# Support for the darcs rcs, <URL:http://darcs.net/>.
# Copyright (C) 2006  Thomas Schwinge <tschwinge@gnu.org>
#               2007  Benjamin A'Lee <bma@bmalee.eu>
#                     Tuomo Valkonen <tuomov@iki.fi>
#               2008  Simon Michael <simon@joyful.com>
#                     Petr Ročkai <me@mornfall.net>
#                     Sven M. Hallberg <pesco@khjk.org>
#
# This program 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; either version 2 of the License, or (at your
# option) any later version.
#
# 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, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

# History (see http://ikiwiki.info/todo/darcs/):
#
#  * Thomas Schwinge wrote the original file, implementing only rcs_commit.
#  * Benjamin A'Lee contributed an alternative implementation.
#  * Tuomo Valkonen contributed rcs_getctime and stub rcs_recentchanges.
#  * Simon Michael contributed multiple changes.
#  * Petr Ročkai fixed rcs_recentchanges and added caching to rcs_getctime.
#  * Sven M. Hallberg merged the above and added missing features.


# We're guaranteed to be the only instance of ikiwiki running at a given
# time.  It is essential that only ikiwiki is working on a particular
# repository.  That means one instance of ikiwiki and it also means that
# you must not 'darcs push' into this repository, as this might create
# race conditions, as I understand it.


package IkiWiki::Plugin::darcs;

use warnings;
use strict;
use IkiWiki;


sub import {
    hook(type => "checkconfig", id => "darcs", call => \&checkconfig);
    hook(type => "getsetup", id => "darcs", call => \&getsetup);
    hook(type => "rcs", id => "rcs_update", call => \&rcs_update);
    hook(type => "rcs", id => "rcs_prepedit", call => \&rcs_prepedit);
    hook(type => "rcs", id => "rcs_commit", call => \&rcs_commit);
    hook(type => "rcs", id => "rcs_commit_staged", call => \&rcs_commit_staged);
    hook(type => "rcs", id => "rcs_add", call => \&rcs_add);
    hook(type => "rcs", id => "rcs_remove", call => \&rcs_remove);
    hook(type => "rcs", id => "rcs_rename", call => \&rcs_rename);
    hook(type => "rcs", id => "rcs_recentchanges", call => \&rcs_recentchanges);
    hook(type => "rcs", id => "rcs_diff", call => \&rcs_diff);
    hook(type => "rcs", id => "rcs_getctime", call => \&rcs_getctime);
}


# Which darcs executable to use.
my $darcs = ($ENV{DARCS} or 'darcs');


# Internal functions

our %cache;

sub loadcache () {
    my $repodir=$config{srcdir};
    if (!defined %cache) {
        my $f = "$repodir/.ikiwiki.ctimes";
        if (-s "$f") {
            my $VAR1;
            my $x = `cat "$f"`;
            $x =~ /^(.*)$/sm; # untaint
            eval "$1";
            %cache = %$VAR1;
        }
    }
}

END {
    my $repodir=$config{srcdir};
    if (defined %cache) {
        debug("dumping ctime cache to $repodir/.ikiwiki.ctimes");
        open CACHE, ">$repodir/.ikiwiki.ctimes";
        print CACHE Dumper(\%cache);
        close CACHE;
    }
}

sub silentsystem (@) {
    open(SAVED_STDOUT, ">&STDOUT");
    open(STDOUT, ">/dev/null");
    my $ret = system @_;
    open(STDOUT, ">&SAVED_STDOUT");
    return $ret;
}

sub darcs_info ($$$) {
    my $field = shift;
    my $repodir = shift;
    my $file = shift; # Relative to the repodir.

    my $child = open(DARCS_CHANGES, "-|");
    if (! $child) {
    exec($darcs, 'changes', '--repodir', $repodir, '--xml-output', $file) or
        error("failed to run 'darcs changes'");
    }

    # Brute force for now.  :-/
    while (<DARCS_CHANGES>) {
    last if /^<\/created_as>$/;
    }
    ($_) = <DARCS_CHANGES> =~ /$field=\'([^\']+)/;
    $field eq 'hash' and s/\.gz//; # Strip away the '.gz' from 'hash'es.

