pgsql rotate table and generate dynamic columns based on values

Question

I want to make a dynamic pivot on pgsql table

Original table :

time	strategy	pnl
1	a	100
2	a	200
3	a	300
1	b	1000
2	b	2000
1	c	22

target table :

time	sum	a	b	c
1	1132	100	1000	32
2	2200	200	2000	0
3	22	0	0	22

the problem that the strategy content is dynamic i can have sometimes over 40 unique values (in this example there are only 3 a,b,c )

i have the following code it looks like a good start but the are some problems i cannot solve

SELECT time,
      --sum(case when strategy='a' then pnl else 0 end) AS "a" ,
      --sum(case when strategy='b' then pnl else 0 end) AS "b" ,
      --sum(case when strategy='c' then pnl else 0 end) AS "c"

      --generate the contect above, (when using the code above the function works)
       (SELECT string_agg(clause, ',')
        FROM (SELECT format('sum(case when strategy=''%s'' then pnl else 0 end) AS "%s" ',
                            strategy, strategy) AS clause
              FROM (SELECT DISTINCT strategy FROM server_logs.logs where strategy != '' and subclass = 'pnl') s
              ORDER BY strategy) clauses)
FROM (
select  case when strategy is null then 'system' else strategy end as strategy,
       time,
       sum(case when value::float!=0  then 0::float else value::float end) as pnl
      FROM server_logs.logs
        where subclass='pnl'
        group by rollup(strategy), time
  ) as t
group by time
order by time desc
;