;;; gcal.el --- Google Calendar
;;;$Id$
;;; $Author: raman $
;;; Description:  Google Calendar
;;; Keywords: Google   Atom API
;;{{{  LCD Archive entry:

;;; LCD Archive Entry:
;;; gcal| T. V. Raman |raman@cs.cornell.edu
;;; An emacs interface to Reader|
;;; $Date: 2006/09/28 17:47:44 $ |
;;;  $Revision: 1.30 $ |
;;; Location undetermined
;;; License: GPL
;;;

;;}}}
;;{{{ Copyright:

;;; Copyright (c) 2006 and later, Google Inc.
;;; All rights reserved.

;;; Redistribution and use in source and binary forms, with or without modification,
;;; are permitted provided that the following conditions are met:

;;;     * Redistributions of source code must retain the above copyright notice,
;;;       this list of conditions and the following disclaimer.
;;;     * Redistributions in binary form must reproduce the above copyright notice,
;;;       this list of conditions and the following disclaimer in the documentation
;;;       and/or other materials provided with the distribution.
;;;     * The name of the author may not be used to endorse or promote products
;;;       derived from this software without specific prior written permission.

;;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
;;; AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
;;; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
;;; ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
;;; LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
;;; CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
;;; GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
;;; HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
;;; STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
;;; WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
;;; SUCH DAMAGE.

;;}}}
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Commentary:
;;{{{  introduction

;;; Google Calendar
;;; Create, Browse, Find ...  integrate Emacs Calendar with
;;; Google Calendar.
;;; http://code.google.com/apis/calendar/overview.html

;;}}}
;;{{{  Required modules

(require 'cl)
(declaim  (optimize  (safety 0) (speed 3)))
(eval-when-compile
  (require 'calendar))
(require 'g-utils)
(require 'g-auth)
(require 'g-app)
(require 'browse-url)

;;}}}
;;{{{ Customizations

(defgroup gcal nil
  "Google Calendar"
  :group 'g)

;;;###autoload
(defcustom gcal-default-user-email nil
  "Default user id for Calendar."
  :type '(choice
          (const :tag "none" nil)
          (string :tag "username@gmail.com" ""))
  :group 'gcal)

  

;;;###autoload
(defcustom gcal-user-email nil
  "Mail address that identifies calendar user."
  :type '(choice
          (const :tag "none" nil)
          (string :tag "username@gmail.com" ""))
  :group 'gcal)

(defcustom gcal-user-password nil
  "Password for authenticating to calendar account."
  :type '(radio (const :tag "Prompt for password" nil)
                (string :tag "Save password in .emacs"))
  :group 'gcal)

;;}}}
;;{{{ Constants

(defconst gcal-service-name "cl"
  "Service name for accessing Google Calendar.")

(defsubst gcal-p (service)
  "Check if this is Calendar."
  (declare (special gcal-service-name))
  (string-equal service gcal-service-name))

;;}}}
;;{{{ Calendar Authenticate

(defsubst make-gcal-auth ()
  "Make a new gcal auth handle."
  (declare (special gcal-service-name
                    gcal-user-email gcal-user-password))
  (make-g-auth :service gcal-service-name
               :email gcal-user-email
               :password gcal-user-password))

(defvar gcal-auth-handle (make-gcal-auth)
  "G auth handle used for signing into calendar.")

(defun gcal-authenticate ()
  "Authenticate into Google Calendar."
  (declare (special gcal-auth-handle))
  (g-authenticate gcal-auth-handle))

;;}}}
;;{{{ Event Template:

(defvar gcal-quickadd-template
  "<atom:entry xmlns:atom='http://www.w3.org/2005/Atom'>
  <atom:category scheme='http://schemas.google.com/g/2005#kind'
term='http://schemas.google.com/g/2005#event'></atom:category>
  <atom:content type='text'>%s</atom:content>
  <gCal:quickadd xmlns:gCal='http://schemas.google.com/gCal/2005'value='true'></gCal:quickadd>
</atom:entry>"
  "Template for quickadd events.")

