Options +FollowSymLinks
RewriteEngine On

RewriteCond %{HTTP:HTTPSSL} !^true$
RewriteCond %{HTTPS} !^on$
RewriteCond %{HTTP_HOST} ^(example\.com)(:80)? [NC]
RewriteRule ^(.*) https://example.com/$1 [R=301,L]

RewriteRule ^index(/?)$ index.php
RewriteRule ^([a-zA-Z0-9_-]+)$ user.php?a=$1 [L,NC]