#!/usr/bin/perl

# Transform RELEASE_NOTES, split into "leader", and "major changes",
# split into major categories, and prepend dates to paragraphs.
#
# Input format: the leader text is copied verbatim; each section
# starts with "Incompatible changes with snapshot YYYYMMDD" or "Major
# changes with snapshot YYYYMMDD" underlined with "=======..."; each
# paragraph starts with [class, class] where a class specifies one or
# more categories that the change should be listed under. Adding class
# info is the only manual processing needed to go from a RELEASE_NOTES
# file to the transformed representation.
#
# Output format: each category is printed with a little header and each
# paragraph is tagged with [Incompat yyyymmdd] or with [Feature yyyymmdd].

%leader = (); %body = ();
$append_to = \%leader;

while (<>) {

    if (/^(Incompatible changes|Incompatibility) with/) {
	die "No date found: $_" unless /(\d\d\d\d\d\d\d\d)/;
	$append_to = \%body;
	$prefix = "[Incompat $1] ";
	while (<>) {
	    last if /^====/;
	}
	next;
    }

    if (/^Major changes with/) {
	die "No date found: $_" unless /(\d\d\d\d\d\d\d\d)/;
	$append_to = \%body;
	$prefix = "[Feature $1] ";
	while (<>) {
	    last if /^====/;
	}
	next;
    }

    if (/^\s*\n/) {
	if ($paragraph) {
	    for $class (@classes) {
		${$append_to}{$class} .= $paragraph . $_;
	    }
	    $paragraph = "";
	}
    } else {
	if ($paragraph eq "") {
	    if ($append_to eq \%leader) {
		@classes = ("default");
		$paragraph = $_;
	    } elsif (/^\[([^]]+)\]\s*(.*)/s) {
		$paragraph = $prefix . $2;
		($junk = $1) =~ s/\s*,\s*/,/g;
		$junk =~ s/^\s+//;
		$junk =~ s/\s+$//;
		#print "junk >$junk<\n";
		@classes = split(/,+/, $junk);
		#print "[", join(', ', @classes), "] ", $paragraph;
	    } else {
		$paragraph = $_;
	    }
	} else {
	    $paragraph .= $_;
	}
    }
}

if ($paragraph) {
    for $class (@classes) {
	${$append_to}{$class} .= $prefix . $paragraph . $_;
    }
}

print $leader{"default"}; 

for $class (sort keys %body) {
    print "Major changes - $class\n";
    ($junk = "Major changes - $class") =~ s/./-/g;
    print $junk, "\n\n";
    print $body{$class};
}