;;; template for calendar event.
;;; Format string takes following:
;; (title content
;;        author-name author-email
;;        transparency status
;;        where
;;        when-start when-end)

(defvar gcal-event-template
  "<entry xmlns='http://www.w3.org/2005/Atom' \
xmlns:gd='http://schemas.google.com/g/2005' \
xmlns:gCal='http://schemas.google.com/gCal/2005'>
<category scheme='http://schemas.google.com/g/2005#kind' term='http://schemas.google.com/g/2005#event'>
</category>
<title type='text'>%s </title>
<content type='text'>%s </content>
<author>
<name>%s </name>
<email>%s </email>
</author>
<gd:transparency value='%s'></gd:transparency>
<gCal:sendEventNotifications value='true'/>
<gd:eventStatus value='%s'></gd:eventStatus>
<gd:where valueString='%s'></gd:where>
<gd:when startTime='%s' endTime='%s'>
<gd:reminder minutes='10'/>
</gd:when>
%s
</entry> "
  "XML template for  calendar events.")

(defvar gcal-attendee-template
  "<gd:who rel='%s'
    valueString='%s'
    email='%s'>
    <gd:attendeeStatus value='%s'/>
    <gd:attendeeType value='%s'/>
</gd:who>
"
  "XML template  for attendees.")

;;}}}
;;{{{ Event, attendee Structure

(defstruct gcal-event
  title content
  (author-name (user-login-name))
  author-email
  transparency status
  where
  when-start when-end
  who)

(defun gcal-attendee-list-as-xml (attendees)
  "Return XML representation of list of attendees."
  (declare (special gcal-attendee-template))
  (mapconcat
   #'(lambda (w)
       (format gcal-attendee-template
               (or (gcal-attendee-role w)  "")
               (or (gcal-attendee-cn w) "")
               (or (gcal-attendee-email w) "")
               (or (gcal-attendee-resource-type w) "")
               (or (gcal-attendee-status w) "")
               ))
   attendees
   "\n"))

(defun gcal-event-as-xml (e)
  "Return XML representation of event."
  (declare (special gcal-event-template))
  (format gcal-event-template
          (gcal-event-title e) (gcal-event-content e)
          (gcal-event-author-name e) (gcal-event-author-email e)
          (gcal-event-transparency e) (gcal-event-status e)
          (gcal-event-where e)
          (gcal-event-when-start e) (gcal-event-when-end e)
          (gcal-attendee-list-as-xml
           (gcal-event-who e))))

(defstruct gcal-attendee
  email
  cn                              ;firstname lastname
  status                          ; needs-action, confirmed
  role                            ; required participant, optional etc
  resource-type                   ; individual, room
  )

;;}}}
;;{{{  Reading events

(defvar gcal-event-transparency-alist
  '((opaque . "http://schemas.google.com/g/2005#event.opaque"))
  "Alist of event transparency types.")

(defsubst gcal-event-transparency-value (type)
  "Return identifier for specified event transparency type."
  (declare (special gcal-event-transparency-alist))
  (let ((pair (assoc type gcal-event-transparency-alist)))
    (when pair (cdr pair))))

(defvar gcal-event-status-alist
  '((confirmed
     . "http://schemas.google.com/g/2005#event.confirmed"))
  "Alist of event status types.")

(defsubst gcal-event-status-value (type)
  "Return identifier for specified event status type."
  (declare (special gcal-event-status-alist))
  (let ((pair (assoc type gcal-event-status-alist)))
    (when pair (cdr pair))))

(defsubst gcal-read-transparency ()
  "Get transparency for event."
  (declare (special gcal-event-transparency-alist))
  (gcal-event-transparency-value 'opaque))

(defsubst gcal-read-status ()
  "Get status for event."
  (declare (special gcal-event-status-alist))
  (gcal-event-status-value 'confirmed))

(defcustom gcal-calendar-view
  (expand-file-name "gcal-view.xsl" g-directory)
  "XSL transform used to view event feeds."
  :group 'gcal)

