fix: check per-post edit_post capability in chart_data REST field

The chart_data REST field callback only checked the generic edit_posts
capability, so any contributor could read the full backend configuration
of any chart (data source query, settings, JSON endpoint auth headers)
via GET /wp-json/wp/v2/visualizer/{id}.

Check edit_post on the requested chart instead, so access follows the
standard post capability map (author or edit_others_posts).

Fixes Codeinwp/visualizer-pro#605

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: lucadobrescu

classes/Visualizer/Gutenberg/Block.php

@@ -276,7 +276,7 @@ public function register_rest_endpoints() {
 	 * Get Post Meta Fields
 	 */
 	public function get_visualizer_data( $post ) {
-		if ( ! current_user_can( 'edit_posts' ) ) {
+		if ( ! current_user_can( 'edit_post', $post['id'] ) ) {
 			return false;
 		}
 

tests/test-chart-data-permissions.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * WordPress unit test plugin.
+ *
+ * @package     visualizer
+ * @subpackage  Tests
+ * @license     http://opensource.org/licenses/gpl-2.0.php GNU Public License
+ */
+
+/**
+ * Test the capability check on the chart_data REST field callback.
+ */
+class Test_Visualizer_Chart_Data_Permissions extends WP_UnitTestCase {
+
+	/**
+	 * Create a chart owned by the given user.
+	 *
+	 * @param int $author_id The chart author.
+	 * @return int The chart id.
+	 */
+	private function create_chart( $author_id ) {
+		$chart_id = self::factory()->post->create(
+			array(
+				'post_type'    => Visualizer_Plugin::CPT_VISUALIZER,
+				'post_author'  => $author_id,
+				'post_content' => wp_slash( serialize( array( array( 'Label' ), array( 'Value' ) ) ) ),
+			)
+		);
+		update_post_meta( $chart_id, Visualizer_Plugin::CF_CHART_TYPE, 'line' );
+		update_post_meta( $chart_id, Visualizer_Plugin::CF_SETTINGS, array() );
+		update_post_meta( $chart_id, Visualizer_Plugin::CF_SERIES, array( array( 'label' => 'Label', 'type' => 'string' ) ) );
+		return $chart_id;
+	}
+
+	/**
+	 * A contributor must not read another user's chart configuration.
+	 */
+	public function test_contributor_cannot_read_others_chart_data() {
+		$author_id = self::factory()->user->create( array( 'role' => 'editor' ) );
+		$chart_id  = $this->create_chart( $author_id );
+
+		wp_set_current_user( self::factory()->user->create( array( 'role' => 'contributor' ) ) );
+
+		$result = Visualizer_Gutenberg_Block::get_instance()->get_visualizer_data( array( 'id' => $chart_id ) );
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * The chart author can still read their own chart configuration.
+	 */
+	public function test_author_can_read_own_chart_data() {
+		$author_id = self::factory()->user->create( array( 'role' => 'editor' ) );
+		$chart_id  = $this->create_chart( $author_id );
+
+		wp_set_current_user( $author_id );
+
+		$result = Visualizer_Gutenberg_Block::get_instance()->get_visualizer_data( array( 'id' => $chart_id ) );
+		$this->assertIsArray( $result );
+	}
+}