;;; p11k.el --- PowerLevel10k prompt for Eshell      -*- lexical-binding: t; -*-

;; Copyright (C) 2023 Mitchell Marquez

;; Author: Mitchell Marquez <dr.m.perseos@gmail.com>
;; Keywords: terminals, convenience, faces
;; Package-Requires: ((dash) (all-the-icons) (eshell-prompt-extras) (f) (shrink-path))

;;; Commentary:
;; PowerLevel10k prompt theme for Eshell.  Tries to emulate everything but may
;; be broken.

;;; Bugs:
;; - styles other than Lean not implemented
;; - right-aligned elements (time display) get pushed to new line when `word-wrap' t

;;; Code:
(require 'f)
(require 'dash)
(require 'eshell-prompt-extras)
(require 'shrink-path)

(defvar p11k/eol-marker "‌") ;; zero width non-joiner, 8204

(defgroup p11k nil
  "PowerLevel11k Prompt for Eshell."
  :group 'eshell
  :prefix "p11k/")

(defcustom p11k/use-transient-prompt t
  "Whether to enable `transient-prompt' for p11k."
  :group 'p11k
  :type 'boolean) ;; or nil to disable transient-prompt

(defcustom p11k/prompt-style 'lean
  "Style of PowerLevel11k Eshell prompt."
  :group 'p11k
  :type '(choice
	  (const :tag "Lean" lean)
	  (const :tag "Classic" classic)
	  (const :tag "Rainbow" rainbow)
	  (const :tag "Pure" pure)))
(defcustom p11k/use-unicode nil
  "Whether or not to use Unicode characters in PowerLevel11k Eshell prompt."
  :group 'p11k
  :type 'boolean)
(defcustom p11k/prompt-color-level 2
  "Darkness of the prompt background for PowerLevel11k."
  :group 'p11k
  :type '(choice
	  (const :tag "Lightest" 1)
	  (const :tag "Light" 2)
	  (const :tag "Dark" 3)
	  (const :tag "darkest" 4)))
(defcustom p11k/show-current-time 12
  "Format of time display, or nil for no time."
  :group 'p11k
  :type '(choice
	  (const :tag "No" nil)
	  (const :tag "24-hour format" 24)
	  (const :tag "12-hour format" 12)))
(defcustom p11k/prompt-segment-separator-type 'angled
  "Type of separator between p11k prompt segments."
  :group 'p11k
  :type '(choice
	  (const :tag "Angled" angled)
	  (const :tag "Vertical" vertical)
	  (const :tag "Slanted" slanted)
	  (const :tag "Round" round))) ;; Only when unicode=t (?)
(defcustom p11k/prompt-segment-head-type 'slanted
  "Type of head character to put on the inner ends of p11k prompt."
  :group 'p11k
  :type '(choice
	  (const :tag "Sharp" sharp)
	  (const :tag "Blurred" blurred)
	  (const :tag "Slanted" slanted)
	  (const :tag "Round" round))) ;; Only when unicode=t (?)
(defcustom p11k/prompt-segment-tail-type 'slanted
  "Type of tail character to put on the outer ends of p11k prompt."
  :group 'p11k
  :type '(choice
	  (const :tag "Flat" flat)
	  (const :tag "Blurred" blurred)
	  (const :tag "Sharp" sharp)
	  (const :tag "Slanted" slanted)
	  (const :tag "Round" round))) ;; Only when unicode=t (?)
(defcustom p11k/prompt-height 2
  "Whether to use one or two lines for p11k prompt."
  :group 'p11k
  :type '(choice
	  (const :tag "One line" 1)
	  (const :tag "Two Lines" 2)))
(defcustom p11k/prompt-segment-connection 'disconnected
  "What style of connector, if any, to draw between p11k prompt segments."
  :group 'p11k
  :type '(choice
	  (const :tag "Disconnected" disconnected)
	  (const :tag "Dotted" dotted)
	  (const :tag "Solid" solid)))
(defcustom p11k/prompt-frame 'full
  "Which side of the window to put a frame between p11k prompt segments."
  :group 'p11k
  :type '(choice
	  (const :tag "No frame" nil)
	  (const :tag "Left" left)
	  (const :tag "Right" right)
	  (const :tag "Full" full)))
(defcustom p11k/prompt-spacing 'compact
  "How much distance to put between consecutive prompts and command outputs."
  :group 'p11k
  :type '(choice
	  (const :tag "Compact" compact)
	  (const :tag "Sparse" sparse)))
(defcustom p11k/use-icons nil
  "Whether to use icons in the p11k prompt."
  :group 'p11k
  :type 'boolean) ;; or t for "many" icons
(defcustom p11k/prompt-flow 'concise
  "Whether to put prepositions and adjectives around p11k segments."
  :group 'p11k
  :type '(choice
	  (const :tag "Concise (fewer words)" concise)
	  (const :tag "Fluent (more words)" fluent)))
(defvar p11k/prompt-caret (if p11k/use-unicode
			      "❯" ">"))
(defvar p11k/prompt-caret-alist
  (if p11k/use-unicode
      '((insert . "❯")
	(normal . "❮")
	(visual . "") ;from nerd-icons
	)
    '((insert . ">")
      (normal . "<")
      (visual . "V"))))
(defvar p11k/unwritable-icon (if p11k/use-unicode
				 "" "!w"))
(defvar p11k/last-prompt-bound 0) ;; internal variable

