#! /usr/bin/perl -w

# This program is free software. It comes without any warranty, to the
# extent permitted by applicable law. You can redistribute it and/or
# modify it under the terms of the Do What The Fuck You Want To Public
# License, Version 2, as published by Sam Hocevar.
# See http://sam.zoy.org/wtfpl/COPYING for more details.


$VERSION = "0.2, 10 August 2011";

use Getopt::Long qw/:config posix_default no_ignore_case gnu_compat
                            bundling auto_version auto_help/;
use Pod::Usage;
use DBI;
use File::Basename;
use File::Spec::Functions qw /catfile catdir splitdir updir/;
use File::Copy;
use Cwd qw /realpath/;
use Env qw /HOME/;
use strict;

################################################################################

# Configuration
my $symlinks  = catdir($HOME,'video','MOVIES');    # Symlinks folder
my $directors = catdir($HOME,'video','DIRECTORS'); # Directors folder

$symlinks  = catdir('','tmp','video','MOVIES');    # Symlinks folder
$directors = catdir('','tmp','video','DIRECTORS'); # Directors folder

my $driver    = "mysql";
my $database  = "videodb";
my $hostname  = "127.0.0.1";
my $user      = "videodb";
my $port      = 3306;
my $password  = "videodb";
my $videodata = "videodb_videodata";

################################################################################

=head1 NAME

videomv.pl - Move your videos to or within your collection.

=head1 SYNOPSIS

B<videomv.pl> [B<--lookup-db>] [B<--ignore-db>] [B<-q>]
I<path/to/oldfile> [{I<MOVIES>,I<DIRECTORS/director/>}I</>[I<newfile>]]

=head1 DESCRIPTION

Your collection is assumed to have the following structure: two
folders, here I<DIRECTORS> and I<MOVIES> that have the same parent.
I<DIRECTORS> contains one subdirectory for each director, and each movie
lies (B<as a regular file>) in the subdirectory of its director.
The folder I<MOVIES> contains symlinks - one for each movie - that target
to I<../DIRECTORS/director_of_the_movie/movie>.
The behavior of B<videomv.pl> is NOT specified if your collection does
not verify these conventions!

  |- ...
  |- DIRECTORS
  |    |- director1
  |    |-   |- movie11
  |    |    `- movie12
  |    |- director2/
  |    `- ...
  `- MOVIES
       |- movie11 -> ../DIRECTORS/director1/movie1
       |- movie12 -> ../DIRECTORS/director1/movie2
       `- ...


Depending on whether I<path/to/> is I<MOVIES/>,
I<DIRECTORS/*/>, or something
else, you will get one of the six behaviors below. For the sake of
readability the paths are relative to the root of your video collection
here, but hopefully other origins or
paths that contain symlinks are fine as well.

=over 4

=item B<videomv.pl> [B<--lookup-db>] I<MOVIES/oldfile> I<MOVIES/newfile>

I<oldfile> is expected to be an existing symlink in I<MOVIES/>,
which targets to I<../DIRECTORS/director/oldfile>. If
I<oldfile>=I<newfile>, an error will be raised. Otherwise, the following
actions will be performed:

=over 4


=item * The old target will be renamed to I<DIRECTORS/director/newfile>,

=item * the old symlink will be deleted,

=item * a new symlink I<MOVIES/newfile> -> I<../DIRECTORS/director/newfile>
will be created, and

=item * the filename in the database will be updated.

=back

If the B<--lookup-db> flag is set, the new I<director> will be found on the
database instead of by parsing the path of the old target.


