<?php

class SegmentRouter implements Router
{
	public array $routes = [];

	/**
	 * Add a route to the router. The route can contain dynamic segments, which are denoted by a colon. They are
	 * inserted into the node tree per segment; if a segment is dynamic, it is stored under the key ':x'.
	 */
	public function add(string $method, string $route, callable $handler): Router
	{
		// Expand the route into segments and make dynamic segments into a common placeholder
		$segments = array_map(function($segment) {
			return str_starts_with($segment, ':') ? ':x' : $segment;
		}, explode('/', trim($route, '/')));

		// Push each segment into the routes array as a node, except if this is the root node
		$node = &$this->routes;
		foreach ($segments as $segment) {
			// skip an empty segment, which allows us to register handlers for the root node
			if ($segment === '') continue;
			$node = &$node[$segment]; // build the node tree as we go
		}

		// Add the handler to the last node
		$node[$method] = $handler;

		return $this;
	}

	/**
	 * Lookup a route in the router. This method will return the handler for the route if it is found, or a 404 or 405
	 * status code if the route is not found or the method is not allowed. If the route contains dynamic segments, the
	 * method will return an array with the handler and the dynamic segments.
	 *
	 * @return [callable, array] | int
	 */
	public function lookup(string $method, string $uri): int|array
	{
		// node is a reference to our current location in the node tree
		$node = $this->routes;

		// params will hold any dynamic segments we find
		$params = [];

		// We'll split up the URI into segments and traverse the node tree
		foreach (explode('/', trim($uri, '/')) as $segment) {
			// if there is a node for this segment, move to it
			if (isset($node[$segment])) {
				$node = $node[$segment];
				continue;
			}

			// if there is a dynamic segment, move to it and store the value
			if (isset($node[':x'])) {
				$params[] = $segment;
				$node = $node[':x'];
				continue;
			}

			// if we can't find a node for this segment, return 404
			return 404;
		}

		// if we fail to find a handler for the method, return 405
		if (!isset($node[$method])) return 405;

		// return the handler and any dynamic segments we found
		return [$node[$method], $params];
	}


	public function clear(): Router
	{
		$this->routes = [];
		return $this;
	}
}