;;; R7RS-PNM --- Library for reading and writing PNM (Portable Any Map) files for R7RS
;;; Copyright © 2024 Masaya Tojo <masaya@tojo.tokyo>
;;;
;;; This file is part of R7RS-PNM.
;;;
;;; R7RS-PNM is free software: you can redistribute it and/or modify it
;;; under the terms of the GNU Lesser General Public License as published
;;; by the Free Software Foundation, either version 3 of the License, or
;;; (at your option) any later version.
;;;
;;; R7RS-PNM is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public License
;;; along with R7RS-PNM. If not, see <https://www.gnu.org/licenses/>.

(define-library (pnm write)
  (export image-write)
  (import (scheme base)
          (pnm image))
  (begin
    (define (image-write image out)
      (define (write-string-u8 str)
        (string-for-each (lambda (c) (write-u8 (char->integer c) out))
                         str))
      (case (image-type image)
        ((ppm)
         (write-string-u8 "P6\n"))
        ((pgm)
         (write-string-u8 "P5\n"))
        ((pbm)
         (write-string-u8 "P4\n"))
        (else
         (error "(pnm write) pnm-write: Not supported type" (image-type image))))
      (write-string-u8 (number->string (image-width image)))
      (write-string-u8 "\n")
      (write-string-u8 (number->string (image-height image)))
      (write-string-u8 "\n")
      (case (image-type image)
        ((pgm ppm)
         (write-string-u8 (number->string (image-maxval image)))
         (write-string-u8 "\n")))
      (write-bytevector (image-data image) out))))