#!/usr/bin/perl

=head1 NAME

json_xs - JSON::XS commandline utility

=head1 SYNOPSIS

   json_xs [-v] [-f inputformat] [-t outputformat]

=head1 DESCRIPTION

F<json_xs> converts between some input and output formats (one of them is
JSON).

The default input format is C<json> and the default output format is
C<json-pretty>.

=head1 OPTIONS

=over 4

=item -v

Be slightly more verbose.

=item -f fromformat

Read a file in the given format from STDIN.

C<fromformat> can be one of:

=over 4

=item json - a json text encoded, either utf-8, utf16-be/le, utf32-be/le

=item cbor - CBOR (RFC 7049, L<CBOR::XS>), a kind of binary JSON

=item storable - a L<Storable> frozen value

=item storable-file - a L<Storable> file (Storable has two incompatible formats)

=item bencode - use L<Convert::Bencode>, if available (used by torrent files, among others)

=item clzf - L<Compress::LZF> format (requires that module to be installed)

=item eval - evaluate the given code as (non-utf-8) Perl, basically the reverse of "-t dump"

=item yaml - L<YAML> format (requires that module to be installed)

=item string - do not attempt to decode the file data

=item none - nothing is read, creates an C<undef> scalar - mainly useful with C<-e>

=back

=item -t toformat

Write the file in the given format to STDOUT.

C<toformat> can be one of:

=over 4

=item json, json-utf-8 - json, utf-8 encoded

=item json-pretty - as above, but pretty-printed

=item json-utf-16le, json-utf-16be - little endian/big endian utf-16

=item json-utf-32le, json-utf-32be - little endian/big endian utf-32

=item cbor - CBOR (RFC 7049, L<CBOR::XS>), a kind of binary JSON

=item cbor-packed - CBOR using extensions to make it smaller

=item storable - a L<Storable> frozen value in network format

=item storable-file - a L<Storable> file in network format (Storable has two incompatible formats)

=item bencode - use L<Convert::Bencode>, if available (used by torrent files, among others)

=item clzf - L<Compress::LZF> format

=item yaml - L<YAML::XS> format

=item dump - L<Data::Dump>

=item dumper - L<Data::Dumper>

=item string - writes the data out as if it were a string

=item none - nothing gets written, mainly useful together with C<-e>

Note that Data::Dumper doesn't handle self-referential data structures
correctly - use "dump" instead.

=back

=item -e code

Evaluate perl code after reading the data and before writing it out again
- can be used to filter, create or extract data. The data that has been
written is in C<$_>, and whatever is in there is written out afterwards.

=back

=head1 EXAMPLES

   json_xs -t none <isitreally.json

"JSON Lint" - tries to parse the file F<isitreally.json> as JSON - if it
is valid JSON, the command outputs nothing, otherwise it will print an
error message and exit with non-zero exit status.

   <src.json json_xs >pretty.json

Prettify the JSON file F<src.json> to F<dst.json>.

   json_xs -f storable-file <file

Read the serialised Storable file F<file> and print a human-readable JSON
version of it to STDOUT.

   json_xs -f storable-file -t yaml <file

Same as above, but write YAML instead (not using JSON at all :)

   json_xs -f none -e '$_ = [1, 2, 3]'

Dump the perl array as UTF-8 encoded JSON text.

   <torrentfile json_xs -f bencode -e '$_ = join "\n", map @$_, @{$_->{"announce-list"}}' -t string

Print the tracker list inside a torrent file.

   lwp-request http://cpantesters.perl.org/show/JSON-XS.json | json_xs

Fetch the cpan-testers result summary C<JSON::XS> and pretty-print it.