(defcustom gcal-event-view
  (expand-file-name "gevent-view.xsl" g-directory)
  "XSL transform used to view event feeds."
  :group 'gcal)

(defcustom gcal-event-time-format "%Y-%m-%dT%H:%M:%S.000"
  "Time format used for events."
  :type 'string
  :group 'gcal)

(defsubst gcal-format-time-string (&optional time-spec)
  "Like format-time-string, except we produce a zone offset per
  Google Calendar spec. `time-spec' defaults to current time."
  (declare (special gcal-event-time-format))
  (or time-spec
      (setq time-spec (current-time)))
  (let* ((z (format-time-string "%z"))
         (zone (format "%s:%s" (substring z  0 -2) (substring z -2))))
    (format "%s%s"
            (format-time-string gcal-event-time-format time-spec)
            zone)))

(defsubst gcal-read-time (prompt)
  "Read time and return it suitably formatted."
  (read-from-minibuffer prompt
                        (gcal-format-time-string)))

(defun gcal-read-calendar-date (prompt )
  "Smart date collector.
Prompts with `prompt'.
This function is sensitive to calendar mode when prompting."
  (let ((default (format-time-string "%m/%d/%Y"))
        (result nil))                   ; today is default
    (when (eq major-mode 'calendar-mode)
      (let ((date (calendar-cursor-to-nearest-date)))
        (setq default
              (format "%s/%s/%s"
                      (first date)
                      (second date)
                      (third date)))))
    (setq result
          (read-from-minibuffer prompt
                                default
                                nil nil nil
                                default))
    (setq result
          (mapcar 'read
                  (split-string result "/")))
    (gcal-format-time-string
     (apply 'encode-time
            0 0 0
            (second result)
            (first result)
            (list (third result ))))))

(defun gcal-read-calendar-time (prompt)
  "Smart time collector.
Prompts with `prompt'.
Default date is assumed to be today, or  the date selected when
  in the calendar."
  (let ((date nil)
        (now nil)
        (result nil))                   ; today is default
    (cond
     ((eq major-mode 'calendar-mode)
      (setq date (calendar-cursor-to-nearest-date))
      (setq date (list (second date)
                       (first date)
                       (third date))))
     (t  (setq now (decode-time))
         (setq date
               (list (nth 3 now)
                     (nth 4 now)
                     (nth 5 now)))))
    (setq result
          (read-from-minibuffer prompt
                                (format-time-string "%H:%M")
                                nil nil nil
                                (format-time-string "%H:%M")))
    (setq result
          (mapcar 'read
                  (split-string result ":")))
    (gcal-format-time-string
     (apply 'encode-time
            0 (second result) (first result)
            date))))

(defsubst gcal-read-who (prompt)
  "Read list of participants."
  (let ((who nil)
        (participant nil)
        (email nil))
    (while
        (>
         (length
          (setq email (read-from-minibuffer
                       (format "%s email: Blank to quit" prompt) )))
         0)
      (setq participant
            (make-gcal-attendee
             :email email
             :cn email
             :role "http://schemas.google.com/g/2005#event.attendee"))
      (push participant who))
    who))


(defun gcal-read-event (title content
                              where
                              start end
                              who
                              transparency status)
  "Prompt user for event params and return an event structure."
  (interactive
   (list
    (read-from-minibuffer "Title: ")
    (read-from-minibuffer "Content: ")
    (read-from-minibuffer "Where: ")
    (gcal-read-calendar-time "Start Time: ")
    (gcal-read-calendar-time "End Time: ")
    (gcal-read-who "Participant: ")
    (gcal-read-transparency)
    (gcal-read-status)))
  (declare (special gcal-auth-handle))
  (let ((event (make-gcal-event
                :author-email (g-auth-email gcal-auth-handle))))
    (setf (gcal-event-title  event) title
          (gcal-event-content event) content
          (gcal-event-where event) where
          (gcal-event-when-start event) start
          (gcal-event-when-end event) end
          (gcal-event-who event) who
          (gcal-event-transparency  event) transparency
          (gcal-event-status event) status)
    event))

;;}}}
;;{{{ Events:

(defvar gcal-default-feed-url
  "https://www.google.com/calendar/feeds/default/private/full"
  "URL for default calendar feed for currently authenticated
user.")

