;;
;; ansi.scm
;;
;; ANSI terminal support.
;;
;; ISC License
;;
;; Copyright 2023 Brmlab, z.s.
;; Dominik Pantůček <dominik.pantucek@trustica.cz>
;;
;; Permission to use, copy, modify, and/or distribute this software
;; for any purpose with or without fee is hereby granted, provided
;; that the above copyright notice and this permission notice appear
;; in all copies.
;; 
;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
;;

(declare (unit ansi))

(module
 ansi
 (
  ansi
  a:error
  a:warning
  a:success
  a:neutral
  a:default
  a:muted
  a:highlight
  ansi-string-length
  ansi-tests!
  )

 (import scheme
	 (chicken base)
	 (chicken string)
	 (chicken irregex)
	 testing
	 utils)

 ;; Only basic ANSI colors and bold attribute support.
 (define colors
   '((#:black . 30)
     (#:red . 31)
     (#:green . 32)
     (#:yellow . 33)
     (#:blue . 34)
     (#:magenta . 35)
     (#:cyan . 36)
     (#:white . 37)
     (#:default . 0)
     (#:bold . 1)))

 ;; Returns ANSI sequence changing color and/or bold attribute.
 (define (ansi . args)
   (let ((argsl
	  (map
	   (lambda (key-color)
	     (number->string (cdr key-color)))
	   (filter
	    identity
	    (map (lambda (arg) (assq arg colors)) args)))))
     (if (null? argsl)
	 ""
	 (string-append "\x1b["
			(string-intersperse argsl ";")
			"m"))))

 ;; Nice styles to be used everywhere for consistency
 (define a:error (ansi #:red #:bold))
 (define a:warning (ansi #:default #:yellow))
 (define a:success (ansi #:green #:bold))
 (define a:neutral (ansi #:default #:white))
 (define a:default (ansi #:default))
 (define a:muted (ansi #:black #:bold))
 (define a:highlight (ansi #:blue #:bold))

 ;; Returns visual string length in characters skipping any ANSI CSI
 ;; SGR sequences.
 ;;
 ;; Internal states:
 ;; 0 - regular string
 ;; 1 - seen escape
 ;; 2 - CSI started
 (define (ansi-string-length str)
   (let loop ((lst (irregex-extract (irregex "." 'u) str))
	      (state 0)
	      (len 0))
     (if (null? lst)
	 len
	 (let ((ch (car lst)))
	   (case state
	     ((0) (if (equal? ch "\x1b")
		      (loop (cdr lst) 1 len)
		      (loop (cdr lst) 0 (add1 len))))
	     ((1) (if (equal? ch "[")
		      (loop (cdr lst) 2 len)
		      (loop (cdr lst) 0 len)))
	     ((2) (if (equal? ch "m")
		      (loop (cdr lst) 0 len)
		      (loop (cdr lst) 2 len))))))))

 ;; Performs ANSI module self-tests.
 (define (ansi-tests!)
   (run-tests
    ansi
    (test-equal? ansi (ansi #:red) "\x1b[31m")
    (test-equal? ansi (ansi #:nonsense) "")
    (test-equal? ansi (ansi #:default) "\x1b[0m")
    (test-eq? ansi-string-length (ansi-string-length "test") 4)
    (test-eq? ansi-string-length (ansi-string-length "\x1b[1mtest") 4)
    (test-eq? ansi-string-length (ansi-string-length "\x1b[30mtest\x1b[0m") 4)
    (test-eq? ansi-string-length (ansi-string-length "\x1b[30mščřž\x1b[0m") 4)
    ))

 )