<?php // phpcs:ignoreFile

declare(strict_types=1);

require_once __DIR__ . '/../config/control-settings.php';

/**
 * Procedural helper functions for talking to the Kepware IoT Gateway REST API.
 */

if (!function_exists('kepware_config')) {
    /**
     * Retrieve Kepware REST configuration values.
     *
     * @return array<string, mixed>
     */
    function kepware_config(): array
    {
        static $config;

        if ($config === null) {
            $settings = include __DIR__ . '/../config/control-settings.php';
            $config = $settings['kepware'] ?? [];
        }

        return $config;
    }
}

if (!function_exists('kepware_rest_request')) {
    /**
     * Issue an HTTP request to the Kepware REST server.
     *
     * @param string                    $method HTTP verb (GET, POST, ...).
     * @param string                    $path   Relative REST path.
     * @param array<string, mixed>|null $body   Optional JSON payload.
     *
     * @return array<string, mixed>
     */
    function kepware_rest_request(string $method, string $path, ?array $body = null): array
    {
        $config = kepware_config();
        $baseUrl = rtrim((string) ($config['base_url'] ?? ''), '/');
        if ($baseUrl === '') {
            throw new RuntimeException('Kepware base URL is not configured.');
        }

        $url = $baseUrl . '/' . ltrim($path, '/');
        $username = (string) ($config['username'] ?? '');
        $password = (string) ($config['password'] ?? '');
        $timeout = (float) ($config['timeout'] ?? 5.0);
        $verify = (bool) ($config['verify_tls'] ?? false);
        $attempts = (int) ($config['retry_attempts'] ?? 1);
        if ($attempts < 1) {
            $attempts = 1;
        }

        $retryDelay = (float) ($config['retry_delay'] ?? 0.0);
        if ($retryDelay < 0) {
            $retryDelay = 0.0;
        }

        $postFields = null;
        if ($body !== null) {
            $postFields = json_encode($body, JSON_THROW_ON_ERROR);
        }

        $options = [
            CURLOPT_URL => $url,
            CURLOPT_CUSTOMREQUEST => strtoupper($method),
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_USERPWD => $username . ':' . $password,
            CURLOPT_HTTPHEADER => [
                'Content-Type: application/json',
                'Accept: application/json',
            ],
            CURLOPT_TIMEOUT => $timeout,
            CURLOPT_CONNECTTIMEOUT => $timeout,
            CURLOPT_SSL_VERIFYPEER => $verify,
            CURLOPT_SSL_VERIFYHOST => $verify ? 2 : 0,
        ];

        if ($postFields !== null) {
            $options[CURLOPT_POSTFIELDS] = $postFields;
        }

        $retryableCurlErrors = [
            CURLE_COULDNT_CONNECT,
            CURLE_COULDNT_RESOLVE_HOST,
            CURLE_COULDNT_RESOLVE_PROXY,
            CURLE_GOT_NOTHING,
            CURLE_OPERATION_TIMEDOUT,
            CURLE_PARTIAL_FILE,
            CURLE_RECV_ERROR,
            CURLE_SEND_ERROR,
            CURLE_SSL_CONNECT_ERROR,
        ];

        for ($attempt = 1; $attempt <= $attempts; $attempt++) {
            $handle = curl_init();
            if ($handle === false) {
                throw new RuntimeException('Unable to initialise cURL for Kepware request.');
            }

            curl_setopt_array($handle, $options);

            $response = curl_exec($handle);
            $error = curl_error($handle);
            $errno = curl_errno($handle);
            $status = (int) curl_getinfo($handle, CURLINFO_HTTP_CODE);
            curl_close($handle);

            if ($response === false) {
                $shouldRetry = in_array($errno, $retryableCurlErrors, true) && $attempt < $attempts;
                if ($shouldRetry) {
                    error_log(sprintf(
                        'Kepware request to %s attempt %d failed with cURL error %d: %s. Retrying in %.2f seconds.',
                        $path,
                        $attempt,
                        $errno,
                        $error,
                        $retryDelay
                    ));

                    if ($retryDelay > 0.0) {
                        usleep((int) round($retryDelay * 1_000_000));
                    }

                    continue;
                }

                throw new RuntimeException('Kepware request failed: ' . $error, $errno);
            }

            $decoded = json_decode($response, true);
            if (!is_array($decoded)) {
                $snippet = substr($response, 0, 200);
                error_log('Kepware returned a non-JSON payload: ' . $snippet);

                if ($attempt < $attempts) {
                    if ($retryDelay > 0.0) {
                        usleep((int) round($retryDelay * 1_000_000));
                    }

                    continue;
                }

                throw new RuntimeException('Invalid JSON response from Kepware: ' . $snippet);
            }

            if ($status >= 400) {
                if ($status >= 500 && $status < 600 && $attempt < $attempts) {
                    error_log(sprintf(
                        'Kepware request to %s attempt %d returned HTTP %d. Retrying in %.2f seconds.',
                        $path,
                        $attempt,
                        $status,
                        $retryDelay
                    ));

                    if ($retryDelay > 0.0) {
                        usleep((int) round($retryDelay * 1_000_000));
                    }

                    continue;
                }

                throw new RuntimeException('Kepware request error (HTTP ' . $status . ').');
            }

            if ($attempt > 1) {
                error_log(sprintf('Kepware request to %s succeeded on attempt %d.', $path, $attempt));
            }

            return $decoded;
        }

        throw new RuntimeException('Kepware request failed after ' . $attempts . ' attempts.');
    }
}

if (!function_exists('kepware_read')) {
    /**
     * Read tag values from Kepware.
     *
     * @param string[] $tagIds List of tag identifiers.
     *
     * @return array<string, array<string, mixed>>
     */
    function kepware_read(array $tagIds): array
    {
        if ($tagIds === []) {
            return [];
        }

        $query = http_build_query(['ids' => implode(',', $tagIds)]);
        $payload = kepware_rest_request('GET', 'read?' . $query);

        $results = [];
        foreach ($payload['readResults'] ?? [] as $result) {
            if (!isset($result['id'])) {
                continue;
            }

            $results[$result['id']] = [
                'value' => $result['v'] ?? null,
                'timestamp' => $result['t'] ?? null,
                'status' => $result['s'] ?? null,
            ];
        }

        return $results;
    }
}

if (!function_exists('kepware_write')) {
    /**
     * Write tag values via Kepware.
     *
     * @param array<int, array<string, mixed>> $writeRequest
     *
     * @return array<int, array<string, mixed>>
     */
    function kepware_write(array $writeRequest): array
    {
        if ($writeRequest === []) {
            return [];
        }

        $payload = kepware_rest_request('POST', 'write', $writeRequest);

        if (isset($payload['writeResults']) && is_array($payload['writeResults'])) {
            return $payload['writeResults'];
        }

        return $payload;
    }
}