;; -*- lexical-binding: t; -*-
;;; yekneb-pandoc.el --- Functions for working with pandoc.

;; Copyright © 2021 - 2025 Ben Key

;; This file is part of the yekneb package.
;;
;; The yekneb package is free software: you can redistribute it and/or modify it
;; under the terms of the GNU General Public License as published by the Free
;; Software Foundation, either version 3 of the License, or (at your option) any
;; later version.
;;
;; The yekneb package is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
;; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
;; details.
;;
;; You should have received a copy of the GNU General Public License along with
;; the yekneb package. If not, see <http://www.gnu.org/licenses/>.

(require 'yekneb-debug)
(require 'yekneb-file-utilities)
(require 'yekneb-process)

;;;###autoload
(defvar yekneb-pandoc--load-file--directory
  (file-name-directory (expand-file-name load-file-name))
  "The path of the directory containing this package.")

(defun yekneb-find-pandoc ()
  "This function attempts to obtain the path of pandoc.exe."
  (cond
   ((yekneb-executable-find "pandoc")
    (yekneb-executable-find "pandoc")
    )
   ((and
     (getenv "LOCALAPPDATA")
     (file-exists-p (substitute-in-file-name "${LOCALAPPDATA}/Pandoc/pandoc.exe")))
    (substitute-in-file-name "${LOCALAPPDATA}/Pandoc/pandoc.exe")
    )
   ((file-exists-p (substitute-in-file-name "/mnt/c/Users/${USER}/AppData/Local/Pandoc/pandoc.exe"))
    (substitute-in-file-name "/mnt/c/Users/${USER}/AppData/Local/Pandoc/pandoc.exe")
    )
   ((and
     (getenv "ProgramFiles(x86)")
     (file-exists-p
      (substitute-in-file-name "${ProgramFiles(x86)}/Pandoc/pandoc.exe")))
    (substitute-in-file-name "${ProgramFiles(x86)}/Pandoc/pandoc.exe")
    )
   ((and
     (getenv "ProgramFiles")
     (file-exists-p
      (substitute-in-file-name "${ProgramFiles}/Pandoc/pandoc.exe")))
    (substitute-in-file-name "${ProgramFiles}/Pandoc/pandoc.exe")
    )
   )
  )

(defun yekneb-get-pandoc-template-path (template-file-name)
  "Obtain the path to the TEMPLATE-FILE-NAME file. It will first search for a
project local file. If the project local file could not be found, it will return
the path to the html5.template file in the `user-emacs-directory'."
  (let ((current-directory (yekneb-get-default-directory)) (ret nil))
    (setq ret
      (cond
       ((and
         current-directory
         (file-exists-p (expand-file-name template-file-name current-directory)))
        (expand-file-name template-file-name current-directory)
        )
       ((and
         current-directory
         (locate-dominating-file current-directory template-file-name))
        (expand-file-name
         template-file-name (locate-dominating-file current-directory template-file-name))
        )
       ((locate-user-emacs-file template-file-name)
        (expand-file-name (locate-user-emacs-file template-file-name))
        )
       ((and
         yekneb-pandoc--load-file--directory
         (file-exists-p
          (expand-file-name
           template-file-name
           yekneb-pandoc--load-file--directory)))
        (expand-file-name
         template-file-name yekneb-pandoc--load-file--directory)
        )
       )
      )
    ret
    )
  )

(defun yekneb-get-pandoc-template-path-l (template-file-names)
  "Obtain the path to the TEMPLATE-FILE-NAME file. It will first search for a
project local file. If the project local file could not be found, it will return
the path to the html5.template file in the `user-emacs-directory'."
  (let
    (
     (function-name "yekneb-get-pandoc-template-path-l")
     (current-directory (yekneb-get-default-directory)) (ret nil)
     )
    (dolist (template-file-name template-file-names)
      (when (null ret)
        (yekneb-log
         yekneb-log-debug "%s status: Looking for %s in the current-directory." function-name template-file-name)
        (when
          (and
           current-directory
           (file-exists-p (expand-file-name template-file-name current-directory))
           )
          (setq ret (expand-file-name template-file-name current-directory))
          )
        )
      )
    (when (null ret)
      (dolist (template-file-name template-file-names)
        (yekneb-log
         yekneb-log-debug
         "%s status: Looking for %s using locate-dominating-file." function-name template-file-name)
        (when
          (and
           (null ret)
           current-directory
           (locate-dominating-file current-directory template-file-name)
           )
          (setq
           ret
           (expand-file-name
            template-file-name (locate-dominating-file current-directory template-file-name)))
          )
        )
      )
    (when (null ret)
      (dolist (template-file-name template-file-names)
        (yekneb-log
         yekneb-log-debug
         "%s status: Looking for %s using locate-user-emacs-file." function-name template-file-name)
        (when (and (null ret) (locate-user-emacs-file template-file-name))
          (setq ret (expand-file-name (locate-user-emacs-file template-file-name)))
          )
        )
      )
    (when (null ret) 
      (dolist (template-file-name template-file-names)
        (yekneb-log
         yekneb-log-debug
         "%s status: Looking for %s in the load file directry." function-name template-file-name)
        (when
          (and
           (null ret)
           yekneb-pandoc--load-file--directory
           (file-exists-p (expand-file-name  template-file-name yekneb-pandoc--load-file--directory))
           )
          (setq ret (expand-file-name template-file-name yekneb-pandoc--load-file--directory))
          )
        )
      )
    ret
    )
  )

