# `publish-aur.yml` - Arch Linux AUR Package Workflow
# --------------------
# This workflow automates the validation and publishing of the 'numa-git' package to the
# Arch User Repository (AUR). The AUR is a community-driven repository for Arch Linux users.
#
# Workflow Overview:
# 1. Validate: Builds and tests the package for Arch Linux x86_64 using a clean
#    Arch Linux container.
# 2. Audit: Checks Rust dependencies for known security vulnerabilities using
#    'cargo-audit'.
# 3. Publish: If on the 'main' branch, it pushes the updated PKGBUILD and
#    .SRCINFO to the AUR.
#
# Security Best Practices:
# - SHA Pinning: All GitHub Actions are pinned to a full-length commit SHA (e.g., v6.0.2 @ SHA)
#   to ensure the code is immutable and protects against supply-chain attacks where a tag
#   might be maliciously moved to a compromised commit.
# - SSH Hygiene: Uses ssh-agent to keep the private key in memory rather than on disk.
# - Audit: Runs 'cargo audit' to prevent publishing known vulnerable dependencies.

name: Publish - Arch Linux AUR Package

on:
  push:
    branches: [main]
    paths-ignore:
      - 'site/**'
      - 'blog/**'
      - 'drafts/**'
      - '*.md'
      - 'scripts/serve-site.sh'
      - 'scripts/generate-blog-index.sh'
  workflow_dispatch:

permissions:
  contents: read

jobs:
  # The 'validate' job ensures that the PKGBUILD is correct and the software builds/tests
  # successfully on Arch Linux before we attempt to publish it.
  validate:
    name: Validate PKGBUILD (${{ matrix.arch }})
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        arch: [x86_64]
    steps:
      - name: Checkout code
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2

      - name: Build and Test Package
        timeout-minutes: 60
        env:
          AUR_PKGNAME: ${{ secrets.AUR_PACKAGE_NAME }}
        run: |
          # We use a temporary directory to avoid Docker permission issues with the workspace.
          mkdir -p build-dir
          cp PKGBUILD build-dir/

          docker run --rm -v $PWD/build-dir:/pkg -w /pkg archlinux:latest /bin/bash -c "
            # ARCH LINUX SECURITY REQUIREMENT:
            # 'makepkg' (the tool that builds Arch packages) refuses to run as root for safety.
            # We must create a standard user and give them sudo access.

            # Install build-time dependencies.
            # 'base-devel' includes essential tools like gcc, make, and binutils.
            # Install 'rust' directly to avoid the interactive virtual-package
            # prompt for 'cargo' on current Arch images.
            pacman -Syu --noconfirm --needed base-devel rust git sudo cargo-audit

            useradd -m builduser
            chown -R builduser:builduser /pkg

            # Allow the build user to install dependencies during the build process.
            echo 'builduser ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/builduser

            # Fetch the source tree first so pkgver() and cargo-audit have a
            # real Cargo.lock to inspect.
            sudo -u builduser makepkg -o --nobuild --nocheck --nodeps --noprepare

            # SECURITY AUDIT:
            # Fail early if any dependencies have known security vulnerabilities.
            sudo -u builduser sh -lc 'cd /pkg/src/numa && cargo audit'

            # BUILD & TEST:
            # 'makepkg -s' will:
            # 1. Download source files (cloning this repo)
            # 2. Run prepare(), build(), and check() (running cargo test)
            # 3. Create the final .pkg.tar.zst package
            sudo -u builduser makepkg -s --noconfirm
          "

  # The 'publish' job updates the AUR repository with our latest PKGBUILD and .SRCINFO.
  publish:
    name: Publish to AUR
    needs: validate
    runs-on: ubuntu-latest
    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
    steps:
      - name: Checkout code
        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2

      # Securely configure SSH for AUR access.
      - name: Configure SSH
        run: |
          mkdir -p ~/.ssh
          # Official AUR Ed25519 fingerprint (prevents Man-in-the-Middle attacks).
          echo "aur.archlinux.org ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEuBKrPzbawxA/k2g6NcyV5jmqwJ2s+zpgZGZ7tpLIcN" >> ~/.ssh/known_hosts

          # Use ssh-agent to keep the private key in memory rather than writing it to disk.
          eval $(ssh-agent -s)
          echo "${{ secrets.AUR_SSH_PRIVATE_KEY }}" | tr -d '\r' | ssh-add -

          # Export the agent socket so subsequent 'git' commands can use it.
          echo "SSH_AUTH_SOCK=$SSH_AUTH_SOCK" >> $GITHUB_ENV
          echo "SSH_AGENT_PID=$SSH_AGENT_PID" >> $GITHUB_ENV

      - name: Push to AUR
        env:
          AUR_PKGNAME: ${{ secrets.AUR_PACKAGE_NAME }}
          AUR_EMAIL: ${{ secrets.AUR_EMAIL }}
          AUR_USER: ${{ secrets.AUR_USERNAME }}
        run: |
          # AUR repos are managed via Git. Each package has its own repo at:
          # ssh://aur@aur.archlinux.org/<package-name>.git
          git clone ssh://aur@aur.archlinux.org/$AUR_PKGNAME.git aur-repo

          # AUR's git server no longer advertises HEAD's symref, so clone
          # lands in detached HEAD. Attach to master before committing.
          git -C aur-repo checkout master

          cp PKGBUILD aur-repo/
          cd aur-repo

          # METADATA GENERATION:
          # '.SRCINFO' is a machine-readable version of the PKGBUILD.
          # We must run this as a non-root user ('builduser') inside the container.
          docker run --rm -v $(pwd):/pkg archlinux:latest /bin/bash -c "
            pacman -Syu --noconfirm --needed binutils git sudo
            useradd -m builduser
            chown -R builduser:builduser /pkg
            cd /pkg
            sudo -u builduser git config --global --add safe.directory '*'
            # makepkg -od fetches the source first so pkgver() can calculate the version.
            # --noprepare skips the prepare() function, which invokes cargo and would
            # otherwise require a full rust toolchain in this metadata-only container.
            # pkgver() runs before prepare(), so .SRCINFO still gets the correct version.
            sudo -u builduser makepkg -od --noprepare && sudo -u builduser makepkg --printsrcinfo > .SRCINFO
          "

          # Reclaim ownership: the in-container 'chown -R builduser:builduser /pkg'
          # propagates through the bind mount, leaving .git/ owned by the container's
          # builduser UID. Without this, subsequent 'git config' on the host fails with
          # "could not lock config file .git/config: Permission denied".
          sudo chown -R "$(id -u):$(id -g)" .

          # Set the commit identity using secrets for security and auditability.
          git config user.name "$AUR_USER"
          git config user.email "$AUR_EMAIL"

          # Stage and commit both the human-readable PKGBUILD and machine-readable .SRCINFO.
          git add PKGBUILD .SRCINFO

          if ! git diff --cached --quiet; then
            git commit -m "chore: update PKGBUILD to ${{ github.sha }}"
            git push origin master
          else
            echo "No changes to commit (metadata and PKGBUILD are already up-to-date)."
          fi
