;; Major mode for editing Michelson smart contracts.

(require 'cl-lib)
(require 'deferred)
(require 'font-lock)

(defvar michelson-mode-hook nil)

(defgroup michelson nil
  "Major mode for editing Michelson smart contracts."
  :prefix "michelson-"
  :group 'languages)

(defgroup michelson-options nil
  "General options for Michelson mode."
  :prefix "michelson-"
  :group 'michelson)

(defcustom michelson-client-command "tezos-client"
  "Path to the `tezos-client' binary."
  :type 'string
  :group 'michelson-options)

(defcustom michelson-alphanet nil
  "Is the client command currently using the alphanet.sh script?"
  :type 'boolean
  :group 'michelson-options)

(defgroup michelson-faces nil
  "Font lock faces for Michelson mode."
  :prefix "michelson-"
  :group 'michelson
  :group 'faces)

(defcustom michelson-live-editing t
  "Toggles live types and error printing.
Overrides `michelson-print-errors' and `michelson-highlight-errors'"
  :group 'michelson-options)

(defcustom michelson-print-errors t
  "Print the errors in the output buffer."
  :type 'boolean
  :group 'michelson-options)

(defcustom michelson-highlight-errors t
  "Highlight errors in the source buffer."
  :type 'boolean
  :group 'michelson-options)

(defvar michelson-face-instruction
  'michelson-face-instruction
  "Face name for Michelson instructions.")
(defface michelson-face-instruction
  '((t (:inherit font-lock-keyword-face)))
  "Face for Michelson instructions."
  :group 'michelson-faces)

(defvar michelson-face-type
  'michelson-face-type
  "Face name for Michelson types.")
(defface michelson-face-type
   '((t (:inherit font-lock-type-face)))
   "Face for Michelson types."
   :group 'michelson-faces)

(defvar michelson-face-constant
  'michelson-face-constant
  "Face name for Michelson constants.")
(defface michelson-face-constant
   '((t (:inherit font-lock-constant-face)))
   "Face for Michelson constants."
   :group 'michelson-faces)

(defvar michelson-face-var-annotation
  'michelson-face-var-annotation
  "Face name for Michelson variable or binding annotations.")
(defface michelson-face-var-annotation
   '((t (:inherit font-lock-variable-name-face)))
   "Face for Michelson variable or binding annotations."
   :group 'michelson-faces)

(defvar michelson-face-type-annotation
  'michelson-face-type-annotation
  "Face name for Michelson type or field annotations.")
(defface michelson-face-type-annotation
   '((t (:inherit font-lock-string-face)))
   "Face for Michelson type or field annotations."
   :group 'michelson-faces)

(defvar michelson-face-comment
  'michelson-face-comment
  "Face name for Michelson comments.")
(defface michelson-face-comment
   '((t (:inherit font-lock-comment-face)))
   "Face for Michelson comments."
   :group 'michelson-faces)

(defvar michelson-face-declaration
  'michelson-face-declaration
  "Face name for Michelson declarations.")

(defface michelson-face-declaration
   '((t (:inherit font-lock-keyword-face)))
   "Face for Michelson constants."
   :group 'michelson-faces)

(defvar michelson-face-error
  'michelson-face-error
  "Face name for Michelson comments.")

(defface michelson-face-error
  '(( ((class color) (background light)) (:background "MistyRose") )
    ( ((class color) (background dark)) (:background "DarkRed") ))
   "Face for Michelson annotations."
   :group 'michelson-faces)

(defface michelson-stack-highlight-face
  '(( ((class color) (background light)) (:background "gray86") )
    ( ((class color) (background dark)) (:background "grey21") ))
  "Face for alternating lines of the stack."
  :group 'michelson-faces)

(defun michelson-customize-options ()
  "Open the general customization group for Michelson mode."
  (interactive)
  (customize-group-other-window `michelson-options))

(defun michelson-customize-faces ()
  "Open the face customization group for Michelson mode."
  (interactive)
  (customize-group-other-window `michelson-faces))

(defun michelson-toggle-print-errors ()
  (interactive)
  (setq michelson-print-errors (not michelson-print-errors)))

(defun michelson-highlight-errors ()
  (interactive)
  (setq michelson-highlight-errors (not michelson-highlight-errors)))

