;; -*- lexical-binding: t -*-

(require 'ennu-html)
(require 'ennu-image)
(require 'ox)
(require 'seq)
(require 'cl)
(require 'memoize)

(defvar ennu-version "0.1.0"
  "Ennu version string")

(defmacro ennu-with-file-contents (file &rest body)
  "Create a temporary buffer, insert contents of FILE into that
buffer and evaluate BODY. The value returned is the value of the
last form in BODY."
  (declare (indent defun))
  `(with-temp-buffer
     (insert-file-contents ,file)
     ,@body))

(defun ennu--org-output-filename (filename)
  (concat (file-name-sans-extension filename) ".html"))

(defun ennu-publish-post (post)
  ;; TODO: Tangle post
  `((,post)
    (,(ennu--org-output-filename post))
    ,(lambda (output-file)
       (ennu-with-file-contents post
         (org-export-to-file 'ennu-html output-file))
       ;; (when-let (tangle-dir (or (plist-get posts-plist :valai-tangle-directory)
       ;;                           valai-tangle-directory))
       ;;   (dolist (tangled-file
       ;;            (org-babel-tangle-file post-path))
       ;;     (when (member (file-name-extension tangled-file) '("sh" "py"))
       ;;       (chmod tangled-file (string-to-number "755" 8)))
       ;;     (make-directory tangle-dir t)
       ;;     (rename-file tangled-file
       ;;                  (expand-file-name (file-name-nondirectory tangled-file)
       ;;                                    tangle-dir)
       ;;                  t)))
       )))

(defun ennu-publish-page (pages-directory page)
  `((,page)
    (,(ennu--org-output-filename
       (string-remove-prefix
        (file-name-as-directory pages-directory)
        page)))
    ,(lambda (output-file)
       (ennu-with-file-contents page
         (org-export-to-file 'html output-file)))))

(defun ennu-video-poster (video)
  (pcase (directory-files (ennu-setting :images-directory) nil
                          (concat (file-name-sans-extension video)
                                  "\\.\\(jpg\\|png\\)$"))
    (`(,poster . ,_) poster)
    (`() (user-error "Poster for %s not found" video))))

(defun ennu-post-thumbnail (post)
  (or (plist-get (ennu-post-metadata post) :thumbnail)
      (seq-some (lambda (link)
                  (pcase link
                    (`("image" . ,path) path)
                    (`("video" . ,path) (ennu-video-poster path))))
                (ennu-post-links post))))

(defun ennu-add-tongue-suffix (filename tongue)
  (pcase tongue
    ("en" filename)
    (_ (format "%s.%s.%s"
               (file-name-sans-extension filename)
               tongue
               (file-name-extension filename)))))

(defun ennu-publish-index (filename-prefix tongue title subtitle posts-per-page posts)
(defun ennu-index-filename (filename-prefix tongue &optional extension page-number)
  (let ((extension (if extension (concat "." extension) "")))
    (ennu-add-tongue-suffix
     (if page-number
         (format "%s-%s%s" filename-prefix page-number extension)
       (concat filename-prefix extension))
     tongue)))

