Different url rewriting according to locations - nginx

Question

I really don't find any documentation I find clear about URL rewriting (I can't understand it, as I unexpectedly find the documentation really hard to read for a non-native).
I'm looking for a way to rewrite all routes that matches /*\.(js|png|jpg|css|ttf|xml)$/ toward path/media/ and try existance of file then return it if exists, else 404 not found
then if it begins with /ajax/ redirect all of it toward path/ajax/index.php
else redirect all of it toward path/www/index.php
I don't quite understand how I should do it, for now I created 3 locations /media/, /ajax/ and /www/ but I don't know if it is the right way to use rewrite and not return, or are the locations the correct way to do it.
I don't really understand what I've written in my sites-enabled/file regarding fastcgi. is this a interpretor path ?
location ~ \.php$ {
try_files $uri =404;
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;
}
If I get it right, it means "if it ends with .php, and it exists in hierarchy, then execute it".
And I don't know if I should put that kind of stuff for each location that has to deal with php (/www/ and /ajax/), especially since I'm going to do some routing for both. Moreover, I don't know if it should be done that way.

Answer 1

The simplest PHP configurations use a common root directive which is inherited by the location blocks, and in your case would be:
root path;
This means that /www/index.php and /ajax/index.php are both processed by the location ~ \.php$ block.
The default action can be defined by the try_files directive within a location / block:
location / {
try_files $uri $uri/ /www/index.php;
}
If you need a different default action for URIs which begin with /ajax, add a more specific location:
location /ajax {
try_files $uri $uri/ /ajax/index.php;
}
If you do not want your media URIs to begin with /media you can override the root for one specific location:
location ~* \.(js|png|jpg|css|ttf|xml)$ {
root path/media;
}
The fastcgi_split_path_info and fastcgi_index directives are unnecessary in your specific case. The include fastcgi_params; statement should be placed before any fastcgi_param directive to avoid the latter being inadvertently overridden:
location ~ \.php$ {
try_files $uri =404;
include fastcgi_params;
fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
}
See the nginx documentation for details.