emacs-rpgdm/rpgdm-fate.el
2025-11-21 10:14:35 -06:00

76 lines
3.8 KiB
EmacsLisp

(defun rpgdm--fate-die ()
"Return a cons of a Fate die and its visual representation."
(seq-random-elt '((-1 . "[-]")
( 0 . "[ ]")
( 1 . "[+]"))))
(defun rpgdm--fate-roll-dice (&optional number)
"Return a list of Fate roll results. Each element of the list
is a cons of its value and its visual representation, see
`rpgdm--fate-die'."
(unless number
(setq number 4))
(let (results)
(--dotimes number
(push (rpgdm--fate-die) results))
results))
(defun rpgdm--fate-roll (modifier &optional number)
"Simulate a FATE dice roll and return the results.
Return a list where the first element is the total results,
and the second element is a user-formatted view of the results. "
(unless number (setq number 4))
(let* ((roll (rpgdm--fate-roll-dice number))
(vals (-map 'car roll))
(dice (-map 'cdr roll))
(roll (s-join " " dice))
(sum (apply '+ vals))
(total (+ sum modifier))
(results (propertize (number-to-string total) 'face '(:foreground "green"))))
(list total (format "Rolled: %s :: %s + %d" results roll modifier))))
(defun rpgdm-fate-roll (modifier)
"Simulate a FATE dice roll and display the results.
The total is the difference of the `+' to `-' plus the MODIFIER.
Note that the NUMBER of dice defaults to 4."
(interactive (list (rpgdm-fate-ladder "effort level")))
(rpgdm-message (second (rpgdm--fate-roll modifier 4))))
(let ((rpgdm-fate-ladder-values '((-2 "t" "Terrible" "Trivial") (-1 "p" "Poor" "Easy") (0 "m" "Mediocre" "Simple") (1 "a" "Average" "Average") (2 "f" "Fair" "") (3 "g" "Good" "Hard") (4 "r" "Great" "Daunting") (5 "s" "Superb" "Extreme") (6 "f" "Fantastic" "Impossible") (7 "e" "Epic" "") (8 "l" "Legendary" ""))))
(defvar rpgdm-fate-ladder rpgdm-fate-ladder-values "The FATE RPG ladder of challenge levels.")
)
(defun rpgdm-fate-ladder (&optional request-type)
"Prompt for a choice on the FATE ladder, and return the numeric value of that level.
The REQUEST-TYPE is an optional string inserted into the prompt to describe the request."
(interactive)
(unless request-type (setq request-type "challenge level"))
(let* ((choices (mapconcat 'rpgdm--fate-ladder-prompt rpgdm-fate-ladder " "))
(prompt (format "What is the %s?\n%s"
(propertize request-type 'face '(:foreground "yellow"))
choices))
(choice (char-to-string (read-char prompt)))
(entry (--filter (equal (second it) choice) rpgdm-fate-ladder)))
(first (first entry))))
(defun rpgdm--fate-ladder-prompt (entry)
(let* ((entry-number (format "[%d]" (first entry)))
(render-number (propertize entry-number
'face '(:foreground "#888888")))
(keyed-prompt (propertize (second entry) 'face '(:foreground "green"))))
(format "%s) %s %s" keyed-prompt (third entry) render-number))))
(defun rpgdm-fate-challenge (opposition-level effort-level)
"Return a user message for a FATE dice challenge.
Given a numeric EFFORT-LEVEL as well as the OPPOSITION-LEVEL,
this function rolls the Fate dice and interprets the results."
(interactive (list (rpgdm-fate-ladder "opposition level")
(rpgdm-fate-ladder "effort level")))
(let* ((die-roll (rpgdm--fate-roll effort-level))
(shifts (- (first die-roll) opposition-level))
(results (cond
((< shifts 0) (propertize "Failed" 'face '(:foregound "red")))
((= shifts 0) (propertize "Tie" 'face '(:foreground "yellow")))
((> shifts 3) (propertize "Succeed with Style!" 'face '(:foregound "green")))
(t (propertize "Success" 'face '(:foregound "green"))))))
(rpgdm-message "%s ... %s" results (second die-roll))))