#!/usr/bin/env perl
#
# InspIRCd -- Internet Relay Chat Daemon
#
#   Copyright (C) 2020 Sadie Powell <sadie@witchery.services>
#
# This file is part of InspIRCd.  InspIRCd 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, version 2.
#
# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
#


use v5.10.0;
use strict;
use warnings FATAL => qw(all);

use File::Basename qw(dirname);
use File::Util     ();
use FindBin        qw($RealDir);
use List::Util     qw(uniq);
use POSIX          qw(strftime);

use lib dirname $RealDir;
use make::common;
use make::console;

my @ignored_revisions = (
	'0b4285abd12323920d92fee51e199edd7527dbec', # adding copyright headers
	'46a39046196f55b52336e19662bb7bac85b731ac', # adding copyright headers
	'4a6fedd9324d87349a806c9c1d0ae6e7d3c1fd38', # mass-updating descriptions
	'56375392ba94f2552bbeeeab4fd39e1e50295525', # sadie's name change
	'bab14f0dd2345c9d7dcbc47c918563709e1ac094', # peavey breaking line endings
	'f2acdbc3820f0f4f5ef76a0a64e73d2a320df91f', # peavey fixing line endings
);

my @paths = File::Util->new->list_dir(dirname($RealDir) => { recurse => 1 });
my @updated;
for my $path (@paths) {
	next unless -f $path;
	next if $path =~ /\/\./;
	next if $path =~ /\/build\//;
	next if $path =~ /\/vendor\//;

	if (system "git ls-files --error-unmatch -- $path 1>/dev/null 2>/dev/null") {
		print_format "Skipping <|YELLOW $path|> as it has not been committed.\n" if defined $ENV{MKHEADERS_VERBOSE};
		next;
	}

	open(my $fh, $path) or print_error "unable to read from $path: $!";
	my ($copyright, $indent, @lines);
	for my $line (<$fh>) {
		chomp $line;
		if ($line =~ /^([^0-9A-Za-z]+\s)Copyright\s+\(C\)\s+[^<]+\s+<[^>]+>$/) {
			$copyright = scalar @lines;
			$indent = $1;
		} else {
			push @lines, $line;
		}
	}
	close $fh;

	if (defined $copyright) {
		print_format "Updating copyright headers in <|GREEN $path|>.\n" if defined $ENV{MKHEADERS_VERBOSE};
		my (%author, %authors);
		my $ignored_args = join ' ', map { "--ignore-rev $_" } @ignored_revisions;
		for my $line (split /\n+/, `git blame $ignored_args --incremental -w HEAD -- $path`) {
			if ($line =~ /^([0-9a-f]{40})(?:\s\d+){3}$/) {
				$author{COMMITS} //= [];
				push @{$author{COMMITS}}, $1;
			} elsif ($line =~ /^author (.+)/) {
				$author{NAME} = $1;
			} elsif ($line =~ /^author-mail <(.+)>/) {
				$author{EMAIL} = $1;
			} elsif ($line =~ /^author-time (.+)/) {
				$author{YEAR} = strftime '%Y', gmtime $1;
			} elsif ($line =~ /^filename /) {
				next unless scalar keys %author > 1;
				my $display = sprintf "%s <%s>", $author{NAME}, $author{EMAIL};
				$authors{$display} //= [];
				push @{$authors{$display}}, $author{YEAR};
				for my $commit (uniq @{$author{COMMITS}}) {
					my $details = `git rev-list --format=%B --max-count=1 $commit`;
					while ($details =~ /co-authored-by: ([^<]+<[^>]+>)/gi) {
						$authors{$1} //= [];
						push @{$authors{$1}}, $author{YEAR};
					}
				}
				undef %author;
			}
		}

		my @copyrights;
		while (my ($display, $years) = each %authors) {
			next if $display eq 'InspIRCd Robot <noreply@inspircd.org>';
			my ($last_year, $start_year, @year_ranges);
			for my $year (uniq sort @$years) {
				if (!defined $last_year) {
					$start_year = $last_year = $year
				} elsif ($year == $last_year + 1) {
					$last_year = $year;
				} else {
					if ($last_year == $start_year) {
						push @year_ranges, $last_year;
					} else {
						push @year_ranges, "$start_year-$last_year";
					}
					$start_year = $last_year = $year;
				}
			}
			if (defined $last_year) {
				if ($last_year == $start_year) {
					push @year_ranges, $last_year;
				} else {
					push @year_ranges, "$start_year-$last_year";
				}
			}

			my $joined_years = join ', ', @year_ranges;
			push @copyrights, "${\$indent}Copyright (C) $joined_years $display";
		}

		splice @lines, $copyright, 0, reverse sort @copyrights;
		open(my $fh, '>', $path) or print_error "unable to write to $path: $!";
		for my $line (@lines) {
			say $fh $line;
		}
		close $fh;
		push @updated, $path;
	} else {
		print_format "Skipping <|YELLOW $path|> as it contains no copyright headers.\n" if defined $ENV{MKHEADERS_VERBOSE};
	}
}

execute 'git', 'commit',
	'--author', 'InspIRCd Robot <noreply@inspircd.org>',
	'--message', 'Update copyright headers.',
	'--', @updated;