;;; mastodon-http.el --- HTTP request/response functions for mastodon.el  -*- lexical-binding: t -*-

;; Copyright (C) 2017-2019 Johnson Denen
;; Author: Johnson Denen <johnson.denen@gmail.com>
;; Maintainer: Marty Hiatt <martianhiatus@riseup.net>
;; Version: 1.0.0
;; Package-Requires: ((emacs "27.1") (request "0.3.0"))
;; Homepage: https://codeberg.org/martianh/mastodon.el

;; This file is not part of GNU Emacs.

;; This file is part of mastodon.el.

;; mastodon.el 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.

;; mastodon.el 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 mastodon.el.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; mastodon-http.el provides HTTP request/response functions.

;;; Code:

(require 'json)
(require 'request) ; for attachments upload
(require 'url)

(defvar mastodon-instance-url)
(defvar mastodon-toot--media-attachment-ids)
(defvar mastodon-toot--media-attachment-filenames)

(autoload 'mastodon-auth--access-token "mastodon-auth")
(autoload 'mastodon-toot--update-status-fields "mastodon-toot")


(defvar mastodon-http--api-version "v1")

(defconst mastodon-http--timeout 15
  "HTTP request timeout, in seconds.  Has no effect on Emacs < 26.1.")

(defun mastodon-http--api (endpoint)
  "Return Mastodon API URL for ENDPOINT."
  (concat mastodon-instance-url "/api/"
          mastodon-http--api-version "/" endpoint))

(defun mastodon-http--response ()
  "Capture response buffer content as string."
  (with-current-buffer (current-buffer)
    (buffer-substring-no-properties (point-min) (point-max))))

(defun mastodon-http--response-body (pattern)
  "Return substring matching PATTERN from `mastodon-http--response'."
  (let ((resp (mastodon-http--response)))
    (string-match pattern resp)
    (match-string 0 resp)))

(defun mastodon-http--status ()
  "Return HTTP Response Status Code from `mastodon-http--response'."
  (let* ((status-line (mastodon-http--response-body "^HTTP/1.*$")))
    (string-match "[0-9][0-9][0-9]" status-line)
    (match-string 0 status-line)))

(defun mastodon-http--url-retrieve-synchronously (url &optional silent)
  "Retrieve URL asynchronously.

This is a thin abstraction over the system
`url-retrieve-synchronously'.  Depending on which version of this
is available we will call it with or without a timeout.
SILENT means don't message."
  (if (< (cdr (func-arity 'url-retrieve-synchronously)) 4)
      (url-retrieve-synchronously url)
    (url-retrieve-synchronously url (or silent nil) nil mastodon-http--timeout)))

(defun mastodon-http--triage (response success)
  "Determine if RESPONSE was successful. Call SUCCESS if successful.

Message status and JSON error from RESPONSE if unsuccessful."
  (let ((status (with-current-buffer response
                  (mastodon-http--status))))
    (if (string-prefix-p "2" status)
        (funcall success)
      (switch-to-buffer response)
      (let ((json-response (mastodon-http--process-json)))
        (message "Error %s: %s" status (alist-get 'error json-response))))))

(defun mastodon-http--read-file-as-string (filename)
  "Read a file FILENAME as a string. Used to generate image preview."
  (with-temp-buffer
    (insert-file-contents filename)
    (string-to-unibyte (buffer-string))))

(defmacro mastodon-http--authorized-request (method body &optional unauthenticated-p)
  "Make a METHOD type request using BODY, with Mastodon authorization.
Unless UNAUTHENTICATED-P is non-nil."
  (declare (debug 'body))
  `(let ((url-request-method ,method)
         (url-request-extra-headers
          (unless ,unauthenticated-p
            (list (cons "Authorization"
                        (concat "Bearer " (mastodon-auth--access-token)))))))
     ,body))

(defun mastodon-http--build-query-string (args)
  "Build a request query string from ARGS."
  ;; (url-build-query-string args nil))
  ;; url-build-query-string adds 'nil' to empty params so lets stay with our
  ;; own:
  (mapconcat (lambda (arg)
               (concat (url-hexify-string (car arg))
                       "="
                       (url-hexify-string (cdr arg))))
             args
             "&"))

(defun mastodon-http--post (url args headers &optional unauthenticated-p)
  "POST synchronously to URL with ARGS and HEADERS.

