<?php

namespace WConvert\Rest;

use WConvert\Stats\Dashboard;
use WConvert\Stats\StatDay;
use WP_REST_Request;
use WP_REST_Response;

defined('ABSPATH') || exit;

/**
 * REST reporting: one read-only route, optional complete-period comparison.
 *
 * ============================================================================
 * THE CALLER NAMES A WINDOW, NEVER THE SITE'S CURRENT DAY.
 * ============================================================================
 * The screen says "Today", and that has to mean the merchant's today
 * (ADR 0019). A browser asked for ITS date would answer with the VISITOR's
 * day: a merchant in Tokyo checking their numbers from a hotel in Los Angeles
 * would be handed yesterday's window and told it was today's, and the numbers
 * would be right about the wrong day. So `days` names the length, and the
 * one end that is a date is {@see StatDay::today()} — read here, on the
 * server, against the site's own `timezone_string`.
 *
 * That also makes the range unspoofable in the direction that matters: the
 * server chooses today, or yesterday and its adjacent comparison when
 * `complete` is enabled. A named calendar month supports stable target links;
 * its end is still capped at the site's yesterday (ADR 0090). Custom dates
 * (`from`/`to`, ADR 0132) are days the merchant typed into the date picker,
 * refused when they end after the server's today; they are compared with the
 * same number of days immediately before, and are complete only when they end
 * before today. There is no caller-supplied "as at" date, and the response
 * carries `today` back so the picker never has to guess it.
 *
 * **Read-only, with no exception**, and for a sharper reason than the [[Lead]]
 * log's. A counter cannot be recomputed — there is no raw data behind it
 * (ADR 0019) — so a write route here is a route that can destroy a merchant's
 * history permanently, and the only writer is the beacon counting one act.
 *
 * @since 0.1.0
 */
final class DashboardController implements RestController
{
    public function __construct(
        private readonly Dashboard $dashboard,
    ) {
    }

    public function registerRoutes(): void
    {
        register_rest_route(Routes::NAMESPACE, '/dashboard', [
            [
                'methods' => 'GET',
                'callback' => [$this, 'index'],
                'permission_callback' => [Routes::class, 'canManage'],
                'args' => ReportWindow::args(),
            ],
        ]);
    }

    public function index(WP_REST_Request $request): WP_REST_Response|\WP_Error
    {
        try { $range = ReportWindow::read($request); }
        catch (\InvalidArgumentException $refusal) { return ReportWindow::error($refusal); }
        $custom = ReportWindow::custom($request);
        $month = $custom ? null : $request->get_param('month');
        // Custom dates always carry their comparison, even when they end today.
        $data = $custom || ReportWindow::complete($request, $range) ? $this->dashboard->compare($range) : $this->dashboard->read($range);
        if (is_string($month) && $month !== '') $data['month'] = $month;
        if ($custom) $data['custom'] = true;
        // Said either way, so a live read (Today) is told apart from a complete one.
        $data['complete_days'] = ReportWindow::complete($request, $range);
        $data['today'] = StatDay::today();
        return new WP_REST_Response($data);
    }
}