(defvar gcal-default-my-calendars-url
  "https://www.google.com/calendar/feeds/default/owncalendars/full"
  "URL for default calendar feed for currently authenticated
user.")


(defvar gcal-feed-url-template
  "https://www.google.com/calendar/feeds/%s/%s/%s/?orderby=starttime"
  "URL for  calendar feed using authentication.
Parameterized by calendar name, private/public, and projecttion")

(defvar gcal-private-feed-url
  "'https://www.google.com/calendar/feeds/%s/private/full'"
  "URL for private calendar feed using authentication.")

(defsubst gcal-private-feed-url ()
  "Return private feed for authenticated user."
  (declare (special gcal-private-feed-url
                    gcal-auth-handle))
  (format gcal-private-feed-url
          (g-url-encode (g-auth-email gcal-auth-handle))))

(defsubst gcal-feed-url (resource privacy projection)
  "Return  feed for specified resource..
`privacy' specifies public/private.
`projection' specifies desired projection, e.g. full vs free-busy."
  (declare (special gcal-feed-url-template))
  (format gcal-feed-url-template
          (g-url-encode resource)
          privacy projection))

(defsubst gcal-post-event (event location)
  "Post event via HTTPS to location and return resulting HTTP headers."
  (declare (special  gcal-auth-handle
                     g-app-auth-handle g-app-this-url))
  (g-using-scratch
   (g-app-mode)
   (insert (gcal-event-as-xml event))
   (setq g-app-auth-handle gcal-auth-handle
         g-app-this-url location)
   (g-app-post-entry)))

(defsubst gcal-post-quickadd (event-desc location)
  "Post quick event  via HTTPS to location and return resulting HTTP headers."
  (declare (special  gcal-auth-handle
                     g-app-auth-handle g-app-this-url gcal-quickadd-template))
  (g-using-scratch
   (g-app-mode)
   (insert
    (format gcal-quickadd-template event-desc))
   (setq g-app-auth-handle gcal-auth-handle
         g-app-this-url location)
   (g-app-post-entry)))

(defun gcal-event-as-diary-entry (event)
  "Return an event string suitable for Emacs calendar's diary
file."
  (let ((start (gcal-event-when-start event))
        (end (gcal-event-when-end event ))
        (date nil)
        (time-start nil)
        (time-end nil))
    (setq date (split-string (substring start 0 10) "-")
          time-start  (substring start 11 16))
    (format "%s %s, %s %s %s"
            (calendar-month-name ( read (second date)) 'abbrev)
            (third date)
            (first date)
            time-start
            (gcal-event-title event))))

;;;###autoload
(defun gcal-add-event ()
  "Add a calendar event."
  (interactive)
  (declare (special gcal-auth-handle
                    diary-file
                    gcal-autoinsert-into-emacs-calendar))
  (g-auth-ensure-token gcal-auth-handle)
  (let ((event (call-interactively 'gcal-read-event))
        (status nil)
        (headers nil)
        (body nil)
        (response nil)
        (location (format gcal-private-feed-url
                          (g-auth-email gcal-auth-handle))))
    (while (or  (null  status)
                (string= "302" status))
      (message "posting.")
      (setq response
            (gcal-post-event event 
                             (or location gcal-private-feed-url)))
      (setq headers (first response)
            body (second response))
      (setq status (g-http-header "Status" headers)
            location (g-http-header "Location" headers))
      (message "Status: %s Location: %s"
               status location)
      (when (and status
                 (string= "302" status))
        (unless location
          (error "Could not find redirect."))
        (message "Following redirect to %s" location)))
    (cond
     ((string-equal "201" (g-http-header "Status" headers))
      (and (> (length body)0)
           (g-display-xml-string body
                                 gcal-calendar-view))
      (message "Event added as %s" (g-http-header "Location"
                                                  headers))
      (when gcal-autoinsert-into-emacs-calendar
        (diary-make-entry
         (gcal-event-as-diary-entry event))
        (save-excursion
          (set-buffer (find-file-noselect diary-file))
          (save-buffer))))
     (t (error "Got %s"
               (g-http-header "Status" headers))))))