(defconst michelson-mode-map
  (let ((michelson-mode-map (make-sparse-keymap)))
    ;; menu
    (define-key michelson-mode-map
      [menu-bar michelson-menu]
      (cons "Michelson" (make-sparse-keymap "michelson-menu")))
    (define-key michelson-mode-map
      [menu-bar michelson-menu faces]
      (cons "Display options group" 'michelson-customize-faces))
    (define-key michelson-mode-map
      [menu-bar michelson-menu options]
      (cons "General options group" 'michelson-customize-options))
    (define-key michelson-mode-map
      [menu-bar michelson-menu separator]
      '(menu-item "--"))
    (define-key michelson-mode-map
      [menu-bar michelson-menu what]
      (cons "What's under the cursor?" 'michelson-type-at-point))
    ;; keys
    (define-key michelson-mode-map
      (kbd "C-j") 'newline-and-indent)
    (define-key michelson-mode-map
      (kbd "TAB") 'indent-for-tab-command)
    (define-key michelson-mode-map
      (kbd "<f1>") 'michelson-type-at-point)
    michelson-mode-map))

(defun michelson-font-lock-syntactic-face-function (s)
  (cond ((nth 3 s) 'font-lock-constant-face)
        (t 'michelson-face-comment)))

(defconst michelson-font-lock-defaults
  (list
   (list
    '("\\<[\$@][A-Za-z-_0-9\.]*\\>" . michelson-face-var-annotation)
    '("\\<[%:][A-Za-z-_0-9\.]*\\>" . michelson-face-type-annotation)
    '("\\<[0-9]+\\>" . michelson-face-constant)
    '("\\<[A-Z][a-z_0-9]+\\>" . michelson-face-constant)
    '("\\<[A-Z][A-Z_0-9]*\\>" . michelson-face-instruction)
    ;; This will have problems if users have whitespace in front of the declarations
    '("^parameter\\|^return\\|^storage\\|^code" . michelson-face-declaration)
    '("\\<[a-z][a-z_0-9]*\\>" . michelson-face-type))
   nil nil nil nil
   '(font-lock-syntactic-face-function . michelson-font-lock-syntactic-face-function)))

(defconst michelson-mode-syntax-table
  (let ((michelson-mode-syntax-table (make-syntax-table)))
    (modify-syntax-entry ?_ "w" michelson-mode-syntax-table)
    (modify-syntax-entry ?@ "w" michelson-mode-syntax-table)
    (modify-syntax-entry ?: "w" michelson-mode-syntax-table)
    (modify-syntax-entry ?% "w" michelson-mode-syntax-table)
    (modify-syntax-entry ?/ ". 1n4" michelson-mode-syntax-table)
    (modify-syntax-entry ?* ". 23" michelson-mode-syntax-table)
    (modify-syntax-entry ?# "<b" michelson-mode-syntax-table)
    (modify-syntax-entry ?\n ">b" michelson-mode-syntax-table)
    michelson-mode-syntax-table))

(defun in-space ()
  (or (looking-at "[[:space:]\n]")
      (equal (get-text-property (point) 'face)
             'michelson-face-comment)))

(defun michelson-goto-previous-token ()
  (interactive)
  (if (bobp)
      (cons 0 nil)
    (progn
      (backward-char 1)
      (while (and (not (bobp)) (in-space)) (backward-char 1))
      (let ((token-face (get-text-property (point) 'face)))
        (forward-char 1)
        (let ((end-of-token (point)))
          (backward-char 1)
          (unless (looking-at "[{()};]")
            (while (and (not (bobp))
                        (equal (get-text-property (point) 'face) token-face))
              (backward-char 1))
            (when (not (equal (get-text-property (point) 'face) token-face))
              (forward-char 1)))
          (cons (point) (buffer-substring-no-properties (point) end-of-token)))))))

(defun michelson-goto-next-token ()
  (interactive)
  (if (eobp)
      (cons (point) nil)
    (progn
      (while (and (not (eobp)) (in-space)) (forward-char 1))
      (let ((token-face (get-text-property (point) 'face)))
        (let ((start-of-token (point)))
          (if (looking-at "[{()};]")
              (forward-char 1)
            (progn
              (while (and (not (eobp))
                          (equal (get-text-property (point) 'face) token-face))
                (forward-char 1))))
          (cons start-of-token (buffer-substring-no-properties start-of-token (point))))))))

(defun michelson-goto-opener ()
  (interactive)
  (let ((paren-level 0))
    (while (and (not (bobp))
                (or (> paren-level 0)
                    (not (looking-at "[{(]"))))
      (cond ((looking-at "[{(]")
             (setq paren-level (- paren-level 1)))
            ((looking-at "[})]")
             (setq paren-level (+ paren-level 1))))
      (michelson-goto-previous-token))
    (cons (point)
          (when (looking-at "[{(]")
            (buffer-substring-no-properties (point) (+ (point) 1))))))

