<?php

declare(strict_types=1);

namespace Evomedien\Vitec\Service;

use TYPO3\CMS\Core\Database\ConnectionPool;
use TYPO3\CMS\Core\Core\Environment;
use TYPO3\CMS\Core\Http\RequestFactory;

/**
 * Talks to the SSR node's POST /__purge endpoint (contract 0054-FE) and
 * keeps a log of every attempt in tx_vitec_ssrpurgelog.
 *
 * Endpoint + secret live OUTSIDE the repository in var/vitec-ssr-purge.env
 * (KEY=VALUE lines: SSR_PURGE_ENDPOINT, SSR_PURGE_SECRET, SSR_HEALTH_ENDPOINT,
 * SSR_ALERT_EMAIL, SSR_FAILOVER_AFTER)
 * - same pattern as the routing flag file, nothing secret in git.
 */
final class SsrPurgeService
{
    private ?array $config = null;

    public function __construct(
        private readonly RequestFactory $requestFactory,
        private readonly ConnectionPool $connectionPool,
    ) {}

    public static function getConfigPath(): string
    {
        return Environment::getVarPath() . '/vitec-ssr-purge.env';
    }

    public function isConfigured(): bool
    {
        $c = $this->getConfig();
        return ($c['SSR_PURGE_ENDPOINT'] ?? '') !== '' && ($c['SSR_PURGE_SECRET'] ?? '') !== '';
    }

    public function getHealthEndpoint(): string
    {
        return $this->getConfig()['SSR_HEALTH_ENDPOINT'] ?? '';
    }

    /**
     * The /__stats sibling of the health endpoint (cumulative hit/miss/
     * error counters, in the node since release 20261109-211544). Derived
     * from SSR_HEALTH_ENDPOINT; SSR_STATS_ENDPOINT overrides explicitly.
     */
    public function getStatsEndpoint(): string
    {
        $explicit = $this->getConfig()['SSR_STATS_ENDPOINT'] ?? '';
        if ($explicit !== '') {
            return $explicit;
        }
        $health = $this->getHealthEndpoint();
        return $health === '' ? '' : str_replace('/__health', '/__stats', $health);
    }

    /**
     * Comma-separated recipient list for vitec:ssr-health transition and
     * failover alerts (SSR_ALERT_EMAIL); empty string = alerting off.
     */
    public function getAlertEmail(): string
    {
        return trim($this->getConfig()['SSR_ALERT_EMAIL'] ?? '');
    }

    /**
     * Consecutive DOWN samples after which vitec:ssr-health fails over to
     * the SPA (SSR_FAILOVER_AFTER, default 2 = ~10 minutes at the 5-minute
     * cron cadence). Never below 1.
     */
    public function getFailoverAfter(): int
    {
        return max(1, (int)($this->getConfig()['SSR_FAILOVER_AFTER'] ?? 2));
    }

    /**
     * POST /__warm on the node (contract 0066-FE), derived from
     * SSR_PURGE_ENDPOINT; SSR_WARM_ENDPOINT overrides explicitly.
     */
    public function getWarmEndpoint(): string
    {
        $explicit = $this->getConfig()['SSR_WARM_ENDPOINT'] ?? '';
        if ($explicit !== '') {
            return $explicit;
        }
        $purge = $this->getConfig()['SSR_PURGE_ENDPOINT'] ?? '';
        return $purge === '' ? '' : str_replace('/__purge', '/__warm', $purge);
    }

    /**
     * Starts a background warm run on the node: no paths (or '*') = every
     * page of sitemap.xml, otherwise exactly the given paths. The node
     * answers at once and renders in the background; progress shows up as
     * "warming" in /__health and /__stats. Not written to the purge log -
     * a warm run evicts nothing, and the log feeds the purge statistics.
     *
     * @param string[] $paths
     * @return array{success:bool, httpCode:int, message:string, data:array}
     */
    public function warm(array $paths = []): array
    {
        if (!$this->isConfigured()) {
            return ['success' => false, 'httpCode' => 0, 'message' => 'not configured (var/vitec-ssr-purge.env missing)', 'data' => []];
        }
        $paths = $this->normalize($paths);
        $payload = ($paths === [] || $paths === ['*']) ? ['source' => 'sitemap'] : ['paths' => $paths];
        try {
            $response = $this->requestFactory->request($this->getWarmEndpoint(), 'POST', [
                'headers' => [
                    'X-Purge-Secret' => $this->getConfig()['SSR_PURGE_SECRET'],
                    'Content-Type' => 'application/json',
                ],
                'body' => json_encode($payload, JSON_THROW_ON_ERROR),
                // The node reads the sitemap (index + sub-sitemaps) before
                // it answers; the pages themselves are not awaited.
                'timeout' => 30,
                'connect_timeout' => 3,
                'http_errors' => false,
            ]);
            $code = $response->getStatusCode();
            $body = (string)$response->getBody();
            $data = json_decode($body, true);
            $data = is_array($data) ? $data : [];
            if ($code === 200 && !empty($data['started'])) {
                $message = sprintf(
                    'Warm run started: %d pages queued (source: %s, %d at a time)',
                    (int)($data['queued'] ?? 0),
                    (string)($data['source'] ?? '?'),
                    (int)($data['concurrency'] ?? 0)
                );
                return ['success' => true, 'httpCode' => $code, 'message' => $message, 'data' => $data];
            }
            if ($code === 200 && !empty($data['running'])) {
                $w = (array)($data['warming'] ?? []);
                $message = sprintf(
                    'A warm run is already active: %d of %d pages done',
                    (int)($w['done'] ?? 0) + (int)($w['skipped'] ?? 0) + (int)($w['failed'] ?? 0),
                    (int)($w['queued'] ?? 0)
                );
                return ['success' => true, 'httpCode' => $code, 'message' => $message, 'data' => $data];
            }
            $message = 'HTTP ' . $code . ' - ' . (string)($data['error'] ?? substr($body, 0, 200));
            return ['success' => false, 'httpCode' => $code, 'message' => $message, 'data' => $data];
        } catch (\Throwable $e) {
            return ['success' => false, 'httpCode' => 0, 'message' => substr($e->getMessage(), 0, 200), 'data' => []];
        }
    }

