<?php

/**
 * @package koko-analytics
 * @license GPL-3.0+
 * @author Danny van Kooten
 */

namespace KokoAnalytics;

use WP_Error;

class Endpoint_Installer
{
    public function get_file_name(): string
    {
        return rtrim(ABSPATH, '/') . '/koko-analytics-collect.php';
    }

    public function make_relative_to_abspath(string $path): string
    {
        // make path relative to ABSPATH again
        if (str_starts_with($path, ABSPATH)) {
            $path = ltrim(substr($path, strlen(ABSPATH)), '/');
        }
        return $path;
    }

    public function get_file_contents(): string
    {
        $settings = get_settings();
        $upload_dir = $this->make_relative_to_abspath(get_upload_dir());
        $wp_timezone_string = wp_timezone_string();
        $excluded_ip_addresses_string = var_export($settings['exclude_ip_addresses'], true);

        // create require statements for all necessary files
        $files = [
            'wp-includes/plugin.php',
            KOKO_ANALYTICS_PLUGIN_DIR . '/src/Resources/functions/collect.php',
        ];
        $files = apply_filters('koko_analytics_endpoint_files', $files);
        $files = array_unique($files);
        $files = array_map([$this, 'make_relative_to_abspath'], $files);
        $require_statements = array_reduce($files, function ($result, $f) {
            $result .= "require '$f';\n";
            return $result;
        }, '');

        return <<<EOT
<?php
/**
 * @package koko-analytics
 * @license GPL-3.0+
 * @author Danny van Kooten
 *
 * This file acts as an optimized endpoint file for the Koko Analytics plugin.
 */

// path to pageviews.php file in uploads directory
define('KOKO_ANALYTICS_UPLOAD_DIR', '$upload_dir');
define('KOKO_ANALYTICS_TIMEZONE', '$wp_timezone_string');

// required files
$require_statements

// check if IP address is on list of addresses to ignore
if (!isset(\$_POST['test']) && in_array(KokoAnalytics\get_client_ip(), $excluded_ip_addresses_string)) {
    exit;
}

// function call to collect the request data
KokoAnalytics\collect_request();

EOT;
    }

    /**
     * @return string|bool
     */
    public function install()
    {
        /* Do nothing if KOKO_ANALYTICS_CUSTOM_ENDPOINT is defined (means users disabled this feature or is using their own version of it) */
        if (defined('KOKO_ANALYTICS_CUSTOM_ENDPOINT') || is_multisite()) {
            return false;
        }

        /* If we made it this far we ideally want to use the custom endpoint file */
        /* Therefore we schedule a recurring health check event to periodically re-attempt and re-test */
        if (! wp_next_scheduled('koko_analytics_test_custom_endpoint')) {
            wp_schedule_event(time() + HOUR_IN_SECONDS, 'hourly', 'koko_analytics_test_custom_endpoint');
        }

        // attempt to overwrite file with latest contents to ensure it's up-to-date
        file_put_contents($this->get_file_name(), $this->get_file_contents());

        return $this->test(true);
    }

    public function uninstall(): void
    {
        $file_name = $this->get_file_name();
        if (is_file($file_name)) {
            unlink($file_name);
        }

        wp_clear_scheduled_hook('koko_analytics_test_custom_endpoint');
    }

    /**
     * @return string|bool
     */
    public function test($force_test = false)
    {
        // No need to test if not using it
        if (!$force_test && ! get_option('koko_analytics_use_custom_endpoint')) {
            return true;
        }

        // Check if file exists
        // Note that we're not checking whether we were able to write to the file
        // To allow for users manually creating the file with the correct contents
        $exists = is_file($this->get_file_name());

        // Check if endpoint returns correct HTTP response
        $works = $this->verify();

        update_option('koko_analytics_use_custom_endpoint', $exists && !is_wp_error($works), true);

        if (! $exists) {
            return __('Error creating file.', 'koko-analytics');
        }

        if (is_wp_error($works)) {
            return __('Error verifying HTTP response.', 'koko-analytics') . ' ' . join(', ', $works->get_error_messages());
        }

        return true;
    }

    /**
     * Performs an HTTP request to the optimized endpoint to verify that it works
     */
    private function verify()
    {
        $tracker_url = site_url('/koko-analytics-collect.php?test=1');
        $response    = wp_remote_post($tracker_url, [
            'body' => [
                'pa' => '/',
                'po' => 0,
                'test' => 1,
            ],
            'timeout' => 10,
            'sslverify' => false,
        ]);
        if (is_wp_error($response)) {
            return $response;
        }

        $status  = wp_remote_retrieve_response_code($response);
        $headers = wp_remote_retrieve_headers($response);
        if ($status != 200 || ! isset($headers['Content-Type']) || ! str_contains($headers['Content-Type'], 'text/plain')) {
            error_log(sprintf("Koko Analaytics: Error verifying optimized endpoint because it did not return the expected HTTP response.\nHTTP code: %s\nHTTP headers: %s\nHTTP body: %s", $status, var_export($headers, true), wp_remote_retrieve_body($response)));
            return new WP_Error('response_mismatch', __('Unexpected response headers.', 'koko-analytics'));
        }

        return true;
    }
}