(defun michelson-goto-closer ()
  (interactive)
  (let ((paren-level 0) (last-token ""))
    (while (and (not (eobp))
                (or (> paren-level 0)
                    (not (string-match "[)}]" last-token))))
      (cond ((looking-at "[{(]")
             (setq paren-level (+ paren-level 1)))
            ((looking-at "[})]")
             (setq paren-level (- paren-level 1))))
      (setq last-token (cdr (michelson-goto-next-token))))
    (cons (point)
          (when (looking-at "[)}]")
            (buffer-substring-no-properties (point) (+ (point) 1))))))

(defun michelson-goto-previous-application-start ()
  (interactive)
  (let ((paren-level 0) (application-start 0))
    (while (and (not (bobp))
                (or (> paren-level 0)
                    (not (looking-at "[{(;]"))))
      (cond ((looking-at "[{(]")
             (setq paren-level (- paren-level 1)))
            ((looking-at "[})]")
             (setq paren-level (+ paren-level 1))))
      (setq application-start (point))
      (michelson-goto-previous-token))
    (cons application-start (goto-char application-start))))

(defun michelson-indent ()
  "Indent current line of Michelson code."
  (interactive)
  (let ((new-indentation 0)
        (previous-indentation (current-indentation))
        (previous-column (current-column))
        (current-token
         (save-excursion
           (beginning-of-line 1)
           (michelson-goto-next-token))))
    (save-excursion
      (end-of-line 0)
      (let ((previous-token
             (save-excursion (michelson-goto-previous-token)))
            (previous-opener
             (save-excursion (michelson-goto-opener))))
        (cond ((and (not (cdr previous-opener))
                    (not (cdr previous-token)))
               (setq new-indentation 0))
              ((and (not (cdr previous-opener))
                    (equal (cdr previous-token) ";"))
               (setq new-indentation 0))
              ((not (cdr previous-opener))
               (setq new-indentation 2))
              ((and (equal (cdr current-token) "}")
                    (equal (cdr previous-opener) "{"))
               (goto-char (car previous-opener))
               (setq new-indentation (current-column)))
              ((and (or (equal (cdr previous-token) ";")
                        (equal (cdr previous-token) "{"))
                    (equal (cdr previous-opener) "{"))
               (goto-char (car previous-opener))
               (setq new-indentation (+ (current-column) 2)))
              ((equal (cdr previous-opener) "{")
               (progn
                 (michelson-goto-previous-application-start)
                 (let ((default-param-indentation
                         (+ (current-column) 2))
                       (first-param-point
                        (save-excursion
                          (michelson-goto-next-token)
                          (car (michelson-goto-next-token)))))
                   (if (= first-param-point (car current-token))
                       (setq new-indentation default-param-indentation)
                     (progn
                       (goto-char first-param-point)
                       (setq new-indentation (current-column)))))))
              ((and (equal (cdr current-token) ")")
                    (equal (cdr previous-opener) "("))
               (goto-char (car previous-opener))
               (setq new-indentation (current-column)))
              ((equal (cdr previous-token) "(")
               (goto-char (car previous-token))
               (setq new-indentation (+ (current-column) 1)))
              ((equal (cdr previous-opener) "(")
               (goto-char (car previous-opener))
               (setq new-indentation (+ (current-column) 3))))))
    (indent-line-to new-indentation)
    (beginning-of-line)
    (forward-char
     (+ (- previous-column previous-indentation) new-indentation))
    (when (< (current-column) new-indentation)
      (beginning-of-line)
      (forward-char new-indentation))))

(defun michelson-token-at-point ()
  "Display the token closest to the cursor."
  (interactive)
  (let ((message
         (cdr (save-excursion
                (michelson-goto-next-token)
                (michelson-goto-previous-token)))))
    (display-message-or-buffer message "*Michelson*")))

(cl-defstruct cache
  "Cache for types. Invalid entries are removed"
  types
  errors)

(defvar michelson-cached-buffer-info (make-cache :types '() :errors '()))

(defvar michelson-process-output-buffer "*Michelson-process*")

(defun michelson-erase-process-buffer ()
  "Remove all text from process buffer."
  (get-buffer-create michelson-process-output-buffer)
  (with-current-buffer michelson-process-output-buffer
    (erase-buffer)))

