<?php

namespace App\Services\Wb;

use Illuminate\Support\Facades\Http;
use RuntimeException;

class WbApiClient
{
    private string $baseUrl;
    private string $apiKey;
    private int $limit;
    private int $timeout;
    private int $requestSleepMs;
    private int $tooManyAttemptsSleepSeconds;
    private int $max429Retries;

    public function __construct()
    {
        $this->baseUrl = rtrim((string) config('wb_api.base_url'), '/');
        $this->apiKey = (string) config('wb_api.key');
        $this->limit = max(1, min((int) config('wb_api.limit', 100), 500));
        $this->timeout = (int) config('wb_api.timeout', 30);
        $this->requestSleepMs = (int) config('wb_api.request_sleep_ms', 1000);
        $this->tooManyAttemptsSleepSeconds = (int) config('wb_api.too_many_attempts_sleep_seconds', 30);
        $this->max429Retries = (int) config('wb_api.max_429_retries', 20);

        if ($this->baseUrl === '') {
            throw new RuntimeException('WB_API_BASE_URL is empty. Check your .env file.');
        }

        if ($this->apiKey === '') {
            throw new RuntimeException('WB_API_KEY is empty. Check your .env file.');
        }
    }

    public function limit(): int
    {
        return $this->limit;
    }

    public function fetchPage(string $endpoint, array $params, int $page): array
    {
        $url = $this->baseUrl . '/api/' . ltrim($endpoint, '/');

        $query = array_filter(array_merge($params, [
            'key' => $this->apiKey,
            'limit' => $this->limit,
            'page' => $page,
        ]), static fn ($value) => $value !== null && $value !== '');

        $attempt429 = 0;

        while (true) {
            if ($this->requestSleepMs > 0) {
                usleep($this->requestSleepMs * 1000);
            }

            $response = Http::timeout($this->timeout)
                ->acceptJson()
                ->get($url, $query);

            if ($response->status() === 429) {
                $attempt429++;

                if ($attempt429 > $this->max429Retries) {
                    throw new RuntimeException("Too many 429 responses for {$endpoint} page {$page}");
                }

                $retryAfter = $response->header('Retry-After');
                $sleepSeconds = is_numeric($retryAfter)
                    ? max(1, (int) $retryAfter)
                    : $this->tooManyAttemptsSleepSeconds;

                echo "{$endpoint} page={$page} got 429, sleeping {$sleepSeconds}s, retry {$attempt429}/{$this->max429Retries}\n";

                sleep($sleepSeconds);
                continue;
            }

            if (!$response->successful()) {
                throw new RuntimeException(sprintf(
                    'API request failed: endpoint=%s page=%d http=%d body=%s',
                    $endpoint,
                    $page,
                    $response->status(),
                    mb_substr($response->body(), 0, 1000)
                ));
            }

            $json = $response->json();

            if (!is_array($json)) {
                throw new RuntimeException("Unexpected non-array API response for {$endpoint}, page {$page}");
            }

            $items = $json['data'] ?? $json;

            if (!is_array($items)) {
                throw new RuntimeException("Unexpected API response shape for {$endpoint}, page {$page}");
            }

            if ($items !== [] && array_keys($items) !== range(0, count($items) - 1)) {
                $items = [$items];
            }

            return array_values(array_filter($items, 'is_array'));
        }
    }
}