/* ==========================================================
   KIT EDA POSTGRESQL – 15 QUERIES CLAVE
   Autor: NeoAnd

   📌 Instrucciones rápidas:

-- Ejecuta:
SELECT run_eda_auto_export('public','clientes');

-- Luego en DBeaver:
-- Busca en el navegador las tablas temporales que empiezan con "tmp_"
-- Ej: tmp_total_rows, tmp_nulls, tmp_top10_micolumna, tmp_stats_micolumna, tmp_time_midate, tmp_corr

Ejecuta por bloque (Cmd+Enter en Mac, Ctrl+Enter en Windows).
   ========================================================== */


CREATE OR REPLACE FUNCTION run_eda_auto_export(p_schema TEXT, p_table TEXT)
RETURNS void AS


DECLARE
    r RECORD;
    col_num TEXT[];
    col_cat TEXT[];
    col_date TEXT[];
    sql_cmd TEXT;
BEGIN
    -- 🔍 Clasificación automática de columnas
    SELECT array_agg(column_name) FILTER (WHERE data_type LIKE '%int%' OR data_type LIKE '%numeric%' OR data_type LIKE '%double%')
    INTO col_num
    FROM information_schema.columns
    WHERE table_schema = p_schema AND table_name = p_table;

    SELECT array_agg(column_name) FILTER (WHERE data_type IN ('character varying','text','uuid'))
    INTO col_cat
    FROM information_schema.columns
    WHERE table_schema = p_schema AND table_name = p_table;

    SELECT array_agg(column_name) FILTER (WHERE data_type LIKE '%date%' OR data_type LIKE '%timestamp%')
    INTO col_date
    FROM information_schema.columns
    WHERE table_schema = p_schema AND table_name = p_table;

    -- 📊 1. Conteo total
    EXECUTE format('DROP TABLE IF EXISTS tmp_total_rows;
                    CREATE TEMP TABLE tmp_total_rows AS
                    SELECT COUNT(*) AS total FROM %I.%I',
                   p_schema, p_table);

    -- 📊 2. Nulos por columna
    sql_cmd := '';
    FOR r IN
        SELECT column_name
        FROM information_schema.columns
        WHERE table_schema = p_schema AND table_name = p_table
    LOOP
        sql_cmd := sql_cmd || format(
            'SELECT %L AS columna, COUNT(*) AS nulls FROM %I.%I WHERE %I IS NULL UNION ALL ',
            r.column_name, p_schema, p_table, r.column_name
        );
    END LOOP;
    sql_cmd := left(sql_cmd, length(sql_cmd)-11); -- quitar último UNION ALL
    EXECUTE format('DROP TABLE IF EXISTS tmp_nulls;
                    CREATE TEMP TABLE tmp_nulls AS %s', sql_cmd);

    -- 📊 3. Top 10 valores más frecuentes por columna categórica
    IF col_cat IS NOT NULL THEN
        FOREACH r IN ARRAY col_cat LOOP
            EXECUTE format(
              'DROP TABLE IF EXISTS tmp_top10_%I;
               CREATE TEMP TABLE tmp_top10_%I AS
               SELECT %I, COUNT(*) AS freq
               FROM %I.%I
               GROUP BY %I
               ORDER BY freq DESC
               LIMIT 10',
               r, r, r, p_schema, p_table, r
            );
        END LOOP;
    END IF;

    -- 📊 4. Estadísticas descriptivas de columnas numéricas
    IF col_num IS NOT NULL THEN
        FOREACH r IN ARRAY col_num LOOP
            EXECUTE format(
              'DROP TABLE IF EXISTS tmp_stats_%I;
               CREATE TEMP TABLE tmp_stats_%I AS
               SELECT MIN(%I) AS minimo,
                      MAX(%I) AS maximo,
                      AVG(%I) AS media,
                      PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY %I) AS mediana
               FROM %I.%I',
               r, r, r, r, r, r, r, p_schema, p_table
            );
        END LOOP;
    END IF;

    -- 📊 5. Distribución temporal por columnas de fecha
    IF col_date IS NOT NULL THEN
        FOREACH r IN ARRAY col_date LOOP
            EXECUTE format(
              'DROP TABLE IF EXISTS tmp_time_%I;
               CREATE TEMP TABLE tmp_time_%I AS
               SELECT date_trunc(''day'', %I) AS dia, COUNT(*)
               FROM %I.%I
               GROUP BY dia
               ORDER BY dia',
               r, r, r, p_schema, p_table
            );
        END LOOP;
    END IF;

    -- 📊 6. Correlaciones numéricas
    IF array_length(col_num,1) >= 2 THEN
        EXECUTE 'DROP TABLE IF EXISTS tmp_corr;
                 CREATE TEMP TABLE tmp_corr (col_x TEXT, col_y TEXT, correlacion NUMERIC)';
        FOR i IN 1..array_length(col_num,1)-1 LOOP
            FOR j IN i+1..array_length(col_num,1) LOOP
                EXECUTE format(
                  'INSERT INTO tmp_corr
                   SELECT %L, %L, corr(%I,%I)
                   FROM %I.%I',
                   col_num[i], col_num[j], col_num[i], col_num[j], p_schema, p_table
                );
            END LOOP;
        END LOOP;
    END IF;

    RAISE NOTICE '✅ Tablas temporales creadas. Revísalas en el navegador de DBeaver (prefijo tmp_)';
END;


LANGUAGE plpgsql;