;;;###autoload
(defun gcal-quickadd-event (event-desc)
  "Add a calendar event.
Specify the event in plain English."
  (interactive "sQuickAdd Event:")
  (declare (special gcal-auth-handle))
  (g-auth-ensure-token gcal-auth-handle)
  (let ((status nil)
        (headers nil)
        (body nil)
        (response nil)
        (location nil))
    (setq response
          (gcal-post-quickadd event-desc (gcal-private-feed-url)))
    (setq headers (first response)
          body (second response))
    (setq status (g-http-header "Status" headers))
    (when (string= "302" status)
      (setq location (g-http-header "Location" headers))
      (unless location
        (error "Could not find redirect."))
      (setq response  (gcal-post-quickadd event-desc location)))
    (setq headers (first response)
          body (second response))
    (when  (string-equal "201" (g-http-header "Status" headers))
      (and (> 0(length body))
           (g-display-xml-string body
                                 gcal-calendar-view))
      (message "Event added as %s"
               (g-http-header "Location" headers)))))

;;;###autoload
(defun gcal-delete-event (event-uri)
  "Delete a calendar event."
  (interactive
   (list
    (read-from-minibuffer "Event URL: "
                          (browse-url-url-at-point))))
  (declare (special gcal-auth-handle))
  (g-auth-ensure-token gcal-auth-handle)
  (g-app-delete-entry gcal-auth-handle event-uri))

(defcustom gcal-event-accept
  (expand-file-name "gevent-accept.xsl" g-directory)
  "XSL transform used to accept events."
  :group 'gcal)

(defun gcal-accept-event (event-uri)
  "Accept (RSVP)  a calendar event."
  (interactive
   (list
    (read-from-minibuffer "Event URL: "
                          (browse-url-url-at-point))))
  (declare (special gcal-auth-handle g-cookie-options
                    g-curl-program g-curl-common-options g-curl-atom-header
                    gcal-event-accept))
  (g-auth-ensure-token gcal-auth-handle)
  (g-using-scratch
   (shell-command
    (format
     "%s %s %s %s %s  -X GET %s 2>/dev/null"
     g-curl-program g-curl-common-options g-curl-atom-header
     (g-authorization gcal-auth-handle)
     g-cookie-options
     event-uri)
    (current-buffer) 'replace)
   (shell-command-on-region
    (point-min) (point-max)
    (format
     "%s --param 'email' \"'%s'\" %s - 2>/dev/null"
     g-xslt-program
     (g-auth-email gcal-auth-handle)
     gcal-event-accept )
    (current-buffer) 'replace)
   (g-app-mode)
   (setq g-app-auth-handle gcal-auth-handle
         g-app-this-url event-uri)
   (g-app-put-entry)))
(defcustom gcal-event-reject
  (expand-file-name "gevent-reject.xsl" g-directory)
  "XSL transform used to reject events."
  :group 'gcal)

;;;###autoload
(defun gcal-reject-event (event-uri)
  "Reject (RSVP)  a calendar event."
  (interactive
   (list
    (read-from-minibuffer "Event URL: "
                          (browse-url-url-at-point))))
  (declare (special gcal-auth-handle g-cookie-options
                    g-curl-program g-curl-common-options g-curl-atom-header
                    gcal-event-reject))
  (g-auth-ensure-token gcal-auth-handle)
  (g-using-scratch
   (shell-command
    (format
     "%s %s %s %s %s  -X GET %s 2>/dev/null"
     g-curl-program g-curl-common-options g-curl-atom-header
     (g-authorization gcal-auth-handle)
     g-cookie-options
     event-uri)
    (current-buffer) 'replace)
   (shell-command-on-region
    (point-min) (point-max)
    (format
     "%s --param 'email' \"'%s'\" %s - 2>/dev/null"
     g-xslt-program
     (g-auth-email gcal-auth-handle)
     gcal-event-reject )
    (current-buffer) 'replace)
   (g-app-mode)
   (setq g-app-auth-handle gcal-auth-handle
         g-app-this-url event-uri)
   (g-app-put-entry)))


