;; -*- lexical-binding: t; -*-

(defvar hmm-search-engines nil "hmm web search engines.")
(defvar hmm-web-browsers nil "hmm web browers.")
(defvar hmm-query-handlers nil "hmm query handlers.")
(defvar hmm-favourite-commands nil)

(defmacro hmm-define-web-search-engine (engine browser)
  (let* ((engine-name (plist-get engine :name))
         (browser-name (plist-get browser :name))
         (function-name (intern
                         (format "hmm-search-%s-%s" engine-name browser-name))))
    `(progn
       (defun ,function-name (query)
         ,(format "Search %s in %s." engine-name browser-name)
         (interactive ,(format "sSearch %s in %s for: " engine-name browser-name))
         (,(plist-get browser :command)
          (format ,(plist-get engine :format) query)))
       (hmm-add-to-favourite-commands ',function-name))))

(defun hmm-add-to-favourite-commands (command)
  (add-to-list 'hmm-favourite-commands command))

(defun hmm-search-region (from to)
  (interactive "r")
  (unless (region-active-p) (error "Region not active."))
  (let* ((query (buffer-substring from to)))
    (hmm-search-internal query)))

(defun hmm-search (query)
  (interactive "sQuery: ")
  (hmm-search-internal query))

(defun hmm-search-internal (query)
  (let ((selected (completing-read
                   (format "Search %s using: " query)
                   (mapcar
                    (lambda (command)
                      (format "%s (%s)" command
                              (if (documentation command)
                                  (car
                                   (split-string
                                    (documentation command)
                                    "\n"))
                                "Undocumented")))
                    hmm-favourite-commands))))
    (funcall (intern (car (split-string selected " ("))) query)))

(dolist (engine hmm-web-search-engines)
  (dolist (browser hmm-web-browsers)
    (eval `(hmm-define-web-search-engine ,engine ,browser))))

(mapc 'hmm-add-to-favourite-commands hmm-query-handlers)