(defun michelson-async-command-to-string (command callback)
  "Asynchronously execute `COMMAND' and call the `CALLBACK' on the resulting string."
  (lexical-let ((command command)
                (callback-fun callback))
    (deferred:$
      (deferred:$
          (apply 'deferred:process command)
          (deferred:nextc it callback-fun))
      ;; TODO: make this show only the client error
      (deferred:error it (lambda (err) (michelson-write-output-buffer (cadr err)))))))

(defun michelson-clean-cache ()
  "Clean the buffer's program info cache."
  (let ((types (cache-types michelson-cached-buffer-info))
        (errors (cache-errors michelson-cached-buffer-info))
        (clean-cache-entry
         (lambda (alist)
           (remove-if (lambda (entry)
                        (let ((tok-end (cadr entry)))
                          (> tok-end (point))))
                      alist))))
    (setq michelson-cached-buffer-info
          (make-cache :types (funcall clean-cache-entry types)
                      :errors (funcall clean-cache-entry errors)))))

(defun michelson-get-info (buffer-name)
  "Refresh the info about the program in `BUFFER-NAME' from the command."
  (lexical-let ((tmp-file (make-temp-file buffer-name)))
    (write-region (point-min) (point-max) tmp-file nil 'no-message)
    (let ((command
           (append (split-string michelson-client-command " ")
                   (list
                    "typecheck"
                    "program"
                    (if michelson-alphanet
                        (concat "container:" tmp-file)
                      tmp-file)
                    "-details"
                    "--emacs"))))
          (michelson-async-command-to-string
           command
           (lambda (output)
             (condition-case err
                 (let*
                     ((record (car (read-from-string output)))
                      (errors (cdr (assoc 'errors record)))
                      (types  (cdr (assoc 'types record))))
                   (setq michelson-cached-buffer-info (make-cache :types types :errors errors))
                   (delete-file tmp-file))
               ((error err)
                (let ((inhibit-message t))
                  (message output)))))))))

(defvar michelson-output-buffer-name
  "*Michelson*")

(defun michelson-output-width ()
  (lexical-let* ((buffer (get-buffer-create michelson-output-buffer-name))
                 (message-window
                  (if (get-buffer-window buffer)
                      (get-buffer-window buffer)
                    (display-buffer-below-selected buffer nil))))
    (window-body-width message-window)))

(defvar michelson-output-buffer-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map special-mode-map)
    (define-key map "g" nil)
    map)
  "Keymap for types buffer.")

(define-derived-mode michelson-stack-mode fundamental-mode "Michelson-stack"
  "Major mode for visualizing the Michelson stack."
  (interactive)
  (use-local-map michelson-output-buffer-map)
  (set-syntax-table michelson-mode-syntax-table)
  (set
   (make-local-variable 'font-lock-defaults)
   michelson-font-lock-defaults)
  (setq major-mode 'michelson-stack-mode)
  (setq mode-name "Michelson-stack")
  (setq indent-tabs-mode nil))

(defun michelson-write-output-buffer (data &optional do-not-overwrite)
  "Write the given `DATA' to the output buffer.
If `DATA' is a string, it is written directly,
overwriting the data in the buffer.
If `DATA' is a list of strings, the strings are written into the buffer,
with alternating lines highlighted.
If `DO-NOT-OVERWRITE' is non-nil, the existing contents of the buffer are maintained."
  (lexical-let*
      ((buffer (get-buffer-create michelson-output-buffer-name))
       (message-window
        (if (get-buffer-window buffer)
            (get-buffer-window buffer)
          (display-buffer-below-selected buffer nil)))
       (lines 0))
    (when (get-buffer-window buffer)
      (set-window-dedicated-p (get-buffer-window buffer) t))
    (save-excursion
      (set-buffer michelson-output-buffer-name)
      (read-only-mode -1)
      (unless do-not-overwrite
        (erase-buffer))
      (goto-char (point-min))
      (remove-overlays)
      (if (listp data)
          (lexical-let ((michelson-highlighting t))
            (dolist (ele (reverse data))
              (lexical-let ((prev-point (point)))
                (insert ele)
                (when michelson-highlighting
                  (overlay-put (make-overlay prev-point (point))
                               'face 'michelson-stack-highlight-face))
                (setq michelson-highlighting (not michelson-highlighting)))))
        (insert data))
      (with-current-buffer buffer (michelson-stack-mode))
      (read-only-mode 1)
      (goto-char (point-min))
      (while (not (eobp))
        (vertical-motion 1)
        (setq lines (+ 1 lines)))
      (window-resize
       message-window
       (min (- (window-total-height) 5)
            (+ (- (max 4 lines)
                  (window-size message-window))
               2))))))