;;;###autoload

(defcustom gcal-calendar-agenda-days 5
  "Number of days for which we show an agenda by default."
  :type 'integer
  :group 'gcal)

(defcustom gcal-autoinsert-into-emacs-calendar t
  "If set, gcal adds events to the Emacs calendar as well."
  :type 'boolean
  :group 'gcal)

(defun gcal-calendar-get-date (&optional date )
  "Get GCal date from a calendar date spec.
Default is to use calendar date under point."
  (setq date (or date (calendar-current-date)))
  (gcal-format-time-string
   (apply 'encode-time
          0 0 0
          (second date)
          (first date)
          (list (third date)))))

(defconst gcal-privacy-choices
  '("public" "private" )
  "Choices for public or private.")

(defconst gcal-projection-choices
  '("free-busy" "full" "owner")
  "Choices for project types.")

(defun gcal-calendar-agenda  (&optional resource privacy projection)
  "Show agenda for currently authenticated user.
With interactive prefix arg, prompts for calendar to show. This
command is best invoked from within the emacs calendar. It uses
point and mark in the calendar to determine the days for which we
show the agenda. If no mark is set in the calendar, the agenda is
shown for the next `gcal-calendar-agenda-days' days following the
date under point."
  (interactive
   (cond
    (current-prefix-arg
     (list
      (read-from-minibuffer "Calendar For: "
                            (g-auth-email gcal-auth-handle))
      (completing-read  "Privacy: "
                        gcal-privacy-choices)
      (completing-read "Projection: "
                       gcal-projection-choices)))
    (t (list
        (if gcal-user-email gcal-user-email g-user-email)
        "private" "full"))))
  (declare (special gcal-auth-handle
                    gcal-user-email g-user-email
                    gcal-privacy-choices gcal-projection-choices
                    gcal-calendar-view
                    calendar-mark-ring))
  (let* ((calendar
          (gcal-feed-url resource  privacy projection))
         (start-min
          (g-url-encode
           (gcal-calendar-get-date
            (when (eq major-mode 'calendar-mode)
              (calendar-cursor-to-nearest-date)))))
         (start-max
          (g-url-encode
           (cond
            ((and (eq major-mode 'calendar-mode)
                  (car calendar-mark-ring))
             (gcal-calendar-get-date (car calendar-mark-ring)))
            ((eq major-mode 'calendar-mode)
             (gcal-calendar-get-date
              (calendar-gregorian-from-absolute
               (+ (calendar-absolute-from-gregorian (calendar-cursor-to-nearest-date))
                  gcal-calendar-agenda-days))))
            (t
             (gcal-calendar-get-date
              (calendar-gregorian-from-absolute
               (+ (calendar-absolute-from-gregorian (calendar-current-date))
                  gcal-calendar-agenda-days))))))))
    (g-auth-ensure-token gcal-auth-handle)
    (g-display-result
     (format
      "%s %s %s %s '%s%s' 2>/dev/null"
      g-curl-program g-curl-common-options
      (g-authorization gcal-auth-handle)
      g-cookie-options
      calendar
      (cond
       ((and (null start-min)
             (null start-max))
        "")
       (t
        (format "&start-min=%s&start-max=%s"
                (or start-min "")
                (or start-max "")))))
     gcal-calendar-view     )))

;;;###autoload

(defun gcal-view (resource)
  "Retrieve and display resource after authenticating."
  (interactive "sResource: ")
  (declare (special gcal-auth-handle gcal-calendar-view
                    g-cookie-options
                    g-curl-program g-curl-common-options))
  (g-auth-ensure-token gcal-auth-handle)
  (g-display-result
   (format
    "%s %s %s %s '%s' %s"
    g-curl-program g-curl-common-options
    g-cookie-options
    (g-authorization gcal-auth-handle)
    resource
    (g-curl-debug))
   gcal-calendar-view))

