#!/usr/bin/perl -T

use warnings;
use strict;
use File::Find;
use Memoize;
use File::Spec;

BEGIN {
	$blosxom::version="is a proper perl module too much to ask?";
	do "/usr/bin/markdown";
}

memoize('pagename');
memoize('bestlink');

sub usage {
	die "usage: ikiwiki [options] source dest\n";
}

my $link=qr/\[\[([^\s]+)\]\]/;
my $verbose=0;
my $rebuild=0;
my $wikiname="wiki";
if (grep /^-/, @ARGV) {
	eval {use Getopt::Long};
	GetOptions(
		"wikiname=s" => \$wikiname,
		"verbose|v" => \$verbose,
		"rebuild" => \$rebuild,
	) || usage();
}
usage() unless @ARGV == 2;
my ($srcdir) = shift =~ /(.*)/; # untaint
my ($destdir) = shift =~ /(.*)/; # untaint

my %links;
my %oldlinks;
my %oldpagemtime;
my %renderedfiles;
my %pagesources;

sub error ($) {
	die @_;
}

sub debug ($) {
	print "@_\n" if $verbose;
}

sub mtime ($) {
	my $page=shift;
	
	return (stat($page))[9];
}

sub basename {
	my $file=shift;

	$file=~s!.*/!!;
	return $file;
}

sub dirname {
	my $file=shift;

	$file=~s!/?[^/]+$!!;
	return $file;
}

sub pagetype ($) {
	my $page=shift;
	
	if ($page =~ /\.mdwn$/) {
		return ".mdwn";
	}
	else {
		return "unknown";
	}
}

sub pagename ($) {
	my $file=shift;

	my $type=pagetype($file);
	my $page=$file;
	$page=~s/\Q$type\E*$// unless $type eq 'unknown';
	return $page;
}

sub htmlpage ($) {
	my $page=shift;

	return $page.".html";
}

sub readpage ($) {
	my $page=shift;

	local $/=undef;
	open (PAGE, "$srcdir/$page") || error("failed to read $page: $!");
	my $ret=<PAGE>;
	close PAGE;
	return $ret;
}

sub writepage ($$) {
	my $page=shift;
	my $content=shift;

	my $dir=dirname("$destdir/$page");
	if (! -d $dir) {
		my $d="";
		foreach my $s (split(m!/+!, $dir)) {
			$d.="$s/";
			if (! -d $d) {
				mkdir($d) || error("failed to create directory $d: $!");
			}
		}
	}
	
	open (PAGE, ">$destdir/$page") || error("failed to write $page: $!");
	print PAGE $content;
	close PAGE;
}

sub findlinks {
	my $content=shift;

	my @links;
	while ($content =~ /$link/g) {
		push @links, lc($1);
	}
	return @links;
}

# Given a page and the text of a link on the page, determine which existing
# page that link best points to. Prefers pages under a subdirectory with
# the same name as the source page, failing that goes down the directory tree
# to the base looking for matching pages.
sub bestlink ($$) {
	my $page=shift;
	my $link=lc(shift);
	
	my $cwd=$page;
	do {
		my $l=$cwd;
		$l.="/" if length $l;
		$l.=$link;

		if (exists $links{$l}) {
			#debug("for $page, \"$link\", use $l");
			return $l;
		}
	} while $cwd=~s!/?[^/]+$!!;

	#print STDERR "warning: page $page, broken link: $link\n";
	return "";
}

sub isinlinableimage ($) {
	my $file=shift;
	
	$file=~/\.(png|gif|jpg|jpeg)$/;
}

sub htmllink ($$) {
	my $page=shift;
	my $link=shift;

	my $bestlink=bestlink($page, $link);

	return $link if $page eq $bestlink;
	
	# TODO BUG: %renderedfiles may not have it, if the linked to page
	# was also added and isn't yet rendered! Note that this bug is
	# masked by the bug mentioned below that makes all new files
	# be rendered twice.
	if (! grep { $_ eq $bestlink } values %renderedfiles) {
		$bestlink=htmlpage($bestlink);
	}
	if (! grep { $_ eq $bestlink } values %renderedfiles) {
		return "<a href=\"?\">?</a>$link"
	}
	
