Set proxy for all apps on Mac, including GUI and terminal, according to wi-fi AP name. Should be used together with proxy.sh <https://gist.github.com/JerryFleming/9825285>.

proxy.scpt

property my_wifi : "off"
tell application "System Events" to tell menu bar 1 of process "SystemUIServer" of application "System Events"
	set wifi_menu to first item of (value of attribute "AXChildren" as list) whose (value of attribute "AXDescription") contains "Wi-Fi"
	tell wifi_menu
		click
		set my_wifi to (name of menu items of menu 1 whose name of attributes contains "AXMenuItemMarkChar" and value of attribute "AXMenuItemMarkChar" is "✓")
		click
	end tell
end tell

if my_wifi is equal to {"S3-wireless"} then
	set param to "sgp"
else
	set param to "none"
end if
do shell script "sed -i '' '/^\\. \\/etc\\/proxy/d' ~/.bash_profile ;echo '. /etc/proxy " & param & "' >> ~/.bash_profile"
do shell script "bash /etc/proxy " & param --with administrator privileges
display dialog "WiFi \"" & my_wifi & "\" requires \"" & param & "\" proxy." with title "Proxy Changed" buttons {"Ok"} with icon caution