;;; taskrunner-mix.el --- Provide functions to retrieve elixir tasks via mix -*- lexical-binding: t; -*-
;; Copyright (C) 2019 Yavor Konstantinov

;;;; Commentary:
;; Provide support for Mix(elixir)

;;;; Code:

(require 'cl-lib)

;;;; Functions
;; These are here just to silence the bytecompiler. They are defined in
;; `taskrunner.el' and will be loaded later on but due to these files being
;; required before the function being loaded, a warning is emitted.
(declare-function taskrunner--make-task-buff-name "ext:taskrunner")

(defun taskrunner--get-elixir-tasks-from-buffer ()
  "Retrieve all mix tasks from the currently visited buffer."
  (cl-map 'list (lambda (elem)
                  (let ((split-task-line (split-string elem " ")))
                    (cond
                     ;; Match the last line of mix 'iex -S mix'
                     ((string-match "^iex" elem)
                      (concat "MIX" " " (car (split-string elem "#"))))
                     ;; Match the first line 'mix #some_comment'
                     ;; This is presented as MIX mix in the output
                     ((string-match "^mix[[:space:]]+#" elem)
                      (concat "MIX" " " "mix"))
                     ;; Match all other regular lines
                     (t
                      (concat "MIX" " " (cadr split-task-line)))
                     )
                    )
                  )
          (split-string (buffer-string) "\n")))


(defun taskrunner-get-mix-tasks (DIR)
  "Retrieve the mix tasks for the project in directory DIR.
This function returns a list of the form:
\(\"MIX TASK1\" \"MIX TASK2\"...)"
  (let ((default-directory DIR)
        (elixir-tasks) ;; Store the elixir tasks retrieved
        )
    (call-process "mix" nil (taskrunner--make-task-buff-name "mix") nil "help")
    (with-temp-buffer
      (set-buffer (taskrunner--make-task-buff-name "mix"))
      (goto-char (point-min))
      ;; Use regexp to find start of region since 'mix help' can sometimes show
      ;; errors in the output and we do not want to match those
      (search-forward-regexp "^mix[[:space:]]+" nil t)
      (narrow-to-region (progn
                          (beginning-of-line)
                          (point))
                        ;; Find last line
                        (progn
                          (goto-char (point-max))
                          (beginning-of-line)
                          (point)))
      (setq elixir-tasks (taskrunner--get-elixir-tasks-from-buffer))
      (kill-current-buffer))
    ;; Return the tasks explicitly. Cannot do it any other way since the buffer
    ;; used must be killed before returning from this function
    elixir-tasks))

(provide 'taskrunner-mix)
;;; taskrunner-mix.el ends here