(defface p11k/green '((t (:foreground "green")))
  "Face for \"green\" parts of p11k prompt and git status segment.")
(defface p11k/yellow '((t (:foreground "yellow")))
  "Face for \"yellow\" parts of p11k prompt and git status segment.")
(defface p11k/blue '((t (:foreground "blue")))
  "Face for \"blue\" parts of p11k prompt and git status segment.")
(defface p11k/red '((t (:foreground "red")))
  "Face for \"red\" parts of p11k prompt and git status segment.")
(defface p11k/cyan '((t (:foreground "cyan")))
  "Face for \"cyan\" parts of p11k prompt.")

(defun p11k/setup-git-status ()
  "Declare variables and faces for git info in p11k prompt."
  (face-spec-set 'gitstatus-clean-face '((t (:inherit 'p11k/green))))
  (face-spec-set 'gitstatus-modified-face '((t (:inherit 'p11k/yellow))))
  (face-spec-set 'gitstatus-untracked-face '((t (:inherit 'p11k/blue)))))
(defun p11k/spaced-concat (&rest strings)
  (string-trim-left
   (mapconcat
    (lambda (str) (format " %s" str))
    strings)))
;; (p11k/spaced-concat "one" "two" (propertize "five" 'face 'p11k/yellow))

(defun p11k/format-directory (dir &optional maxwidth)
  "Format DIR for use in p11k Eshell prompt.  Returneth a string.

if MAXWIDTH is non-nil, abbreviate."
  (let* ((writable-symbol (if (file-writable-p dir) "" p11k/unwritable-icon))
	 (dir (string-replace (getenv "HOME") "~" dir)))
    (p11k/spaced-concat
     writable-symbol
     (if (or maxwidth (>= (* 2 (length dir)) (window-text-width)))
	 (shrink-path-dirs dir) dir))))

(defun p11k/caret-color-status (status)
  "Return the propertized `p11k/prompt-caret', according to STATUS."
  (let ((facecolor (if (zerop status) 'p11k/green 'p11k/red)))
    (propertize (format "%s" (alist-get (p11k/get-modal-status) p11k/prompt-caret-alist))
		'face facecolor)))
(defun p11k/get-modal-status ()
  (if (bound-and-true-p meow--current-state)
      meow--current-state
    evil-state))

(defvar p11k/sep-str-alist
  '((angled   . (""   . ""))
    (sharp    . (""   . ""))
    (vertical . (""    . ""))
    (flat     . (""    . ""))
    (slanted  . (""   . ""))
    (round    . (""   . ""))
    (blurred  . ("▓▒░" . "░▒▓")))
  "Alist of separator names and their canonical string appearances.

Each string appearance is a cons cell corresponding with the left-handed form as
the car and right-handed form as the cdr.")

(defun p11k/get-sep-char (sym &optional direction)
  "Given symbol SYM name of a prompt style, return matching string.

Corresponds with DIRECTION in only a specific idealized context.  If DIRECTION
is omitted, just return the cons of bolth."
  (let ((symcons (alist-get sym p11k/sep-str-alist))
	(getter (if (eq direction 'left) #'car #'cdr)))
    (if direction
	(funcall getter symcons)
      symcons)))

(defun p11k/status-formatter (timestamp duration)
  "Return status display for `epe-status'.  Replaceth `epe-status-formatter'.

TIMESTAMP is the value returned by `current-time' and DURATION is the floating
time the command took to complete in seconds.

Outputteth a string."
  ;; TIMESTAMP is irrelevant for us
  (let ((durstring (format "%.3fs" duration)))
    (p11k/spaced-concat
     (if (eq p11k/prompt-flow 'fluent) "took" "")
     (propertize durstring 'face 'p11k/yellow))))

(defun p11k/justificate (left-items right-items)
  "Concatenate LEFT-ITEMS and RIGHT-ITEMS with a gap between.
Use 'window-width' to calculate the total final width."
  (let* ((left-str (eval `(p11k/spaced-concat ,@left-items)))
	 (right-str (eval `(p11k/spaced-concat ,@right-items)))
	 (left-length (length left-str))
	 (right-length (length right-str))
	 (middle-spc (- (window-width nil 'remap) (+ left-length right-length))))
    (concat left-str (make-string middle-spc (string-to-char " ")) right-str)))
;; (eval `(concat ,@'("one" "two")))
;; (p11k/justificate '("one" "wto" "three") '("twenty" "23" "forthy-three"))

