wp_get_code_editor_settings() WordPress Function

function wp_get_code_editor_settings( $args ) {
	$settings = array(
		'codemirror' => array(
			'indentUnit'       => 4,
			'indentWithTabs'   => true,
			'inputStyle'       => 'contenteditable',
			'lineNumbers'      => true,
			'lineWrapping'     => true,
			'styleActiveLine'  => true,
			'continueComments' => true,
			'extraKeys'        => array(
				'Ctrl-Space' => 'autocomplete',
				'Ctrl-/'     => 'toggleComment',
				'Cmd-/'      => 'toggleComment',
				'Alt-F'      => 'findPersistent',
				'Ctrl-F'     => 'findPersistent',
				'Cmd-F'      => 'findPersistent',
			),
			'direction'        => 'ltr', // Code is shown in LTR even in RTL languages.
			'gutters'          => array(),
		),
		'csslint'    => array(
			'errors'                    => true, // Parsing errors.
			'box-model'                 => true,
			'display-property-grouping' => true,
			'duplicate-properties'      => true,
			'known-properties'          => true,
			'outline-none'              => true,
		),
		'jshint'     => array(
			// The following are copied from <https://github.com/WordPress/wordpress-develop/blob/4.8.1/.jshintrc>.
			'boss'     => true,
			'curly'    => true,
			'eqeqeq'   => true,
			'eqnull'   => true,
			'es3'      => true,
			'expr'     => true,
			'immed'    => true,
			'noarg'    => true,
			'nonbsp'   => true,
			'onevar'   => true,
			'quotmark' => 'single',
			'trailing' => true,
			'undef'    => true,
			'unused'   => true,

			'browser'  => true,

			'globals'  => array(
				'_'        => false,
				'Backbone' => false,
				'jQuery'   => false,
				'JSON'     => false,
				'wp'       => false,
			),
		),
		'htmlhint'   => array(
			'tagname-lowercase'        => true,
			'attr-lowercase'           => true,
			'attr-value-double-quotes' => false,
			'doctype-first'            => false,
			'tag-pair'                 => true,
			'spec-char-escape'         => true,
			'id-unique'                => true,
			'src-not-empty'            => true,
			'attr-no-duplication'      => true,
			'alt-require'              => true,
			'space-tab-mixed-disabled' => 'tab',
			'attr-unsafe-chars'        => true,
		),
	);

	$type = '';
	if ( isset( $args['type'] ) ) {
		$type = $args['type'];

		// Remap MIME types to ones that CodeMirror modes will recognize.
		if ( 'application/x-patch' === $type || 'text/x-patch' === $type ) {
			$type = 'text/x-diff';
		}
	} elseif ( isset( $args['file'] ) && false !== strpos( basename( $args['file'] ), '.' ) ) {
		$extension = strtolower( pathinfo( $args['file'], PATHINFO_EXTENSION ) );
		foreach ( wp_get_mime_types() as $exts => $mime ) {
			if ( preg_match( '!^(' . $exts . ')$!i', $extension ) ) {
				$type = $mime;
				break;
			}
		}

		// Supply any types that are not matched by wp_get_mime_types().
		if ( empty( $type ) ) {
			switch ( $extension ) {
				case 'conf':
					$type = 'text/nginx';
					break;
				case 'css':
					$type = 'text/css';
					break;
				case 'diff':
				case 'patch':
					$type = 'text/x-diff';
					break;
				case 'html':
				case 'htm':
					$type = 'text/html';
					break;
				case 'http':
					$type = 'message/http';
					break;
				case 'js':
					$type = 'text/javascript';
					break;
				case 'json':
					$type = 'application/json';
					break;
				case 'jsx':
					$type = 'text/jsx';
					break;
				case 'less':
					$type = 'text/x-less';
					break;
				case 'md':
					$type = 'text/x-gfm';
					break;
				case 'php':
				case 'phtml':
				case 'php3':
				case 'php4':
				case 'php5':
				case 'php7':
				case 'phps':
					$type = 'application/x-httpd-php';
					break;
				case 'scss':
					$type = 'text/x-scss';
					break;
				case 'sass':
					$type = 'text/x-sass';
					break;
				case 'sh':
				case 'bash':
					$type = 'text/x-sh';
					break;
				case 'sql':
					$type = 'text/x-sql';
					break;
				case 'svg':
					$type = 'application/svg+xml';
					break;
				case 'xml':
					$type = 'text/xml';
					break;
				case 'yml':
				case 'yaml':
					$type = 'text/x-yaml';
					break;
				case 'txt':
				default:
					$type = 'text/plain';
					break;
			}
		}
	}

