name: inject-content
description: Inject content into a file by appending or overwriting

inputs:
  content:
    description: Content to write into the target file
    required: true
  target-file:
    description: Path to the target file
    required: true
  mode:
    description: "Write mode: 'append' adds to the end of the file; 'overwrite' replaces its contents"
    required: false
    default: append

outputs:
  target-file:
    description: Path of the file that was written
    value: ${{ steps.inject.outputs.target-file }}

runs:
  using: composite
  steps:
    - name: Validate target-file input
      shell: bash
      env:
        TARGET_FILE: ${{ inputs.target-file }}
      run: |
        if [[ -z "$TARGET_FILE" ]]; then
          echo "::error::target-file must not be empty"
          exit 1
        fi

    - name: Validate mode input
      shell: bash
      env:
        MODE: ${{ inputs.mode }}
      run: |
        if [[ "$MODE" != "append" && "$MODE" != "overwrite" ]]; then
          echo "::error::Invalid mode '$MODE'. Must be 'append' or 'overwrite'."
          exit 1
        fi

    - name: Inject content into file
      id: inject
      shell: bash
      env:
        CONTENT: ${{ inputs.content }}
        TARGET_FILE: ${{ inputs.target-file }}
        MODE: ${{ inputs.mode }}
      run: |
        set -euo pipefail

        mkdir -p "$(dirname "$TARGET_FILE")"

        if [[ "$MODE" == "overwrite" ]]; then
          printf '%s\n' "$CONTENT" > "$TARGET_FILE"
        else
          if [[ -s "$TARGET_FILE" ]]; then
            printf '\n%s\n' "$CONTENT" >> "$TARGET_FILE"
          else
            printf '%s\n' "$CONTENT" >> "$TARGET_FILE"
          fi
        fi

        echo "Content injected into $TARGET_FILE (mode: $MODE)"
        echo "target-file=$TARGET_FILE" >> "$GITHUB_OUTPUT"