<?php

namespace App\Services\Events;

use App\Models\QrCode;
use App\Models\User;
use Illuminate\Support\Str;

class EventSpeakerInviteService
{
    public const SOURCE_PROGRAMME = 'programme';

    public const SOURCE_MANUAL = 'manual';

    public function __construct(
        private readonly EventEmailService $email,
        private readonly EventProgrammeService $programmes,
        private readonly EventSpeakerService $speakers,
    ) {}

    /** @return list<array<string, mixed>> */
    public function rosterWithInviteState(QrCode $event): array
    {
        return collect((array) ($event->content()['speakers'] ?? []))
            ->map(fn ($speaker) => $this->normalizeSpeakerRow(is_array($speaker) ? $speaker : []))
            ->filter(fn ($speaker) => ($speaker['name'] ?? '') !== '')
            ->values()
            ->all();
    }

    public function canSendManualInvite(QrCode $event, array $speaker): bool
    {
        return ($speaker['email'] ?? '') !== '';
    }

    /** @return array{ok: true}|array{ok: false, error: string} */
    public function sendManualInvite(QrCode $event, User $owner, string $email): array
    {
        $email = strtolower(trim($email));
        $event = $event->fresh() ?? $event;
        $speaker = $this->findSpeakerByEmail($event, $email);

        if ($speaker === null) {
            return [
                'ok' => false,
                'error' => 'That speaker is not on the saved roster. Click Save speakers first, then send the invitation.',
            ];
        }

        if (! $this->canSendManualInvite($event, $speaker)) {
            return [
                'ok' => false,
                'error' => 'Add a valid email address for this speaker before sending an invitation.',
            ];
        }

        return $this->deliverInvite($event, $owner, $speaker, self::SOURCE_MANUAL);
    }

    public function inviteProgrammeHosts(QrCode $programme, User $owner): int
    {
        if ($programme->type !== QrCode::TYPE_ITINERARY) {
            return 0;
        }

        $sent = 0;

        foreach ($this->programmes->eventsLinkedToProgramme($programme) as $event) {
            $sent += $this->inviteHostsForEvent($event->fresh(), $owner, $programme);
        }

        return $sent;
    }

    public function inviteHostsForEvent(QrCode $event, User $owner, ?QrCode $programme = null): int
    {
        $programme ??= $this->speakers->linkedProgramme($event);
        if (! $programme) {
            return 0;
        }

        $hostEmails = $this->hostSpeakerEmailsFromProgramme($programme);
        if ($hostEmails === []) {
            return 0;
        }

        $sent = 0;
        $speakers = $this->rosterWithInviteState($event);

        foreach ($speakers as $speaker) {
            $email = strtolower((string) ($speaker['email'] ?? ''));
            if ($email === '' || ! in_array($email, $hostEmails, true)) {
                continue;
            }

            if (($speaker['invite_source'] ?? '') === self::SOURCE_PROGRAMME && ! empty($speaker['invited_at'])) {
                continue;
            }

            if ($this->deliverInvite($event, $owner, $speaker, self::SOURCE_PROGRAMME)['ok']) {
                $sent++;
            }
        }

        return $sent;
    }

    /** @return array{event: QrCode, speaker: array<string, mixed>}|null */
    public function resolvePortal(string $shortCode, string $token): ?array
    {
        $token = trim($token);
        if ($token === '') {
            return null;
        }

        $event = QrCode::query()
            ->where('short_code', $shortCode)
            ->where('type', QrCode::TYPE_EVENT)
            ->where('is_active', true)
            ->first();

        if (! $event) {
            return null;
        }

        foreach ($this->rosterWithInviteState($event) as $speaker) {
            if (hash_equals((string) ($speaker['invite_token'] ?? ''), $token)) {
                return ['event' => $event, 'speaker' => $speaker];
            }
        }

        return null;
    }

    /** @return array<string, mixed>|null */
    public function verifyToken(QrCode $event, string $token): ?array
    {
        $token = trim($token);
        if ($token === '') {
            return null;
        }

        foreach ($this->rosterWithInviteState($event) as $speaker) {
            if (hash_equals((string) ($speaker['invite_token'] ?? ''), $token)) {
                return [
                    'email' => $speaker['email'],
                    'name' => $speaker['name'],
                    'role' => $speaker['role'] ?? '',
                ];
            }
        }

        return null;
    }

    public function portalUrl(QrCode $event, string $token): string
    {
        return $event->publicPath('speaker/'.$token);
    }

    /** @param  array<string, mixed>  $session */
    public function speakerJoinUrl(QrCode $event, array $session, string $token): ?string
    {
        $joinUrl = trim((string) ($session['join_url'] ?? ''));
        if ($joinUrl === '') {
            return null;
        }

        $separator = str_contains($joinUrl, '?') ? '&' : '?';

        return $joinUrl.$separator.'speaker='.urlencode($token);
    }

    /** @return list<array{session: string, day: string, time: string, location: string}> */
    public function assignmentsForSpeaker(QrCode $event, array $speaker): array
    {
        $programme = $this->speakers->linkedProgramme($event);
        $snapshot = $this->programmes->snapshot($programme);
        if (! $snapshot) {
            return [];
        }

