;;; sx-auth.el --- user authentication  -*- lexical-binding: t; -*-

;; Copyright (C) 2014  Sean Allred

;; Author: Sean Allred <code@seanallred.com>

;; This program 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.

;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;

;;; Code:

(require 'sx)
(require 'sx-request)
(require 'sx-cache)

(defconst sx-auth-root
  "https://stackexchange.com/oauth/dialog")
(defconst sx-auth-redirect-uri
  "http://vermiculus.github.io/stack-mode/auth/auth.htm")
(defconst sx-auth-client-id
  "3291")
(defvar sx-auth-access-token
  nil
  "Your access token.

This is needed to use your account to write questions, make
comments, and read your inbox.  Do not alter this unless you know
what you are doing!")

(defvar sx-auth-method-auth '((me . t)
                              (inbox . t)
                              (notifications . t)
                              (events . t)
                              (posts (comments add))
                              (comments delete
                                        edit
                                        flags
                                        upvote)
                              (answers accept
                                       delete
                                       downvote
                                       edit
                                       flags
                                       upvote)
                              (questions answers
                                         add
                                         close
                                         delete
                                         downvote
                                         edit
                                         favorite
                                         flags
                                         render
                                         upvote
                                         (unanswered my-tags)))
  "List of methods that require auth.
Methods are of form (METHOD SUBMETHODS) where SUBMETHODS
  is (METHOD METHOD METHOD ...).

If all SUBMETHODS require auth or there are no submethods, form
will be (METHOD  . t)")

(defvar sx-auth-filter-auth '(question.upvoted
                              question.downvoted)
  "List of filter types that require auth.
Keywords are of form (OBJECT TYPES) where TYPES is (FILTER FILTER
FILTER).")

(defun sx-auth-authenticate ()
  "Authenticate this application.

Authentication is required to read your personal data (such as
notifications) and to write with the API (asking and answering
questions)."
  (interactive)
  (setq
   sx-auth-access-token
   (let ((url (concat
               sx-auth-root
               "?"
               (sx-request--build-keyword-arguments
                `((client_id . ,sx-auth-client-id)
                  (scope . (read_inbox
                            no_expiry
                            write_access))
                  (redirect_uri . ,(url-hexify-string
                                    sx-auth-redirect-uri)))
                ","))))
     (browse-url url)
     (read-string "Enter the access token displayed on the webpage: ")))
  (if (string-equal "" sx-auth-access-token)
      (progn (setq sx-auth-access-token nil)
             (error "You must enter this code to use this client fully"))
    (sx-cache-set 'auth `((access_token . ,sx-auth-access-token)))))

(defun sx-auth--method-p (method &optional submethod)
  "Check if METHOD is one that may require authentication.
If it has `auth-required' SUBMETHODs, or no submethod, return t."
  (let ((method-auth (cdr (assoc method sx-auth-method-auth)))
        ;; If the submethod has additional options, they may all be
        ;; eligible, in which case we only need to check the `car'.
        (sub-head (if (listp submethod)
                      (car submethod))))
    (lwarn " sx-auth method" :debug "Method %s requires auth" method-auth)
    (and method-auth
         (or
          ;; All submethods require auth.
          (eq t method-auth)
          ;; All sub-submethods require auth.
          (member sub-head method-auth)
          ;; Specific submethod requires auth.
          (member submethod method-auth)))))

;; Temporary solution.  When we switch to pre-defined filters we will
;; have to change the logic to match against specific filters.
(defun sx-auth--filter-p (filter)
  "Check if FILTER contains properties that require authentication.
If it has `auth-required' properties, return a filter that has
removed those properties."
  (let ((auth-filters (cl-remove-if #'nil
                                 ;; Only retrieve the elements that
                                 ;; are issues.
                                 (mapcar (lambda (prop)
                                           (car
                                            (member prop
                                                    sx-auth-filter-auth)))
                                         filter)))
        (clean-filter))
        ;; Auth-filters is the filters that are issues
    (when auth-filters
      (setq clean-filter
            (cl-remove-if (lambda (prop)
                            (member prop auth-filters))
                          filter)))
    clean-filter))

(provide 'sx-auth)
;;; sx-auth.el ends here

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