  (let* ((number-of-pages (ceiling (length posts) posts-per-page))
         (page-numbers (number-sequence 1 number-of-pages)))
    `(,posts
      ,(cons (ennu-add-tongue-suffix (format "%s.html" filename-prefix) tongue)
             (seq-map (apply-partially 'ennu-index-filename filename-prefix tongue "html")
                      page-numbers))
      ,(lambda (home-page &rest output-files)
         (seq-mapn
          (lambda (posts page-number output-file)
            (with-temp-buffer
              (insert (format "#+TITLE: %s\n" title subtitle))
              (insert (format "#+LANGUAGE: %s\n" tongue))
              (insert "#+OPTIONS: num:nil toc:nil\n\n")
              (when subtitle
                (insert (format "%s\n\n" subtitle)))
              (seq-do (lambda (post)
                        (let ((metadata (ennu-post-metadata post)))
                          (insert (format "* [[post:%s]]\n" (file-name-base post)))
                          (insert (format-time-string
                                   "/%b %e, %Y/\n\n"
                                   (plist-get metadata :date)))
                          (when-let ((thumbnail (ennu-post-thumbnail post)))
                            (insert (format "[[thumbnail:%s]]\n\n" thumbnail)))
                          (when-let ((summary (plist-get metadata :summary)))
                            (insert summary)
                            (insert "\n\n"))
                          (when-let ((tags (plist-get metadata :filetags)))
                            (insert "Tags: ")
                            (insert
                             (string-join (seq-map (apply-partially 'format "[[tag:%s]]")
                                                   tags)
                                          ", "))
                            (insert "\n\n"))))
                      posts)
              (unless (= page-number 1)
                (insert (format "[[./%s][Newer posts]]\n"
                                (ennu-index-filename (file-name-nondirectory filename-prefix)
                                                     tongue nil (1- page-number)))))
              (unless (= page-number number-of-pages)
                (insert (format "[[./%s][Older posts]]\n"
                                (ennu-index-filename (file-name-nondirectory filename-prefix)
                                                     tongue nil (1+ page-number)))))
              (org-export-to-file 'ennu-html output-file)))
          (seq-partition posts posts-per-page)
          page-numbers
          output-files)
         (copy-file (first output-files) home-page)))))

(defun ennu--absolute-uri (path)
  (format "%s://%s/%s"
          (ennu-setting :blog-scheme)
          (ennu-setting :blog-domain)
          path))

(defun ennu--atom-date (date)
  (format-time-string "%Y-%m-%dT%H:%M:%SZ" date))

(defun ennu-publish-feed (feed-file title subtitle rights posts)
  `(,posts
    (,feed-file)
    ,(lambda (output-file)
       (with-temp-file output-file
         (insert
          (xmlgen
           `(feed :xmlns "http://www.w3.org/2005/Atom"
                  (id ,(ennu--absolute-uri ""))
                  (title ,title)
                  (updated ,(ennu--atom-date (plist-get (ennu-post-metadata (first posts)) :date)))
                  (link :rel "self" :href ,(ennu--absolute-uri feed-file))
                  (generator
                   ,(format "Emacs %d.%d Org-mode %s ennu %s"
                            emacs-major-version emacs-minor-version (org-version) ennu-version))
                  (rights ,rights)
                  ,@(when subtitle
                      `((subtitle ,subtitle)))
                  ,@(seq-map 'ennu--feed-entry posts))))))))

(defun ennu--feed-entry (post)
  (let* ((metadata (ennu-post-metadata post))
         (lang (plist-get metadata :lang))
         (link (ennu--absolute-uri (ennu--org-output-filename post))))
    `(entry (id ,link)
            (title :xml:lang ,lang ,(plist-get metadata :title))
            (updated ,(ennu--atom-date (plist-get metadata :date)))
            (author
             (name ,(plist-get metadata :author))
             (email ,user-mail-address))
            (content :type "html" :xml:lang ,lang
                     ,(ennu-with-file-contents post
                        (org-export-as 'ennu-html nil nil t)))
            (link :rel "alternate" :href ,link)
            ,@(seq-map (lambda (tag) `(category :term ,tag))
                       (plist-get metadata :filetags)))))

(defun ennu-setting (property)
  (pcase property
    (:blog-scheme
     (or (plist-get ennu-blog :blog-scheme)
         "https"))
    (:atom-feed-file
     (or (plist-get ennu-blog :atom-feed-file)
         "blog.atom"))
    (:index-posts-per-page
     (or (plist-get ennu-blog :index-posts-per-page)
         12))
    (:atom-feed-number-of-posts
     (or (plist-get ennu-blog :atom-feed-number-of-posts)
         12))
    (:thumbnail-image-width
     (or (plist-get ennu-blog :thumbnail-image-width)
         320))
    (:default-image-width
     (or (plist-get ennu-blog :default-image-width)
         640))
    (:image-link-width
     (or (plist-get ennu-blog :image-link-width)
         1024))
    ((or :blog-domain :blog-license :blog-title
         :images-directory :output-directory :posts-directory
         :static-directory :tag-directory :video-directory)
     (or (plist-get ennu-blog property)
         (user-error "Property %s not defined" property)))
    ((or :blog-subtitle :pages-directory :unattached-static-files)
     (plist-get ennu-blog property))
    (_ (error "Unknown property %s" property))))

