;;; helm-exec.el --- simple execution framework for Helm -*- lexical-binding: t; -*-

;;; Copyright © 2018-2018 Jonathan Jin <jjin082693@gmail.com>

;; Author: Jonathan Jin <jjin082693@gmail.com>

;; URL: https://github.com/jinnovation/helm-exec

;; Keywords: helm, execution

;; Version: 0.1.0

;; TODO: Package-Requires

;; This file is NOT part of GNU Emacs.

;; 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, 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 GNU Emacs; see the file COPYING. If not, write to the

;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

;; Boston, MA 02110-1301, USA.

;;; Commentary:

;;

;; This libary provides a rudimentary execution framework for commonly-used

;; "applications" within Emacs. It's intended to be used for applications that

;; have alternate, one-off forms of execution, e.g. refreshing feeds for an RSS

;; application, or pulling recent emails for an email application.

;;; Code:

(require 'helm)

(defcustom helm-exec-prompt "> "

"Completion prompt for execution input."

:type 'string)

(defcustom helm-exec-applications nil

"Mapping between symbolic identifiers and corresponding

'execution functions.' Use this mapping to expose functions to

`helm-exec-execute' for easy access"

:type '(alist

:key-type symbol

:value-type (list

(list (const executable) function)

(list (const alternate) (choice function (const nil))))))

;; TODO: Update docstring to reflect plist arguments

(defun helm-exec-register-executable (exec &rest args)

"Register EXEC as a function to be accessible via

`helm-exec-execute'. An explicit ID can be provided that the

function will be listed as; if not provided, the function is

listed under its own name. Similarly, an optional alternate

execution can be provided via ALT that defaults to nil.

"

(let* ((id (or (plist-get args :id) exec))

(alt (or (plist-get args :alt) nil))

(entry `(,id . ((executable . ,exec)

(alternate . ,alt)))))

(add-to-list 'helm-exec-applications entry)))

(defun helm-exec--action/execute (selection)

"Action that executes the executable corresponding to the given

SELECTION."

(let* ((spec (alist-get (intern selection) helm-exec-applications))

(exec (alist-get 'executable spec)))

(funcall exec)))

(defun helm-exec--action/alternate (selection)

"Action that executes the alternate executable corresponding to

the given SELECTION."

(let* ((spec (alist-get (intern selection) helm-exec-applications))

(exec (alist-get 'alternate spec)))

(if (not exec)

(message "No alternate execution for ID %s." selection)

(funcall exec))))

(defun helm-exec--execution-candidates ()

(mapcar (lambda (asoc) (car asoc)) helm-exec-applications))

(defconst helm-exec--actions

(helm-make-actions

"Execute" 'helm-exec--action/execute

"Alternate" 'helm-exec--action/alternate))

(setq helm-exec-map

(let ((map (make-sparse-keymap)))

(define-key map (kbd "M-e") (lambda ()

(interactive)

(helm-exit-and-execute-action 'helm-exec--action/alternate)))

map))

(defconst helm-exec--exec-source

(helm-build-sync-source

"Available Applications"

:candidates 'helm-exec--execution-candidates

:action helm-exec--actions

:keymap helm-exec-map))

(defun helm-exec-execute ()

(interactive)

(helm :sources helm-exec--exec-source

:buffer "*helm execute*"

:prompt helm-exec-prompt))

(provide 'helm-exec)

;;; helm-exec.el ends here