	$bestlink=File::Spec->abs2rel($bestlink, dirname($page));
	
	if (isinlinableimage($bestlink)) {
		return "<img src=\"$bestlink\">";
	}
	return "<a href=\"$bestlink\">$link</a>";
}

sub linkify ($$) {
	my $content=shift;
	my $file=shift;

	$content =~ s/$link/htmllink(pagename($file), $1)/eg;
	
	return $content;
}

sub htmlize ($$) {
	my $type=shift;
	my $content=shift;
	
	if ($type eq '.mdwn') {
		return Markdown::Markdown($content);
	}
	else {
		error("htmlization of $type not supported");
	}
}

sub linkbacks ($$) {
	my $content=shift;
	my $page=shift;

	my @links;
	foreach my $p (keys %links) {
		next if bestlink($page, $p) eq $page;
		if (grep { length $_ && bestlink($p, $_) eq $page } @{$links{$p}}) {
			my $href=File::Spec->abs2rel(htmlpage($p), dirname($page));
			
			# Trim common dir prefixes from both pages.
			my $p_trimmed=$p;
			my $page_trimmed=$page;
			my $dir;
			1 while (($dir)=$page_trimmed=~m!^([^/]+/)!) &&
			        defined $dir &&
			        $p_trimmed=~s/^\Q$dir\E// &&
			        $page_trimmed=~s/^\Q$dir\E//;
				       
			push @links, "<a href=\"$href\">$p_trimmed</a>";
		}
	}

	$content.="<hr><p>Links: ".join(" ", sort @links)."</p>\n" if @links;
	return $content;
}

sub finalize ($$) {
	my $content=shift;
	my $page=shift;

	my $title=basename($page);
	$title=~s/_/ /g;
	
	my $pagelink="";
	my $path="";
	foreach my $dir (reverse split("/", $page)) {
		if (length($pagelink)) {
			$pagelink="<a href=\"$path$dir.html\">$dir</a>/ $pagelink";
		}
		else {
			$pagelink=$dir;
		}
		$path.="../";
	}
	$path=~s/\.\.\/$/index.html/;
	$pagelink="<a href=\"$path\">$wikiname</a>/ $pagelink";
	
	$content="<html>\n<head><title>$title</title></head>\n<body>\n".
	          "<h1>$pagelink</h1>\n".
	          $content.
	          "</body>\n</html>\n";
	
	return $content;
}

sub render ($) {
	my $file=shift;
	
	my $type=pagetype($file);
	my $content=readpage($file);
	if ($type ne 'unknown') {
		my $page=pagename($file);
		
		$links{$page}=[findlinks($content)];
		
		$content=linkify($content, $file);
		$content=htmlize($type, $content);
		$content=linkbacks($content, $page);
		$content=finalize($content, $page);
		
		writepage(htmlpage($page), $content);
		$oldpagemtime{$page}=time;
		$renderedfiles{$page}=htmlpage($page);
	}
	else {
		$links{$file}=[];
		writepage($file, $content);
		$oldpagemtime{$file}=time;
		$renderedfiles{$file}=$file;
	}
}

sub loadindex () {
	open (IN, "$srcdir/.index") || return;
	while (<IN>) {
		($_)=/(.*)/; # untaint
		chomp;
		my ($mtime, $file, $rendered, @links)=split(' ', $_);
		my $page=pagename($file);
		$pagesources{$page}=$file;
		$oldpagemtime{$page}=$mtime;
		$oldlinks{$page}=[@links];
		$links{$page}=[@links];
		$renderedfiles{$page}=$rendered;
	}
	close IN;
}	