(defun michelson-format-stack-top (bef-ele aft-ele width)
  (lexical-let*
      ((pp-no-trailing-newline
        (lambda (sexp)
          (let* ((str (pp-to-string sexp))
                 (len (length str)))
            (if (equal "\n" (substring str (- len 1) len))
                (substring str 0 (- len 1))
              str))))
       (bef-strs (if bef-ele (split-string (funcall pp-no-trailing-newline bef-ele) "\n") '("")))
       (aft-strs (if aft-ele (split-string (funcall pp-no-trailing-newline aft-ele) "\n") '("")))
       (width width))
    (letrec ((format-strings
              (lambda (befs afts)
                (if (or befs afts)
                    (let ((aft-stack (if afts (car afts) "")))
                      (concat (format (format "%%-%ds|%s%%s\n"
                                              (/ width 2)
                                              (if (equal aft-stack "") "" "     "))
                                      (if befs (car befs) "")
                                      aft-stack)
                              (funcall format-strings (cdr befs) (cdr afts))))
                  ""))))
      (funcall format-strings bef-strs aft-strs))))


(defun michelson-format-stacks (bef-stack aft-stack)
  (letrec ((michelson-format-stacks-help
            (lambda (bef aft)
              (if (or bef aft)
                  (cons (michelson-format-stack-top (car bef) (car aft) (michelson-output-width))
                        (funcall michelson-format-stacks-help (cdr bef) (cdr aft)))
                '()))))
    (funcall michelson-format-stacks-help (reverse bef-stack) (reverse aft-stack))))

(cl-defstruct michelson-stacks
  "A pair of stacks, from `BEF' (before) and `AFT' (after) the instruction"
  bef
  aft)

(defun michelson-get-previous-stack ()
  (save-excursion
    (michelson-goto-previous-token)
    (lexical-let ((stacks nil)
                  (brace-count 0)
                  (break nil))
      (while (and (not break)
                  (not stacks)
                  (> (point) 0)
                  (>= brace-count 0))
        (backward-char)
        (cond ((and (equal (get-text-property (point) 'face)
                           'michelson-face-instruction)
                    (= brace-count 0))
               (setq break t)
               (setq stacks (michelson-stacks-at-loc (point))))
              ((equal (string (char-after (point))) "{")
               (setq brace-count (- brace-count 1)))
              ((equal (string (char-after (point))) "}")
               (setq brace-count (+ brace-count 1)))
              (t nil)))
      stacks)))


(defun michelson-completion-at-point ()
  (let ((prev-stack (michelson-get-previous-stack)))
    (if prev-stack
        (let* ((bds (bounds-of-thing-at-point 'word))
               (start (car bds))
               (end (cdr bds))
               (completion-stack (michelson-stacks-aft prev-stack))
               (instrs (michelson-get-suggestion-list completion-stack)))
          (list start end instrs . nil))
      nil)))

(defun michelson-stacks-at-loc (loc)
  (let ((types-info nil))
    (dolist (elt (cache-types michelson-cached-buffer-info))
      (when (and (<= (car elt) loc) (<= loc (cadr elt))
                 (equal (get-text-property loc 'face)
                        'michelson-face-instruction))
          (setq types-info (make-michelson-stacks :bef (caddr elt)
                                                  :aft (cadddr elt)))))
    types-info))

(defun michelson-show-program-info ()
  "Show the program's `TYPES' and `ERRORS'."
  (interactive)
  (remove-overlays)
  (lexical-let* ((stacks (michelson-stacks-at-loc (point)))
                 (types-info (and stacks (michelson-format-stacks (michelson-stacks-bef stacks)
                                                                  (michelson-stacks-aft stacks))))
                 (errors-info nil))
    (when michelson-highlight-errors
      (dolist (elt (cache-errors michelson-cached-buffer-info))
        (overlay-put (make-overlay (car elt) (cadr elt)) 'face 'michelson-face-error)
        (when (and (<= (car elt) (point)) (<= (point) (cadr elt)))
          (progn
            (when michelson-print-errors
              (unless errors-info
                (setq errors-info (concat errors-info "\n")))
              (setq errors-info (concat errors-info (cadr (cdr elt)))))))))
    (cond ((and types-info errors-info)
           (michelson-write-output-buffer errors-info nil)
           (michelson-write-output-buffer types-info t))
          (types-info
           (michelson-write-output-buffer types-info nil))
          (errors-info
           (michelson-write-output-buffer errors-info nil))
          (t (michelson-write-output-buffer "\nNo information available at point")))))

