package File::Move::Undoable;

our $DATE = '2016-06-10'; # DATE
our $VERSION = '0.08'; # VERSION

use 5.010001;
use strict;
use warnings;
use Log::Any::IfLOG '$log';

use File::MoreUtil qw(file_exists l_abs_path);
use File::Trash::Undoable;
use IPC::System::Options 'system', -log=>1;
use Proc::ChildError qw(explain_child_error);

our %SPEC;

$SPEC{mv} = {
    v           => 1.1,
    summary     => 'Move file/directory using rename/rsync, with undo support',
    description => <<'_',

If moving to the same filesystem, will move using `rename()`. On undo will
restore the old name.

If moving to a different filesystem, will copy to `target` using `rsync` and
then trash `source`. On undo, will trash `target` and restore `source` from
trash.

Fixed state: `source` does not exist and `target` exists. Content or sizes are
not checked; only existence.

Fixable state: `source` exists and `target` doesn't exist.

Unfixable state: `source` does not exist, or both `source` and `target` exist
(unless we are moving to a different filesystem, in which it means an
interrupted transfer and thus fixable).

_
    args        => {
        source => {
            schema => 'str*',
            req    => 1,
            pos    => 0,
        },
        target => {
            schema => 'str*',
            summary => 'Target location',
            description => <<'_',

Note that to avoid ambiguity, you must specify full location instead of just
directory name. For example: mv(source=>'/dir', target=>'/a') will move /dir to
/a and mv(source=>'/dir', target=>'/a/dir') will move /dir to /a/dir.

_
            req    => 1,
            pos    => 1,
        },
        rsync_opts => {
            schema => [array => {of=>'str*', default=>['-a']}],
            summary => 'Rsync options',
            description => <<'_',

By default, `-a` is used. You should not use rsync options that modify or
destroy source, like `--remove-source-files` as it will make recovery of
interrupted move impossible.

_
        },
    },
    features => {
        tx => {v=>2},
        idempotent => 1,
    },
    deps => {
        prog => 'rsync',
    },
};
sub mv {
    require Sys::Filesystem::MountPoint; # a bit heavy

    my %args = @_;

    # TMP, schema
    my $tx_action  = $args{-tx_action} // '';
    my $taid      = $args{-tx_action_id}
        or return [412, "Please specify -tx_action_id"];
    my $dry_run    = $args{-dry_run};
    my $source     = $args{source};
    defined($source) or return [400, "Please specify source"];
    my $target     = $args{target};
    defined($target) or return [400, "Please specify target"];
    my $rsync_opts = $args{rsync_opts} // ['-a'];
    $rsync_opts = [$rsync_opts] unless ref($rsync_opts) eq 'ARRAY';

    my $se      = file_exists($source);
    my $te      = file_exists($target);
    my $asource = l_abs_path($source) or return [400, "Invalid path $source"];
    my $atarget = l_abs_path($target) or return [400, "Invalid path $target"];
    # since path_to_mount_point resolves symlink (sigh), we need to remove the
    # leaf. otherwise: /mnt/sym -> / will cause mount point to become / instead
    # of /mnt
    for ($asource, $atarget) {
        s!/[^/]+\z!! if (-l $_);
    }
    my $mpsource = Sys::Filesystem::MountPoint::path_to_mount_point($asource);
    my $mptarget = Sys::Filesystem::MountPoint::path_to_mount_point($atarget);
    my $same_fs  = $mpsource eq $mptarget;
    if ($same_fs) {
        $log->tracef("Source %s & target %s are on the same filesystem (%s)",
                     $source, $target, $mpsource);
    } else {
        $log->tracef("Source %s and target %s are on different filesystems ".
                         "(%s and %s)", $source, $target, $mpsource, $mptarget);
    }

    if ($tx_action eq 'check_state') {
        return [304, "Source $source already does not exist and ".
                    "target $target exists"] if !$se && $te;
        return [412, "Source $source does not exist"] unless $se;
        return [412, "Target $target already exists"] if $te && $same_fs;

        my @undo;
        if ($te || !$same_fs) {
            unshift @undo, (
                ["File::Trash::Undoable::trash" =>
                     {path=>$target, suffix=>substr($taid,0,8)}],
                ["File::Trash::Undoable::untrash" =>
                     {path=>$source, suffix=>substr($taid,0,8)}],
            );
        } else {
            unshift @undo, (
                [mv => {source=>$target, target=>$source}],
            );
        }

        $log->info("(DRY) ".($te ? "Continue moving" : "Moving").
                       " $source -> $target ...") if $dry_run;
        return [200, "$source needs to be ".
                    ($te ? "continued to be moved":"moved")." to $target",
                undef, {undo_actions=>\@undo}];

