Oracle : Script which tells free space left in tablespaces and datafiles in terms of percentage

SET PAGESIZE 100 LINES 132 ECHO OFF VERIFY OFF FEEDB OFF SPACE 1 TRIMSP ON
COMPUTE SUM OF a_byt t_byt f_byt ON REPORT
BREAK ON REPORT ON tablespace_name ON pf
COL tablespace_name FOR A17   TRU HEAD 'Tablespace|Name'
COL file_name       FOR A40   TRU HEAD 'Filename'
COL a_byt           FOR 9,990.999 HEAD 'Allocated|GB'
COL t_byt           FOR 9,990.999 HEAD 'Current|Used GB'
COL f_byt           FOR 9,990.999 HEAD 'Current|Free GB'
COL pct_free        FOR 990.0     HEAD 'File %|Free'
COL pf              FOR 990.0     HEAD 'Tbsp %|Free'
COL seq NOPRINT
DEFINE b_div=1073741824
--
SELECT 1 seq, b.tablespace_name, nvl(x.fs,0)/y.ap*100 pf, b.file_name file_name,
  b.bytes/&&b_div a_byt, NVL((b.bytes-SUM(f.bytes))/&&b_div,b.bytes/&&b_div) t_byt,
  NVL(SUM(f.bytes)/&&b_div,0) f_byt, NVL(SUM(f.bytes)/b.bytes*100,0) pct_free
FROM dba_free_space f, dba_data_files b
 ,(SELECT y.tablespace_name, SUM(y.bytes) fs
   FROM dba_free_space y GROUP BY y.tablespace_name) x
    ,(SELECT x.tablespace_name, SUM(x.bytes) ap
      FROM dba_data_files x GROUP BY x.tablespace_name) y
   WHERE f.file_id(+) = b.file_id
   AND   x.tablespace_name(+) = y.tablespace_name
   and   y.tablespace_name =  b.tablespace_name
   AND   f.tablespace_name(+) = b.tablespace_name
   GROUP BY b.tablespace_name, nvl(x.fs,0)/y.ap*100, b.file_name, b.bytes
   UNION
   SELECT 2 seq, tablespace_name,
     j.bf/k.bb*100 pf, b.name file_name, b.bytes/&&b_div a_byt,
     a.bytes_used/&&b_div t_byt, a.bytes_free/&&b_div f_byt,
     a.bytes_free/b.bytes*100 pct_free
   FROM v$temp_space_header a, v$tempfile b
     ,(SELECT SUM(bytes_free) bf FROM v$temp_space_header) j
     ,(SELECT SUM(bytes) bb FROM v$tempfile) k
   WHERE a.file_id = b.file#
   ORDER BY 1,2,4,3;