Create a plugin for thunderbird mail client

I need a plugin for thunderbird 45 that have followed functions: 1) 1. Button: Access to a IMAP folder and get the selected mails in batch, add a signature (contained in a separate file with images), add a choosen file (or files) as attachment and store it in the draft folder in the thunderbird client program with a choosen send account. 2) 2. Button: Access to the (in the step 1 created) mails in the draft folder, add a digital sigature to the mail and send the mail from the setting mail account. I need the source code, so that I can compile the code on my machine and make the plugin self. Then I must installed the plugin on my thunderbird instance.