/** Vigencia documental y contexto de alta IMSS. */

export type ValidityMode = "none" | "freshness" | "expiry";
export type ValidityStatus = "ok" | "missing" | "expired" | "stale_for_alta" | "missing_dates";
export type ImssStatus = "sin_alta" | "alta" | "baja_imss";

export type DocTypePolicy = {
  code: string;
  label: string;
  required: boolean;
  validity_mode: ValidityMode;
  freshness_days: number | null;
  requires_issued_at: boolean;
  requires_expires_at: boolean;
};

export type CurrentDocDates = {
  type_code: string;
  issued_at: string | null;
  expires_at: string | null;
  uploaded_at: string;
  imss_alta_at?: string | null;
};

export type WorkerImssContext = {
  imss_status: ImssStatus;
  last_rehire_at: string | null;
  /** Fecha de la alta IMSS vigente (documento o worker.imss_alta_at). */
  current_alta_at: string | null;
};

function parseDay(value: string | null | undefined): Date | null {
  if (!value) return null;
  const raw = String(value).trim().slice(0, 10);
  if (!/^\d{4}-\d{2}-\d{2}$/.test(raw)) return null;
  const d = new Date(`${raw}T12:00:00`);
  return Number.isNaN(d.getTime()) ? null : d;
}

function daysBetween(from: Date, to: Date): number {
  return Math.floor((to.getTime() - from.getTime()) / 86_400_000);
}

/** True cuando el expediente debe exigir frescor (alta o reingreso pendiente de alta). */
export function freshnessRequired(ctx: WorkerImssContext): boolean {
  if (ctx.imss_status !== "alta") return true;
  if (!ctx.last_rehire_at) return false;
  const rehire = parseDay(ctx.last_rehire_at);
  const alta = parseDay(ctx.current_alta_at);
  if (!rehire) return false;
  if (!alta) return true;
  return alta < rehire;
}

export function evaluateDocumentValidity(
  policy: DocTypePolicy,
  doc: CurrentDocDates | null | undefined,
  ctx: WorkerImssContext,
  today = new Date(),
): {
  present: boolean;
  valid: boolean;
  validity_status: ValidityStatus;
  issued_at: string | null;
  expires_at: string | null;
} {
  if (!doc) {
    return {
      present: false,
      valid: false,
      validity_status: "missing",
      issued_at: null,
      expires_at: null,
    };
  }

  const issuedAt = doc.issued_at;
  const expiresAt = doc.expires_at;
  const needFresh = freshnessRequired(ctx);

  if (policy.validity_mode === "expiry") {
    if (policy.requires_expires_at && !expiresAt) {
      return {
        present: true,
        valid: false,
        validity_status: "missing_dates",
        issued_at: issuedAt,
        expires_at: expiresAt,
      };
    }
    const exp = parseDay(expiresAt);
    if (exp && exp < new Date(today.toISOString().slice(0, 10) + "T12:00:00")) {
      return {
        present: true,
        valid: false,
        validity_status: "expired",
        issued_at: issuedAt,
        expires_at: expiresAt,
      };
    }
    return {
      present: true,
      valid: true,
      validity_status: "ok",
      issued_at: issuedAt,
      expires_at: expiresAt,
    };
  }

  if (policy.validity_mode === "freshness") {
    if (policy.requires_issued_at && !issuedAt) {
      return {
        present: true,
        valid: false,
        validity_status: "missing_dates",
        issued_at: issuedAt,
        expires_at: expiresAt,
      };
    }
    if (needFresh && issuedAt) {
      const issued = parseDay(issuedAt);
      const days = policy.freshness_days ?? 90;
      if (issued && daysBetween(issued, today) > days) {
        return {
          present: true,
          valid: false,
          validity_status: "stale_for_alta",
          issued_at: issuedAt,
          expires_at: expiresAt,
        };
      }
    }
    return {
      present: true,
      valid: true,
      validity_status: "ok",
      issued_at: issuedAt,
      expires_at: expiresAt,
    };
  }

  return {
    present: true,
    valid: true,
    validity_status: "ok",
    issued_at: issuedAt,
    expires_at: expiresAt,
  };
}

export const DOCUMENT_TYPE_SEED: Array<{
  code: string;
  label: string;
  required: number;
  validity_mode: ValidityMode;
  freshness_days: number | null;
  requires_issued_at: number;
  requires_expires_at: number;
}> = [
  { code: "foto", label: "Foto", required: 1, validity_mode: "none", freshness_days: null, requires_issued_at: 0, requires_expires_at: 0 },
  { code: "ine", label: "INE", required: 1, validity_mode: "expiry", freshness_days: null, requires_issued_at: 0, requires_expires_at: 1 },
  { code: "curp", label: "Constancia CURP", required: 1, validity_mode: "freshness", freshness_days: 90, requires_issued_at: 1, requires_expires_at: 0 },
  { code: "nss", label: "Constancia NSS", required: 1, validity_mode: "freshness", freshness_days: 90, requires_issued_at: 1, requires_expires_at: 0 },
  { code: "rfc", label: "Constancia RFC", required: 1, validity_mode: "freshness", freshness_days: 90, requires_issued_at: 1, requires_expires_at: 0 },
  { code: "domicilio", label: "Comprobante de domicilio", required: 1, validity_mode: "freshness", freshness_days: 90, requires_issued_at: 1, requires_expires_at: 0 },
  { code: "alta_imss", label: "Alta IMSS", required: 0, validity_mode: "none", freshness_days: null, requires_issued_at: 0, requires_expires_at: 0 },
  { code: "baja_imss", label: "Baja IMSS", required: 0, validity_mode: "none", freshness_days: null, requires_issued_at: 0, requires_expires_at: 0 },
  { code: "contrato", label: "Contrato", required: 0, validity_mode: "none", freshness_days: null, requires_issued_at: 0, requires_expires_at: 0 },
  { code: "otro", label: "Otro", required: 0, validity_mode: "none", freshness_days: null, requires_issued_at: 0, requires_expires_at: 0 },
];