(defun ennu-image-output-filename (image width)
  (format "%s-%spx.%s"
          (file-name-sans-extension image)
          width (file-name-extension image)))

(defun ennu--expand-relative (name directory)
  (concat (file-name-as-directory directory) name))

(defun ennu-publish-image (widths image)
  `((,image)
    ,(seq-map (apply-partially 'ennu-image-output-filename image)
              widths)
    ,(lambda (&rest output-files)
       (seq-mapn (lambda (output-file width)
                   (ennu-image-optimize-image
                    (ennu-image-resize-image image output-file width)))
                 output-files widths))))

(defun ennu-publish-copy (file)
  `((,file) (,file) ,(apply-partially 'copy-file file)))

(defun ennu-post-links (post)
  (ennu-with-file-contents post
    (org-element-map (org-element-parse-buffer) 'link
      (lambda (link)
        (pcase link
          (`(link ,properties . ,_)
           (let ((link-type (org-element-property :type link)))
             (when (member link-type (list "image" "static" "video"))
               (cons link-type (org-element-property :path link))))))))))

(defun plist-put* (plist &rest key-value-pairs)
  (pcase key-value-pairs
    (`(,key ,value)
     (plist-put plist key value))
    (`(,key ,value . ,tail)
     (apply 'plist-put* (plist-put plist key value) tail))))

(defun ennu-post-metadata (post)
  (ennu--post-metadata-memoized
   post (file-attribute-modification-time
         (file-attributes post))))

(defmemoize ennu--post-metadata-memoized (post last-modified)
  (ennu-with-file-contents post
    (let ((metadata (org-export-get-environment 'ennu-html))
          (export (apply-partially 'org-export-with-backend 'ennu-html)))
      (seq-do (lambda (key)
                (unless (plist-member metadata key)
                  (user-error "Metadata %s not specified" key)))
              ennu-mandatory-metadata)
      (plist-put*
       metadata
       :title (funcall export (first (plist-get metadata :title)))
       :date (org-timestamp-to-time (first (plist-get metadata :date)))
       :author (funcall export (first (plist-get metadata :author)))))))

(defvar ennu-mandatory-metadata
  (list :title :date))

(defun newest-file (files)
  (pcase files
    (`(,head . ,tail)
     (seq-reduce (lambda (file1 file2)
                   (if (file-newer-than-file-p file1 file2)
                       file1 file2))
                 tail head))))

(defun ennu-mkdir-p (directory)
  (make-directory directory t))

(defun ennu-copy (source destination)
  "Copy file or directory from SOURCE to DESTINATION."
  (if (file-directory-p source)
      (copy-directory source destination)
    (make-directory (file-name-directory destination) t)
    (copy-file source destination)))

(defun ennu--do-operation (temporary-directory operation)
  (let ((expand (lambda (directory file)
                  (expand-file-name file directory))))
    (pcase operation
      (`(,input-files ,output-files ,publish)
       (let ((absolute-output-files
              (seq-map (apply-partially expand temporary-directory)
                       output-files))
             (previous-output-files
              (seq-map (apply-partially expand (ennu-setting :output-directory))
                       output-files)))
         (cond
          ((and (seq-every-p 'file-exists-p previous-output-files)
                (file-newer-than-file-p (newest-file previous-output-files)
                                        (newest-file input-files)))
           (message "Skipping publishing %s to %s" input-files output-files)
           (seq-mapn 'ennu-copy previous-output-files absolute-output-files))
          (t (message "Publishing %s to %s" input-files output-files)
             (seq-do 'ennu-mkdir-p
                     (seq-uniq
                      (seq-map 'file-name-directory absolute-output-files)))
             (apply publish absolute-output-files))))))))

(defun ennu--later-post (post1 post2)
  (time-less-p (plist-get (ennu-post-metadata post2) :date)
               (plist-get (ennu-post-metadata post1) :date)))