        $email = strtolower((string) ($speaker['email'] ?? ''));
        $name = trim((string) ($speaker['name'] ?? ''));
        $assignments = [];

        foreach ((array) ($snapshot['days'] ?? []) as $day) {
            $dayLabel = trim((string) ($day['date'] ?? $day['label'] ?? ''));
            foreach ((array) ($day['items'] ?? []) as $item) {
                if (! is_array($item)) {
                    continue;
                }

                $hostEmail = strtolower(trim((string) ($item['host_speaker_email'] ?? '')));
                $hostName = trim((string) ($item['host'] ?? ''));

                $matches = ($email !== '' && $hostEmail === $email)
                    || ($name !== '' && strcasecmp($hostName, $name) === 0);

                if (! $matches) {
                    continue;
                }

                $assignments[] = [
                    'session' => trim((string) ($item['title'] ?? '')),
                    'day' => $dayLabel,
                    'time' => trim((string) ($item['time'] ?? '')),
                    'location' => trim((string) ($item['location'] ?? '')),
                ];
            }
        }

        return $assignments;
    }

    /** @return array{ok: true}|array{ok: false, error: string} */
    private function deliverInvite(QrCode $event, User $owner, array $speaker, string $source): array
    {
        $email = trim((string) ($speaker['email'] ?? ''));
        if ($email === '') {
            return ['ok' => false, 'error' => 'Add a valid email address for this speaker before sending an invitation.'];
        }

        $ownerRef = trim((string) ($owner->public_id ?? ''));
        if ($ownerRef === '') {
            return ['ok' => false, 'error' => 'Could not resolve the event owner account for sending email.'];
        }

        if (! app(EventMailer::class)->isConfigured()) {
            return ['ok' => false, 'error' => 'Outbound email is not configured on this Events instance.'];
        }

        $token = (string) ($speaker['invite_token'] ?? '');
        if ($token === '') {
            $token = Str::random(48);
        }

        $eventName = (string) ($event->content()['name'] ?? $event->label);
        $portalUrl = $this->portalUrl($event, $token);

        $sent = $this->email->sendSpeakerInvite(
            $ownerRef,
            $email,
            $eventName,
            $portalUrl,
            $speaker['name'] ?? null,
            $owner->email,
            $owner->name,
        );

        if (! $sent) {
            return [
                'ok' => false,
                'error' => $this->email->lastError()
                    ?: 'The invitation email could not be sent. Check your Bird email balance and verified sending domain, then try again.',
            ];
        }

        $this->persistSpeakerInviteMeta($event, $email, $token, $source);

        return ['ok' => true];
    }

    /** @return array<string, mixed>|null */
    private function findSpeakerByEmail(QrCode $event, string $email): ?array
    {
        foreach ($this->rosterWithInviteState($event) as $speaker) {
            if (strcasecmp((string) ($speaker['email'] ?? ''), $email) === 0) {
                return $speaker;
            }
        }

        return null;
    }

    private function persistSpeakerInviteMeta(QrCode $event, string $email, string $token, string $source): void
    {
        $email = strtolower(trim($email));
        $content = $event->content();
        $speakers = [];

        foreach ((array) ($content['speakers'] ?? []) as $row) {
            if (! is_array($row)) {
                continue;
            }

            $rowEmail = strtolower(trim((string) ($row['email'] ?? '')));
            if ($rowEmail === $email) {
                $row['invite_token'] = $token;
                $row['invited_at'] = now()->toIso8601String();
                $row['invite_source'] = $source;
            }

            $speakers[] = $row;
        }

        $payload = (array) ($event->payload ?? []);
        $payload['content'] = array_merge($content, ['speakers' => $speakers]);
        $event->payload = $payload;
        $event->save();
    }

    /** @return list<string> */
    private function hostSpeakerEmailsFromProgramme(QrCode $programme): array
    {
        $emails = [];

        foreach ((array) ($programme->content()['days'] ?? []) as $day) {
            foreach ((array) ($day['items'] ?? []) as $item) {
                if (! is_array($item)) {
                    continue;
                }

                $email = strtolower(trim((string) ($item['host_speaker_email'] ?? '')));
                if ($email !== '' && filter_var($email, FILTER_VALIDATE_EMAIL)) {
                    $emails[] = $email;
                }
            }
        }

        return array_values(array_unique($emails));
    }

    /** @param  array<string, mixed>  $speaker */
    private function normalizeSpeakerRow(array $speaker): array
    {
        $name = trim((string) ($speaker['name'] ?? ''));
        $email = trim((string) ($speaker['email'] ?? ''));

        return [
            'name' => $name,
            'email' => filter_var($email, FILTER_VALIDATE_EMAIL) ? $email : '',
            'role' => trim((string) ($speaker['role'] ?? '')),
            'bio' => trim((string) ($speaker['bio'] ?? '')),
            'invite_token' => trim((string) ($speaker['invite_token'] ?? '')),
            'invited_at' => $speaker['invited_at'] ?? null,
            'invite_source' => $speaker['invite_source'] ?? null,
        ];
    }
}