sub saveindex () {
	open (OUT, ">$srcdir/.index") || error("cannot write to .index: $!");
	foreach my $page (keys %oldpagemtime) {
	print OUT "$oldpagemtime{$page} $pagesources{$page} $renderedfiles{$page} ".
	          join(" ", @{$links{$page}})."\n"
			if $oldpagemtime{$page};
	}
	close OUT;
}

sub prune ($) {
	my $file=shift;

	unlink($file);
	my $dir=dirname($file);
	while (rmdir($dir)) {
		$dir=dirname($dir);
	}
}

sub refresh () {
	# Find existing pages.
	my %exists;
	my @files;
	find({
		no_chdir => 1,
		wanted => sub {
			if (/\/\.svn\//) {
				$File::Find::prune=1;
			}
			elsif (! -d $_ && ! /\.html$/ && ! /\/\./) {
				my ($f)=/(^[-A-Za-z0-9_.:\/+]+$)/; # untaint
				if (! defined $f) {
					warn("skipping bad filename $_\n");
				}
				else {
					$f=~s/^\Q$srcdir\E\/?//;
					push @files, $f;
					$exists{pagename($f)}=1;
				}
			}
		},
	}, $srcdir);

	my %rendered;

	# check for added or removed pages
	my @add;
	foreach my $file (@files) {
		my $page=pagename($file);
		if (! $oldpagemtime{$page}) {
			debug("new page $page");
			push @add, $file;
			$links{$page}=[];
			$pagesources{$page}=$file;
		}
	}
	my @del;
	foreach my $page (keys %oldpagemtime) {
		if (! $exists{$page}) {
			debug("removing old page $page");
			push @del, $renderedfiles{$page};
			prune($destdir."/".$renderedfiles{$page});
			delete $renderedfiles{$page};
			$oldpagemtime{$page}=0;
			delete $pagesources{$page};
		}
	}
	
	# render any updated files
	foreach my $file (@files) {
		my $page=pagename($file);
		
		if (! exists $oldpagemtime{$page} ||
		    mtime("$srcdir/$file") > $oldpagemtime{$page}) {
		    	debug("rendering changed file $file");
			render($file);
			$rendered{$file}=1;
		}
	}
	
	# if any files were added or removed, check to see if each page
	# needs an update due to linking to them
	# TODO: inefficient; pages may get rendered above and again here;
	# problem is the bestlink may have changed and we won't know until
	# now
	if (@add || @del) {
FILE:		foreach my $file (@files) {
			my $page=pagename($file);
			foreach my $f (@add, @del) {
				my $p=pagename($f);
				foreach my $link (@{$links{$page}}) {
					if (bestlink($page, $link) eq $p) {
		   				debug("rendering $file, which links to $p");
						render($file);
						$rendered{$file}=1;
						next FILE;
					}
				}
			}
		}
	}

	# handle linkbacks; if a page has added/removed links, update the
	# pages it links to
	# TODO: inefficient; pages may get rendered above and again here;
	# problem is the linkbacks could be wrong in the first pass render
	# above
	if (%rendered) {
		my %linkchanged;
		foreach my $file (keys %rendered, @del) {
			my $page=pagename($file);
			if (exists $links{$page}) {
				foreach my $link (@{$links{$page}}) {
					$link=bestlink($page, $link);
					if (length $link &&
					    ! exists $oldlinks{$page} ||
					    ! grep { $_ eq $link } @{$oldlinks{$page}}) {
						$linkchanged{$link}=1;
					}
				}
			}
			if (exists $oldlinks{$page}) {
				foreach my $link (@{$oldlinks{$page}}) {
					$link=bestlink($page, $link);
					if (length $link &&
					    ! exists $links{$page} ||
					    ! grep { $_ eq $link } @{$links{$page}}) {
						$linkchanged{$link}=1;
					}
				}
			}
		}
		foreach my $link (keys %linkchanged) {
		    	my $linkfile=$pagesources{$link};
			if (defined $linkfile) {
				debug("rendering $linkfile, to update its linkbacks");
				render($linkfile);
			}
		}
	}
}

loadindex() unless $rebuild;
refresh();
saveindex();