#!/usr/bin/env perl
use strict;
use warnings;
use FindBin;
use lib "$FindBin::Bin/..";
use YAMLPatch;
use Getopt::Long qw(GetOptions);

# yamlpatch - command-line front end for YAMLPatch.pm.
#
# Exposes the same path-addressed, formatting-preserving operations as the Perl API to shell
# scripts and non-Perl callers. Uses the SAME code path as the module's API (this script is a
# thin argument-parsing wrapper around YAMLPatch.pm, nothing more), so behavior cannot drift
# between the two - see YAMLPatch.md for the full API reference and the rationale behind the
# supported subset / relaxation flags used below.

my %opt = (
    style          => 'keep',
    'dry-run'      => 0,
    backup         => 0,
    'allow-flow'         => 0,
    'allow-block-scalar' => 0,
    'allow-anchors'      => 0,
    'allow-multidoc'     => 0,
);

GetOptions(
    \%opt,
    'style=s',
    'dry-run',
    'backup',
    'after=s',
    'before=s',
    'allow-flow',
    'allow-block-scalar',
    'allow-anchors',
    'allow-multidoc',
    'help|h',
) or usage(2);

usage(0) if $opt{help};

my $op = shift @ARGV or usage(2, "missing OPERATION");

my %load_opts = (
    allow_flow         => $opt{'allow-flow'},
    allow_block_scalar => $opt{'allow-block-scalar'},
    allow_anchors      => $opt{'allow-anchors'},
    allow_multidoc     => $opt{'allow-multidoc'},
);

my $exit = eval {
    if ($op eq 'get') {
        my ($path, $file) = @ARGV;
        usage(2, "get: usage: get PATH FILE") unless defined $path && defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        my $rec = $y->get($path);
        unless ($rec) {
            print STDERR "yamlpatch: path '$path' does not exist"
                . ($y->exists_commented($path) ? " (it exists, but is commented out)\n" : "\n");
            return 1;
        }
        print defined($rec->{value}) ? "$rec->{value}\n" : "\n";
        return 0;
    }

    if ($op eq 'exists') {
        my ($path, $file) = @ARGV;
        usage(2, "exists: usage: exists PATH FILE") unless defined $path && defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        return $y->exists_path($path) ? 0 : 1;
    }

    if ($op eq 'list') {
        my ($file) = @ARGV;
        usage(2, "list: usage: list FILE") unless defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        print "$_\n" for $y->path_list;
        return 0;
    }

    if ($op eq 'set') {
        my ($path, $value, $file) = @ARGV;
        usage(2, "set: usage: set PATH VALUE FILE") unless defined $path && defined $value && defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        $y->set($path, $value, style => $opt{style});
        return _finish($y, $file);
    }

    if ($op eq 'delete') {
        my ($path, $file) = @ARGV;
        usage(2, "delete: usage: delete PATH FILE") unless defined $path && defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        $y->delete($path);
        return _finish($y, $file);
    }

    if ($op eq 'comment-out') {
        my ($path, $file) = @ARGV;
        usage(2, "comment-out: usage: comment-out PATH FILE") unless defined $path && defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        $y->comment_out($path);
        return _finish($y, $file);
    }

    if ($op eq 'uncomment') {
        my ($path, $file) = @ARGV;
        usage(2, "uncomment: usage: uncomment PATH FILE") unless defined $path && defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        $y->uncomment($path);
        return _finish($y, $file);
    }

    if ($op eq 'insert-kv') {
        my ($parent, $key, $value, $file) = @ARGV;
        usage(2, "insert-kv: usage: insert-kv PARENT KEY VALUE FILE [--after SIBLING|--before SIBLING]")
            unless defined $parent && defined $key && defined $value && defined $file;
        my $y = YAMLPatch->load_file($file, %load_opts);
        my %ins = (parent => $parent, key => $key, value => $value, style => $opt{style});
        $ins{after}  = $opt{after}  if defined $opt{after};
        $ins{before} = $opt{before} if defined $opt{before};
        $y->insert_kv(%ins);
        return _finish($y, $file);
    }

    usage(2, "unknown operation '$op'");
};
if ($@) {
    print STDERR "yamlpatch: $@";
    $exit = 1;
}
exit($exit // 1);

sub _finish {
    my ($y, $file) = @_;
    if ($opt{'dry-run'}) {
        my $diff = $y->diff;
        print $diff eq '' ? "(no changes)\n" : "$diff\n";
        return 0;
    }
    $y->save($file, backup => $opt{backup});
    return 0;
}

sub usage {
    my ($code, $msg) = @_;
    print STDERR "yamlpatch: $msg\n\n" if $msg;
    print STDERR <<'USAGE';
Usage: yamlpatch OPERATION [ARGS...] [OPTIONS]

Operations:
  get          PATH FILE                    print the value at PATH
  exists       PATH FILE                    exit 0 if PATH exists, 1 otherwise
  list         FILE                         print every addressable path, one per line
  set          PATH VALUE FILE              set PATH to VALUE
  delete       PATH FILE                    remove PATH (and its subtree, if a container)
  comment-out  PATH FILE                    comment out PATH (and its subtree), reversibly
  uncomment    PATH FILE                    reverse a previous comment-out
  insert-kv    PARENT KEY VALUE FILE        add a new "KEY: VALUE" under PARENT
                                             [--after SIBLING | --before SIBLING]

Options:
  --style bare|single|double|keep  quoting style for the written value (default: keep)
  --dry-run                        print a diff instead of writing the file
  --backup                         write FILE.bak.<timestamp> before saving
  --allow-flow                     accept flow-style [..]/{..} values as opaque
  --allow-block-scalar             accept |/> block scalars as opaque
  --allow-anchors                  accept &anchor/*alias/!tag values as opaque
  --allow-multidoc                 accept a second '---' document as an opaque tail
  --help                           this message

Examples:
  yamlpatch get transport.compression.method sneakernet.conf.yaml
  yamlpatch set transport.compression.method "'xz'" sneakernet.conf.yaml
  yamlpatch delete datasets.ds1.maxDelta sneakernet.conf.yaml
  yamlpatch comment-out datasets.ds2 sneakernet.conf.yaml
  yamlpatch insert-kv transport verifyFullSendDataset storage/testing/verify \
      sneakernet.conf.yaml --after verifyStream

Exit status: 0 on success; 1 on refusal (subset violation, gate failure, path not
found); 2 on a command-line usage error.
USAGE
    exit $code;
}