Ruby mulitple conditional statment write to same file twice?

I am trying to create a find and replace script in ruby. But I cannot figure out how to write to the same file twice when there are two conditions matched (2 different regex patterns are found and need to be replaced in the same file) I can get it either to provide 2 copyes of the file concatonated with only changes made from one condition in each.

Here is my code (Specifically pattern3 and pattern4):

print "What extension do you want to modify? "
ext = gets.chomp

if ext == "py"
    print("Enter password: " )
    pass = gets.chomp

elsif ext == "bat"  
    print "Enter drive letter: "
    drive = gets.chomp
    print "Enter IP address and Port: "
    ipport = gets.chomp
end

pattern1 = /'Admin', '.+'/
pattern2 = /password='.+'/
pattern3 = /[a-zA-Z]:\\(?i:dir1\\dir2)/
pattern4 = /http:\/\/.+:\d\d\d\d\//


Dir.glob("**/*."+ext).each do |file|
        data = File.read(file)
            File.open(file, "w") do |f|
                if data.match(pattern1)
                    match = data.match(pattern1)
                      replace = data.gsub(pattern1, '\''+pass+'\'')  
                    f.write(replace)
                    puts "File " + file + " modified " + match.to_s
                elsif data.match(pattern2)
                    match = data.match(pattern2)
                      replace = data.gsub(pattern2, 'password=\''+pass+'\'')  
                    f.write(replace)
                    puts "File " + file + " modified "  + match.to_s
                end

                if data.match(pattern3)
                   match = data.match(pattern3)
                       replace = data.gsub(pattern3, drive+':\dir1\dir2')  
                     f.write(replace)
                     puts "File " + file + " modified "  + match.to_s
                if data.match(pattern4)
                     match = data.match(pattern4)
                       replace = data.gsub(pattern4, 'http://' + ipport + '/')  
                     f.write(replace)
                     puts "File " + file + " modified "  + match.to_s   
          end
    end
    end
end

f.truncate(0) makes things better but truncates the first line since it concatonates from the end of the 1st modified portion of the file.