(defun p11k/git-status ()
  "Return propertized git information."
  (if (file-exists-p ".git")
      (let* ((status-alist
	      (--> "git status -s"
		   (shell-command-to-string it)
		   (split-string it "\n" 'omit-nulls search-whitespace-regexp)
		   (if it
		       (--map (let ((parts (split-string it)))
				(cons (car parts) (cadr parts)))
			      it) nil)))
	     (branch (--> "git branch"
			  (shell-command-to-string it)
			  (split-string it "\n" 'omit-nulls search-whitespace-regexp)
			  (if it (progn
				   (--filter (string-match-p (rx bol "* " (+ word)) it) it)
				   (split-string (car it))
				   (cadr it))
			    "")))
	     (modcount (--> status-alist
			    (--map (car it) it)
			    (--count (string-match-p "M" it) it)
			    (if (not (= it 0))
				(format "!%s" it)
			      nil)))
	     (untracked (--> status-alist
			     (--map (car it) it)
			     (--count (string-match-p "\\?\\?" it) it)
			     (if (not (= it 0))
				 (format "?%s" it)
			       nil))))
	(p11k/spaced-concat
	 (if (eq p11k/prompt-flow 'fluent) "on" "")
	 (propertize branch 'face 'p11k/green)
	 (if modcount (propertize modcount 'face 'p11k/yellow) "")
	 (if untracked (propertize untracked 'face 'p11k/blue) "")))
    ""))

(defun p11k/prompt ()
  "Return the propertized face for p11k Eshell prompt."
  (let ((sparsity (if (eq p11k/prompt-spacing 'sparse) "\n" ""))
	(directory (propertize (format "%s" (p11k/format-directory default-directory))
			       'face 'p11k/blue))
	(timedisp
	 (if p11k/show-current-time
	     (p11k/spaced-concat
	      (if (eq p11k/prompt-style 'fluent) "at" "")
	      (propertize (pcase p11k/show-current-time
			    (12 (format-time-string "%I:%M:%S %p"))
			    (24 (format-time-string "%H:%M:%S"))
			    (t "[bad time type]"))
			  'face 'p11k/cyan))
	   ""))
	(status-str (epe-status #'p11k/status-formatter)))
    (p11k/justificate
     `(,sparsity
       ,directory
       ,(p11k/git-status))
     ;; justificate after this
     `(,(concat p11k/eol-marker
		(p11k/spaced-concat
		 status-str
		 timedisp)
		"\n"
		(p11k/caret-color-status eshell-last-command-status)
		" ")))))

(defun p11k/modal-caret (&optional throwaway)
  "Toggle the direction that the prompt points according to `p11k/get-modal-status'."
  (save-match-data
    (save-mark-and-excursion
      (let ((inhibit-read-only t)
	    (new-caret
	     (p11k/caret-color-status
	      eshell-last-command-status)))
	(goto-char (point-max))
	(re-search-backward eshell-prompt-regexp)
	(goto-char (point-at-bol))
	(delete-forward-char 1)
	(insert new-caret))
      )))

(defun p11k/esh-transient-prompt ()
  "Delete the first line of a multi-line eshell prompt.

To be run before every eshell command."
  (if p11k/use-transient-prompt
      (save-match-data
	(save-excursion
	  (setq p11k/last-prompt-bound
		(or (ignore-errors (search-backward p11k/eol-marker nil t))
		    (point-min)))
	  (let ((inhibit-read-only t))
	    (delete-line))))))

(defun p11k/disable ()
  "Turn off p11k and restore the old prompt."
  (remove-hook 'eshell-pre-command-hook #'p11k/esh-transient-prompt)
  (remove-hook 'eshell-mode-hook #'p11k/setup-git-status)
  (setq-default eshell-prompt-function p11k/old-eshell-prompt-function)
  (setq-default eshell-prompt-regexp p11k/old-eshell-prompt-regexp))

;;;###autoload
(progn
  (defun p11k/init ()
    "Run setup functions for p11k."
    (require 'p11k)
    (if p11k/use-transient-prompt
	(add-hook 'eshell-pre-command-hook #'p11k/esh-transient-prompt))
    (p11k/setup-git-status)
    (defvar p11k/old-eshell-prompt-function eshell-prompt-function)
    (defvar p11k/old-eshell-prompt-regexp eshell-prompt-regexp)
    (setq eshell-prompt-function #'p11k/prompt)
    (if (featurep 'meow)
	(add-hook 'meow-switch-state-hook #'p11k/modal-caret nil 'local)
      (if (featurep 'evil)
	  (progn
	    (add-hook 'evil-insert-state-entry-hook #'p11k/modal-caret nil 'local)
	    (add-hook 'evil-normal-state-entry-hook #'p11k/modal-caret nil 'local)
	    (add-hook 'evil-visual-state-entry-hook #'p11k/modal-caret nil 'local))))
    (setq eshell-prompt-regexp
	  (rx bol
	      (regexp (eval `(rx ,(cons 'or (mapcar #'cdr p11k/prompt-caret-alist)))))
	      " ")))
  (define-minor-mode p11k-mode
    "PowerLevel11k Prompt for Eshell."
    :lighter " p11k"
    :require 'p11k
    (p11k/init)))

(provide 'p11k)
;;; p11k.el ends here