(defun yekneb-get-custom-reference-doc-path ()
  "Obtain the path to the custom-reference.docx file. It will first search for a
project local file. If the project local file could not be found, it will return
the path to the custom-reference.docx file in the `user-emacs-directory'."
  (yekneb-get-pandoc-template-path "custom-reference.docx")
  )

(defun yekneb-get-html5-template-path ()
  "Obtain the path to the html5.template file. It will first search for a
project local file. If the project local file could not be found, it will return
the path to the html5.template file in the `user-emacs-directory'."
  (yekneb-get-pandoc-template-path-l '("html5.template" "default.html5"))
  )

(defun yekneb-get-context-template-path ()
  "Obtain the path to the html5.template file. It will first search for a
project local file. If the project local file could not be found, it will return
the path to the html5.template file in the `user-emacs-directory'."
  (yekneb-get-pandoc-template-path-l '("context.template" "default.context"))
  )

;;;###autoload
(defun yekneb-pandoc-html-to-markdown ()
  "Use Pandoc to convert HTML to Markdown."
  (interactive)
  (yekneb-exec-and-output-to-buffer
   (yekneb-find-pandoc)
   "*pandoc output*"
   "--variable"
   "lang=en"
   "-f"
   "html+raw_html"
   "-t"
   "markdown"
   "--atx-headers"
   "--reference-links"
   "-o"
   (concat (file-name-sans-extension buffer-file-name) ".md")
   buffer-file-name
   )
  )

;;;###autoload
(defun yekneb-pandoc-markdown-to-docx ()
  "Use Pandoc to convert Markdown to DOCX."
  (interactive)
  (let ((template (yekneb-get-custom-reference-doc-path)))
    (if (and template (file-exists-p template))
        (yekneb-exec-and-output-to-buffer
         (yekneb-find-pandoc)
         "*pandoc output*"
         "--variable"
         "lang=en"
         "-f"
         "markdown"
         "-t"
         "docx"
         (format "--reference-doc=%s" template)
         "-o"
         (concat (file-name-sans-extension buffer-file-name) ".docx")
         buffer-file-name
         )
      (yekneb-exec-and-output-to-buffer
       (yekneb-find-pandoc)
       "*pandoc output*"
       "--variable"
       "lang=en"
       "-f"
       "markdown"
       "-t"
       "docx"
       "-o"
       (concat (file-name-sans-extension buffer-file-name) ".docx")
       buffer-file-name
       )
      )
    )
  )

;;;###autoload
(defun yekneb-pandoc-markdown-to-html ()
  "Use Pandoc to convert Markdown to HTML."
  (interactive)
  (let ((template (yekneb-get-html5-template-path)))
    (if (and template (file-exists-p template))
        (yekneb-exec-and-output-to-buffer
         (yekneb-find-pandoc)
         "*pandoc output*"
         "--variable"
         "lang=en"
         "-f"
         "markdown"
         "-t"
         "html5"
         (format "--template=%s" template)
         "--mathjax"
         "-s"
         "-o"
         (concat (file-name-sans-extension buffer-file-name) ".html")
         buffer-file-name
         )
      (yekneb-exec-and-output-to-buffer
       (yekneb-find-pandoc)
       "*pandoc output*"
       "--variable"
       "lang=en"
       "-f"
       "markdown"
       "-t"
       "html5"
       "--mathjax"
       "-s"
       "-o"
       (concat (file-name-sans-extension buffer-file-name) ".html")
       buffer-file-name
       )
      )
    )
  )

;;;###autoload
(defun yekneb-pandoc-markdown-to-pdf ()
  "Use Pandoc to convert Markdown to PDF."
  (interactive)
  (let ((template (yekneb-get-context-template-path)))
    (if (and template (file-exists-p template))
        (yekneb-exec-and-output-to-buffer
         (yekneb-find-pandoc)
         "*pandoc output*"
         "--metadata"
         "pdfa:2a"
         "--variable"
         "context-lang=en"
         "--variable"
         "fontsize=16pt"
         "--variable"
         "lang=en"
         "--variable"
         "linkstyle=bold"
         "--variable"
         "papersize=letter"
         (format "--template=%s" template)
         "-f"
         "markdown"
         "--pdf-engine"
         "context"
         "-o"
         (concat (file-name-sans-extension buffer-file-name) ".pdf")
         buffer-file-name
         )
      (yekneb-exec-and-output-to-buffer
       (yekneb-find-pandoc)
       "*pandoc output*"
       "--metadata"
       "pdfa:2a"
       "--variable"
       "context-lang=en"
       "--variable"
       "fontsize=16pt"
       "--variable"
       "lang=en"
       "--variable"
       "linkstyle=bold"
       "--variable"
       "papersize=letter"
       "-f"
       "markdown"
       "--pdf-engine"
       "context"
       "-o"
       (concat (file-name-sans-extension buffer-file-name) ".pdf")
       buffer-file-name
       )
      )
    )
  )

(provide 'yekneb-pandoc)