From 1597a9960128a7ef5c9daa467ddaaa14fda34e7a Mon Sep 17 00:00:00 2001
From: Lucas Wollenhaupt <lucas@Lucas-MacBook-Pro.local>
Date: Tue, 19 Mar 2019 16:34:43 +0100
Subject: [PATCH] ValidatePackageInfo accepts date format yyyy-mm-dd

If the date format is dd/mm/yyyy and InfoLevel InfoPackageLoading is set to at least 2 it prints a hint to change the format.

Add validity check for dates
---
 lib/package.gi | 39 +++++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/lib/package.gi b/lib/package.gi
index 9dbd5eea1f4..ea226e9f671 100644
--- a/lib/package.gi
+++ b/lib/package.gi
@@ -2118,7 +2118,7 @@ InstallGlobalFunction( DeclareAutoreadableVariables,
 InstallGlobalFunction( ValidatePackageInfo, function( info )
     local record, pkgdir, i, IsStringList, IsRecordList, IsProperBool, IsURL,
           IsFilename, IsFilenameList, result, TestOption, TestMandat, subrec,
-          list;
+          list, date, CheckDateValidity;
 
     if IsString( info ) then
       if IsReadableFile( info ) then
@@ -2186,9 +2186,40 @@ InstallGlobalFunction( ValidatePackageInfo, function( info )
         x -> IsString(x) and 0 < Length(x) and x[1] <> '=',
         "a nonempty string that does not start with `='" );
     TestMandat( record, "Date",
-        x -> IsString(x) and Length(x) = 10 and x{ [3,6] } = "//"
-                 and ForAll( x{ [1,2,4,5,7,8,9,10] }, IsDigitChar ),
-        "a string of the form `dd/mm/yyyy'" );
+        x -> IsString(x) and Length(x) = 10
+          and ( ( x{ [3,6] } = "//" and ForAll( x{ [1,2,4,5,7,8,9,10] }, IsDigitChar ) )
+          or ( x{ [5,8] } = "--" and ForAll( x{ [1,2,3,4,6,7,9,10] }, IsDigitChar ) ) ) ,
+        "a string of the form `yyyy-mm-dd` or `dd/mm/yyyy`" );
+
+    #If the date is in the format `dd/mm/yyyy` a message is printed
+    if IsBound( record.Date ) and  record.Date{ [3,6] } = "//" then
+       Info( InfoPackageLoading, 2, Concatenation(record.PackageName, ": Please be adviced to change the date format to `yyyy-mm-dd`"));
+    fi;
+
+    #check if the date is valid
+    CheckDateValidity := function(x)
+      if x{ [3,6] } = "//" then
+        date := List( SplitString( x, "/" ), Int);
+            if not (date[1] in [1..31] and
+                   date[2] in [1..12] and
+                   date[3] > 1999 and # GAP 4 appeared in 1999
+                   date[1] <= DaysInMonth( date[2], date[3] )) then
+              return false;
+            fi;
+      elif x{ [5,8] } = "--" then
+        date := List( SplitString( date, "-" ), Int);
+              if not (date[3] in [1..31] and
+                    date[2] in [1..12] and
+                    date[1] > 1999 and # GAP 4 appeared in 1999
+                    date[3] <= DaysInMonth( date[2], date[1] )) then
+                return false;
+              fi;
+      fi;
+    return true;
+    end;
+    TestMandat( record, "Date", 
+      x -> IsString(x) and CheckDateValidity(x), "a valid date");
+
     TestMandat( record, "ArchiveURL", IsURL, "a string started with http://, https:// or ftp://" );
     TestMandat( record, "ArchiveFormats", IsString, "a string" );
     TestOption( record, "TextFiles", IsStringList, "a list of strings" );