<?php
declare(strict_types=1);

require_once __DIR__ . '/Mailchimp.php';
require_once __DIR__ . '/Sinch.php';

/**
 * Persists a lead FIRST, then runs integrations, recording each outcome so a
 * partial failure never loses the lead and can be retried by cron.
 */
final class LeadProcessor
{
    public const MAX_ATTEMPTS = 5;

    /**
     * @param array<string,mixed> $d Validated data from Validator::planVisit
     * @return array{lead:array<string,mixed>, duplicate:bool}
     */
    public static function persist(array $d, string $ip, string $userAgent): array
    {
        $pdo = Db::pdo();
        $existing = self::find($d['submission_id']);
        if ($existing) {
            return ['lead' => $existing, 'duplicate' => true];
        }
        $now = gmdate('Y-m-d\TH:i:s\Z');
        $st = $pdo->prepare('INSERT INTO leads (
            submission_id, created_at, updated_at, first_name, last_name, email, phone_e164, campus_id, visit_date, service_time,
            adults, children, child_age_ranges, questions, email_consent, sms_consent, consent_version, consent_at, consent_ip_hash,
            attribution, variant, referrer, landing_url, user_agent, mailchimp_status, sms_status
        ) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)');
        $attr = $d['attribution'];
        try {
            $st->execute([
                $d['submission_id'], $now, $now, $d['first_name'], $d['last_name'], $d['email'], $d['phone_e164'], $d['campus_id'], $d['visit_date'], $d['service_time'],
                $d['adults'], $d['children'], $d['child_age_ranges'], $d['questions'], (int)$d['email_consent'], (int)$d['sms_consent'], $d['consent_version'], $now,
                hash('sha256', $ip . '|' . (Config::get('HASH_SALT') ?? 'visit')),
                json_encode($attr, JSON_UNESCAPED_SLASHES), $attr['variant'] ?? null, $attr['referrer'] ?? null, $attr['landing_url'] ?? null, mb_substr($userAgent, 0, 300),
                $d['email_consent'] ? 'pending' : 'skipped', $d['sms_consent'] ? 'pending' : 'skipped',
            ]);
        } catch (PDOException $e) {
            // Unique constraint race: another request with the same id got there first.
            if (str_contains($e->getMessage(), 'UNIQUE') || str_contains($e->getMessage(), 'Duplicate')) {
                $row = self::find($d['submission_id']);
                if ($row) {
                    return ['lead' => $row, 'duplicate' => true];
                }
            }
            throw $e;
        }
        $lead = self::find($d['submission_id']);
        if (!$lead) {
            throw new RuntimeException('Lead insert failed');
        }
        return ['lead' => $lead, 'duplicate' => false];
    }

    /** @return array<string,mixed>|null */
    public static function find(string $submissionId): ?array
    {
        $st = Db::pdo()->prepare('SELECT * FROM leads WHERE submission_id = ?');
        $st->execute([$submissionId]);
        $row = $st->fetch();
        return $row ?: null;
    }

    /**
     * Runs Mailchimp then Sinch for a stored lead. Each step is guarded by a
     * status transition so concurrent requests/cron cannot double-send.
     *
     * @param array<string,mixed> $lead
     * @return array{email:string, sms:string}
     */
    public static function runIntegrations(array $lead): array
    {
        $campus = Campuses::get($lead['campus_id']) ?? ['id' => $lead['campus_id'], 'name' => $lead['campus_id'], 'address' => ['line1' => '', 'city' => ''], 'serviceTimes' => []];
        $out = ['email' => $lead['mailchimp_status'], 'sms' => $lead['sms_status']];

        if (self::claim($lead['id'], 'mailchimp')) {
            try {
                $r = Mailchimp::upsertVisitor($lead, $campus);
            } catch (Throwable $e) {
                Log::error('Mailchimp adapter threw', ['error' => $e->getMessage()]);
                $r = ['status' => 'failed', 'detail' => 'exception: ' . $e->getMessage(), 'transient' => true];
            }
            $out['email'] = self::record($lead['id'], 'mailchimp', $r['status'], $r['detail'] ?? null, $r['transient'] ?? false);
        }

        if (self::claim($lead['id'], 'sms')) {
            try {
                $r = Sinch::sendVisitConfirmation($lead, $campus);
            } catch (Throwable $e) {
                Log::error('Sinch adapter threw', ['error' => $e->getMessage()]);
                $r = ['status' => 'failed', 'detail' => 'exception: ' . $e->getMessage(), 'message_id' => null, 'transient' => true];
            }
            $out['sms'] = self::record($lead['id'], 'sms', $r['status'], $r['detail'] ?? null, $r['transient'] ?? false, $r['message_id'] ?? null);
            if (in_array($r['status'], ['sent', 'mock'], true)) {
                try {
                    Sinch::sendInternalLeadNotification($lead, $campus);
                } catch (Throwable $e) {
                    Log::warn('Internal notify failed', ['error' => $e->getMessage()]);
                }
            }
        }
        return $out;
    }

