comment_form() WordPress Function

function comment_form( $args = array(), $post_id = null ) {
	if ( null === $post_id ) {
		$post_id = get_the_ID();
	}

	// Exit the function when comments for the post are closed.
	if ( ! comments_open( $post_id ) ) {
		/**
		 * Fires after the comment form if comments are closed.
		 *
		 * @since 3.0.0
		 */
		do_action( 'comment_form_comments_closed' );

		return;
	}

	$commenter     = wp_get_current_commenter();
	$user          = wp_get_current_user();
	$user_identity = $user->exists() ? $user->display_name : '';

	$args = wp_parse_args( $args );
	if ( ! isset( $args['format'] ) ) {
		$args['format'] = current_theme_supports( 'html5', 'comment-form' ) ? 'html5' : 'xhtml';
	}

	$req   = get_option( 'require_name_email' );
	$html5 = 'html5' === $args['format'];

	// Define attributes in HTML5 or XHTML syntax.
	$required_attribute = ( $html5 ? ' required' : ' required="required"' );
	$checked_attribute  = ( $html5 ? ' checked' : ' checked="checked"' );

	// Identify required fields visually.
	$required_indicator = ' <span class="required" aria-hidden="true">*</span>';

	$fields = array(
		'author' => sprintf(
			'<p class="comment-form-author">%s %s</p>',
			sprintf(
				'<label for="author">%s%s</label>',
				__( 'Name' ),
				( $req ? $required_indicator : '' )
			),
			sprintf(
				'<input id="author" name="author" type="text" value="%s" size="30" maxlength="245"%s />',
				esc_attr( $commenter['comment_author'] ),
				( $req ? $required_attribute : '' )
			)
		),
		'email'  => sprintf(
			'<p class="comment-form-email">%s %s</p>',
			sprintf(
				'<label for="email">%s%s</label>',
				__( 'Email' ),
				( $req ? $required_indicator : '' )
			),
			sprintf(
				'<input id="email" name="email" %s value="%s" size="30" maxlength="100" aria-describedby="email-notes"%s />',
				( $html5 ? 'type="email"' : 'type="text"' ),
				esc_attr( $commenter['comment_author_email'] ),
				( $req ? $required_attribute : '' )
			)
		),
		'url'    => sprintf(
			'<p class="comment-form-url">%s %s</p>',
			sprintf(
				'<label for="url">%s</label>',
				__( 'Website' )
			),
			sprintf(
				'<input id="url" name="url" %s value="%s" size="30" maxlength="200" />',
				( $html5 ? 'type="url"' : 'type="text"' ),
				esc_attr( $commenter['comment_author_url'] )
			)
		),
	);

	if ( has_action( 'set_comment_cookies', 'wp_set_comment_cookies' ) && get_option( 'show_comments_cookies_opt_in' ) ) {
		$consent = empty( $commenter['comment_author_email'] ) ? '' : $checked_attribute;

		$fields['cookies'] = sprintf(
			'<p class="comment-form-cookies-consent">%s %s</p>',
			sprintf(
				'<input id="wp-comment-cookies-consent" name="wp-comment-cookies-consent" type="checkbox" value="yes"%s />',
				$consent
			),
			sprintf(
				'<label for="wp-comment-cookies-consent">%s</label>',
				__( 'Save my name, email, and website in this browser for the next time I comment.' )
			)
		);

		// Ensure that the passed fields include cookies consent.
		if ( isset( $args['fields'] ) && ! isset( $args['fields']['cookies'] ) ) {
			$args['fields']['cookies'] = $fields['cookies'];
		}
	}

	$required_text = sprintf(
		/* translators: %s: Asterisk symbol (*). */
		' <span class="required-field-message" aria-hidden="true">' . __( 'Required fields are marked %s' ) . '</span>',
		trim( $required_indicator )
	);

	/**
	 * Filters the default comment form fields.
	 *
	 * @since 3.0.0
	 *
	 * @param string[] $fields Array of the default comment fields.
	 */
	$fields = apply_filters( 'comment_form_default_fields', $fields );

