=head1 NAME

  Google::ContentAPI - Interact with Google's Content API for Shopping

=head1 DESCRIPTION

  Add, modify and delete items from the Google Merchant Center platform via
  the Content API for Shopping.

  Authentication is done via Service Account credentials. See the following for details:
  https://developers.google.com/shopping-content/v2/how-tos/service-accounts

  You will also need to create a Merchant Center Account:
  https://developers.google.com/shopping-content/v2/quickstart

  For convenince, add your Merchant account ID to the *.json file provided by Google.
  Your complete *.json file, after adding your merchant ID, will look something like this:

  {
    "merchant_id": "120960455",
    "type": "service_account",
    "project_id": "content-api-test-197421",
    "private_key_id": "11b8e20c2540c788e98b49e623ae8167dc3e4a6f",
    "private_key": "-----BEGIN PRIVATE KEY-----
    ...
    -----END PRIVATE KEY-----\n",
    "client_email": "google@content-api.iam.gserviceaccount.com",
    "client_id": "999999999",
    "auth_uri": "https://accounts.google.com/o/oauth2/auth",
    "token_uri": "https://accounts.google.com/o/oauth2/token",
    "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
    "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/google%40content-api.iam.gserviceaccount.com"
  }

=head1 SYNOPSIS

  use Google::ContentAPI;
  use Data::Dumper;

  # get account auth info (merchantId)
  my $google = Google::ContentAPI->new({
      debug => 0,
      config_file => 'content-api-key.json'
  });

  my ($result, $products, $batch_id);

  # get account auth info (merchantId)
  $result = $google->get(
    resource => 'accounts',
    method   => 'authinfo'
  );
  print "authinfo: \n". Dumper $result;
  print "$result->{code} ". ($result->{code} eq '200' ? 'success' : 'failure') ."\n";

  # list products

  $result = $google->get(
      resource => 'products',
      method   => 'list',
      params   => ['includeInvalidInsertedItems' => 'true']
  );
  print "Products list: \n". Dumper $result;
  print "$result->{code} ". ($result->{code} eq '200' ? 'success' : 'failure') ."\n";

  # insert a product

  $result = $google->post(
      resource => 'products',
      method   => 'insert',
      params   => ['dryRun' => 'true'],
      body => {
        contentLanguage => 'en',
        targetCountry => 'US',
        channel => 'online',
        offerId => '333333',
        title => 'Item title',
        description => 'The item description',
        link => 'http://www.google.com',
        imageLink => 'https://www.google.com/images/logo.png',
        availability => 'in stock',
        condition => 'new',
        price => {
            value => '99.95',
            currency => 'USD',
        },
        shipping => [
          {
            country => 'US',
            service => 'Standard Shipping',
            price => {
                value => '7.95',
                currency => 'USD',
            },
          },
        ],
        brand => 'Apple',
        gtin => '333333-67890',
        mpn => '333333',
        googleProductCategory => 'Home & Garden > Household Supplies > Apples',
        productType => 'Home & Garden > Household Supplies > Apples',
        customLabel1 => 'apples'
      }
  );
  print "$result->{code} ". ($result->{code} eq '200' ? 'success' : 'failure') ."\n";

  # get single product info

  my $product_id = '333333';
  $result = $google->get(
      resource => 'products',
      method   => 'get',
      id => 'online:en:US:'. $product_id
  );
  print "Products info: \n". Dumper $result;
  print "$result->{code} ". ($result->{code} eq '200' ? 'success' : 'failure') ."\n";

  # delete a product

  my $del_product_id = '333333';
  $result = $google->delete(
      resource => 'products',
      method   => 'delete',
      id => 'online:en:US:'. $del_product_id,
      #params   => ['dryRun' => 'true']
  );
  print "$result->{code} ". ($result->{code} eq '204' ? 'success' : 'failure') ."\n"; # 204 = delete success

