I have a repository of PDF documents, and most of the text contained in these documents are formatted in Comic Sans. I would like to change this to something similar to Arial. The original font is embedded in the document. I haven't found any existing tool to do this for me (I'm on Linux), and I wonder if it's possible to do it programmaticaly. A Python library would be perfect, but a library in any programming language would do.
In which library will I be able to substitute fonts with the least effort? And which parts of the API would I use?