name: update-helium

on:
  schedule:
    - cron: "0 6 * * *"
  workflow_dispatch:

permissions:
  contents: write

concurrency:
  group: update-helium
  cancel-in-progress: false

jobs:
  update-helium:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: cachix/install-nix-action@v31
        with:
          extra_nix_config: |
            experimental-features = nix-command flakes

      - name: Bump sources.nix to the latest upstream release
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          set -euo pipefail

          SOURCES_FILE="modules/sources.nix"

          # Anchor on the leading whitespace and the opening quote so this only
          # matches the `versions` block and never the `x86_64-linux = versions:`
          # attribute names further down the file.
          get_current_version() {
            grep -E "^[[:space:]]+$1 = \"" "$SOURCES_FILE" | head -1 | sed 's/.*= "\(.*\)";/\1/'
          }

          get_latest_release() {
            curl -fsSL -H "Authorization: Bearer $GH_TOKEN" \
              "https://api.github.com/repos/$1/releases/latest" | jq -r .tag_name
          }

          # prefetch-file reports an SRI hash directly, so there is no separate
          # `nix hash convert` step that could drift out of sync.
          fetch_sri_hash() {
            nix store prefetch-file --json "$1" | jq -r .hash
          }

          update_version() {
            sed -i "s|$1 = \"$2\";|$1 = \"$3\";|" "$SOURCES_FILE"
          }

          # Every hash sits on the line directly below the url it belongs to.
          update_hash() {
            sed -i "/$1/{n; s|hash = \"[^\"]*\";|hash = \"$2\";|}" "$SOURCES_FILE"
          }

          echo "--- Linux ---"
          CURRENT_LINUX=$(get_current_version linux)
          LATEST_LINUX=$(get_latest_release imputnet/helium-linux)

          if [ "$LATEST_LINUX" != "$CURRENT_LINUX" ]; then
            echo "$CURRENT_LINUX -> $LATEST_LINUX"
            BASE="https://github.com/imputnet/helium-linux/releases/download/$LATEST_LINUX"
            X86_HASH=$(fetch_sri_hash "$BASE/helium-$LATEST_LINUX-x86_64_linux.tar.xz")
            ARM_HASH=$(fetch_sri_hash "$BASE/helium-$LATEST_LINUX-arm64_linux.tar.xz")
            update_version linux "$CURRENT_LINUX" "$LATEST_LINUX"
            update_hash "x86_64_linux\.tar\.xz" "$X86_HASH"
            update_hash "arm64_linux\.tar\.xz" "$ARM_HASH"
          else
            echo "already at $LATEST_LINUX"
          fi

          echo "--- macOS ---"
          CURRENT_DARWIN=$(get_current_version darwin)
          LATEST_DARWIN=$(get_latest_release imputnet/helium-macos)

          if [ "$LATEST_DARWIN" != "$CURRENT_DARWIN" ]; then
            echo "$CURRENT_DARWIN -> $LATEST_DARWIN"
            BASE="https://github.com/imputnet/helium-macos/releases/download/$LATEST_DARWIN"
            X86_HASH=$(fetch_sri_hash "$BASE/helium_${LATEST_DARWIN}_x86_64-macos.dmg")
            ARM_HASH=$(fetch_sri_hash "$BASE/helium_${LATEST_DARWIN}_arm64-macos.dmg")
            update_version darwin "$CURRENT_DARWIN" "$LATEST_DARWIN"
            update_hash "x86_64-macos\.dmg" "$X86_HASH"
            update_hash "arm64-macos\.dmg" "$ARM_HASH"
          else
            echo "already at $LATEST_DARWIN"
          fi

          echo "HELIUM_LINUX=$(get_current_version linux)" >> "$GITHUB_ENV"
          echo "HELIUM_DARWIN=$(get_current_version darwin)" >> "$GITHUB_ENV"

      # A bad hash or a reshuffled upstream tarball should fail here rather than
      # land on main and break everyone who tracks this flake.
      - name: Verify the flake still builds
        run: nix build --no-link --print-build-logs .#helium

      - name: Commit and push
        run: |
          set -euo pipefail

          if [ -z "$(git status --porcelain)" ]; then
            echo "No changes to commit."
            exit 0
          fi

          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git add modules/sources.nix
          git commit -m "chore: update helium (linux: $HELIUM_LINUX, darwin: $HELIUM_DARWIN)"
          git push