name: Conditional Variables

description: |
  Evaluates a set of rules and exposes variables as outputs.

  Rules are evaluated in the order they are defined.

  A rule matches when any of its conditions match the supplied context.

  If multiple matching rules set the same variable,
  the last matching value wins.

inputs:
  context:
    description: |
      Context variables available during rule evaluation.

      Example:

        branch=9.0-alpine-24
        event=push
        install_something=1

    required: true

  rules:
    description: |
      Rules to evaluate.

      Example:

        - conditions:
            - branch == 9.0-alpine-24
            - branch == 9.0-alpine-23
          set:
            DOTNET_VERSION=9.0
            DOTNET_RUNTIME_VERSION=9.0.18

        - conditions:
            - install_something == 1
          set:
            INSTALL_DEPENDENCY=true

      Conditions within a rule are evaluated as OR.

    required: true

  fail-on-no-match:
    description: |
      Fail the action if no rule matches.
    required: false
    default: "false"

outputs:
  matched:
    description: Indicates whether at least one rule matched.
    value: ${{ steps.evaluate.outputs.matched }}

runs:
  using: composite

  steps:
    - name: Evaluate rules
      id: evaluate
      shell: bash
      env:
        CONTEXT: ${{ inputs.context }}
        RULES: ${{ inputs.rules }}
        FAIL_ON_NO_MATCH: ${{ inputs.fail-on-no-match }}
      run: |
        "${{ github.action_path }}/evaluate.sh"