    /**
     * Normalizes, dedupes and sends the paths; logs the outcome.
     * Never throws - editors' saves must not fail on a purge problem.
     *
     * @param string[] $paths page paths, or ['*'] for everything
     * @return array{success:bool, httpCode:int, message:string, paths:string[]}
     */
    public function purge(array $paths, string $trigger): array
    {
        $paths = $this->normalize($paths);
        if ($paths === []) {
            return ['success' => true, 'httpCode' => 0, 'message' => 'nothing to purge', 'paths' => []];
        }
        if (!$this->isConfigured()) {
            $result = ['success' => false, 'httpCode' => 0, 'message' => 'not configured (var/vitec-ssr-purge.env missing)', 'paths' => $paths];
            $this->log($trigger, $result, 0);
            return $result;
        }

        $c = $this->getConfig();
        $start = microtime(true);
        try {
            $response = $this->requestFactory->request($c['SSR_PURGE_ENDPOINT'], 'POST', [
                'headers' => [
                    'X-Purge-Secret' => $c['SSR_PURGE_SECRET'],
                    'Content-Type' => 'application/json',
                ],
                'body' => json_encode(['paths' => $paths], JSON_THROW_ON_ERROR),
                'timeout' => 4,
                'connect_timeout' => 2,
                'http_errors' => false,
            ]);
            $code = $response->getStatusCode();
            $body = substr((string)$response->getBody(), 0, 200);
            $result = [
                'success' => $code === 200,
                'httpCode' => $code,
                'message' => $body,
                'paths' => $paths,
            ];
        } catch (\Throwable $e) {
            $result = ['success' => false, 'httpCode' => 0, 'message' => substr($e->getMessage(), 0, 200), 'paths' => $paths];
        }
        $this->log($trigger, $result, (int)round((microtime(true) - $start) * 1000));
        return $result;
    }

    public function purgeQuietly(array $paths, string $trigger): void
    {
        try {
            $this->purge($paths, $trigger);
        } catch (\Throwable) {
            // Logged inside purge(); never disturb the caller.
        }
    }

    /**
     * Path rules from 0055-BE Q3 / 0054-FE section 3: path only, query
     * stripped, no trailing slash (root stays '/'), '*' wins over all.
     *
     * @param string[] $paths
     * @return string[]
     */
    public function normalize(array $paths): array
    {
        $out = [];
        foreach ($paths as $p) {
            $p = trim((string)$p);
            if ($p === '') {
                continue;
            }
            if ($p === '*') {
                return ['*'];
            }
            $p = parse_url($p, PHP_URL_PATH) ?: '/';
            if ($p !== '/' ) {
                $p = '/' . trim($p, '/');
            }
            $out[$p] = true;
        }
        return array_keys($out);
    }

    private function getConfig(): array
    {
        if ($this->config !== null) {
            return $this->config;
        }
        $this->config = [];
        $file = self::getConfigPath();
        if (is_readable($file)) {
            foreach (file($file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES) ?: [] as $line) {
                if (str_starts_with(ltrim($line), '#') || !str_contains($line, '=')) {
                    continue;
                }
                [$k, $v] = explode('=', $line, 2);
                $this->config[trim($k)] = trim($v);
            }
        }
        return $this->config;
    }

    private function log(string $trigger, array $result, int $durationMs): void
    {
        try {
            $this->connectionPool->getConnectionForTable('tx_vitec_ssrpurgelog')->insert(
                'tx_vitec_ssrpurgelog',
                [
                    'crdate' => time(),
                    'trigger_source' => substr($trigger, 0, 100),
                    'paths' => implode(', ', $result['paths']),
                    'success' => $result['success'] ? 1 : 0,
                    'http_code' => $result['httpCode'],
                    'message' => substr($result['message'], 0, 255),
                    'duration_ms' => $durationMs,
                ]
            );
        } catch (\Throwable) {
            // Table missing (before schema update) must not break anything.
        }
    }
}