    close(DARCS_CHANGES) or error("'darcs changes' exited " . $?);

    return $_;
}

sub darcs_rev($) {
    my $file = shift; # Relative to the repodir.
    my $repodir = $config{srcdir};

    my $child = open(DARCS_MANIFEST, "-|");
    if (! $child) {
        exec($darcs, 'query', 'manifest', '--repodir', $repodir) or
            error("failed to run 'darcs query manifest'");
    }
    my $found=0;
    while (<DARCS_MANIFEST>) {
        $found = 1, last if /^$file$/;
    }
    return "" if (! $found);
    close(DARCS_MANIFEST) or error("'darcs query manifest' exited " . $?);

    my $hash = darcs_info('hash', $repodir, $file);
    return defined $hash ? $hash : "";
}


# Exported functions.

sub checkconfig() {
    if (defined $config{darcs_wrapper} && length $config{darcs_wrapper}) {
	push @{$config{wrappers}}, {
	    wrapper => $config{darcs_wrapper},
	    wrappermode => (defined $config{darcs_wrappermode} ? $config{darcs_wrappermode} : "06755"),
	};
    }
}

sub getsetup() {
    return
	plugin => {
	    safe => 0, # rcs plugin
	    rebuild => undef,
	},
	darcs_wrapper => {
	    type => "string",
	    example => "/darcs/repo/_darcs/ikiwiki-wrapper",
	    description => "wrapper to generate (set as master repo apply hook)",
	    safe => 0, # file
	    rebuild => 0,
	},
	darcs_wrappermode => {
	    type => "string",
	    example => '06755',
	    description => "mode for darcs_wrapper (can safely be made suid)",
	    safe => 0,
	    rebuild => 0,
	},
	historyurl => {
	    type => "string",
	    example => "http://darcs.example.com/darcsweb.cgi?r=wiki;a=filehistory;f=[[file]]",
	    description => "darcsweb url to show file history ([[file]] substituted)",
	    safe => 1,
	    rebuild => 1,
	},
	diffurl => {
	    type => "string",
	    example => "http://darcs.example.com/darcsweb.cgi?r=wiki;a=filediff;h=[[hash]];f=[[file]]",
	    description => "darcsweb url to show a diff ([[hash]] and [[file]] substituted)",
	    safe => 1,
	    rebuild => 1,
	},
}

sub rcs_update () {
    silentsystem($darcs, "pull", "--repodir", $config{srcdir}, "-qa")
}

sub rcs_prepedit ($) {
    # Prepares to edit a file under revision control.  Returns a token that
    # must be passed to rcs_commit() when the file is to be commited.  For us,
    # this token the hash value of the latest patch that modifies the file,
    # i.e. something like its current revision.  If the file is not yet added
    # to the repository, we return TODO: the empty string.

    my $file = shift; # Relative to the repodir.
    my $rev = darcs_rev($file);
    return $rev;
}

sub rcs_commit ($$$;$$) {
    # Commit the page.  Returns 'undef' on success and a version of the page
    # with conflict markers on failure.

    my ($file, $message, $rcstoken, $user, $ipaddr) = @_;

    # Compute if the "revision" of $file changed.
    my $changed = darcs_rev($file) ne $rcstoken;

    # Yes, the following is a bit convoluted.
    if ($changed) {
    # TODO.  Invent a better, non-conflicting name.
    rename("$config{srcdir}/$file", "$config{srcdir}/$file.save") or
        error("failed to rename $file to $file.save: $!");

    # Roll the repository back to $rcstoken.

    # TODO.  Can we be sure that no changes are lost?  I think that
    # we can, if we make sure that the 'darcs push' below will always
    # succeed.

