Applescript to open .url files on OS X Firefox - macos

Question

For reasons that only the developers can understand, Firefox will create and open .url files on Windows and .webloc files on OS X but won't allow the Windows version of Firefox to open .webloc files or the OS X version of Firefox to open .url files. (.url files open in Safari but that's not good enough for reasons that aren't worth going into here.) As part of my efforts to use either filetype on either system, I'm writing an applescript to open .url files on OS X Firefox.
on open the_droppings
set filePath to the_droppings
set fp to open for access filePath
set fileContents to read fp
close access fp
set secondLine to paragraph 2 of fileContents
set tid to AppleScript's text item delimiters
set AppleScript's text item delimiters to "="
set URLstring to last text item of secondLine
set AppleScript's text item delimiters to tid
tell application "Firefox"
activate
OpenURL URLstring
end tell
end open
I thought this would work but in the 3rd to last line it says "Expected end of line, etc. but found identifier." Why is this?
EDIT sakra's answer below mostly works but breaks on urls containing "=" such as: http://example.com?foo=a&bar=z

Answer 1

Firefox does not seem to feature an AppleScript dictionary at all. Therefore the term OpenURL within the tell app "Firefox" statement is interpreted as an AppleScript identifier and not as an AppleScript command. Two AppleScript identifiers in a row result in a syntax error.
As a work-around you can use the shell command open in combination with the standard AppleScript command do shell script:
on open the_droppings
set filePath to the_droppings
set fileContents to read filePath
set theOffset to offset of "URL=" in fileContents
set URLstring to text (theOffset + 4) through -1 of fileContents
do shell script "/usr/bin/open -a Firefox.app " & quoted form of URLstring
end open

Answer 2

EDIT: download my script in an app here: http://www.mediafire.com/?v77bv9gl9e7oj40
This works even better:
on open the_droppings
set filePath to the_droppings
set fileContents to read filePath
set theOffsetA to offset of "URL=" in fileContents
set theOffsetB to offset of "IDList=" in fileContents
set URLstring to text (theOffsetA + 4) through (theOffsetB - 3) of fileContents
do shell script "/usr/bin/open -a Firefox.app " & quoted form of URLstring
end open
It reads the URL= line to the next line ( IDList ) minus 3 steps ( to ignore the \r\n ) and sends it to firefox. Works like a charm for me.
I however have seen url files with weird layout ( example: http://forums.mozillazine.org/viewtopic.php?p=2619487 ), which I'm not sure of if it would work there. But I checked a lot of my url files and they dont have that, so atleast it works fine for me. Let me know if you run into troubles with this script. For the moment I'm setting it as default app to open URL files, instead of Safari!
To be able of opening url files with an applescript file, it needs to have the proper doctypes and identifier set in its plist, like this:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>CFBundleAllowMixedLocalizations</key>
<true/>
<key>CFBundleDevelopmentRegion</key>
<string>English</string>
<key>CFBundleDocumentTypes</key>
<array>
<dict>
<key>CFBundleTypeExtensions</key>
<array>
<string>url</string>
</array>
<key>CFBundleTypeIconFile</key>
<string>document.icns</string>
<key>CFBundleTypeName</key>
<string>URL File</string>
<key>CFBundleTypeOSTypes</key>
<array>
<string>URL</string>
</array>
<key>CFBundleTypeRole</key>
<string>Viewer</string>
</dict>
</array>
<key>CFBundleExecutable</key>
<string>droplet</string>
<key>CFBundleIdentifier</key>
<string>filehandler.url.mozilla.firefox</string>
<key>CFBundleIconFile</key>
<string>droplet</string>
<key>CFBundleInfoDictionaryVersion</key>
<string>6.0</string>
<key>CFBundleName</key>
<string>FirefoxURLHandler</string>
<key>CFBundlePackageType</key>
<string>APPL</string>
<key>CFBundleSignature</key>
<string>dplt</string>
<key>LSMinimumSystemVersionByArchitecture</key>
<dict>
<key>x86_64</key>
<string>10.6</string>
</dict>
</dict>
</plist>

Answer 3

I know it's not apple script, but I did this to open them on Linux, but it has the problem that if and when the terminal closes, it kills the browser. I opened another question about this, but this may help.
#!/bin/bash
#bash -c "cat $1 | grep URL | cut -d'=' -f2 | xargs firefox &"
echo OpenWinURL in firefox
echo Closing this window will close your firefox.
echo Try opening firefox before opening a OpenWinURL
#echo Copyright 2021 Aaron Peterson GPL V2 or later
#echo The ampersand doesn't work after firefox
#echo "$1"
#
jobs -l
cat "$1" | grep -m 1 URL= | cut -d'=' -f2- | xargs -0 -i firefox {} #&
jobs -l
disown -h -a
jobs -l
#read -n 1 -p "Input Selection:" mainmenuinput
#echo testing
#wait 1000
#
#| head -n 1
#| cut -d'=' -f2 | xargs firefox &