action.yaml

name: Regex Extract

description: 'Reusable action to run a command and extract substrings for an arbitrary list of regex patterns.'

inputs:
  command:
    description: 'The shell command to execute.'
    required: true
  regex-inputs:
    description: |
      New line **or** comma separated list of regex patterns.
    required: true

outputs:
  matches:
    value: ${{ steps.extract.outputs.matches }}
    description: 'A JSON array (single line) containing the extracted substrings in the same order the patterns were supplied.'

runs:
  using: composite
  steps:
    - name: Run command and extract substrings
      id: extract
      shell: bash
      run: |
        set -euo pipefail

        OUTPUT=$(eval "${{ inputs.command }}")
        echo "Command output: $OUTPUT"

        mapfile -t PATTERNS < <(printf '%s\n' "${{ inputs.regex-inputs }}" | tr ',' '\n' | sed '/^[[:space:]]*$/d')

        if [[ ${#PATTERNS[@]} -eq 0 ]]; then
          echo "No regex patterns provided." >&2
          exit 1
        fi

        declare -a MATCHES=()

        for PAT in "${PATTERNS[@]}"; do
          if [[ $OUTPUT =~ $PAT ]]; then
            MATCHES+=("${BASH_REMATCH[1]}")
          else
            echo "Pattern did not match: $PAT" >&2
            exit 1
          fi
        done

        JSON_MATCHES=$(printf '%s\n' "${MATCHES[@]}" | jq -R . | jq -cs .)
        echo "Extracted matches: $JSON_MATCHES"
        echo "matches=$JSON_MATCHES" >> "$GITHUB_OUTPUT"