	$defaults = array(
		'fields'               => $fields,
		'comment_field'        => sprintf(
			'<p class="comment-form-comment">%s %s</p>',
			sprintf(
				'<label for="comment">%s%s</label>',
				_x( 'Comment', 'noun' ),
				$required_indicator
			),
			'<textarea id="comment" name="comment" cols="45" rows="8" maxlength="65525"' . $required_attribute . '></textarea>'
		),
		'must_log_in'          => sprintf(
			'<p class="must-log-in">%s</p>',
			sprintf(
				/* translators: %s: Login URL. */
				__( 'You must be <a href="%s">logged in</a> to post a comment.' ),
				/** This filter is documented in wp-includes/link-template.php */
				wp_login_url( apply_filters( 'the_permalink', get_permalink( $post_id ), $post_id ) )
			)
		),
		'logged_in_as'         => sprintf(
			'<p class="logged-in-as">%s%s</p>',
			sprintf(
				/* translators: 1: Edit user link, 2: Accessibility text, 3: User name, 4: Logout URL. */
				__( '<a href="%1$s" aria-label="%2$s">Logged in as %3$s</a>. <a href="%4$s">Log out?</a>' ),
				get_edit_user_link(),
				/* translators: %s: User name. */
				esc_attr( sprintf( __( 'Logged in as %s. Edit your profile.' ), $user_identity ) ),
				$user_identity,
				/** This filter is documented in wp-includes/link-template.php */
				wp_logout_url( apply_filters( 'the_permalink', get_permalink( $post_id ), $post_id ) )
			),
			$required_text
		),
		'comment_notes_before' => sprintf(
			'<p class="comment-notes">%s%s</p>',
			sprintf(
				'<span id="email-notes">%s</span>',
				__( 'Your email address will not be published.' )
			),
			$required_text
		),
		'comment_notes_after'  => '',
		'action'               => site_url( '/wp-comments-post.php' ),
		'id_form'              => 'commentform',
		'id_submit'            => 'submit',
		'class_container'      => 'comment-respond',
		'class_form'           => 'comment-form',
		'class_submit'         => 'submit',
		'name_submit'          => 'submit',
		'title_reply'          => __( 'Leave a Reply' ),
		/* translators: %s: Author of the comment being replied to. */
		'title_reply_to'       => __( 'Leave a Reply to %s' ),
		'title_reply_before'   => '<h3 id="reply-title" class="comment-reply-title">',
		'title_reply_after'    => '</h3>',
		'cancel_reply_before'  => ' <small>',
		'cancel_reply_after'   => '</small>',
		'cancel_reply_link'    => __( 'Cancel reply' ),
		'label_submit'         => __( 'Post Comment' ),
		'submit_button'        => '<input name="%1$s" type="submit" id="%2$s" class="%3$s" value="%4$s" />',
		'submit_field'         => '<p class="form-submit">%1$s %2$s</p>',
		'format'               => 'xhtml',
	);

	/**
	 * Filters the comment form default arguments.
	 *
	 * Use {@see 'comment_form_default_fields'} to filter the comment fields.
	 *
	 * @since 3.0.0
	 *
	 * @param array $defaults The default comment form arguments.
	 */
	$args = wp_parse_args( $args, apply_filters( 'comment_form_defaults', $defaults ) );

	// Ensure that the filtered arguments contain all required default values.
	$args = array_merge( $defaults, $args );

	// Remove `aria-describedby` from the email field if there's no associated description.
	if ( isset( $args['fields']['email'] ) && false === strpos( $args['comment_notes_before'], 'id="email-notes"' ) ) {
		$args['fields']['email'] = str_replace(
			' aria-describedby="email-notes"',
			'',
			$args['fields']['email']
		);
	}

	/**
	 * Fires before the comment form.
	 *
	 * @since 3.0.0
	 */
	do_action( 'comment_form_before' );
	?>
	<div id="respond" class="<?php echo esc_attr( $args['class_container'] ); ?>">
		<?php
		echo $args['title_reply_before'];

		comment_form_title( $args['title_reply'], $args['title_reply_to'] );

		if ( get_option( 'thread_comments' ) ) {
			echo $args['cancel_reply_before'];

			cancel_comment_reply_link( $args['cancel_reply_link'] );

			echo $args['cancel_reply_after'];
		}

		echo $args['title_reply_after'];

		if ( get_option( 'comment_registration' ) && ! is_user_logged_in() ) :

			echo $args['must_log_in'];
			/**
			 * Fires after the HTML-formatted 'must log in after' message in the comment form.
			 *
			 * @since 3.0.0
			 */
			do_action( 'comment_form_must_log_in_after' );

		else :

			printf(
				'<form action="%s" method="post" id="%s" class="%s"%s>',
				esc_url( $args['action'] ),
				esc_attr( $args['id_form'] ),
				esc_attr( $args['class_form'] ),
				( $html5 ? ' novalidate' : '' )
			);

			/**
			 * Fires at the top of the comment form, inside the form tag.
			 *
			 * @since 3.0.0
			 */
			do_action( 'comment_form_top' );

			if ( is_user_logged_in() ) :

