#!/usr/bin/env perl

=pod

=head1 NAME

notes-links - work with links within my notes

=head1 SYNOPSIS

Currently this is vimwiki-dependent.

    # List pages linking to foo:
    notes links --target foo

    # Pages linking to foo.wiki:
    notes links --file ./foo.wiki

    # Pages with a date (i.e. logs and diaries) linking to foo:
    notes links --with-date --target foo

    # Links in foo (experimental, probably broken):
    notes links --source foo

    # Format (defaults to location):
    notes links --format target

=head1 OUTPUT FORMATS

B<--format> options include C<vimwiki>, C<tsv>, C<location>, C<target>,
C<full>, and C<name>.

Formats may be glitchy.

=head1 AUTHOR

Brennen Bearnes

=cut

use warnings;
use strict;
use 5.10.0;

use Cwd;
use Data::Dumper;
use DBI;
use File::Basename;
use File::Spec;
use Getopt::Long;
use Pod::Usage;
use SQL::Abstract;
use Sys::Hostname;

# Display formats:
my %FORMATS = (
  vimwiki => sub {
    my ($data) = @_;
    my $timestamp = '';
    if (defined $data->{timestamp}) {
      $timestamp = $data->{timestamp} . " ";
    }

    return '  - '
         . $timestamp
         . '[[/' . $data->{page} . '|'
         . $data->{title}
         . "]]\n";
  },

  tsv => sub {
    my ($data) = @_;
    my $timestamp = '(null)';
    if (defined $data->{timestamp}) {
      $timestamp = $data->{timestamp};
    }
    return (join "\t", ($timestamp, $data->{page}, $data->{title})) . "\n";
  },

  # vim location list
  #
  # TODO: Note that the "1" here is, theoretically, a line number.
  # Unfortunately, there's no obvious way to extract that from Pandoc's parsing
  # of the original file, and thus no non-hacky way for notes-collect-metadata to
  # store an approximate value in the database.  We _could_ read the file
  # line-by-line, or run grep, looking for the file's basename, but this is
  # tricky to get right.
  #
  # If I keep using this long-term, I should solve this problem.
  location => sub {
    my ($data) = @_;

    my $result = "$ENV{HOME}/notes/vimwiki/$data->{page}.wiki";
    if ($data->{title}) {
      $result .= ":1:$data->{title}";
    } else {
      $result .= print ":1:$data->{page}"
    }

    return $result . "\n";
  },

  # List of bare link _target_ names
  target => sub {
    my ($data) = @_;
    return $data->{target} . "\n";
  },

  # Fulltext of vimwiki pages:
  full => sub {
    my ($data) = @_;
    my $result = '';
    my $pagepath = "$ENV{HOME}/notes/vimwiki/$data->{page}.wiki";
    $result .= "%% $pagepath {{{\n\n";
    $result .= file_get_contents($pagepath);
    $result .= "\n%% }}}\n\n";

    return $result;
  },

  # Bare names of wiki pages (no extension):
  name => sub {
    my ($data) = @_;
    return $data->{page} . "\n";
  },
);

# Handle options, including help generated from the POD above.
my $debug = 0;
my $with_date = 0;
my $target;
my $source;
my $file;
my $format = 'location';
GetOptions(
  'debug'     => \$debug,
  'target=s'  => \$target,
  'file=s'    => \$file,
  'format=s'  => \$format,
  'with-date' => \$with_date,
  'help'      => sub { pod2usage(0) },
) or pod2usage(2);

if (defined $file)
{
  my ($name, $path, $suffix) = fileparse($file, '.wiki');

  # XXX: This is a dirty fucking hack - get rid of the leading path stuff, but
  # keep subdirs within the vimwiki directory:
  $path =~ s{^.*?notes/vimwiki/}{};

  $target = $path . $name;
}

my %where = ();

# Require that the link point to a given page:
if (defined $target) {
  $where{target} = $target;
}

# Get only links from pages that have a datetime:
if ($with_date) {
  # NOT NULL:
  $where{'pages.datetime'} = { '!=', undef };
}

my $dbfile = $ENV{HOME} . "/notes/metadata.db";
my $dbh = DBI->connect("dbi:SQLite:dbname=$dbfile", "", "");

my $sql = SQL::Abstract->new;
my ($query, @bind) = $sql->select(
  'links JOIN pages ON links.page = pages.page',
  # timestamp will be null if datetime is
  "*, DATETIME(datetime, 'localtime') AS timestamp",
  \%where,
  {-desc => [ 'datetime', 'page' ] }
);

if ($debug) {
  say STDERR $query;
  say STDERR Dumper(%where);
}

my $sth = $dbh->prepare($query);
$sth->execute(@bind);

while (my $data = $sth->fetchrow_hashref())
{
  if ($debug) {
    print STDERR Dumper($data);
  }

  print $FORMATS{$format}->($data);
}

$sth->execute();

# PHP-style file-content grabbing:
sub file_get_contents {
  my ($file) = @_;

  open my $fh, '<', $file
    or die "Couldn't open $file: $!\n";

  my $contents;
  {
    # line separator:
    local $/ = undef;
    $contents = <$fh>;
  }

  close $fh or die "Couldn't close $file: $!";
  return $contents;
}

1;