How can I swap URL parameters and discarding others with mod_rewrite?

I need to redirect the simplified:

/search.ht开发者_开发百科ml?param1=val1&param2=val2&param3=val3&location=UK

To:

/search/United-Kingdom/arg4=val2&arg5=val1

Parameters may be in any order or missing, location is a code with expansions in a map file (UK United Kingdom, etc).

If there are no matching parameters redirect to:

/search-info/

Current code for location expansion:

RewriteMap location_map txt:/path/to/locations_map.txt
RewriteCond %{REQUEST_URI} .*search.html.* [NC]
RewriteCond %{QUERY_STRING} .*location=([^&]+).* [NC]
RewriteCond ${location_map:%1} ^(.*)$
RewriteRule ^(.*)$ /search/%1/ [R=301]

How can I swap out the parameter names and discard parameters that aren't needed (i.e. param3 above)?

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This would work if it weren't the changing parameter order requirement. Can't you make the order constant?

RewriteMap location_map txt:/path/to/locations_map.txt
RewriteCond %{REQUEST_URI} /search.html [NC]
RewriteCond %{QUERY_STRING} (param1=(.+?)&)?(param2=(.+?)&)?(param3=(.+?)&)?location=(.+?) [NC]
RewriteRule ^(.*)$ /search/${location_map:%7}/?arg4=%4&arg5=%2 [R=301,last]

RewriteCond %{REQUEST_URI} /search.html [NC]
RewriteRule / /search-info/ [last]