#!/usr/bin/perl
# hgl

use warnings;
use strict;
use File::Slurp;
use File::Spec;
use JSON::XS;
use Data::Dumper;

our $VERSION = '0.01';

my $mode;
if($ARGV[0] =~ /^tip$|^diff$/){
	$mode= shift @ARGV;
}else{
	$mode='commit';
}

die "hg-lite (hgl) simple text-file version control.\n\nCommands:\n tip\tShow tip revision information.\n\nUsage: hgl [tip] <filenames>\n" unless @ARGV;

for my $path (@ARGV) {
	my $raw = read_file( $path );

	if($mode eq 'tip'){
		if($raw =~ /__HGLITE__/){
			my ($file,$json) = split(/\n\n__HGLITE__\n/, $raw);
			my $data = JSON::XS->new->decode($json);
			my $tip = $#$data;

			print "\nRev:\t$tip (tip)\nFile:\t$path\t[Modified: ".localtime(${ $$data[-1]->{stat} }[9] )."]\n";
		}else{
			print "File is not versioned by hg-lite. Skipping.\n"; next;
		}
	}elsif($mode eq 'diff'){
		if($raw =~ /__HGLITE__/){
			my ($file,$json) = split(/\n\n__HGLITE__\n/, $raw);
			my $data = JSON::XS->new->decode($json);
			my $tip = $#$data;

			write_file("hglite.rev$tip.tmp", $$data[-1]->{raw});
			write_file('hglite.curr.tmp', $file);

			my $diff = `diff -u hglite.rev$tip.tmp hglite.curr.tmp`;

			unlink("hglite.rev$tip.tmp");
			unlink('hglite.curr.tmp');

			if($diff eq ''){
				print "No changes in $path. Skipping.\n"; next;
			}else{
				print "$diff\n";
			}
		}else{
			print "File is not versioned by hg-lite. Skipping.\n"; next;
		}
	}else{
		if($raw =~ /__HGLITE__/){	## implicit commit
			my ($file,$json) = split(/\n\n__HGLITE__\n/, $raw);
			my $data = JSON::XS->new->decode($json);
			my $tip = $#$data;

			## diff curr against prev version
			write_file("hglite.rev$tip.tmp", $$data[-1]->{raw});
			write_file('hglite.curr.tmp', $file);
			my $diff = `diff hglite.rev$tip.tmp hglite.curr.tmp`;
			if($diff eq ''){ print "No changes in $path. Skipping.\n"; next; }

			unlink("hglite.rev$tip.tmp");
			unlink('hglite.curr.tmp');

			## write our custom weave
			my @stat = stat($path);
			$stat[7] = length($file);
			delete($$data[-1]->{raw});
			my @path = File::Spec->splitpath( $path );
			push(@$data,{ filename => $path[-1], stat => \@stat, diff => $diff, raw => $file });
			$json = JSON::XS->new->pretty->encode($data);
			write_file($path, $file."\n\n__HGLITE__\n".$json);
		}else{				## implicit init
			print "Versioning init.\n";
			## diff against null
			write_file('hglite.null.tmp', '');
			write_file('hglite.rev0.tmp', $raw);
			my $diff = `diff hglite.null.tmp hglite.rev0.tmp`;

			unlink('hglite.null.tmp');
			unlink('hglite.rev0.tmp');

			## write our custom weave
			my $data = [];
			my @stat = stat($path);
			my @path = File::Spec->splitpath( $path );
			push(@$data,{ filename => $path[-1], stat => \@stat, diff => $diff, raw => $raw });
			my $json = JSON::XS->new->pretty->encode($data);
			write_file($path, $raw."\n\n__HGLITE__\n".$json);
		}
	}
}