Add a mediawiki API fetcher.

Applicable to wikihow. Also clean up the code to reduce duplication
with fetching and finding files. And fix when the wiki entry is under
a directory naming itself which is common in mediawiki: both foo and
foo/bar could be a valid wiki title. So locally files need to have an
extension (by default .wiki). Also add the extension to
auto-mode-alist.

1 files changed, 72 insertions, 42 deletions

diff --git a/wiki-utils.el b/wiki-utils.el
index 0e204b1..61357d2 100644
--- a/wiki-utils.el
+++ b/wiki-utils.el
@@ -25,6 +25,7 @@
 
 ;;; Code:
 (require 'url-parse)
+(require 'json)
 
 (defvar wiki-local-dir (locate-user-emacs-file "wiki")
   "Path to local directory of wiki files.")
@@ -32,40 +33,17 @@
 (defvar wiki-fetch-prefer-local t
   "If non-nil, visit the local file if exists when fetching.")
 
-(defun wiki-fetch-url (url dir &optional callback title)
-  "Fetch URL asynchronously to a file in DIR.
-
-Then call CALLBACK which is a closure taking no argument.
-
-A non-nil TITLE overrides title inferred from the url."
-  (interactive "sURL: ")
-  (let ((file-name (expand-file-name
-                    (or title (wiki-make-file-name-from-url url))
-                    dir))
-        (cb (lambda (status file-name)
-              (wiki-fetch-url-save-and-switch status file-name)
-              (when callback (funcall callback)))))
-    (url-retrieve url cb (list file-name)))
-  )
-
-(defun wiki-fetch-url-save-and-switch (status file-name)
-  "Fetch url to FILE-NAME if STATUS is ok.
-
-And switch to the corresponding buffer."
-  (when (plist-get status :error)
-    (error "Wiki fetch failed: %s" (plist-get status :error)))
-  (wiki-delete-http-header)
-  (let ((to-insert (buffer-string))
-        (buffer (find-file-noselect file-name))
-        (coding-system-for-write 'utf-8))
-    (kill-buffer)
-    (with-current-buffer buffer
-      (insert to-insert)
-      (goto-char (point-min))
-      (save-buffer)
-      (revert-buffer t t))
-    (switch-to-buffer buffer))
-  )
+(defvar wiki-extension ".wiki"
+  "The extension of local wiki files.")
+
+(add-to-list 'auto-mode-alist
+             `(,(format "\\%s\\'" wiki-extension) . wiki-mode))
+
+(defun wiki-kill-http-header ()
+  "Kill the http header in current buffer.
+
+Assuming the current buffer to be a `url-retrieve' response buffer."
+  (kill-region (point-min) (progn (wiki-skip-http-header) (point))))
 
 (defun wiki-delete-http-header ()
   "Delete the http header in current buffer.
@@ -80,14 +58,7 @@ Assuming the current buffer to be a `url-retrieve' response buffer."
   (goto-char (point-min))
   (re-search-forward "\r?\n\r?\n"))
 
-(defun wiki-make-file-name-from-url (url)
-  "Make a file name from URL."
-  (file-name-nondirectory
-   (directory-file-name
-    (car (url-path-and-query (url-generic-parse-url
-                              (url-unhex-string url)))))))
-
-;; TODO: add wikihow; generalise fandom
+;; TODO: generalise fandom
 ;; TODO: default engine to mediawiki
 (defvar wiki-sites
   '((local)
@@ -134,6 +105,10 @@ Assuming the current buffer to be a `url-retrieve' response buffer."
      :base-url "https://help.ubuntu.com/community/"
      :engine moinmoin
      :display-name "Ubuntu Community Help Wiki")
+    (wikihow :base-url "https://www.wikihow.com/"
+             :engine mediawiki
+             :display-name "wikiHow"
+             :fetcher wiki-engine-mediawiki-api-fetch)
     (wikiindex :base-url "https://wikiindex.org/"
                :engine mediawiki
                :display-name "WikiIndex")
@@ -162,5 +137,60 @@ One of the sites is (local), meaning a local filesystem.")
       (intern (format "wiki-%s-fetch" site-id))
     'wiki-find-file))
 
+(defvar wiki-client-buffer-name "*wiki api*"
+  "Name of the buffer recording wiki API calls.")
+
+(defun wiki-parse-http-header (text)
+  "Parse the http header TEXT."
+  (let ((status) (fields))
+    (with-temp-buffer
+      (insert text)
+      (goto-char (point-min))
+      (re-search-forward "^HTTP.*\\([0-9]\\{3\\}\\).*$")
+      (setq status (match-string 1))
+      (while (re-search-forward "^\\(.*?\\): \\(.*\\)$" nil t)
+        (push (cons (intern (match-string 1)) (match-string 2)) fields)))
+    (list (cons 'status status) (cons 'fields fields))))
+
+(defun wiki-url-fetch-internal (url processor &optional
+                                    decompression with-header)
+  "Fetch from URL and process the response payload using PROCESSOR.
+
+PROCESSOR is a function that takes no argument and processes the
+current buffer.
+With non-nil DECOMPRESSION, decompress the response.
+With non-nil WITH-HEADER, include the header in the result."
+  (with-current-buffer (get-buffer-create wiki-client-buffer-name)
+    (goto-char (point-max))
+    (insert "[" (current-time-string) "] Request: " url "\n"))
+  (with-current-buffer (url-retrieve-synchronously url t)
+    (let ((header) (status) (fields))
+      (wiki-kill-http-header)
+      (goto-char (point-min))
+      (setq header (wiki-parse-http-header (car kill-ring))
+            status (alist-get 'status header)
+            fields (alist-get 'fields header))
+      (with-current-buffer wiki-client-buffer-name
+        (insert "[" (current-time-string) "] Response: " status "\n"))
+      (when decompression
+        (call-process-region (point) (point-max) "gunzip" t t t)
+        (goto-char (point-min)))
+      (call-interactively 'delete-trailing-whitespace)
+      (if (string= status "200")
+          (unless (= (point) (point-max))
+            (if with-header
+                (list
+                 (cons 'header fields)
+                 (cons 'json (funcall processor)))
+              (funcall processor)))
+        (error "HTTP error: %s" (buffer-substring (point) (point-max)))))))
+
+(defun wiki-url-fetch-json (url &optional decompression with-header)
+  "Fetch and parse a json object from URL.
+
+With non-nil DECOMPRESSION, decompress the response.
+With non-nil WITH-HEADER, include the header in the result."
+  (wiki-url-fetch-internal url 'json-read decompression with-header))
+
 (provide 'wiki-utils)
 ;;; wiki-utils.el ends here