    } elsif ($tx_action eq 'fix_state') {
        if ($same_fs) {
            $log->infof("Renaming %s -> %s ...", $source, $target);
            if (rename $source, $target) {
                return [200, "OK"];
            } else {
                return [500, "Can't rename: $!"];
            }
        } else {
            my @cmd = ("rsync", @$rsync_opts, "$source/", "$target/");
            $log->infof("Rsync-ing %s -> %s ...", $source, $target);
            system @cmd;
            return [500, "rsync: ".explain_child_error($?)] if $?;
            return File::Trash::Undoable::trash(
                -tx_action=>'fix_state',
                path=>$source, suffix=>substr($taid,0,8));
        }
    }
    [400, "Invalid -tx_action"];
}

1;
# ABSTRACT: Move file/directory using rename/rsync, with undo support

__END__

=pod

=encoding UTF-8

=head1 NAME

File::Move::Undoable - Move file/directory using rename/rsync, with undo support

=head1 VERSION

This document describes version 0.08 of File::Move::Undoable (from Perl distribution File-Move-Undoable), released on 2016-06-10.

=head1 FUNCTIONS


=head2 mv(%args) -> [status, msg, result, meta]

Move file/directory using rename/rsync, with undo support.

If moving to the same filesystem, will move using C<rename()>. On undo will
restore the old name.

If moving to a different filesystem, will copy to C<target> using C<rsync> and
then trash C<source>. On undo, will trash C<target> and restore C<source> from
trash.

Fixed state: C<source> does not exist and C<target> exists. Content or sizes are
not checked; only existence.

Fixable state: C<source> exists and C<target> doesn't exist.

Unfixable state: C<source> does not exist, or both C<source> and C<target> exist
(unless we are moving to a different filesystem, in which it means an
interrupted transfer and thus fixable).

This function is not exported.

This function is idempotent (repeated invocations with same arguments has the same effect as single invocation). This function supports transactions.


Arguments ('*' denotes required arguments):

=over 4

=item * B<rsync_opts> => I<array[str]> (default: ["-a"])

Rsync options.

By default, C<-a> is used. You should not use rsync options that modify or
destroy source, like C<--remove-source-files> as it will make recovery of
interrupted move impossible.

=item * B<source>* => I<str>

=item * B<target>* => I<str>

Target location.

Note that to avoid ambiguity, you must specify full location instead of just
directory name. For example: mv(source=>'/dir', target=>'/a') will move /dir to
/a and mv(source=>'/dir', target=>'/a/dir') will move /dir to /a/dir.

=back

Special arguments:

=over 4

=item * B<-tx_action> => I<str>

For more information on transaction, see L<Rinci::Transaction>.

=item * B<-tx_action_id> => I<str>

For more information on transaction, see L<Rinci::Transaction>.

=item * B<-tx_recovery> => I<str>

For more information on transaction, see L<Rinci::Transaction>.

=item * B<-tx_rollback> => I<str>

For more information on transaction, see L<Rinci::Transaction>.

=item * B<-tx_v> => I<str>

For more information on transaction, see L<Rinci::Transaction>.

=back

Returns an enveloped result (an array).

First element (status) is an integer containing HTTP status code
(200 means OK, 4xx caller error, 5xx function error). Second element
(msg) is a string containing error message, or 'OK' if status is
200. Third element (result) is optional, the actual result. Fourth
element (meta) is called result metadata and is optional, a hash
that contains extra information.

Return value:  (any)

=head1 FAQ

=head2 Why do you use rsync? Why not, say, File::Copy::Recursive?

With C<rsync>, we can continue interrupted transfer. We need this ability for
recovery. Also, C<rsync> can handle hardlinks and preservation of ownership,
something which L<File::Copy::Recursive> currently does not do. And, being
implemented in C, it might be faster when processing large files/trees.

=head1 HOMEPAGE

Please visit the project's homepage at L<https://metacpan.org/release/File-Move-Undoable>.

=head1 SOURCE

Source repository is at L<https://github.com/perlancar/perl-File-Move-Undoable>.

=head1 BUGS

Please report any bugs or feature requests on the bugtracker website L<https://rt.cpan.org/Public/Dist/Display.html?Name=File-Move-Undoable>

When submitting a bug or request, please include a test-file or a
patch to an existing test-file that illustrates the bug or desired
feature.

=head1 SEE ALSO

L<Setup>

L<Rinci::Transaction>

=head1 AUTHOR

perlancar <perlancar@cpan.org>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2016 by perlancar@cpan.org.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut