From 452e29ff7f6502cef3f5f4d1c49a2cb92face209 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonyg@leastfixedpoint.com>
Date: Fri, 4 Jun 2021 16:39:54 +0200
Subject: [PATCH] fixcopyright: only change tracked files by default

---
 fixcopyright.rkt | 50 ++++++++++++++++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 12 deletions(-)

diff --git a/fixcopyright.rkt b/fixcopyright.rkt
index 8bb565e..d0b71db 100755
--- a/fixcopyright.rkt
+++ b/fixcopyright.rkt
@@ -14,7 +14,14 @@
 
 (define (get-git-config key)
   (string-trim (with-output-to-string
-                 (lambda () (system (format "git config --get ~a" key))))))
+                 (lambda () (system* "/usr/bin/env" "git" "config" "--get" key)))))
+
+(define (is-tracked? f)
+  (call-with-output-file "/dev/null" #:exists 'append
+    (lambda (sink)
+      (parameterize ((current-error-port sink)
+                     (current-output-port sink))
+        (system* "/usr/bin/env" "git" "ls-files" "--error-unmatch" f)))))
 
 (define user-name (get-git-config "user.name"))
 (define user-email (get-git-config "user.email"))
@@ -29,9 +36,15 @@
 (define total-file-count 0)
 (define total-changed-files 0)
 (define dry-run? #f)
+(define modify-untracked? #f)
 
-(define (fix-files file-type-name file-pattern front-matter-re leading-comment-re comment-prefix)
-  (define matched-files (glob file-pattern))
+(define (fix-files #:file-type-name file-type-name
+                   #:file-pattern file-pattern
+                   #:front-matter-re [front-matter-re #f]
+                   #:leading-comment-re leading-comment-re
+                   #:comment-prefix comment-prefix
+                   #:file-filter [file-filter (lambda (x) #t)])
+  (define matched-files (filter file-filter (glob file-pattern)))
   (define file-count (length matched-files))
   (define changed-files 0)
   (for [(file-number (in-naturals))
@@ -72,17 +85,21 @@
                                  (make-copyright user low this-year))]
                           [_ l]))
                       head))
-           (head (map (lambda (l) (string-append comment-prefix
-                                                 (match l
-                                                   [(list #f v) v]
-                                                   [(list k v) (format "~a: ~a" k v)])))
+           (head (map (lambda (l)
+                        (if (string=? (cadr l) "")
+                            (string-trim comment-prefix)
+                            (string-append comment-prefix
+                                           (match l
+                                             [(list #f v) v]
+                                             [(list k v) (format "~a: ~a" k v)]))))
                       head))
            (new-lines `(,@front-matter
                         ,@head
                         ""
                         ,@(dropf tail (lambda (l) (string=? (string-trim l) "")))))
-           (changed? (not (equal? all-lines new-lines))))
-      (when (and changed? (not dry-run?))
+           (would-change-if-written? (not (equal? all-lines new-lines)))
+           (write-needed? (and would-change-if-written? (or modify-untracked? (is-tracked? f)))))
+      (when (and write-needed? (not dry-run?))
         (call-with-atomic-output-file
          f
          (lambda (port _tmp-path)
@@ -90,7 +107,7 @@
            (for [(l head)] (displayln l port))
            (newline port)
            (for [(l (dropf tail (lambda (l) (string=? (string-trim l) ""))))] (displayln l port)))))
-      (if changed?
+      (if write-needed?
           (begin (set! changed-files (+ changed-files 1))
                  (printf "\e[41mchanged\e[0m\n"))
           (printf "\r\e[K"))))
@@ -101,9 +118,16 @@
 
 (command-line #:once-each
               [("-n" "--dry-run") "Do not write back changes to files"
-               (set! dry-run? #t)])
+               (set! dry-run? #t)]
+              [("--modify-untracked") "Modify files not tracked by git as well as those that are"
+               (set! modify-untracked? #t)])
+
+(void (fix-files #:file-type-name "Racket"
+                 #:file-pattern "**.rkt"
+                 #:front-matter-re #px"^#"
+                 #:leading-comment-re #px"^;+ *"
+                 #:comment-prefix ";;; "))
 
-(void (fix-files "Racket" "**.rkt" #px"^#" #px"^;+ *" ";;; "))
 (printf "fixcopyright: ~a files examined, ~a ~a\n"
         total-file-count
         total-changed-files
@@ -114,5 +138,7 @@
             (if (zero? total-changed-files)
                 "changes were needed"
                 "files were updated")))
+
 (void (system "chmod a+x fixcopyright.rkt"))
+
 (exit (if (positive? total-changed-files) 1 0))