;;; pivot.el --- Elisp library for the Pivotal Tracker API  -*- lexical-binding: t; -*-

;; Copyright (C) 2014  Tom Willemse

;; Author: Tom Willemse <tom@ryuslash.org>
;; Keywords: comm, hypermedia

;; 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 'json)
(require 'url)

(defgroup pivotel nil
  "Communicate with Pivotal Tracker."
  :group 'external)

(defcustom pivotel-api-token nil
  "API token from Pivotal Tracker.

From Pivotal Tracker: Your token enables access to your project
and story data via the API, and needs to be kept private."
  :group 'pivotel)

(defvar pivotel-api-url
  "https://www.pivotaltracker.com/services/v5"
  "Base URL of the Pivotal Tracker API.

Does not need a final `/'.")

(defvar pivotel-user-id nil
  "The user id of the current user.")
(defvar pivotel-projects nil
  "The projects from the current user.")

(defmacro with-pivotel-headers (headers &rest body)
  "Add `X-TrackerTocken' to HEADERS and bind them around BODY."
  (declare (indent 1))
  `(let ((url-request-extra-headers
          (append (list (cons "X-TrackerToken" pivotel-api-token))
                  ,headers)))
     ,@body))

(defun pivotel--retrieve-from (url)
  "Retrieve data from URL."
  (with-current-buffer
      (url-retrieve-synchronously (concat pivotel-api-url url))
    (goto-char (point-min))
    (search-forward "\n\n")
    (let ((results (json-read)))
      (kill-buffer)
      results)))

(defun pivotel-get-story (project story)
  "Get data from PROJECT for STORY."
  (with-pivotel-headers nil
    (pivotel--retrieve-from
     (format "/projects/%d/stories/%d" project story))))

(defun pivotel-get-projects ()
  "Get a list of all projects."
  (or pivotel-projects
      (setq pivotel-projects
            (with-pivotel-headers nil
              (pivotel--retrieve-from "/projects")))))

(defun pivotel-get-stories (project)
  "Get a list of all stories in PROJECT."
  (with-pivotel-headers nil
    (pivotel--retrieve-from (format "/projects/%d/stories" project))))

(defun pivotel-get-me ()
  "Get information about currently logged-in user."
  (with-pivotel-headers nil (pivotel--retrieve-from "/me")))

(defun pivotel-get-me-id ()
  "Get and cache the current user's id."
  (or pivotel-user-id
      (setq pivotel-user-id
            (cdr (assoc 'id (pivotel-get-me))))))

(defun pivotel-get-all-stories ()
  "Get all stories for the current user."
  (let ((project-ids (mapcar (lambda (itm) (cdr (assoc 'id itm)))
                             (pivotel-get-projects))))
    (apply #'append
           (append (mapcar #'pivotel-get-stories project-ids) '(nil)))))

(defun pivotel--my-story-p (story)
  "Check whether or not STORY belongs to the current user."
  (memql (pivotel-get-me-id)
         (append (cdr (assoc 'owner_ids story)) '(nil))))

(defun pivotel-get-my-owned-stories ()
  "Get the stories for which the user is an owner."
  (let ((stories (pivotel-get-all-stories)))
    (delq nil
          (mapcar (lambda (itm) (when (pivotel--my-story-p itm) itm))
                  stories))))

(provide 'pivot)
;;; pivot.el ends here