// engine.js

const { writeLedgerEntry } = require('./ledger');

// Invariant set F1–F9
const INVARIANTS = {
  F1_NO_SEMANTIC_INTERPRETATION: true,
  F2_NO_EMOTIONAL_INFERENCE: true,
  F3_NO_PROBABILISTIC_ROUTING: true,
  F4_NO_AUTONOMOUS_STATE_MUTATION: true,
  F5_NO_MEANING_GENERATION: true,
  F6_NO_TEMPLATE_REWRITING: true,
  F7_NO_CAPABILITY_EXPANSION: true,
  F8_NO_MEMORY_INJECTION: true,
  F9_NO_CROSS_SIGNAL_CONTAMINATION: true,
};

function checkInvariants(input) {
  const report = {
    inputType: typeof input,
    length: typeof input === 'string' ? input.length : null,
    invariants: { ...INVARIANTS },
    violations: [],
  };

  if (typeof input !== 'string') {
    report.violations.push('F1: input must be a string (opaque signal)');
  }

  return report;
}

function processSignal(input) {
  const invariantReport = checkInvariants(input);

  let result;
  if (invariantReport.violations.length > 0) {
    result = {
      input,
      output: null,
      timestamp: 0,
      invariants: invariantReport,
      status: 'error',
    };
  } else {
    const output = `processed:${input}`;
    result = {
      input,
      output,
      timestamp: 0,
      invariants: invariantReport,
      status: 'ok',
    };
  }

  // Write ledger entry (deterministic, append-only)
  const ledgerPath = writeLedgerEntry({
    input: result.input,
    output: result.output,
    timestamp: result.timestamp,
    status: result.status,
    invariants: result.invariants,
  });

  return { ...result, ledgerPath };
}

module.exports = { processSignal };