const VALID_CLASSIFICATIONS = [
  'ACTIONABLE_NOW', 'UNASSIGNED_ACTIONABLE', 'WAITING_REQUESTER', 'WAITING_VENDOR',
  'WAITING_APPROVAL', 'SCHEDULED', 'DEPENDENCY_BLOCKED', 'NEEDS_COORDINATION',
  'PROJECT_LONG_TERM', 'DUPLICATE_OR_OBSOLETE', 'INSUFFICIENT_CONTEXT',
];

// O modelo, apesar do schema permitir null de verdade em blocker_type/waiting_for, as vezes
// devolve a STRING "null" (ou variantes equivalentes) em vez do valor JSON null. Normaliza
// aqui, na camada de validacao -- unico lugar que toca a resposta crua da IA.
const NULL_LIKE_STRINGS = new Set(['null', 'none', 'n/a', 'na', '']);

function normalizeNullableString(value) {
  if (value === null || value === undefined) return null;
  const trimmed = String(value).trim();
  if (NULL_LIKE_STRINGS.has(trimmed.toLowerCase())) return null;
  return trimmed;
}

function validateAiClassification(raw) {
  const errors = [];
  if (!raw || typeof raw !== 'object') {
    return { valid: false, data: null, errors: ['resposta nao e um objeto JSON'] };
  }
  if (!VALID_CLASSIFICATIONS.includes(raw.classification)) {
    errors.push(`classification invalida: ${raw.classification}`);
  }
  if (typeof raw.actionable_today !== 'boolean') errors.push('actionable_today deve ser boolean');
  const confidence = Number(raw.confidence);
  if (!Number.isFinite(confidence) || confidence < 0 || confidence > 1) errors.push('confidence deve estar entre 0 e 1');
  if (typeof raw.next_action !== 'string' || raw.next_action.trim().length === 0 || raw.next_action.length > 200) errors.push('next_action invalido (vazio ou muito longo)');
  if (raw.evidence != null && !Array.isArray(raw.evidence)) errors.push('evidence deve ser array');
  if (typeof raw.reason !== 'string') errors.push('reason deve ser string');

  if (errors.length) return { valid: false, data: null, errors };

  return {
    valid: true,
    errors: [],
    data: {
      classification: raw.classification,
      actionable_today: raw.actionable_today,
      confidence,
      blocker_type: normalizeNullableString(raw.blocker_type),
      waiting_for: normalizeNullableString(raw.waiting_for),
      next_action: raw.next_action,
      suggested_action_type: raw.suggested_action_type ?? 'technical_action',
      business_risk: raw.business_risk ?? 'medium',
      reason: raw.reason,
      evidence: Array.isArray(raw.evidence) ? raw.evidence.slice(0, 5) : [],
      is_fallback: false,
      fallback_reason: null,
    },
  };
}

module.exports = { VALID_CLASSIFICATIONS, validateAiClassification, normalizeNullableString };