<?php

namespace Ladon;

if (!defined('ABSPATH')) {
    exit;
}

/**
 * Pushes inventory on change and once a day. Never polls. Changes within a couple of minutes
 * are coalesced into one report, and an unchanged report is skipped before it leaves the site.
 */
class Sync
{
    const DEBOUNCE = 120;
    const BACKOFF = 900;

    public function register()
    {
        add_action('activated_plugin', array($this, 'schedule'));
        add_action('deactivated_plugin', array($this, 'schedule'));
        add_action('switch_theme', array($this, 'schedule'));
        add_action('upgrader_process_complete', array($this, 'schedule'));

        add_action(Plugin::CRON_SYNC, array($this, 'onScheduled'));
        add_action(Plugin::CRON_HEARTBEAT, array($this, 'onHeartbeat'));
    }

    public function schedule()
    {
        if (!Settings::isConnected()) {
            return;
        }

        if (!wp_next_scheduled(Plugin::CRON_SYNC)) {
            wp_schedule_single_event(time() + self::DEBOUNCE, Plugin::CRON_SYNC);
        }
    }

    public function onScheduled()
    {
        $this->run('change');
    }

    public function onHeartbeat()
    {
        $this->run('heartbeat');
    }

    /**
     * @return array{ok: bool, status: int, body: array<string, mixed>, error: string|null}|null
     */
    public function run($reason)
    {
        if (!Settings::isConnected()) {
            return null;
        }

        $inventory = new Inventory();
        $payload = $inventory->collect();
        $hash = $inventory->hash($payload);

        $always = in_array($reason, array('manual', 'connect', 'heartbeat'), true);

        if (!$always && $hash === Settings::get('inventory_hash')) {
            return null;
        }

        $result = (new Client())->pushInventory($payload);

        if ($result['ok']) {
            $body = $result['body'];

            Settings::merge(array(
                'inventory_hash' => isset($body['inventory_hash']) ? $body['inventory_hash'] : $hash,
                'last_sync' => time(),
                'last_error' => null,
                'needs_reconnect' => false,
            ));

            return $result;
        }

        if ($result['status'] === 401 || $result['status'] === 403) {
            Settings::merge(array(
                'needs_reconnect' => true,
                'last_error' => $result['error'],
            ));

            return $result;
        }

        if ($result['status'] === 429 && !wp_next_scheduled(Plugin::CRON_SYNC)) {
            wp_schedule_single_event(time() + self::BACKOFF, Plugin::CRON_SYNC);
        }

        Settings::merge(array('last_error' => $result['error']));

        return $result;
    }
}