RewriteEngine On
RewriteRule ^([_A-Za-z0-9-]+).html$ index.php?action=$1 [L]
RewriteRule ^([_A-Za-z0-9-]+)/([_A-Za-z0-9-]+).html$ index.php?action=$1&date=$2 [L]
RewriteRule ^([_A-Za-z0-9-]+)/([_A-Za-z0-9-]+)/(.*).html$ index.php?action=$1&date=$2&filter=$3 [L]
RewriteRule ^([_A-Za-z0-9-]+)/([_A-Za-z0-9-]+)/(.*)_([0-9]+).html$ index.php?action=$1&date=$2&filter=$3&page=$4 [L]