=head1 AUTHOR

Copyright (C) 2008 Marc Lehmann <json@schmorp.de>

=cut

use strict;

use Getopt::Long;
use Storable ();
use Encode;

use JSON::XS;

my $opt_verbose;
my $opt_from = "json";
my $opt_to   = "json-pretty";
my $opt_eval;

Getopt::Long::Configure ("bundling", "no_ignore_case", "require_order");

GetOptions(
   "v"   => \$opt_verbose,
   "f=s" => \$opt_from,
   "t=s" => \$opt_to,
   "e=s" => \$opt_eval,
) or die "Usage: $0 [-v] -f fromformat [-e code] [-t toformat]\n";

my %F = (
   "none"          => sub { undef },
   "string"        => sub { $_ },
   "json"          => sub {
      my $enc =
         /^\x00\x00\x00/s  ? "utf-32be"
       : /^\x00.\x00/s     ? "utf-16be"
       : /^.\x00\x00\x00/s ? "utf-32le"
       : /^.\x00.\x00/s    ? "utf-16le"
       :                     "utf-8";
      warn "input text encoding is $enc\n" if $opt_verbose;
      JSON::XS->new->decode (decode $enc, $_)
   },
   "cbor"          => sub { require CBOR::XS; CBOR::XS->new->allow_cycles->decode ($_) },
   "storable"      => sub { Storable::thaw $_ },
   "storable-file" => sub { open my $fh, "<", \$_; Storable::fd_retrieve $fh },
   "bencode"       => sub { require Convert::Bencode; Convert::Bencode::bdecode ($_) },
   "clzf"          => sub { require Compress::LZF; Compress::LZF::sthaw ($_) },
   "yaml"          => sub { require YAML::XS; YAML::XS::Load ($_) },
   "eval"          => sub { my $v = eval "no strict; no warnings; no utf8;\n#line 1 \"input\"\n$_"; die "$@" if $@; $v },
);

my %T = (
   "none"          => sub { "" },
   "string"        => sub { $_ },
   "json"          => sub { encode_json $_ },
   "json-utf-8"    => sub { encode_json $_ },
   "json-pretty"   => sub { JSON::XS->new->utf8->pretty->canonical->encode ($_) },
   "json-utf-16le" => sub { encode "utf-16le", JSON::XS->new->encode ($_) },
   "json-utf-16be" => sub { encode "utf-16be", JSON::XS->new->encode ($_) },
   "json-utf-32le" => sub { encode "utf-32le", JSON::XS->new->encode ($_) },
   "json-utf-32be" => sub { encode "utf-32be", JSON::XS->new->encode ($_) },
   "cbor"          => sub { require CBOR::XS; CBOR::XS::encode_cbor ($_) },
   "cbor-packed"   => sub { require CBOR::XS; CBOR::XS->new->pack_strings->encode ($_) },
   "storable"      => sub { Storable::nfreeze $_ },
   "storable-file" => sub { open my $fh, ">", \my $buf; Storable::nstore_fd $_, $fh; $buf },
   "bencode"       => sub { require Convert::Bencode; Convert::Bencode::bencode ($_) },
   "clzf"          => sub { require Compress::LZF; Compress::LZF::sfreeze_cr ($_) },
   "yaml"          => sub { require YAML::XS; YAML::XS::Dump ($_) },
   "dumper"        => sub {
      require Data::Dumper;
      #local $Data::Dumper::Purity    = 1; # hopeless case
      local $Data::Dumper::Terse     = 1;
      local $Data::Dumper::Indent    = 1;
      local $Data::Dumper::Useqq     = 1;
      local $Data::Dumper::Quotekeys = 0;
      local $Data::Dumper::Sortkeys  = 1;
      Data::Dumper::Dumper($_)
   },
   "dump"          => sub {
      require Data::Dump;
      local $Data::Dump::TRY_BASE64 = 0;
      Data::Dump::dump ($_) . "\n"
   },
);

$F{$opt_from}
   or die "$opt_from: not a valid fromformat\n";

$T{$opt_to}
   or die "$opt_to: not a valid toformat\n";

if ($opt_from ne "none") {
   local $/;
   binmode STDIN; # stupid perl sometimes thinks its funny
   $_ = <STDIN>;
}

$_ = $F{$opt_from}->();

eval $opt_eval;
die $@ if $@;

$_ = $T{$opt_to}->();

binmode STDOUT;
syswrite STDOUT, $_;