Getting all lines by author per file in git

Question

I want to get all authors that contributed to a file (working). Additionally I want the number of lines from each author of a file (working). And in the end I also want each line number that was contributed by each author. The format should not be 1, 2, 3, 4, 5, 11, 12, 13, 14 but instead be something like 1-5, 11-14. Is that doable in an "easy" way on the command line? I can't do anything by hand as we have thousands of files with around 2 million lines of code.

files=$(git ls-tree -r HEAD | cut -c54-)
for file in $files
do
        echo $file
        git blame $file --line-porcelain | grep  "^author " | sort | uniq -c | sort -r
done

is doing what i want besides the line numbers.