;;; guix-forge --- Guix software forge meta-service
;;; Copyright © 2022 Arun Isaac <arunisaac@systemreboot.net>
;;;
;;; This file is part of guix-forge.
;;;
;;; guix-forge is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published
;;; by the Free Software Foundation, either version 3 of the License,
;;; or (at your option) any later version.
;;;
;;; guix-forge 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
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with guix-forge.  If not, see
;;; <https://www.gnu.org/licenses/>.

(define-module (doc skribilo)
  #:use-module (rnrs conditions)
  #:use-module (rnrs io ports)
  #:use-module (srfi srfi-28)
  #:use-module (ice-9 match)
  #:use-module (ice-9 regex)
  #:use-module (skribilo ast)
  #:use-module (skribilo engine)
  #:use-module (skribilo lib)
  #:use-module (skribilo writer)
  #:use-module (skribilo package base)
  #:use-module (skribilo parameters)
  #:use-module (skribilo source lisp)
  #:use-module (skribilo utils keywords)
  #:export (file
            command
            scheme-source
            scheme-source-form
            source-ref))

;; Constants
(define %source-uri-base
  "https://git.systemreboot.net/guix-forge/tree/")

;; Aliases
(define file samp)
(define command code)

;; Abbreviations
(define-markup (abbr #:rest opts
		     #:key (ident #f) (class "abbr") (short #f) (long #f))
  (new container
       (markup 'abbr)
       (ident (or ident (symbol->string (gensym "abbr"))))
       (class class)
       (loc &invocation-location)
       (required-options '(#:short #:long))
       (options `((#:short ,short)
		  (#:long ,long)
		  ,@(the-options opts #:ident #:class #:short #:long)))
       (body (the-body opts))))

;; S-exp source links
(define (source-uri file start-line end-line)
  "Return a URI referring to source FILE from START-LINE to END-LINE."
  (string-append %source-uri-base
                 file
                 "#n"
                 (number->string start-line)))

(define (sexp-position str regexp)
  "Return (START . END) where START is the start of the match to
REGEXP in STR and END is the end of the sexp beginning at START. START
and END are character positions indexed from 0. If multiple matches
are found, error out."
  (cond
   ((string-match regexp str)
    => (lambda (match-struct)
         (let ((start (match:start match-struct)))
           (if (string-match regexp (substring str (1+ start)))
               (raise-exception (condition (make-message-condition
                                            (format "source-ref: regexp ~s found on multiple lines"
                                                    regexp))
                                           (make-irritants-condition regexp)))
               (cons start
                     (1- (- (string-length str)
                            (string-length
                             (call-with-input-string (substring str start)
                               (lambda (port)
                                 (read port)
                                 (get-string-all port)))))))))))
   (else
    (raise-exception (condition (make-message-condition
                                 (format "source-ref: regexp ~s not found" regexp))
                                (make-irritants-condition regexp))))))

(define (position->line-number str position)
  "Return the line number in STR corresponding to POSITION."
  (string-fold (lambda (c result)
                 (if (char=? c #\newline)
                     (1+ result)
                     result))
               1
               (substring str 0 position)))

(define (sexp-file-lines file regexp)
  "Return (START . END) where START is the start of the match to
REGEXP in STR and END is the end of the sexp beginning at START. START
and END are line numbers indexed from 1."
  (let ((str (call-with-input-file file get-string-all)))
    (match (sexp-position str regexp)
      ((start . end)
       (cons (position->line-number str start)
             (position->line-number str end))))))

(define (source-ref file regexp text)
  "Link to S-expression in FILE whose beginning matches REGEXP. TEXT
is the text of the link."
  (ref #:url (match (sexp-file-lines (search-path (*source-path*) file)
                                     regexp)
               ((start-line . end-line)
                (source-uri file start-line end-line)))
       #:text text))

;; Extract forms from scheme source
(define (scheme-source-form file regexp)
  "Extract form from scheme source FILE whose beginning matches
REGEXP. Return it enclosed in a prog form."
  (prog (match (sexp-file-lines (search-path (*source-path*) file)
                                regexp)
          ((start . stop)
           (source #:language scheme
                   #:file file
                   #:start (1- start)
                   #:stop (1- stop))))
        #:line #f))

;; HTML engine customizations
(let ((html-engine (find-engine 'html)))
  (engine-custom-set! html-engine 'css "/style.css")
  (engine-custom-set! html-engine 'charset "UTF-8")
  (markup-writer 'abbr html-engine
                 #:options '(#:short #:long)
                 #:action (lambda (markup engine)
                            (display (format "<abbr title=\"~a\">~a</abbr> (~a)"
                                             (markup-option markup #:long)
                                             (markup-option markup #:short)
                                             (markup-option markup #:long))
                                     (current-output-port)))))