name: Check Shared CLAUDE.md Block
description: Fails when a repo's shared CLAUDE.md block has drifted from the canonical copy in stat-tackler-infra

inputs:
  TARGET:
    description: "Path to the CLAUDE.md file to check"
    default: "CLAUDE.md"
  CANONICAL_URL:
    description: "Raw URL of the canonical shared fragment"
    default: "https://gitea.pixelparasol.com/stat-tackler/stat-tackler-infra/raw/branch/main/docs/CLAUDE.shared.md"
  GITEA_TOKEN:
    description: "Gitea token with read access to stat-tackler-infra, if it is private"
    default: ""

runs:
  using: composite
  steps:
    - name: Checkout
      uses: actions/checkout@v4

    - name: Check shared CLAUDE.md block
      shell: sh
      env:
        TARGET: ${{ inputs.TARGET }}
        CANONICAL_URL: ${{ inputs.CANONICAL_URL }}
        GITEA_TOKEN: ${{ inputs.GITEA_TOKEN }}
      run: |
        set -e

        if [ ! -f "$TARGET" ]; then
          echo "::error::$TARGET not found"
          exit 1
        fi

        extract() {
          # Everything between the markers, markers included.
          awk '/<!-- SHARED:BEGIN/{f=1} f{print} /SHARED:END -->/{f=0}' "$1"
        }

        mine=$(extract "$TARGET")
        if [ -z "$mine" ]; then
          echo "::error::$TARGET has no SHARED:BEGIN/SHARED:END block."
          echo "Copy it from $CANONICAL_URL"
          exit 1
        fi

        tmp=$(mktemp)
        if [ -n "$GITEA_TOKEN" ]; then
          curl -sfSL -H "Authorization: token $GITEA_TOKEN" "$CANONICAL_URL" -o "$tmp"
        else
          curl -sfSL "$CANONICAL_URL" -o "$tmp"
        fi

        theirs=$(extract "$tmp")
        if [ -z "$theirs" ]; then
          echo "::error::Could not read the canonical block from $CANONICAL_URL"
          exit 1
        fi

        if [ "$mine" = "$theirs" ]; then
          echo "Shared CLAUDE.md block matches the canonical copy."
          rm -f "$tmp"
          exit 0
        fi

        echo "::error::The shared CLAUDE.md block has drifted from the canonical copy."
        echo "Canonical: $CANONICAL_URL"
        echo
        echo "--- canonical"
        echo "+++ $TARGET"
        printf '%s\n' "$theirs" > "$tmp.canon"
        printf '%s\n' "$mine" > "$tmp.mine"
        diff -u "$tmp.canon" "$tmp.mine" || true
        rm -f "$tmp" "$tmp.canon" "$tmp.mine"
        exit 1