=item B<videomv.pl> I<MOVIES/oldfile> I<DIRECTORS/newdirector/>[I<newfile>]

I<oldfile> is expected to be an existing symlink in I<MOVIES/>,
which targets to I<../DIRECTORS/olddirector/oldfile>. If
I<olddirector/oldfile>=I<newdirector/newfile>
(or if I<olddirector>=I<newdirector> and I<newfile> was not given),
an error will be raised.
Otherwise, the following actions will be performed:

=over 4

=item * The old target will be moved to I<DIRECTORS/newdirector/newfile>,
(or to I<DIRECTORS/newdirector/oldfile> if I<newfile> was not given),

=item * the old symlink will be deleted,

=item * a new symlink I<MOVIES/newfile> -> I<../DIRECTORS/newdirector/newfile>
(or -> I<../DIRECTORS/newdirector/oldfile> if I<newfile> was not given)
will be created, and

=item * the filename in the database will be updated unless I<oldfile>=I<newfile>.

=back


=item B<videomv.pl> [B<--lookup-db>] I<DIRECTORS/director/oldfile> I<MOVIES/newfile>

A symlink I<MOVIES/oldfile> -> I<../DIRECTORS/director/oldfile> is
expected to exist.
If I<oldfile>=I<newfile>, an error will be raised. Otherwise, the following
actions will be performed:

=over 4

=item * The old target I<DIRECTORS/director/oldfile> will be renamed to
I<DIRECTORS/director/newfile>,

=item * the old symlink will be deleted,

=item * a new symlink I<MOVIES/newfile> -> I<../DIRECTORS/director/newfile>
will be created, and

=item * the filename in the database will be updated.

=back

If the B<--lookup-db> flag is set, the new I<director> will be found on the
database instead of by parsing the path of the old target.


=item B<videomv.pl> I<DIRECTORS/olddirector/oldfile> I<DIRECTOR/newdirector/>[I<newfile>]

A symlink I<MOVIES/oldfile> -> I<../DIRECTORS/olddirector/oldfile> is
expected to exist.
If I<olddirector/oldfile>=I<newdirector/newfile>
(or if I<olddirector>=I<newdirector> and I<newfile> was not given),
an error will be raised.
Otherwise, the following actions will be performed:

=over 4

=item * The old target I<../DIRECTORS/olddirector/oldfile> will be moved to
I<../DIRECTORS/newdirector/newfile>,

=item * the old symlink will be deleted,

=item * a new symlink I<MOVIES/newfile> -> I<../DIRECTORS/newdirector/newfile>
will be created, and

=item * the filename in the database will be updated unless I<oldfile>=I<newfile>.

=back


=item B<videomv.pl> B<--lookup-db> I<path/to/oldfile> [I<MOVIES>[I</newfile>]]

Where I<path/to/> is neither of I<MOVIES/> nor I<DIRECTORS/*/>,
and I<oldfile> is a regular file.
The I<director> will found in the database, and and error will be
raised if no entry is (or multiple entries are) found.
In case of success, the following actions will be performed:

=over 4

=item * I<oldfile> will be moved to I<DIRECTORS/director/newfile>
(or to I<DIRECTORS/director/oldfile> if I<newfile> was not given),

=item * a symlink I<MOVIES/newfile> -> I<../DIRECTORS/director/newfile>
(or I<MOVIES/oldfile> -> I<../DIRECTORS/director/oldfile> if I<newfile>
was not given) will be created, and

=item * the filename in the database will be updated unless I<oldfile>=I<newfile>.

=back

Note that the B<--lookup-db> flag has to be set for this to work; if not, an error
will be raised.


=item B<videomv.pl> I<path/to/oldfile> I<DIRECTOR/director/>[I<newfile>]

Where I<path/to/> is neither of I<MOVIES/> nor I<DIRECTORS/*/>,
and I<oldfile> is a regular file.
The following actions will be performed:

=over 4

=item * I<oldfile> will be moved to I<DIRECTORS/director/newfile>
(or to I<DIRECTORS/director/oldfile> if I<newfile> was not given),

=item * a symlink I<MOVIES/newfile> -> I<../DIRECTORS/director/newfile>
(or I<MOVIES/oldfile> -> I<../DIRECTORS/director/oldfile> if the second
argument was not given) will be created,

=item * the filename in the database will be updated unless I<oldfile>=I<newfile>.


=back

=back

The actions above will be performed in the given order. If some action
fails, B<videomv.pl> will try to revert the successful ones (in reverse
order).

