Mixing query in PostgreSQL (join tables)

mixing_query_in_postgreSQL.sql

SELECT salesforce_accounts.*, salesforce_tasks.*, salesforce_accounts.id AS salesforce_account_id, salesforce_tasks.id AS salesforce_task_id FROM "salesforce_accounts" 
LEFT JOIN salesforce_tasks ON salesforce_accounts.salesforce_id = salesforce_tasks.account_id 
LEFT JOIN companies ON companies.salesforce_id = salesforce_accounts.salesforce_id 
WHERE 
(
  (
    salesforce_tasks.owner_id = 'xxxxxxxxxxxxx' 
    AND salesforce_tasks.is_deleted = 'f' 
    AND salesforce_tasks.activity_date <= '2017-06-11' 
    AND salesforce_tasks.activity_date >= '2017-04-04' 
    AND salesforce_tasks.status = 'Not Started' 
    AND salesforce_tasks.activity_date < '2017-06-02'
  ) 
  OR 
  ( 
    salesforce_accounts.is_deleted = 'f'
    AND salesforce_accounts.owner_id = 'xxxxxxxxxxxxx'
    AND salesforce_accounts.id NOT IN (
      SELECT distinct(salesforce_accounts.id) FROM salesforce_accounts
      RIGHT OUTER JOIN salesforce_tasks ON salesforce_tasks.account_id = salesforce_accounts.salesforce_id
      WHERE (salesforce_accounts.owner_id = 'xxxxxxxxxxxxx')
      AND (salesforce_tasks.status = 'Not Started')
    )
    AND
    (
      salesforce_tasks.id IN (
      SELECT max(salesforce_tasks.id) FROM salesforce_tasks
      WHERE (salesforce_tasks.status = 'Completed')
      AND salesforce_tasks.is_deleted = 'f'
      GROUP BY salesforce_tasks.account_id
    )
    OR
    salesforce_tasks.id IS NULL
    OR
    salesforce_tasks.is_deleted = 't'
  )
)) 
ORDER BY companies.score DESC NULLS LAST, salesforce_tasks.activity_date ASC NULLS LAST, salesforce_tasks.id ASC LIMIT 10 OFFSET 0