	if ( in_array( $type, array( 'text/css', 'text/x-scss', 'text/x-less', 'text/x-sass' ), true ) ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => $type,
				'lint'              => false,
				'autoCloseBrackets' => true,
				'matchBrackets'     => true,
			)
		);
	} elseif ( 'text/x-diff' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode' => 'diff',
			)
		);
	} elseif ( 'text/html' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => 'htmlmixed',
				'lint'              => true,
				'autoCloseBrackets' => true,
				'autoCloseTags'     => true,
				'matchTags'         => array(
					'bothTags' => true,
				),
			)
		);

		if ( ! current_user_can( 'unfiltered_html' ) ) {
			$settings['htmlhint']['kses'] = wp_kses_allowed_html( 'post' );
		}
	} elseif ( 'text/x-gfm' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'                => 'gfm',
				'highlightFormatting' => true,
			)
		);
	} elseif ( 'application/javascript' === $type || 'text/javascript' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => 'javascript',
				'lint'              => true,
				'autoCloseBrackets' => true,
				'matchBrackets'     => true,
			)
		);
	} elseif ( false !== strpos( $type, 'json' ) ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => array(
					'name' => 'javascript',
				),
				'lint'              => true,
				'autoCloseBrackets' => true,
				'matchBrackets'     => true,
			)
		);
		if ( 'application/ld+json' === $type ) {
			$settings['codemirror']['mode']['jsonld'] = true;
		} else {
			$settings['codemirror']['mode']['json'] = true;
		}
	} elseif ( false !== strpos( $type, 'jsx' ) ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => 'jsx',
				'autoCloseBrackets' => true,
				'matchBrackets'     => true,
			)
		);
	} elseif ( 'text/x-markdown' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'                => 'markdown',
				'highlightFormatting' => true,
			)
		);
	} elseif ( 'text/nginx' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode' => 'nginx',
			)
		);
	} elseif ( 'application/x-httpd-php' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => 'php',
				'autoCloseBrackets' => true,
				'autoCloseTags'     => true,
				'matchBrackets'     => true,
				'matchTags'         => array(
					'bothTags' => true,
				),
			)
		);
	} elseif ( 'text/x-sql' === $type || 'text/x-mysql' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => 'sql',
				'autoCloseBrackets' => true,
				'matchBrackets'     => true,
			)
		);
	} elseif ( false !== strpos( $type, 'xml' ) ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode'              => 'xml',
				'autoCloseBrackets' => true,
				'autoCloseTags'     => true,
				'matchTags'         => array(
					'bothTags' => true,
				),
			)
		);
	} elseif ( 'text/x-yaml' === $type ) {
		$settings['codemirror'] = array_merge(
			$settings['codemirror'],
			array(
				'mode' => 'yaml',
			)
		);
	} else {
		$settings['codemirror']['mode'] = $type;
	}

	if ( ! empty( $settings['codemirror']['lint'] ) ) {
		$settings['codemirror']['gutters'][] = 'CodeMirror-lint-markers';
	}

	// Let settings supplied via args override any defaults.
	foreach ( wp_array_slice_assoc( $args, array( 'codemirror', 'csslint', 'jshint', 'htmlhint' ) ) as $key => $value ) {
		$settings[ $key ] = array_merge(
			$settings[ $key ],
			$value
		);
	}

	/**
	 * Filters settings that are passed into the code editor.
	 *
	 * Returning a falsey value will disable the syntax-highlighting code editor.
	 *
	 * @since 4.9.0
	 *
	 * @param array $settings The array of settings passed to the code editor.
	 *                        A falsey value disables the editor.
	 * @param array $args {
	 *     Args passed when calling `get_code_editor_settings()`.
	 *
	 *     @type string   $type       The MIME type of the file to be edited.
	 *     @type string   $file       Filename being edited.
	 *     @type WP_Theme $theme      Theme being edited when on the theme file editor.
	 *     @type string   $plugin     Plugin being edited when on the plugin file editor.
	 *     @type array    $codemirror Additional CodeMirror setting overrides.
	 *     @type array    $csslint    CSSLint rule overrides.
	 *     @type array    $jshint     JSHint rule overrides.
	 *     @type array    $htmlhint   HTMLHint rule overrides.
	 * }
	 */
	return apply_filters( 'wp_code_editor_settings', $settings, $args );
}