(defun michelson-type-at-point ()
  "Display the type of the expression under the cursor."
  (interactive)
  (michelson-get-info (buffer-name))
  (michelson-show-program-info))

(defun michelson-make-suggest (instr pred)
  "Suggest `INSTR' if `PRED' is not nil."
  (lexical-let ((instr instr)
                (pred pred))
    (lambda (stack)
      (if (funcall pred stack)
          (if (listp instr)
              instr
            `(,instr))
        nil))))


(defun michelson-constrained-p (var hash)
  (not (equal var (gethash var hash var))))

(defun michelson-polymorphic-match (tbl match-types stack)
  (cond ((not match-types) t)
        ((not stack) nil)
        ((and (consp match-types) (consp stack))
         (and (michelson-polymorphic-match tbl (car match-types) (car stack))
              (michelson-polymorphic-match tbl (cdr match-types) (cdr stack))))
        ((and (symbolp match-types) (symbolp stack))
         (if (and (michelson-constrained-p match-types tbl)
                  (gethash match-types tbl))
             (equal (gethash match-types tbl nil) stack)
           (progn
             (puthash match-types stack tbl)
             t)))
        (t nil)))

(defmacro forall (vars matching-stack)
  (unless (listp ',vars)
    (error "forall must take a list of vars"))
  `(lambda (stack)
     (let ((tbl (make-hash-table :test 'equal)))
       ,@(mapcar (lambda (var) `(puthash ',var ',var tbl)) vars)
       (michelson-polymorphic-match tbl ',matching-stack stack))))

(defun michelson-literals-match-p (types)
  "Generate a predicate that matches `TYPES' against the top of the stack."
  (lexical-let ((types types))
    (lambda (stack)
      (michelson-polymorphic-match
       (make-hash-table :test 'equal)
       types
       stack))))

(defun michelson-suggest-literals (instr &rest types)
  "Suggest `INSTR' when `TYPES' are on the top of the stack."
  (michelson-make-suggest
   instr
   (michelson-literals-match-p types)))
                            

(defun michelson-suggest-or (instr pred1 pred2)
  (lexical-let ((pred1 pred1)
                (pred2 pred2))
    (michelson-make-suggest
     instr
     (lambda (stack) (or (funcall pred1 stack) (funcall pred2 stack))))))

(defun michelson-suggest-reorderable (instr type1 type2)
  (michelson-suggest-or instr
                        (michelson-literals-match-p `(,type1 ,type2))
                        (michelson-literals-match-p `(,type2 ,type1))))

(defvar michelson-suggest-always-available
  '("FAIL" "PUSH" "UNIT" "LAMBDA" "NONE"
    "EMPTY_SET" "EMPTY_MAP" "NIL" "BALANCE"
    "AMOUNT" "STEPS_TO_QUOTA" "NOW"))

(defun michelson-comparable-p (type)
  "Is the `TYPE' comparable?"
  (memq type '(int nat string tez bool key timestamp)))


(defun michelson-suggest-pairs-help (pair-type accessor-prefix)
  "Suggest all possible pair accessors on the given `PAIR-TYPE' and `ACCESSOR-PREFIX'."
  (cons (concat accessor-prefix "R")
        (if (and (consp pair-type) (equal (car pair-type) 'pair))
            (let ((car-ele (cadr pair-type))
                  (cdr-ele (caddr pair-type)))
              (append
               (michelson-suggest-pairs-help car-ele
                                             (concat accessor-prefix "A"))
               (michelson-suggest-pairs-help car-ele
                                             (concat accessor-prefix "D"))
               '())))))

(defun michelson-suggest-pairs (stack)
  "Suggest all possible pair accessors on the given `STACK'."
  (if (and (consp (car stack)) (equal (caar stack) 'pair))
      (append (michelson-suggest-pairs-help (cadar stack) "CA")
              (michelson-suggest-pairs-help (caddar stack) "CD")
      nil)))

(defconst michelson-comparison-operations
  '("EQ" "NEQ" "LT" "LE" "GT" "GE"))