Authorization header is included by default unless UNAUTHENTICATED-P is non-nil."
  (mastodon-http--authorized-request
   "POST"
   (let ((url-request-data
          (when args
            (mastodon-http--build-query-string args)))
         (url-request-extra-headers
          (append url-request-extra-headers ; auth set in macro
                  ;; pleroma compat:
                  (unless (assoc "Content-Type" headers)
                    '(("Content-Type" . "application/x-www-form-urlencoded")))
                  headers)))
     (with-temp-buffer
       (mastodon-http--url-retrieve-synchronously url)))
   unauthenticated-p))

(defun mastodon-http--get (url &optional silent)
  "Make synchronous GET request to URL.
Pass response buffer to CALLBACK function.
SILENT means don't message."
  (mastodon-http--authorized-request
   "GET"
   (mastodon-http--url-retrieve-synchronously url silent)))

(defun mastodon-http--get-response (url &optional silent)
  "Make synchronous GET request to URL. Return JSON and response headers.
SILENT means don't message.
HEADERS means also return http response headers."
  (with-current-buffer (mastodon-http--get url silent)
    (mastodon-http--process-response)))

(defun mastodon-http--get-json (url &optional silent)
  "Return only JSON data from URL request.
SILENT means don't message."
  (car (mastodon-http--get-response url silent)))

(defun mastodon-http--process-json ()
  "Return only JSON data from async URL request.
Callback for `mastodon-http--get-json-async'."
  (car (mastodon-http--process-response)))

(defun mastodon-http--process-response ()
  "Process http response.
Return a cons of JSON list and http response headers."
  ;; view raw response:
  ;; (switch-to-buffer (current-buffer))
  (let ((headers (mastodon-http--process-headers)))
    (goto-char (point-min))
    (re-search-forward "^$" nil 'move)
    (let ((json-array-type 'list)
          (json-string
           (decode-coding-string
            (buffer-substring-no-properties (point) (point-max))
            'utf-8)))
      (kill-buffer)
      (unless (or (string-empty-p json-string) (null json-string))
        `(,(json-read-from-string json-string) . ,headers)))))

(defun mastodon-http--process-headers ()
  "Return an alist of http response headers."
  (switch-to-buffer (current-buffer))
  (goto-char (point-min))
  (let* ((head-str (buffer-substring-no-properties
                    (point-min)
                    (re-search-forward "^$" nil 'move)))
         (head-list (split-string head-str "\n")))
    (mapcar (lambda (x)
              ;; FIXME: use dotted notation so alist-get doesn't return a list
              (split-string x ": "))
            head-list)))

(defun mastodon-http--delete (url)
  "Make DELETE request to URL."
  (mastodon-http--authorized-request
   "DELETE"
   (with-temp-buffer
     (mastodon-http--url-retrieve-synchronously url))))

(defun mastodon-http--append-query-string (url params)
  "Append PARAMS to URL as query strings and return it.

PARAMS should be an alist as required by `url-build-query-string'."
  (let ((query-string (url-build-query-string params)))
    (concat url "?" query-string)))

;; search functions:
(defun mastodon-http--process-json-search ()
  "Process JSON returned by a search query to the server."
  (goto-char (point-min))
  (re-search-forward "^$" nil 'move)
  (let ((json-string
         (decode-coding-string
          (buffer-substring-no-properties (point) (point-max))
          'utf-8)))
    (kill-buffer)
    (json-read-from-string json-string)))

(defun mastodon-http--get-search-json (url query &optional param silent)
  "Make GET request to URL, searching for QUERY and return JSON response.
PARAM is any extra parameters to send with the request.
SILENT means don't message."
  (let ((buffer (mastodon-http--get-search url query param silent)))
    (with-current-buffer buffer
      (mastodon-http--process-json-search))))

(defun mastodon-http--get-search (base-url query &optional param silent)
  "Make GET request to BASE-URL, searching for QUERY.
Pass response buffer to CALLBACK function.
PARAM is a formatted request parameter, eg 'following=true'.
SILENT means don't message."
  (mastodon-http--authorized-request
   "GET"
   (let ((url (if param
                  (concat base-url "?" param "&q=" (url-hexify-string query))
                (concat base-url "?q=" (url-hexify-string query)))))
     (mastodon-http--url-retrieve-synchronously url silent))))

