITHUB_PATH
      - name: Install Go
        uses: actions/setup-go@v6
        with:
          go-version: '~1.25'
      - name: Checkout
        uses: actions/checkout@v6
        with:
          fetch-depth: 0 # fetch all history (no sparse checkout)
          submodules: true
      - uses: ./.github/actions/setup-llvm
        with:
          save-cache: "false"
      - name: Cache Go
        uses: actions/cache@v5
        with:
          key: go-cache-linux-sizediff-v2-${{ hashFiles('go.mod') }}
          path: |
            ~/.cache/go-build
            ~/go/pkg/mod
      - run: make gen-device -j4
      - name: Download drivers repo
        run: git clone https://github.com/tinygo-org/drivers.git
      - name: Save PR configuration
        id: pr
        run: |
          # Keep the action available after checking out the base commit.
          cp -r .github/actions/setup-llvm .github/actions/setup-llvm-base
          echo "base_sha=$(git rev-parse HEAD^1)" >> "$GITHUB_OUTPUT"
          echo "llvm_version=$(cat llvm-version.txt)" >> "$GITHUB_OUTPUT"

      # Compute sizes for the PR branch
      - name: Build tinygo binary for the PR branch
        run: make tinygo
      - name: Determine binary sizes on the PR branch
        run: |
          set -o pipefail
          export PATH="$PWD/build:$PATH"
          (cd drivers; make smoke-test | tee sizes-pr.txt)

      # Compute sizes for the dev branch
      - name: Checkout dev branch
        id: dev
        run: |
          git checkout --force "${{ steps.pr.outputs.base_sha }}"
          git submodule update --init
          rm -rf build
          git clean -fdX src/device
          export GOCACHE="$RUNNER_TEMP/go-build-base"
          export XDG_CACHE_HOME="$RUNNER_TEMP/cache-base"
          echo "GOCACHE=$GOCACHE" >> "$GITHUB_ENV"
          echo "XDG_CACHE_HOME=$XDG_CACHE_HOME" >> "$GITHUB_ENV"
          make gen-device -j4
          echo "llvm_version=$(cat llvm-version.txt)" >> "$GITHUB_OUTPUT"
      - name: Remove LLVM build for the PR branch
        if: steps.pr.outputs.llvm_version != steps.dev.outputs.llvm_version
        run: rm -rf llvm-build llvm-project
      - name: Set up LLVM for the dev branch
        uses: ./.github/actions/setup-llvm-base
        if: steps.pr.outputs.llvm_version != steps.dev.outputs.llvm_version
        with:
          save-cache: "false"
      - name: Build tinygo binary for the dev branch
        run: make tinygo
      - name: Determine binary sizes on the dev branch
        run: |
          set -o pipefail
          export PATH="$PWD/build:$PATH"
          (cd drivers; make smoke-test | tee sizes-dev.txt)

      # Create comment
      # TODO: add a summary, something like:
      #  - overall size difference (percent)
      #  - number of binaries that grew / shrank / remained the same
      #  - don't show the full diff when no binaries changed
      - name: Calculate size diff
        run: |
          set -o pipefail
          ./tools/sizediff drivers/sizes-dev.txt drivers/sizes-pr.txt | tee sizediff.txt
      - name: Create comment
        run: |
          echo "Size difference with the dev branch:" > comment.txt
          echo "<details><summary>Binary size difference</summary>" >> comment.txt
          echo "<pre>" >> comment.txt
          cat sizediff.txt >> comment.txt
          echo "</pre></details>" >> comment.txt
      - name: Comment contents
        run: cat comment.txt
      - name: Add comment
        if: ${{ github.event.pull_request.head.repo.full_name == github.event.pull_request.base.repo.full_name }}
        uses: thollander/actions-comment-pull-request@v2.3.1
        with:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          filePath: comment.txt
          comment_tag: sizediff