Re: read-epub.el

[Bob Newell]

Here's a much improved version, which I now consider a viable alternative to 
epubmode.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; begin read-epub.el

;; read-epub
;; Read an epub in Emacs.

;; Requires that Calibre is installed, to provide the command-line
;; utility ebook-convert.

;; Probably only works under Linux. Untested with Windows or Mac or
;; anything else. Tested under Linux Mint 13 and 17, with Emacs 23.3
;; and 24.3.

;; M-x read-epub and give the path to the epub you want to
;; read. Tabbing after entering a partial path / filename will, as
;; usual, bring up a buffer with choices.

;; Inspired by epub-mode, but much simpler because it 
;; depends on the Calibre ebook-convert utility to do
;; the hard stuff.

;; There is reasonable error checking, but see the *Messages* buffer
;; if you run into problems.

;; 2014-06-17 Foist upon newsgroup.
;; 2014-06-09 Deal with filenames properly instead of
;;            lazily. This means not just tacking .txt
;;            on the end of the epub name, and messing
;;            with embedded blanks.
;;            Do some error checking.
;;            Add some documentary comments.
;;            Option to reuse an already-converted file.
;;            v.0.1.0.
;; 2014-06-08 Bob Newell (address@hidden),
;;            Honolulu, Hawai`i.
;;            Fast and dirty initial coding. v.0.01.

;; This software is released into the public domain.

(defun read-epub (epub-file)
  "Read epub files in emacs"
  (interactive "fname of epub: ")

;; I prefer the following to using 'let' because it makes debugging
;; easier.

      (defvar epub-version "0.10")
      (defvar epub-filebase)
      (defvar epub-extension)
      (defvar epub-oldname)
      (defvar epub-newname)

      (setq epub-filebase (file-name-sans-extension epub-file))
      (setq epub-extension (file-name-extension epub-file))
      (setq epub-oldname epub-file)
      (setq epub-newname (concat epub-filebase ".txt"))

      (if (not (file-exists-p epub-oldname))
          (error (concat epub-file " not found")))
      (if (not (string= "epub" epub-extension))
          (error (concat epub-file " does not have an epub extension")))
      (if (= 1 (shell-command "which ebook-convert"))
          (error "Can't find the ebook-convert utility"))

;; If there is no existing text file with the 'conversion' name, or if
;; there is one and we don't want to reuse it, we do the
;; conversion. Otherwise we reuse the existing text file with no
;; further checking.

      (if (or (not (file-exists-p epub-newname))
              (not (yes-or-no-p (concat "Reuse existing " epub-newname "?"))))
          (progn
            (message "Converting %s, this can take a while" epub-file)

;; shell-quote-argument deals with embedded blanks in the filenames.
;; expand-file-name is needed because ebook-convert expands the tilde
;; incorrectly.

            (shell-command 
                (concat "ebook-convert " 
                        (shell-quote-argument (expand-file-name epub-oldname)) 
" "
                        (shell-quote-argument (expand-file-name epub-newname))))
            (find-file epub-newname)

;; Comment out the next three lines if you don't want to fill
;; paragraphs. This might be the case if things like embedded tables
;; get rendered in a way that paragraph fill will mangle them. This
;; shouldn't be an issue for novels and most texts that are reasonable
;; to read in an emacs buffer.

            (message "Realigning text, this may take some time")
            (mark-whole-buffer)
            (fill-paragraph nil 1)
            (save-buffer)
          )
      )

;; Now open the output file (even though it may already be open), make
;; a single window, and go to the top of the file.

      (find-file epub-newname)
      (delete-other-windows)
      (goto-char (point-min))

;; Put in view mode for easier reading.

      (view-mode)
)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; end read-epub.el