Calculation of Due Dates Based on Number of Plots Chosen

Question

In a function I want to put the parameters that would:

Number of Plots and Total Value

My problem would be how to generate maturity dates of installments

in Postgresql how to work with the dates to generate the plots

Ex: 03 plots

13.11.2019

13.12.2019

13.01.2020

How to generate dates based on the number of plots ?

Thanks for the help

How was your help

CREATE OR REPLACE FUNCTION public.gerar_parcelas (
  p_data_vencimento date,
  p_parcelas integer,
  p_tipo_intervalo integer,
  p_dias_intervalo integer,
  p_dias_para_1_parcela integer,
  p_documento integer
)
RETURNS TABLE (
  data_vencimento date,
  documento varchar
) AS
$body$
declare
    contador integer;
    dia integer;
    mes integer;
    ano integer;
    script text;
    resulta date;
    r record;
BEGIN

    -- Por Dia
    if p_tipo_intervalo = 1 then

        script = 'select '||''''||lpad(cast(p_documento as varchar),7,'0')||''''||'||'||''''||'.'||''''||'||lpad(cast(i+1 as VARCHAR),2,'||''''|| '0'||''''||')||'||''''||'/'||''''||'||'||''''||lpad(cast(p_parcelas as varchar),2,'0')||''''||' as documento,        
            '||''''||p_data_vencimento+p_dias_para_1_parcela||''''||'::date + ((i*'||p_dias_intervalo||')|| '||''''||' days'||''''||')::interval as data_venc
            from generate_series(0,' || p_parcelas - 1 || ') as i;';
    end if;

    -- Por Mes
    if p_tipo_intervalo = 2 then

        script = 'select '||''''||p_data_vencimento+p_dias_para_1_parcela||''''||'::date + ((i)|| '||''''||' Months'||''''||')::interval as data_venc
            from generate_series(0,' || p_parcelas - 1 || ') as i;';
    end if;

    for r in execute script loop  
        documento = r.documento;
        data_vencimento = r.data_venc;
        return next;
    end loop;

END;