				/**
				 * Filters the 'logged in' message for the comment form for display.
				 *
				 * @since 3.0.0
				 *
				 * @param string $args_logged_in The logged-in-as HTML-formatted message.
				 * @param array  $commenter      An array containing the comment author's
				 *                               username, email, and URL.
				 * @param string $user_identity  If the commenter is a registered user,
				 *                               the display name, blank otherwise.
				 */
				echo apply_filters( 'comment_form_logged_in', $args['logged_in_as'], $commenter, $user_identity );

				/**
				 * Fires after the is_user_logged_in() check in the comment form.
				 *
				 * @since 3.0.0
				 *
				 * @param array  $commenter     An array containing the comment author's
				 *                              username, email, and URL.
				 * @param string $user_identity If the commenter is a registered user,
				 *                              the display name, blank otherwise.
				 */
				do_action( 'comment_form_logged_in_after', $commenter, $user_identity );

			else :

				echo $args['comment_notes_before'];

			endif;

			// Prepare an array of all fields, including the textarea.
			$comment_fields = array( 'comment' => $args['comment_field'] ) + (array) $args['fields'];

			/**
			 * Filters the comment form fields, including the textarea.
			 *
			 * @since 4.4.0
			 *
			 * @param array $comment_fields The comment fields.
			 */
			$comment_fields = apply_filters( 'comment_form_fields', $comment_fields );

			// Get an array of field names, excluding the textarea.
			$comment_field_keys = array_diff( array_keys( $comment_fields ), array( 'comment' ) );

			// Get the first and the last field name, excluding the textarea.
			$first_field = reset( $comment_field_keys );
			$last_field  = end( $comment_field_keys );

			foreach ( $comment_fields as $name => $field ) {

				if ( 'comment' === $name ) {

					/**
					 * Filters the content of the comment textarea field for display.
					 *
					 * @since 3.0.0
					 *
					 * @param string $args_comment_field The content of the comment textarea field.
					 */
					echo apply_filters( 'comment_form_field_comment', $field );

					echo $args['comment_notes_after'];

				} elseif ( ! is_user_logged_in() ) {

					if ( $first_field === $name ) {
						/**
						 * Fires before the comment fields in the comment form, excluding the textarea.
						 *
						 * @since 3.0.0
						 */
						do_action( 'comment_form_before_fields' );
					}

					/**
					 * Filters a comment form field for display.
					 *
					 * The dynamic portion of the hook name, `$name`, refers to the name
					 * of the comment form field.
					 *
					 * Possible hook names include:
					 *
					 *  - `comment_form_field_comment`
					 *  - `comment_form_field_author`
					 *  - `comment_form_field_email`
					 *  - `comment_form_field_url`
					 *  - `comment_form_field_cookies`
					 *
					 * @since 3.0.0
					 *
					 * @param string $field The HTML-formatted output of the comment form field.
					 */
					echo apply_filters( "comment_form_field_{$name}", $field ) . "\n";

					if ( $last_field === $name ) {
						/**
						 * Fires after the comment fields in the comment form, excluding the textarea.
						 *
						 * @since 3.0.0
						 */
						do_action( 'comment_form_after_fields' );
					}
				}
			}

			$submit_button = sprintf(
				$args['submit_button'],
				esc_attr( $args['name_submit'] ),
				esc_attr( $args['id_submit'] ),
				esc_attr( $args['class_submit'] ),
				esc_attr( $args['label_submit'] )
			);

			/**
			 * Filters the submit button for the comment form to display.
			 *
			 * @since 4.2.0
			 *
			 * @param string $submit_button HTML markup for the submit button.
			 * @param array  $args          Arguments passed to comment_form().
			 */
			$submit_button = apply_filters( 'comment_form_submit_button', $submit_button, $args );

			$submit_field = sprintf(
				$args['submit_field'],
				$submit_button,
				get_comment_id_fields( $post_id )
			);

			/**
			 * Filters the submit field for the comment form to display.
			 *
			 * The submit field includes the submit button, hidden fields for the
			 * comment form, and any wrapper markup.
			 *
			 * @since 4.2.0
			 *
			 * @param string $submit_field HTML markup for the submit field.
			 * @param array  $args         Arguments passed to comment_form().
			 */
			echo apply_filters( 'comment_form_submit_field', $submit_field, $args );

			/**
			 * Fires at the bottom of the comment form, inside the closing form tag.
			 *
			 * @since 1.5.0
			 *
			 * @param int $post_id The post ID.
			 */
			do_action( 'comment_form', $post_id );

			echo '</form>';

		endif;
		?>
	</div><!-- #respond -->
	<?php

	/**
	 * Fires after the comment form.
	 *
	 * @since 3.0.0
	 */
	do_action( 'comment_form_after' );
}