  # batch insert

  $products = [];
  $batch_id = 0;

  foreach my $i ('211203'..'211205') {
      push @$products, {
          batchId => ++$batch_id,
          merchantId => $google->{merchant_id},
          method => 'insert', # insert / get / delete
          #productId => '', # for get / delete
          product => { # for insert
              contentLanguage => 'en',
              targetCountry => 'US',
              channel => 'online',
              offerId => "$i",
              title => "item title $i",
              description => "The item description for $i",
              link => 'http://www.google.com',
              imageLink => 'https://www.google.com/images/logo.png',
              availability => 'in stock',
              condition => 'new',
              price => {
                  value => '10.95',
                  currency => 'USD',
              },
              shipping => [
                {
                  country => 'US',
                  service => 'Standard Shipping',
                  price => {
                      value => '7.95',
                      currency => 'USD',
                  },
                },
              ],
              brand => 'Apple',
              gtin => "${i}-67890",
              mpn => "$i",
              googleProductCategory => 'Home & Garden > Household Supplies > Apples',
              productType => 'Home & Garden > Household Supplies > Apples',
              customLabel1 => 'apples'
          }
      };
  }

  $result = $google->post(
      resource => 'products',
      method   => 'batch',
      #params   => ['dryRun' => 'true'],
      body => { entries => $products }
  );
  print "$result->{code} ". ($result->{code} eq '200' ? 'success' : 'failure') ."\n";

  # batch get:

  $products = [];
  $batch_id = 0;
  foreach my $product_id ('211203'..'211205') {
      push @$products, {
          batchId => ++$batch_id,
          merchantId => $google->{merchant_id},
          method => 'get', # insert / get / delete
          productId => 'online:en:US:'. $product_id, # for get / delete
      };
  }

  $result = $google->post(
      resource => 'products',
      method   => 'batch',
      #params   => ['dryRun' => 'true'],
      body => { entries => $products }
  );
  print Dumper $result;
  print "$result->{code} ". ($result->{code} eq '200' ? 'success' : 'failure') ."\n";

  # batch delete:

  $products = [];
  $batch_id = 0;
  foreach my $product_id ('211203'..'211205') {
      push @$products, {
          batchId => ++$batch_id,
          merchantId => $google->{merchant_id},
          method => 'delete', # insert / get / delete
          productId => 'online:en:US:'. $product_id, # for get / delete
      };
  }

  $result = $google->post(
      resource => 'products',
      method   => 'batch',
      #params   => ['dryRun' => 'true'],
      body => { entries => $products }
  );
  print "$result->{code} ". ($result->{code} eq '200' ? 'success' : 'failure') ."\n";

=head1 METHODS AND FUNCTIONS

=head2 ACCOUNTS

=head3 authinfo

  Returns information about the authenticated user.

=head2 PRODUCTS

=head3 custombatch

  Retrieves, inserts, and deletes multiple products in a single request.

=head3 insert

  Uploads a product to your Merchant Center account. If an item with the
  same channel, contentLanguage, offerId, and targetCountry already exists,
  this method updates that entry.

=head3 list

  Lists the products in your Merchant Center account.

=head3 get

  Retrieves a product from your Merchant Center account.

=head3 delete

  Deletes a product from your Merchant Center account.

=head1 UNIMPLEMENTED FEATURES

Certain API methods are not yet implemented (no current personal business need).

=head1 PREREQUISITES

  JSON
  JSON::WebToken
  Crypt::OpenSSL::RSA
  REST::Client
  HTML::Entities

=head1 AUTHOR

  Original Author
  Bill Gerrard <bill@gerrard.org>

=head1 COPYRIGHT AND LICENSE

  Copyright (C) 2018 Bill Gerrard

  This library is free software; you can redistribute it and/or modify
  it under the same terms as Perl itself, either Perl version 5.20.2 or,
  at your option, any later version of Perl 5 you may have available.
  Disclaimer of warranty: This program is provided by the copyright holder
  and contributors "As is" and without any express or implied warranties.
  The implied warranties of merchantability, fitness for a particular purpose,
  or non-infringement are disclaimed to the extent permitted by your local
  law. Unless required by law, no copyright holder or contributor will be
  liable for any direct, indirect, incidental, or consequential damages
  arising in any way out of the use of the package, even if advised of the
  possibility of such damage.

=cut