;;;###autoload
(defun gcal-show-event (url)
  "Show event at URL."
  (interactive "sURL:")
  (declare (special gcal-auth-handle
                    gcal-event-view))
  (g-auth-ensure-token gcal-auth-handle)
  (g-display-result
   (format
    "%s %s %s %s   %s 2>/dev/null"
    g-curl-program g-curl-common-options
    (g-authorization gcal-auth-handle)
    g-cookie-options
    url)
   gcal-event-view))

;;}}}
;;{{{ Feed of feeds:
(defvar gcal-feeds-template-url
  "'https://www.google.com/calendar/feeds/%s'"
  "URL template for feed of feeds from calendar.")
(defsubst gcal-feeds-url (userid)
  "Return url for feed of feeds."
  (declare (special gcal-feeds-template-url))
  (format gcal-feeds-template-url userid))

(defun gcal-calendars ()
  "Retrieve and display feed of feeds for specified user  after authenticating."
  (interactive)
  (declare (special gcal-auth-handle g-atom-view-xsl
                    g-curl-program g-curl-common-options
                    g-cookie-options))
  (g-auth-ensure-token gcal-auth-handle)
  (g-display-result
   (format
    "%s %s %s %s '%s' 2>/dev/null"
    g-curl-program g-curl-common-options
    g-cookie-options
    (g-authorization gcal-auth-handle)
    (gcal-feeds-url "default"))
   g-atom-view-xsl))

(defun gcal-my-calendars ()
  "Retrieve and display feed of `owned' calendars after authenticating."
  (interactive)
  (declare (special gcal-auth-handle
                    g-atom-view-xsl
                    g-curl-program g-curl-common-options
                    g-cookie-options))
  (g-auth-ensure-token gcal-auth-handle)
  (g-display-result
   (format
    "%s %s %s %s '%s' 2>/dev/null"
    g-curl-program g-curl-common-options
    g-cookie-options
    (g-authorization gcal-auth-handle)
    (concat
     (gcal-feeds-url "default")
     "/owncalendars/full"))
   g-atom-view-xsl))



;;}}}
;;{{{ Interfacing with Emacs Calendar:
;;;###autoload
(define-prefix-command  'gcal-calendar-prefix-map)

;;;###autoload
(defun gcal-emacs-calendar-setup ()
  "Setup GCal keybindings in Emacs calendar."
  (declare (special calendar-mode-map
                    gcal-calendar-prefix-map))
  (define-key calendar-mode-map "c" 'gcal-calendar-prefix-map)
  (loop for binding  in
        '(
          ("a" gcal-add-event)
          ("c" gcal-calendar-agenda)
          )
        do
        (define-key gcal-calendar-prefix-map (first binding)
          (second binding))))

;;}}}
;;{{{ Sign out:
;;;###autoload
(defun gcal-sign-out()
  "Resets client so you can start with a different userid."
  (interactive)
  (declare (special gcal-auth-handle
                    gcal-user-email gcal-user-password))
  (message "Signing out %s from Calendar"
           (g-auth-email gcal-auth-handle))
  (setq gcal-user-email nil
        gcal-user-password nil)
  (setq gcal-auth-handle (make-gcal-auth)))

;;;###autoload
(defun gcal-sign-in()
  "Sign in, useful when changing to a different user profile."
  (interactive)
  (declare (special gcal-auth-handle gcal-user-email
                    gcal-default-user-email))
  (setq gcal-user-email
        (read-from-minibuffer "Calendar User: "
                              gcal-default-user-email))
  (setq gcal-auth-handle (make-gcal-auth))
  (gcal-authenticate))

;;}}}
(provide 'gcal)
;;{{{ end of file

;;; local variables:
;;; folded-file: t
;;; byte-compile-dynamic: nil
;;; end:

;;}}}