;; profile update functions

(defun mastodon-http--patch-json (url &optional params)
  "Make synchronous PATCH request to URL. Return JSON response.
Optionally specify the PARAMS to send."
  (with-current-buffer (mastodon-http--patch url params)
    (mastodon-http--process-json)))

(defun mastodon-http--patch (base-url &optional params)
  "Make synchronous PATCH request to BASE-URL.
Optionally specify the PARAMS to send."
  (mastodon-http--authorized-request
   "PATCH"
   (let ((url
          (concat base-url "?"
                  (mastodon-http--build-query-string params))))
     (mastodon-http--url-retrieve-synchronously url))))

 ;; Asynchronous functions

(defun mastodon-http--get-async (url &optional callback &rest cbargs)
  "Make GET request to URL.
Pass response buffer to CALLBACK function with args CBARGS."
  (mastodon-http--authorized-request
   "GET"
   (url-retrieve url callback cbargs)))

(defun mastodon-http--get-response-async (url callback &rest args)
  "Make GET request to URL. Call CALLBACK with http response and ARGS."
  (mastodon-http--get-async
   url
   (lambda (status)
     (when status ;; only when we actually get sth?
       (apply callback (mastodon-http--process-response) args)))))

(defun mastodon-http--get-json-async (url callback &rest args)
  "Make GET request to URL. Call CALLBACK with json-list and ARGS."
  (mastodon-http--get-async
   url
   (lambda (status)
     (when status ;; only when we actually get sth?
       (apply callback (mastodon-http--process-json) args)))))

(defun mastodon-http--post-async (url args headers &optional callback &rest cbargs)
  "POST asynchronously to URL with ARGS and HEADERS.
Then run function CALLBACK with arguements CBARGS.
Authorization header is included by default unless UNAUTHENTICED-P is non-nil."
  (mastodon-http--authorized-request
   "POST"
   (let ((request-timeout 5)
         (url-request-data
          (when args
            (mastodon-http--build-query-string args))))
     (with-temp-buffer
       (url-retrieve url callback cbargs)))))

;; TODO: test for curl first?
(defun mastodon-http--post-media-attachment (url filename caption)
  "Make POST request to upload FILENAME with CAPTION to the server's media URL.
The upload is asynchronous. On succeeding,
`mastodon-toot--media-attachment-ids' is set to the id(s) of the
item uploaded, and `mastodon-toot--update-status-fields' is run."
  (let* ((file (file-name-nondirectory filename))
         (request-backend 'curl))
    (request
      url
      :type "POST"
      :params `(("description" . ,caption))
      :files `(("file" . (,file :file ,filename
                                :mime-type "multipart/form-data")))
      :parser 'json-read
      :headers `(("Authorization" . ,(concat "Bearer "
                                             (mastodon-auth--access-token))))
      :sync nil
      :success (cl-function
                (lambda (&key data &allow-other-keys)
                  (when data
                    (push (alist-get 'id data)
                          mastodon-toot--media-attachment-ids) ; add ID to list
                    (message "%s file %s with id %S and caption '%s' uploaded!"
                             (capitalize (alist-get 'type data))
                             file
                             (alist-get 'id data)
                             (alist-get 'description data))
                    (mastodon-toot--update-status-fields))))
      :error (cl-function
              (lambda (&key error-thrown &allow-other-keys)
                (cond
                 ;; handle curl errors first (eg 26, can't read file/path)
                 ;; because the '=' test below fails for them
                 ;; they have the form (error . error message 24)
                 ((not (proper-list-p error-thrown)) ; not dotted list
		          (message "Got error: %s. Shit went south." (cdr error-thrown)))
                 ;; handle mastodon api errors
                 ;; they have the form (error http 401)
		         ((= (car (last error-thrown)) 401)
                  (message "Got error: %s Unauthorized: The access token is invalid" error-thrown))
                 ((= (car (last error-thrown)) 422)
                  (message "Got error: %s Unprocessable entity: file or file type is unsupported or invalid" error-thrown))
                 (t
                  (message "Got error: %s Shit went south"
                           error-thrown))))))))

(provide 'mastodon-http)
;;; mastodon-http.el ends here