(defun michelson-suggest-comparable (stack)
  (let ((first (car stack))
        (second (cadr stack)))
    (if (and first
             second
             (michelson-comparable-p first)
             (equal first second))
        (cons
         "COMPARE"
         (append
          (mapcar (lambda (x) (concat "CMP" x))
                  michelson-comparison-operations)
          (mapcar (lambda (x) (concat "IFCMP" x))
                  michelson-comparison-operations)))
      '())))

(defun michelson-suggest-depth (instrs depth)
  "Suggest `INSTRS' if the stack depth is greater than or equal to `DEPTH'."
  (michelson-make-suggest
   instrs
   (lexical-let ((depth depth))
     (lambda (stack) (>= (length stack) depth)))))

(defun michelson-suggest-prefix-depth (prefix additional suffix)
  (lexical-let ((prefix prefix)
                (additional additional)
                (suffix suffix))
    (lambda (stack)
      (reverse (car (reduce
                     (lambda (acc ele)
                       (lexical-let ((existing (car acc))
                                     (prefix (concat (cdr acc) additional)))
                         (cons (cons (concat prefix suffix) existing)
                               prefix)))
                     stack
                     :initial-value (cons nil "D")))))))

(defvar michelson-type-completion-list
  (list
   (michelson-make-suggest "EXEC" (forall (arg ret) (arg (lambda arg ret))))
   (michelson-make-suggest "MEM" (forall (val-type) (val-type (set val-type))))
   (michelson-make-suggest "MEM" (forall (key-type val-type) (key-type (map key-type val-type))))
   (michelson-make-suggest "UPDATE" (forall (val-type) (val-type bool (set val-type))))
   (michelson-make-suggest "UPDATE" (forall (key-type val-type)
                                            (key-type (option val-type) (map key-type val-type))))
   (michelson-make-suggest "MAP" (forall (lt rt) ((lambda lt rt) (list lt))))
   (michelson-make-suggest "MAP" (forall (k v b) ((lambda (pair k v) b) (map k v))))
   (michelson-suggest-literals "IF" 'bool)
   (michelson-suggest-literals "LOOP" 'bool)
   (michelson-suggest-literals michelson-comparison-operations 'int)
   'michelson-suggest-comparable
   'michelson-suggest-pairs
   (michelson-suggest-prefix-depth "D" "I" "P")
   (michelson-suggest-prefix-depth "D" "U" "P")
   (lambda (stack) (and (cdr stack)
                        (funcall (michelson-suggest-prefix-depth "PA" "A" "IP") (cdr stack))))
   (michelson-suggest-literals "NOT" 'bool)
   (michelson-suggest-literals '("OR" "AND" "XOR") 'bool 'bool)
   (michelson-suggest-literals "ABS" 'int)
   (michelson-make-suggest
    '("ADD" "SUB" "MUL" "EDIV")
    (lambda (stack)
      (let ((first (car stack))
            (second (cadr stack))
            (intnat '(int nat)))
        (and first
             second
             (memq first intnat)
             (memq second intnat)))))
   (michelson-suggest-reorderable "ADD" 'nat 'timestamp)
   (michelson-suggest-literals "NOT" 'int)
   (michelson-suggest-literals '("OR" "AND" "XOR" "LSL" "LSR") 'nat 'nat)
   (michelson-suggest-literals '("CONCAT") 'string 'string)
   (michelson-suggest-depth '("SOME" "LEFT" "RIGHT") 1)
   (michelson-suggest-literals '("ADD" "SUB") 'tez 'tez)
   (michelson-suggest-reorderable '("ADD" "SUB" "MUL") 'tez 'nat)
   (michelson-suggest-literals "EDIV" 'tez 'nat)
   (michelson-suggest-literals "EDIV" 'tez 'tez)
   (michelson-suggest-literals "IMPLICIT_ACCOUNT" 'key)
   (michelson-suggest-depth "SWAP" 2)
   (michelson-suggest-depth '("DROP" "H") 1)
   (michelson-suggest-literals "CHECK_SIGNATURE" 'key '(pair signature string))
   (michelson-suggest-literals "CREATE_ACCOUNT" 'key '(option key) 'bool 'tez)
   (michelson-make-suggest "IF_NONE" (forall (x) (option x)))
   (michelson-make-suggest "IF_LEFT" (forall (x y) (or x y)))
   ;; This is not exactly the type of TRANSFER_TOKENS.
   ;; It will be changed once the concurrency model is worked out
   (michelson-make-suggest "TRANSFER_TOKENS" (forall (p r g) (p tez (contract p r) g)))
   (michelson-make-suggest
    "CREATE_CONTRACT"
    (forall (p r g) (key (option key) bool bool tez (lambda (pair p g) (pair r g)) g)))
   (michelson-make-suggest "MANAGER" (forall (p r) ((contract p r))))
   (michelson-make-suggest "CONS" (forall (a) (a (list a))))
   (michelson-make-suggest "IF_CONS" (forall (a) (list a)))
   (michelson-make-suggest "GET" (forall (k v) (k (map k v))))
   (michelson-make-suggest "UPDATE" (forall (v) (v bool (set v))))
   (michelson-make-suggest "UPDATE" (forall (k v) (k (option v) (map k v))))
   (michelson-make-suggest "REDUCE" (forall (elt b) ((lambda (pair elt b) b) (set elt) b)))
   (michelson-make-suggest "REDUCE" (forall (key val b) ((lambda (pair (pair key val) b) b) (map key val) b)))
   (michelson-make-suggest "REDUCE" (forall (a b) ((lambda (pair a b) b) (list a) b)))
   
