Both RewriteRule's works fine, except when used together.
1.Remove all queries except query ?callback=.*:
# /api?callback=foo has no rewrite
# /whatever?whatever=foo has 301 redirect /whatever
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^?#\ ]*)\?[^\ ]*\ HTTP/ [NC]
RewriteCond %{REQUEST_URI}?%{QUERY_STRING} !/api(/.*)?\?callback=.*
RewriteRule .*$ %{REQUEST_URI}? [R=301,L]
2.Rewrite index.php queries api and url=$1:
# /api returns data index.php?api&url=
# /api/whatever returns data index.php?api&url=whatever
RewriteRule ^api(?:/([^/]*))?$ index.php?api&url=$1 [QSA,L]
RewriteRule ^([^.]*)$ index.php?url=$1 [QSA,L]
Any valid combination to this RewriteRule's on keeping its functionality?
This combination will return Server Error 404 to /api/?callback=foo:
# Remove all queries except query "callback"
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^?#\ ]*)\?[^\ ]*\ HTTP/ [NC]
RewriteCond %{REQUEST_URI}?%{QUERY_STRING} !/api(/.*)?\?callback=.*
RewriteRule .*$ %{REQUEST_URI}? [R=301,L]
# Rewrite index.php queries
RewriteCond %{REQUEST_URI}?%{QUERY_STRING} !/api(/.*)?\?callback=.*
# Server Error 404 on /api/?callback=foo and /api/whatever?callback=foo
RewriteRule ^api(?:/([^/]*))?$ index.php?api&url=$1 [QSA,L]
RewriteCond %{REQUEST_URI}?%{QUERY_STRING} !/api(/.*)?\?callback=.*
RewriteRule ^([^.]*)$ index.php?url=$1 [QSA,L]