=head1 OPTIONS

=over 8

=item B<--lookup-db>

If the second argument is in I<MOVIES/*/> and this flag is set, B<videomv.pl>
will search the I<director> in the data base. An error will be raied if
no entry is (or multiple entries are) found. Look above for details.

=item B<--ignore-db>

Do not connect to the database, (thus do not update it with the new
filename). This flag is incompatible with B<--lookup-db>.

=item B<-q>, B<--quiet>

By default, B<videomv.pl> prints each action it performs, with their
return status. This flag supresses this behavior. Use at your own risk.

=back

=head1 EXIT STATUS

The exit status is 0 if all the actions went through, 1 if some error
happened, and 2 if some action fails and the successful ones have been
smoothly reverted.

=head1 REQUIREMENTS

The imported modules are available on CPAN. See the source for details.

=head1 AUTHOR

Copyright 2011 Guilhem Moulin. See the source for copying conditions.

=cut

################################################################################


#TODO: overwrite existing files?
#TODO: explore depth>1 in DIRECTORS/

my $lookupdb_flag;
my $ignoredb_flag;

# Get options
GetOptions( "lookup-db"=> \$lookupdb_flag,
            "ignore-db"=> \$ignoredb_flag,
            "q|quiet"  => sub { open LOG, '>', '/dev/null'
                                or die "Cannot open `/dev/null': $!" },
            "man"      => sub { pod2usage(-exitstatus => 0, -verbose => 2) }
          )
    or  pod2usage(2);
pod2usage(2)  if  ($#ARGV < 0 or $#ARGV > 1);
*LOG = *STDERR  unless  defined (fileno LOG);

my ($old_path,$new_path) = @ARGV;
$new_path = $symlinks unless defined $new_path;

die "Error: incompatible options.\n" if
    (defined $lookupdb_flag) and (defined $ignoredb_flag);

die "Error: `" .$old_path. "' is neither a symlink nor a plain file.\n"
    unless (-l $old_path or -f $old_path);

$new_path = catfile ($new_path, basename($old_path))
    if -d realpath($new_path);
die "Error: `" .$new_path. "' exists.\n"
    if (-l $new_path or -f $new_path);

my $old_filename = basename($old_path);
my $new_filename = basename($new_path);

# Get the real paths, {..,symlink}-collapse and so on
my $real_old_path = catfile (realpath (dirname($old_path)), $old_filename);
my $real_new_path = catfile (realpath (dirname($new_path)), $new_filename);

my $real_symlinks  = realpath($symlinks);
my @real_symlinks = splitdir($real_symlinks);
my $real_directors = realpath($directors);
my @real_directors = splitdir($real_directors);


# Connect to database
my ($dsn, $dbh, $RES, $nRES, $id);
unless (defined $ignoredb_flag) {
    $dsn = "DBI:$driver:database=$database;host=$hostname;port=$port";
    $dbh = DBI->connect($dsn, $user, $password)
               or die "Can't connect do database";
    $dbh->do( "set names utf8" ) or die;


    # Lookup for the file in the videodb database
    $RES =
        $dbh->selectall_hashref ( "SELECT id,director,title FROM $videodata
                                   WHERE filename = ?",
                                  'id', undef, $old_filename
        )
        or die "Can't select: " .$dbh->errstr. "\n";
    $nRES = scalar (keys %$RES);

    # The ID of the first movie found in the database, if any
    $id = each %$RES;
}

my $r = 0;
my ($old_director, $new_director);
my ($old_symlink, $new_symlink, $new_target, $old_target);

if (&is_symlink($real_new_path)) {

    # The destination is under $symlinks

    if (defined $lookupdb_flag) {
        # Find the new director on the database

        # Ensure there is exactly one entry in the db
        die "Error: No entry found in the database while the flag `--lookup-db' was set.\n"
            if $nRES == 0;
        die "Error: Multiples entries found in the database while the flag `--lookup-db' was set.\n"
            if $nRES > 1;