    /** Atomically move pending/retry → sending. Returns false if someone else owns it. */
    private static function claim(int $id, string $which): bool
    {
        $col = $which === 'sms' ? 'sms_status' : 'mailchimp_status';
        $att = $which === 'sms' ? 'sms_attempts' : 'mailchimp_attempts';
        $st = Db::pdo()->prepare("UPDATE leads SET $col = 'sending', $att = $att + 1, updated_at = ? WHERE id = ? AND $col IN ('pending','retry')");
        $st->execute([gmdate('Y-m-d\TH:i:s\Z'), $id]);
        return $st->rowCount() === 1;
    }

    /** Persists the outcome and returns the final stored status ('sent', 'mock', 'skipped', 'failed' or 'retry'). */
    private static function record(int $id, string $which, string $status, ?string $detail, bool $transient, ?string $messageId = null): string
    {
        $col = $which === 'sms' ? 'sms_status' : 'mailchimp_status';
        $det = $which === 'sms' ? 'sms_detail' : 'mailchimp_detail';
        $att = $which === 'sms' ? 'sms_attempts' : 'mailchimp_attempts';
        $pdo = Db::pdo();
        $attempts = (int)$pdo->query("SELECT $att FROM leads WHERE id = $id")->fetchColumn();
        $final = $status;
        $nextRetry = null;
        if ($status === 'failed' && $transient && $attempts < self::MAX_ATTEMPTS) {
            $final = 'retry';
            $nextRetry = gmdate('Y-m-d\TH:i:s\Z', time() + self::backoffSeconds($attempts));
        }
        $sql = "UPDATE leads SET $col = ?, $det = ?, updated_at = ?" . ($which === 'sms' ? ', sms_message_id = COALESCE(?, sms_message_id)' : '') . ', next_retry_at = ? WHERE id = ?';
        $params = [$final, $detail ? mb_substr($detail, 0, 500) : null, gmdate('Y-m-d\TH:i:s\Z')];
        if ($which === 'sms') {
            $params[] = $messageId;
        }
        $params[] = $nextRetry;
        $params[] = $id;
        $pdo->prepare($sql)->execute($params);
        // Keep the earliest pending retry across both integrations
        $pdo->prepare("UPDATE leads SET next_retry_at = (SELECT MIN(x) FROM (SELECT next_retry_at AS x FROM leads WHERE id = ?)) WHERE id = ?")->execute([$id, $id]);
        Log::info("Integration $which → $final", ['lead' => $id, 'attempts' => $attempts]);
        return $final;
    }

    public static function backoffSeconds(int $attempt): int
    {
        return min(6 * 3600, (int)(60 * (2 ** max(0, $attempt - 1)))); // 1m, 2m, 4m, 8m … capped at 6h
    }

    /**
     * Cron entry point: retry rows whose integrations are in 'retry' (or stuck in 'sending' for >15 min).
     * @return array{checked:int, processed:int}
     */
    public static function retryDue(int $limit = 25): array
    {
        $pdo = Db::pdo();
        $now = gmdate('Y-m-d\TH:i:s\Z');
        $stale = gmdate('Y-m-d\TH:i:s\Z', time() - 900);
        // Unstick crashed "sending" rows
        $pdo->prepare("UPDATE leads SET mailchimp_status = 'retry' WHERE mailchimp_status = 'sending' AND updated_at < ?")->execute([$stale]);
        $pdo->prepare("UPDATE leads SET sms_status = 'retry' WHERE sms_status = 'sending' AND updated_at < ?")->execute([$stale]);
        $st = $pdo->prepare("SELECT * FROM leads WHERE (mailchimp_status = 'retry' OR sms_status = 'retry') AND (next_retry_at IS NULL OR next_retry_at <= ?) ORDER BY created_at ASC LIMIT $limit");
        $st->execute([$now]);
        $rows = $st->fetchAll();
        $processed = 0;
        foreach ($rows as $row) {
            self::runIntegrations($row);
            $processed++;
        }
        return ['checked' => count($rows), 'processed' => $processed];
    }

    /** Data minimisation: delete leads older than LEAD_RETENTION_DAYS (0 disables). */
    public static function purgeExpired(): int
    {
        $days = Config::int('LEAD_RETENTION_DAYS', 0);
        if ($days <= 0) {
            return 0;
        }
        $cutoff = gmdate('Y-m-d\TH:i:s\Z', time() - $days * 86400);
        $st = Db::pdo()->prepare("DELETE FROM leads WHERE created_at < ? AND mailchimp_status NOT IN ('pending','retry','sending') AND sms_status NOT IN ('pending','retry','sending')");
        $st->execute([$cutoff]);
        return $st->rowCount();
    }
}