   
))

;; Special handling
;; PA+IR


(defun michelson-get-suggestion-list (stack)
  (lexical-let ((stack stack))
    (reduce (lambda (func acc) (append (funcall func stack) acc))
            michelson-type-completion-list
            :from-end t
            :initial-value michelson-suggest-always-available)))


(defun michelson-toggle-live-editing ()
  "Toggle `michelson-live-editing'.
Enables or disables stack and error display."
  (interactive)
  (when (and michelson-live-editing
             (get-buffer michelson-output-buffer-name))
    (save-excursion
      (set-buffer michelson-output-buffer-name)
      (kill-buffer-and-window)))
  (setq michelson-live-editing (not michelson-live-editing)))


(defun michelson-update-minibuffer-info ()
  (when (nth 2 michelson-state)
    (cancel-timer (nth 2 michelson-state)))
  (setf
   (nth 2 michelson-state)
   (run-at-time
    "0.3 sec" nil
    (lambda (buffer)
      (with-current-buffer buffer
        (setf (nth 2 michelson-state) nil)
        (when (and (not (= (nth 0 michelson-state) (point)))
                   michelson-live-editing)
          (setf (nth 0 michelson-state) (point))
          (michelson-type-at-point))))
    (current-buffer))))

(defun michelson-close-output-buffer ()
  "Close the interactive editing buffer."
  (interactive)
  (let ((buffer (get-buffer michelson-output-buffer-name)))
    (when buffer
      (let ((window (get-buffer-window buffer)))
        (if window (quit-window t window) (kill-buffer buffer))))))

(define-derived-mode michelson-mode prog-mode "Michelson"
  "Major mode for editing Michelson smart contracts."
  (interactive)
  (kill-all-local-variables)
  (use-local-map michelson-mode-map)
  (set-syntax-table michelson-mode-syntax-table)
  (set
   (make-local-variable 'font-lock-defaults)
   michelson-font-lock-defaults)
  (set
   (make-local-variable 'indent-line-function)
   'michelson-indent)
  (set
   (make-local-variable 'indent-for-tab-command)
   'michelson-indent)
  (set
   (make-local-variable 'michelson-state)
   (list 0 0 nil))
  (set (make-local-variable 'michelson-cached-buffer-info)
       (make-cache :types nil
                   :errors nil))
  (add-to-list
   (make-local-variable 'pre-command-hook)
   'michelson-update-minibuffer-info)
  (add-to-list
   (make-local-variable 'focus-in-hook)
   'michelson-update-minibuffer-info)
  (add-hook 'post-self-insert-hook 'michelson-clean-cache)
  (add-hook 'kill-buffer-hook 'michelson-close-output-buffer t t)
  (setq major-mode 'michelson-mode)
  (setq mode-name "Michelson")
  (setq indent-tabs-mode nil)
  (setq show-trailing-whitespace t)
  (setq buffer-file-coding-system 'utf-8-unix)
  (add-hook 'completion-at-point-functions 'michelson-completion-at-point nil 'local)
  (setq-local company-backends '(company-capf))
  (setq-local process-environment (cons "ALPHANET_EMACS=true"
                                        (cons "TEZOS_ALPHANET_DO_NOT_PULL=yes"
                                              process-environment)))
  (run-hooks 'michelson-mode-hook))
(add-to-list 'auto-mode-alist '("\\.tz\\'" . michelson-mode))
(add-to-list 'auto-mode-alist '("\\.tez\\'" . michelson-mode))

(provide 'michelson-mode)