name: Detect code changes
description: Detect whether changed files require full code validation
outputs:
  code-changed:
    description: Whether any changed file is outside documentation-only paths
    value: ${{ steps.detect.outputs.code-changed }}
runs:
  using: composite
  steps:
    - id: detect
      shell: bash
      env:
        BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
        HEAD_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
      run: |
        set -euo pipefail

        base_sha="$BASE_SHA"
        head_sha="$HEAD_SHA"

        if [[ -z "$base_sha" || "$base_sha" =~ ^0+$ ]]; then
          base_sha="$(git rev-list --max-parents=0 "$head_sha")"
        fi

        if ! git cat-file -e "$base_sha^{commit}" || ! git cat-file -e "$head_sha^{commit}"; then
          echo "code-changed=true" >> "$GITHUB_OUTPUT"
          exit 0
        fi

        changed_files="$(mktemp)"
        git diff --name-only "$base_sha" "$head_sha" > "$changed_files"

        code_changed=false
        while IFS= read -r path; do
          [[ -z "$path" ]] && continue

          case "$path" in
            docs/*|*.md|*.mdx) ;;
            *) code_changed=true; break ;;
          esac
        done < "$changed_files"

        echo "code-changed=$code_changed" >> "$GITHUB_OUTPUT"