        $new_director = $RES->{$id}->{director};
        $new_director =~ s/ ?: ?/ -/;
        $new_director =~ tr@/@_@;
        $new_director =~ s/[[:cntrl:]]//;

        # Create directory if it doesn't exist
        my $new_dirname = catfile ($directors, $new_director);
        unless (-d $new_dirname) {
            print STDERR "Directory `$new_dirname' does not exist. ";
            until (-d $new_dirname) {
                print STDERR "Should I create it? (Y/n) ";
                my $a = lc <STDIN>;
                chomp $a;
                if ($a eq 'y' or $a eq '') {
                    mkdir $new_dirname
                        or die "Error: Cannot mkdir `$new_dirname': $!\n";
                }
                elsif ($a eq 'n') {
                    exit 0;
                }
            }
        }
    }

    $new_symlink = $new_path;

    if (&is_symlink($real_old_path)) {

        $old_symlink = $old_path;

        # Source is presumably a symlink: ensure it is
        die "Error: `" .$old_path. "' is expected to be a symlink.\n"
            unless -l $real_old_path;

        $old_target = realpath ($old_path);
        die "Error: `" .$old_path. "' is expected to target to `"
                       .catfile(updir(),'DIRECTORS','*',$old_filename). "'.\n"
            unless (defined $new_director
                    || &is_director(\$new_director, $old_target));
        $new_target = catfile ($directors, $new_director, $new_filename);
    }

    elsif (&is_director(\$old_director, $real_old_path)) {

        $old_symlink = catfile ($symlinks, $old_filename);
        die "Error: `" .$old_symlink. "' is expected to be a symlink.\n"
            unless -l $old_symlink;
        die "Error: `" .$old_symlink. "' is expected to target to `"
                       .catfile(updir(),'DIRECTORS',$old_director,$old_filename)
                       ."'.\n"
            unless realpath($old_symlink) eq realpath($old_path);

        $old_target = $old_path;

        $new_director = $old_director unless defined $new_director;
        $new_target = catfile ($directors, $new_director, $new_filename);
    }

    else {
        $old_target = $old_path;
        die "Error: `" .$old_path. "' is expected to be a regular file.\n"
            unless -f $old_path;
        die "Error: Dunno where to put this file. Try the `--lookup-db' flag.\n"
            unless defined $new_director;

        $new_target = catfile ($directors, $new_director, $new_filename);
    }
}

elsif (&is_director(\$new_director, $real_new_path)) {

    # The destination is under $directors/*

    $new_target = $new_path;
    $new_symlink = catfile ($symlinks, $new_filename);

    if (&is_symlink($real_old_path)) {

        # Source is presumably a symlink: ensure it is
        die "Error: `" .$old_path. "' is expected to be a symlink.\n"
            unless -l $real_old_path;

        $old_symlink = $old_path;
        $old_target = realpath ($old_path);
    }

    elsif (&is_director(\$old_director, $real_old_path)) {

        $old_symlink = catfile ($symlinks, $old_filename);
        die "Error: `" .$old_symlink. "' is expected to be a symlink.\n"
            unless -l $old_symlink;
        die "Error: `" .$old_symlink. "' is expected to target to `"
                       .catfile(updir(),'DIRECTORS',$old_director,$old_filename)
                       ."'.\n"
            unless realpath($old_symlink) eq realpath($old_path);

        $old_target = $old_path;
    }

    else {
        $old_target = $old_path;
        die "Error: `" .$old_path. "' is expected to be a regular file.\n"
            unless -f $old_path;
    }
}
else {
    die "Error: destination has to be in `"
                  .$symlinks. "' or in `" .catfile($directors,'*'). "'.\n"
       ."See `" .$0. " --man' for details\n";
}


my @actions;    # Successful actions

if (dirname (realpath $old_target) eq dirname (realpath $new_target)) {
    &perform ("Renaming target...      ", rename $old_target, $new_target)
        unless ($old_filename eq $new_filename);
}
else {
    &perform ("Moving target...        ", move $old_target, $new_target);
}

my $old_tar;
if (defined $old_symlink) {
    $old_tar = readlink $old_symlink;
    &perform ("Deleting old symlink... ", unlink $old_symlink);
}


