endpoints.php

<?php
namespace Artpi\RoamBlock;

add_action(
	'rest_api_init',
	function () {
		register_rest_route(
			'roam-research',
			'/upload-graph',
			array(
				'methods'             => 'POST',
				'callback'            => __NAMESPACE__ . '\roam_update_graph',
				'permission_callback' => __NAMESPACE__ . '\check_permissions_upload',
			)
		);
		register_rest_route(
			'roam-research',
			'/search_block',
			array(
				'methods'             => 'GET',
				'callback'            => __NAMESPACE__ . '\roam_search',
				'permission_callback' => __NAMESPACE__ . '\check_permissions',
			)
		);
		register_rest_route(
			'roam-research',
			'/get_upload_token',
			array(
				'methods'             => 'GET',
				'callback'            => __NAMESPACE__ . '\roam_get_upload_token',
				'permission_callback' => __NAMESPACE__ . '\check_permissions',
			)
		);
	}
);

function check_permissions_upload( \WP_REST_Request $request ) {
	if ( check_permissions() ) {
		return true;
	}
	$params = $request->get_params();
	$token = get_option( 'roam_update_token' );
	if ( $token && $params['token'] === $token ) {
		return true;
	}
	return false;
}

function check_permissions() {
	// Only for admins for time being
	return current_user_can( 'edit_posts' );
}

function roam_get_upload_token( \WP_REST_Request $request ) {
	$token = get_option( 'roam_update_token' );
	if ( ! $token ) {
		$token = wp_generate_password( 20, false );
		update_option( 'roam_update_token', $token );
	}
	$url = get_rest_url( null, 'roam-research/upload-graph' );
	$query = parse_url( $url, PHP_URL_QUERY );

	$url = $url . ( $query ? '&' : '?' ) . 'token=' . $token;
	return array(
		'token' => $token,
		'url' => $url,
	);
}

function roam_update_graph( \WP_REST_Request $request ) {
	$params = $request->get_params();
	if ( ! is_string( $params['graphContent'] ) ) {
		$params['graphContent'] = json_encode( $params['graphContent'] );
	}

	update_option( 'roam_graph_content', $params['graphContent'] );
	update_option( 'roam_graph_name', $params['graphName'] );
	update_option( 'roam_graph_update', time() );
	return array( 'ok' => true );
}

function get_children_content( $node, $depth = 1 ) {
	require_once __DIR__ . '/Parsedown.php';
	$md_parser = new \Parsedown();
	$ret       = '';
	if ( isset( $node['string'] ) ) {
		$line = $md_parser->line( $node['string'] );
		$line = preg_replace( '#\#?\[\[([^\]]+)\]\]#is', '${1}', $line ); // References to pages
		$line = preg_replace( '%#([\w]+)%is', '${1}', $line ); // Tags
		$ret .= "<span class='artpi-roam-block-depth-{$depth}'>{$line}</span>";
	}
	if ( isset( $node['children'] ) ) {
		$ret .= '<ul>';
		foreach ( $node['children'] as $child ) {
			$ret .= '<li>' . get_children_content( $child, $depth + 1 ) . '</li>';
		}
		$ret .= '</ul>';
	}
	return $ret;
}

function search_roam_graph( $node, $search, $title = '', $results = [], $parent = [] ) {
	require_once __DIR__ . '/Parsedown.php';
	$md_parser = new \Parsedown();
	if ( isset( $node['string'] ) && (
		stristr( $node['string'], $search ) || (
			isset( $parent['title'] ) &&
			stristr( $parent['title'], $search )
		)
	) ) {
		$results = array_merge(
			$results,
			[
				[
					'title'   => $title,
					'snippet' => wp_strip_all_tags( $md_parser->line( $node['string'] ) ),
					'content' => get_children_content( $node, 1 ),
					'uid'     => $node['uid'],
				],
			]
		);
	}
	$nodes = array();
	if ( is_array( $node ) ) {
		$nodes = $node;
	} elseif ( isset( $node['children'] ) && is_array( $node['children'] ) ) {
		$nodes = $node['children'];
	}
	foreach ( $nodes as $child ) {
		$item_title = $title;
		if ( ! $title && $child['title'] ) {
			$item_title = $child['title'];
		}
		$results = search_roam_graph( $child, $search, $item_title, $results, $node );
	}
	return $results;
}

function roam_search( \WP_REST_Request $request ) {
	$params = $request->get_params();
	$search = $params['q'];
	$graph  = get_roam_graph();
	if ( ! $graph ) {
		return new \WP_Error( 'graph_missing', 'Please upload your Roam Graph', [ 'status' => 403 ] );
	}
	$results = search_roam_graph( $graph, $search, '', array(), array() );
	return $results;
}

function find_block_by_uid( $uid, $nodes ) {
	foreach ( $nodes as $child ) {
		if ( isset( $child['uid'] ) && $child['uid'] === $uid ) {
			return $child;
		}
		if ( ! isset( $child['children'] ) || ! $child['children'] ) {
			continue;
		}
		$found = find_block_by_uid( $uid, $child['children'] );
		if ( $found ) {
			return $found;
		}
	}
	return false;
}

function get_roam_graph() {
	$data = get_option( 'roam_graph_content' );
	if ( ! $data ) {
		return [];
	}
	return json_decode( $data, true );
}

function render_block( $attributes, $content ) {
	if ( ! isset( $attributes['uid'] ) ) {
		return $content;
	}
	$graph = get_roam_graph();
	if ( ! $graph ) {
		return $content;
	}
	$block = find_block_by_uid( $attributes['uid'], $graph );
	if ( ! $block ) {
		return $content;
	}
	if ( ! isset( $attributes['childrenListView'] ) ) {
		$attributes['childrenListView'] = 'list';
	}

	if ( ! isset( $attributes['showHeader'] ) ) {
		$attributes['showHeader'] = true;
	}
	$classes = join(
		' ',
		array(
			'wp-block-artpi-roam-block',
			'artpi-roam-block-children-' . $attributes['childrenListView'],
			'artpi-roam-block-header-' . ( $attributes['showHeader'] ? 'visible' : 'hidden' ),
		)
	);

	return '<div class="' . $classes . '"><div>' . get_children_content( $block, 1 ) . '</div></div>';
}

\wp_embed_register_handler(
	'roam_research',
	'&https:\/\/roamresearch\.com\/#\/app\/(\w+)\/page\/([a-zA-Z0-9-_]+)&i',
	__NAMESPACE__ . '\wpdocs_embed_handler_roam'
);

function wpdocs_embed_handler_roam( $matches, $attr, $url, $rawattr ) {
	return apply_filters( 'embed_roam_research', render_block( [ 'uid' => $matches[2] ], '' ), $matches, $attr, $url, $rawattr );
}