; bugs:
;#16> (fmt "{x} x {")
;exception! <class 'NameError'> name 'ev' is not defined


(func .fmt-parse (str cur)
    (branch
        ((eq? 0 (length str)) cur)
        ((eq? "{" (first str))
            (block
                (def tmp (.brace-parse (rest str) ""))
                (.fmt-parse (first tmp) (concat cur (first (rest tmp))))))
        (#true (.fmt-parse (rest str) (concat cur (first str))))))

(func .brace-parse :[:string] (str :string cur :string)
    ; returns (remaining value)
    (branch
        ((eq? "}" (first str))
            (list (rest str) (->string (eval (first (parse-neb cur))))))
        ((eq? "," (first str))
            (.special-parse (rest str) "" (->string (eval (first (parse-neb cur))))))
        (#true
            (.brace-parse (rest str) (concat cur (first str))))))

(func .special-parse (str cur val)
    (if (eq? "}" (first str))
        (block
            ; [align][width] (to start)
            (def align-width
                (if (in? (first cur) (split "^<>"))
                    (list (first cur) (string->int (rest cur)))
                    (list "<" (string->int cur))))
            (branch
                ((>= (length val) (last align-width))
                    (list (rest str) val))
                ((eq? "<" (first align-width))  ; align left
                    (list (rest str) (concat val (.repeat (- (last align-width) (length val))))))
                ((eq? ">" (first align-width))  ; align right
                    (list (rest str) (concat (.repeat (- (last align-width) (length val))) val)))
                (#true  ; align center
                    (block
                        (def half (/ (- (last align-width) (length val)) 2))
                        (if (int? half)
                            (list (rest str) (concat (.repeat half) val (.repeat half)))
                            (list (rest str) (concat (.repeat (floor half)) val (.repeat (+ 1 (floor half))))))))))

        (.special-parse (rest str) (concat cur (first str)) val)))

(func .repeat (cnt)
    (def out "")
    (for-count cnt
        (redef out (concat out " ")))
    out)

(func fmt :string (inp :string)
    ; { <neb code> [, [[^<>][:digits:]]]}
    (.fmt-parse inp ""))