RewriteEngine On
RewriteBase /pages

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule .* - [L]

RewriteRule  ^([_0-9a-zA-Z-]+/)?((?:am-.*)|(?:.*\.php)) $2 [L]
# RewriteRule  ^([_0-9a-zA-Z-]+/)?()$ $2 [L] # merged into the rule above

# RewriteCond %{REQUEST_FILENAME} !-f # superfluous, has been asserted by the first two conditions
RewriteCond %{REQUEST_URI} !(.*)/$
RewriteRule (.*)$ /pages/$1/ [R=301,L]

# RewriteRule ^index\.php$ - [L] # superfluous, has been handled by the first rule
# RewriteCond %{REQUEST_FILENAME} !-f # superfluous, has been asserted by the first two conditions
# RewriteCond %{REQUEST_FILENAME} !-d # superfluous, has been asserted by the first two conditions
RewriteRule ^([a-zA-Z0-9\-_\/\s]+)/?$ /pages/index.php [L]