    # We need to revert everything as 'darcs obliterate' might choke
    # otherwise.
        # TODO: 'yes | ...' needed?  Doesn't seem so.
    silentsystem($darcs, "revert", "--repodir", $config{srcdir}, "--all") and
        error("'darcs revert' failed");
    # Remove all patches starting at $rcstoken.
    my $child = open(DARCS_OBLITERATE, "|-");
    if (! $child) {
        open(STDOUT, ">/dev/null");
        exec($darcs, "obliterate", "--repodir", $config{srcdir},
           "--match", "hash " . $rcstoken) and
           error("'darcs obliterate' failed");
    }
    while (print DARCS_OBLITERATE "y") {
        ;
    }
    close(DARCS_OBLITERATE);
    # Restore the $rcstoken one.
    silentsystem($darcs, "pull", "--quiet", "--repodir", $config{srcdir},
           "--match", "hash " . $rcstoken, "--all") and
           error("'darcs pull' failed");

    # We're back at $rcstoken.  Re-install the modified file.
    rename("$config{srcdir}/$file.save", "$config{srcdir}/$file") or
        error("failed to rename $file.save to $file: $!");
    }

    # Record the changes.
    my $author;
    if (defined $user) {
        $author = "$user\@web";
    } elsif (defined $ipaddr) {
        $author = "$ipaddr\@web";
    } else {
        $author = "anon\@web";
    }
    if (!defined $message || !length($message)) {
        $message = "empty message";
    }
    silentsystem($darcs, 'record', '--repodir', $config{srcdir}, '--all',
       '-m', $message, '--author', $author, $file) and
           error("'darcs record' failed");

    # Update the repository by pulling from the default repository, which is
    # master repository.
    silentsystem($darcs, "pull", "--quiet", "--repodir", $config{srcdir},
       "--all") and error("'darcs pull' failed");

    # If this updating yields any conflicts, we'll record them now to resolve
    # them.  If nothing is recorded, there are no conflicts.
    $rcstoken = darcs_rev($file);
    # TODO: Use only the first line here, i.e. only the patch name?
    writefile("$file.log", $config{srcdir}, 'resolve conflicts: ' . $message);
    silentsystem($darcs, 'record', '--repodir', $config{srcdir}, '--all',
       '-m', 'resolve conflicts: ' . $message, '--author', $author, $file) and
           error("'darcs record' failed");
    my $conflicts = darcs_rev($file) ne $rcstoken;
    unlink("$config{srcdir}/$file.log") or
    error("failed to remove '$file.log'");

    # Push the changes to the main repository.
    silentsystem($darcs, 'push', '--quiet', '--repodir', $config{srcdir}, '--all')
    and error("'darcs push' failed");
    # TODO: darcs send?

    if ($conflicts) {
        my $document = readfile("$config{srcdir}/$file");
        # Try to leave everything in a consistent state.
        # TODO: 'yes | ...' needed?  Doesn't seem so.
        silentsystem($darcs, "revert", "--repodir", $config{srcdir}, "--all") and
            warn("'darcs revert' failed");
        return $document;
    } else {
        return undef;
    }
}

sub rcs_commit_staged($$$) {
    my ($message, $user, $ipaddr) = @_;

    my $author;
    if (defined $user) {
        $author = "$user\@web";
    } elsif (defined $ipaddr) {
        $author = "$ipaddr\@web";
    } else {
        $author = "anon\@web";
    }
    if (!defined $message || !length($message)) {
        $message = "empty message";
    }

    silentsystem($darcs, "record", "--repodir", $config{srcdir}, "-a", "-A", $author,
	"-m", $message)	and error("'darcs record' failed");

    # Push the changes to the main repository.
    silentsystem($darcs, 'push', '--quiet', '--repodir', $config{srcdir}, '--all')
    and error("'darcs push' failed");
    # TODO: darcs send?

    return undef;
}

sub rcs_add ($) {
    my $file = shift; # Relative to the repodir.

