{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}

module PGExtras.Queries.VacuumStats (vacuumStatsSQL, displayVacuumStats) where

import PGExtras.Helpers (maybeText)
import Database.PostgreSQL.Simple
import Text.RawString.QQ
import qualified Data.Text as Text
import Control.Monad (forM_)
import Data.List (intercalate)

vacuumStatsSQL :: Query
vacuumStatsSQL = [r|WITH table_opts AS (
  SELECT
    pg_class.oid, relname, nspname, array_to_string(reloptions, '') AS relopts
  FROM
     pg_class INNER JOIN pg_namespace ns ON relnamespace = ns.oid
), vacuum_settings AS (
  SELECT
    oid, relname, nspname,
    CASE
      WHEN relopts LIKE '%autovacuum_vacuum_threshold%'
        THEN substring(relopts, '.*autovacuum_vacuum_threshold=([0-9.]+).*')::integer
        ELSE current_setting('autovacuum_vacuum_threshold')::integer
      END AS autovacuum_vacuum_threshold,
    CASE
      WHEN relopts LIKE '%autovacuum_vacuum_scale_factor%'
        THEN substring(relopts, '.*autovacuum_vacuum_scale_factor=([0-9.]+).*')::real
        ELSE current_setting('autovacuum_vacuum_scale_factor')::real
      END AS autovacuum_vacuum_scale_factor
  FROM
    table_opts
)
SELECT
  vacuum_settings.nspname AS schema,
  vacuum_settings.relname AS table,
  to_char(psut.last_vacuum, 'YYYY-MM-DD HH24:MI') AS last_vacuum,
  to_char(psut.last_autovacuum, 'YYYY-MM-DD HH24:MI') AS last_autovacuum,
  to_char(pg_class.reltuples, '9G999G999G999') AS rowcount,
  to_char(psut.n_dead_tup, '9G999G999G999') AS dead_rowcount,
  to_char(autovacuum_vacuum_threshold
       + (autovacuum_vacuum_scale_factor::numeric * pg_class.reltuples), '9G999G999G999') AS autovacuum_threshold,
  CASE
    WHEN autovacuum_vacuum_threshold + (autovacuum_vacuum_scale_factor::numeric * pg_class.reltuples) < psut.n_dead_tup
    THEN 'yes'
  END AS expect_autovacuum
FROM
  pg_stat_user_tables psut INNER JOIN pg_class ON psut.relid = pg_class.oid
    INNER JOIN vacuum_settings ON pg_class.oid = vacuum_settings.oid
ORDER BY 1;|]

displayVacuumStats :: [(Maybe Text.Text, Maybe Text.Text, Maybe Text.Text, Maybe Text.Text, Maybe Text.Text, Maybe Text.Text, Maybe Text.Text, Maybe Text.Text)] -> IO ()
displayVacuumStats rows = do
  putStrLn $ description
  putStrLn $ intercalate " | " tableHeaders
  forM_ rows $ \(arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8) ->
    putStrLn $ maybeText(arg1) ++ " | " ++ maybeText(arg2) ++ " | " ++ maybeText(arg3) ++ " | " ++ maybeText(arg4) ++ " | " ++ maybeText(arg5) ++ " | " ++ maybeText(arg6) ++ " | " ++ maybeText(arg7) ++ " | " ++ maybeText(arg8)

description :: [Char]
description = "Dead rows and whether an automatic vacuum is expected to be triggered"

tableHeaders :: [[Char]]
tableHeaders = ["schema", "table", "last_vacuum", "last_autovacuum", "rowcount", "dead_rowcount", "autovacuum_threshold", "expect_autovacuum"]