&perform ("Creating new symlink... ",
          symlink catfile(updir(),'DIRECTORS',$new_director,$new_filename),
                  $new_symlink);


unless (defined $ignoredb_flag || $old_filename eq $new_filename) {
    print LOG "Updating database...    ";
    if ($nRES == 0) {
        $r = 2;
        print LOG "failed!: no entry found.\n";
        &revert(@actions);
    }
    elsif ($nRES > 1) {
        $r = 2;
        print LOG "failed!: multiple entries found.\n";
        &revert(@actions);
    }
    else {
        my $rv = $dbh->do ( "UPDATE $videodata SET filename = ? WHERE id = ?",
                            undef, $new_filename, $id
                 );
        &ack (\$r, $rv);
    }
}


# Disconnect
$dbh->disconnect() unless defined $ignoredb_flag;

exit $r;



################################################################################



# Acknowledge the result of a test
sub ack {
    my ($r, $test) = @_;
    if ($test) {
        print LOG "OK\n";
        return 0;
    } else {
        print LOG "failed!: $!\n";
        $$r = 2 if defined $r;
        return 1;
    }
}

# Perform the given action; revert successful changes in case of failing
sub perform {
    return if $r;

    my ($action,$test) = @_;

    print LOG $action;
    if (&ack (\$r, $test)) {
        &revert(@actions);
    }
    else {
        push @actions, $action;
    }
}

# Revert successful changes
sub revert {
    my @actions = reverse @_;

    return if $#actions < 0;

    print LOG "\n";
    print STDERR "Failed!: reverting successful changes...\n";

    while ($#actions >= 0) {
        my $rev;
        if ($actions[0] =~ /^(Renaming target)(\.{3}) {5}( *)/) {
            $actions[0] = $1 .' back'. $2.$3;
            $rev = rename $new_target, $old_target;
        }
        elsif ($actions[0] =~ /^(Moving target)(\.{3}) {5}( *)/) {
            $actions[0] = $1 .' back'. $2.$3;
            $rev = move $new_target, $old_target;
        }
        elsif ($actions[0] =~ /^Deleting( old symlink.*)/) {
            $actions[0] = 'Creating'. $1;
            $rev = symlink $old_tar, $old_symlink;
        }
        elsif ($actions[0] =~ /^Creating( new symlink.*)/) {
            $actions[0] = 'Deleting'. $1;
            $rev = unlink $new_symlink;
        }
        else {
            print STDERR "Error: unknown action `" .$actions[0]. "'!\n";
            $actions[0] = undef;
            $r = 1;
        }

        if (defined $actions[0]) {
            print LOG $actions[0];
            &ack (\$r, $rev);
        }
        shift @actions;
    }
}

# Check wether a path starts with $movies
sub is_symlink {
    my @path = splitdir ($_[0]);
    my @real_symlinks = @real_symlinks; #local copy

    while ($#real_symlinks>=0 && $#path>=0 && $real_symlinks[0] eq $path[0]) {
        shift @real_symlinks;
        shift @path;
    };

    if ($#real_symlinks<0 && $#path==0) {
        return 1; # That's a "symlink"
    } else {
        return 0; # That's not a "symlink"
    }
}

# Check wether a path starts with $director/dir, and put `dir' in the
# first argument if that's the case
sub is_director {
    my @path = splitdir ($_[1]);
    my @real_directors = @real_directors; #local copy

    while ($#real_directors>=0 && $#path>=0 && $real_directors[0] eq $path[0]) {
        shift @real_directors;
        shift @path;
    };

    if ($#real_directors<0 && $#path>=0) {
        ${$_[0]} = $path[0] if defined $_[0];
        return 1; # That's a "director"
    } else {
        return 0; # That's not a "director"
    }
}