    # Intermediate directories will be added automagically.
    system($darcs, 'add', '--quiet', '--repodir', $config{srcdir},
       '--boring', $file) and error("'darcs add' failed");
}

sub rcs_remove ($) {
    my $file = shift; # Relative to the repodir.

    system('rm', $config{srcdir}.'/'.$file)
       and error("'rm' failed");
}

sub rcs_rename ($$) {
    my $a = shift; # Relative to the repodir.
    my $b = shift; # Relative to the repodir.

    system($darcs, 'mv', '--repodir', $config{srcdir}, $a, $b)
       and error("'darcs mv' failed");
}

sub rcs_recentchanges ($) {
    my $num=shift;
    my @ret;

    eval q{use Date::Parse};
    eval q{use XML::Simple};

    my $repodir=$config{srcdir};

    debug("darcs recent changes: $num");

    my $child = open(LOG, "-|");
    if (! $child) {
        $ENV{"DARCS_DONT_ESCAPE_ANYTHING"}=1;
        exec("darcs", "changes", "--xml", 
            "--summary",
             "--repodir", "$repodir",
             "--last", "$num")
        || error("'darcs changes' failed to run");
    }
    my $data;
    $data .= $_ while(<LOG>);
    close LOG;

    my $log = XMLin($data, ForceArray => 1);

    debug("parsing recent changes...");
    foreach my $patch (@{$log->{patch}}) {
        my $date=$patch->{local_date};
        my $hash=$patch->{hash};
        my $when=str2time($date);
        my (@pages, @files, @pg);
        push @pages, $_ for (@{$patch->{summary}->[0]->{modify_file}});
        push @pages, $_ for (@{$patch->{summary}->[0]->{add_file}});
        push @pages, $_ for (@{$patch->{summary}->[0]->{remove_file}});
        for (@pages) {
            my $f = $_;
            $f = $_->{content} if (ref $_);
            $f =~ s,^\s+,,; $f =~ s,\s+$,,; # cut whitespace

	    push @files, $f;
        }
	for (@{$patch->{summary}->[0]->{move}}) {
	    my $p = $_;
	    push @files, $p->{from};
        }

	for (@files) {
	    my $f = $_;
	    my $d = defined $config{'diffurl'} ? $config{'diffurl'} : "";
	    $d =~ s/\[\[file\]\]/$f/go;
	    $d =~ s/\[\[hash\]\]/$hash/go;

            debug("file: $f");
	    debug("diffurl: $d");
            push @pg, {
                page => pagename($f),
		diffurl => $d,
            };
        }
        next unless (scalar @pg > 0);
        debug("recent change: " . $patch->{name}[0] . " ("
            . scalar @pg . " changes)");

        my @message;
        push @message, { line => $_ } for (@{$patch->{name}});

        my $committype;
        if ($patch->{author} =~ /\@web$/) {
            $committype = "web";
        } else {
            $committype = "darcs";
        }

        push @ret, {
            rev => $patch->{hash},
            user => $patch->{author},
            committype => $committype,
            when => $when, 
            message => [@message],
            pages => [@pg],
        };
    }

    return @ret;
}

sub rcs_diff ($) {
    my $rev=shift;
    my @lines;
    foreach my $line (silentsystem("darcs", "diff", "--match", "hash ".$rev)) {
	if (@lines || $line=~/^diff/) {
	    push @lines, $line."\n";
        }
    }
    if (wantarray) {
	return @lines;
    }
    else {
	return join("", @lines);
    }
}

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

    eval q{use Date::Parse};
    eval q{use XML::Simple};
    local $/=undef;

    # Sigh... doing things the hard way again
    my $repodir=$config{srcdir};

    &loadcache;

    my $filer=substr($file, length($repodir));
    $filer =~ s:^[/]+::;

    if (defined $cache{$filer}) {
        #debug("taking cached ctime ".localtime($cache{$filer})." for $filer");
        return $cache{$filer};
    }

    my $child = open(LOG, "-|");
    if (! $child) {
        exec("darcs", "changes", "--xml", "--reverse",
             "--repodir", "$repodir", "$filer")
        || error("'darcs changes $filer' failed to run");
    }

    my $data;
    $data .= $_ while(<LOG>);
    close LOG;

    my $log = XMLin($data, ForceArray => 1);

    my $datestr=$log->{patch}[0]->{local_date};

    if (! defined $datestr) {
        warn "failed to get ctime for $filer";
        $cache{$filer} = 0;
        return 0;
    }

    my $date=str2time($datestr);

    #debug("found ctime ".localtime($date)." for $filer");

    $cache{$filer} = $date;
    return $date;
}

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