(defun ennu-publish-static-file (file)
  `((,file) (,file) ,(apply-partially 'copy-file file)))

(defun ennu-posts (posts-directory)
  (sort (file-expand-wildcards
         (concat (file-name-as-directory
                  (ennu-setting :posts-directory))
                 "*.org"))
        'ennu--later-post))

(defun ennu-publish-link (link)
  (pcase link
    (`("image" . ,path)
     (ennu-publish-image
      (list (ennu-setting :default-image-width)
            (ennu-setting :image-link-width))
      (ennu--expand-relative path (ennu-setting :images-directory))))
    (`("static" . ,path)
     (ennu-publish-copy (ennu--expand-relative path (ennu-setting :static-directory))))
    (`("video" . ,path)
     (ennu-publish-copy (ennu--expand-relative path (ennu-setting :video-directory)))
     (ennu-publish-copy (ennu--expand-relative (ennu-video-poster path)
                                               (ennu-setting :images-directory))))))

(defun ennu-post-tags (post)
  (plist-get (ennu-post-metadata post) :filetags))

(defun ennu-post-tongue (post)
  (plist-get (ennu-post-metadata post) :language))

(defun ennu-publish ()
  (interactive)
  (let ((make-backup-files nil)
        (blog-title (ennu-setting :blog-title))
        (blog-subtitle (ennu-setting :blog-subtitle))
        (posts-per-page (ennu-setting :index-posts-per-page)))
    (let ((temporary-directory (make-temp-file "ennu" t)))
      (unwind-protect
          (progn
            (seq-do
             (apply-partially 'ennu--do-operation temporary-directory)
             (append
              (let* ((posts (ennu-posts (ennu-setting :posts-directory)))
                     (tags (seq-uniq (seq-mapcat 'ennu-post-tags posts)))
                     (tongues (seq-uniq (seq-map 'ennu-post-tongue posts))))
                (append
                 ;; Publish posts
                 (seq-map 'ennu-publish-post posts)
                 ;; Publish feed
                 (list (ennu-publish-feed (ennu-setting :atom-feed-file)
                                          blog-title blog-subtitle
                                          (ennu-setting :blog-license)
                                          (seq-take posts (ennu-setting :atom-feed-number-of-posts))))
                 ;; Publish indices
                 (seq-map
                  (lambda (tongue)
                    (ennu-publish-index
                     "index" tongue blog-title blog-subtitle posts-per-page
                     (seq-filter (lambda (post)
                                   (string= tongue (ennu-post-tongue post)))
                                 posts)))
                  tongues)
                 (seq-map
                  (lambda (tag)
                    (let ((posts (seq-filter (lambda (post)
                                               (member tag (ennu-post-tags post)))
                                             posts)))
                      (ennu-publish-index
                       (ennu--expand-relative tag (ennu-setting :tag-directory))
                       (ennu-post-tongue (first posts)) tag "" posts-per-page posts)))
                  tags)
                 ;; Publish links
                 (seq-map 'ennu-publish-link
                          (seq-uniq (seq-mapcat 'ennu-post-links posts)))
                 ;; Publish thumbnails
                 (seq-map
                  (apply-partially 'ennu-publish-image (list (ennu-setting :thumbnail-image-width)))
                  (seq-map (lambda (image)
                             (ennu--expand-relative image (ennu-setting :images-directory)))
                           (seq-uniq (seq-filter 'identity (seq-map 'ennu-post-thumbnail posts)))))))
              ;; Publish pages
              (when-let ((pages-directory (ennu-setting :pages-directory)))
                (seq-map (apply-partially 'ennu-publish-page pages-directory)
                         (seq-map (apply-partially 'string-remove-prefix
                                                   (file-name-as-directory (expand-file-name default-directory)))
                                  (directory-files-recursively pages-directory "\\.org$"))))
              ;; Publish unattached static files
              (seq-map 'ennu-publish-static-file
                       (ennu-setting :unattached-static-files))))
            ;; Replace old output directory
            (let ((output (ennu-setting :output-directory)))
              (delete-directory output t)
              (rename-file temporary-directory output t)))
        (delete-directory temporary-directory t)))))

(provide 'ennu)