<?php

namespace App\Services;

use App\Models\Reminder;
use App\Models\ReminderTemplate;
use App\Models\Appointment;
use Carbon\Carbon;

class ReminderService
{
    /**
     * Generate reminders for an appointment
     */
    public function generateReminders(Appointment $appointment): void
    {
        $templates = ReminderTemplate::where('is_active', true)->get();

        foreach ($templates as $template) {
            $sendAt = $appointment->appointment_date->copy()->subHours($template->hours_before);
            
            // Don't create if send time is in the past
            if ($sendAt->isPast()) {
                continue;
            }

            $placeholders = [
                'patient_name' => $appointment->patient->fullName(),
                'date' => $appointment->appointment_date->format('Y-m-d'),
                'time' => $appointment->appointment_date->format('H:i'),
                'therapist_name' => $appointment->user->name,
            ];

            Reminder::create([
                'appointment_id' => $appointment->id,
                'template_id' => $template->id,
                'channel' => $template->channel,
                'content' => $template->parseContent($placeholders),
                'send_at' => $sendAt,
                'status' => 'queued',
            ]);
        }
    }

    /**
     * Get due reminders
     */
    public function getDueReminders(int $limit = 50): array
    {
        return Reminder::with('appointment.patient')
            ->where('status', 'queued')
            ->where('send_at', '<=', now())
            ->limit($limit)
            ->get()
            ->toArray();
    }

    /**
     * Process and send reminders
     */
    public function processReminders(): array
    {
        $reminders = Reminder::with('appointment.patient')
            ->where('status', 'queued')
            ->where('send_at', '<=', now())
            ->get();

        $results = [
            'sent' => 0,
            'failed' => 0,
        ];

        foreach ($reminders as $reminder) {
            try {
                $this->sendReminder($reminder);
                $reminder->markAsSent();
                $results['sent']++;
            } catch (\Exception $e) {
                $reminder->markAsFailed($e->getMessage());
                $results['failed']++;
            }
        }

        return $results;
    }

    /**
     * Send a single reminder (stub - implement with actual SMS/WhatsApp provider)
     */
    public function sendReminder(Reminder $reminder): void
    {
        // Stub implementation - integrate with SMS/WhatsApp provider
        $channel = $reminder->channel;
        $content = $reminder->content;
        
        switch ($channel) {
            case 'sms':
                // TODO: Integrate with SMS provider
                break;
            case 'whatsapp':
                // TODO: Integrate with WhatsApp Business API
                break;
            case 'email':
                // TODO: Send email
                break;
            case 'internal':
                // Internal notification - logged only
                break;
        }
    }

    /**
     * Get reminder configuration
     */
    public function getConfiguration(): array
    {
        return ReminderTemplate::where('is_active', true)
            ->get()
            ->map(fn($t) => [
                'id' => $t->id,
                'name' => $t->name,
                'channel' => $t->channel,
                'hours_before' => $t->hours_before,
            ])
            ->toArray();
    }

    /**
     * Update reminder configuration
     */
    public function updateConfiguration(int $templateId, array $data): ReminderTemplate
    {
        $template = ReminderTemplate::findOrFail($templateId);
        $template->update($data);
        return $template;
    }
}