<?php

namespace App\Services;

use App\Models\Consultation;
use Carbon\Carbon;
use Symfony\Component\HttpFoundation\Response;

class CalendarService
{
    private const DEFAULT_DURATION_MINUTES = 45;

    /**
     * Generate an ICS calendar file for a consultation.
     */
    public function generateIcs(Consultation $consultation): string
    {
        $consultation->loadMissing('user');

        $user = $consultation->user;
        $locale = $user?->preferred_language ?? 'ar';

        $startDateTime = Carbon::parse(
            $consultation->booking_date->format('Y-m-d').' '.$consultation->booking_time
        );
        $duration = $consultation->duration ?? self::DEFAULT_DURATION_MINUTES;
        $endDateTime = $startDateTime->copy()->addMinutes($duration);

        $title = $locale === 'ar'
            ? 'استشارة مع مكتب ليبرا للمحاماة'
            : 'Consultation with Libra Law Firm';

        $description = $this->buildDescription($consultation, $locale);
        $location = $this->getLocation($locale);

        $uid = sprintf('consultation-%d@libra.ps', $consultation->id);

        $ics = [
            'BEGIN:VCALENDAR',
            'VERSION:2.0',
            'PRODID:-//Libra Law Firm//Consultation Booking//EN',
            'CALSCALE:GREGORIAN',
            'METHOD:REQUEST',
            'BEGIN:VTIMEZONE',
            'TZID:Asia/Jerusalem',
            'BEGIN:STANDARD',
            'DTSTART:19701025T020000',
            'RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU',
            'TZOFFSETFROM:+0300',
            'TZOFFSETTO:+0200',
            'END:STANDARD',
            'BEGIN:DAYLIGHT',
            'DTSTART:19700329T020000',
            'RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1FR',
            'TZOFFSETFROM:+0200',
            'TZOFFSETTO:+0300',
            'END:DAYLIGHT',
            'END:VTIMEZONE',
            'BEGIN:VEVENT',
            'UID:'.$uid,
            'DTSTAMP:'.gmdate('Ymd\THis\Z'),
            'DTSTART;TZID=Asia/Jerusalem:'.$startDateTime->format('Ymd\THis'),
            'DTEND;TZID=Asia/Jerusalem:'.$endDateTime->format('Ymd\THis'),
            'SUMMARY:'.$this->escapeIcs($title),
            'DESCRIPTION:'.$this->escapeIcs($description),
            'LOCATION:'.$this->escapeIcs($location),
            'STATUS:CONFIRMED',
            'SEQUENCE:0',
            'BEGIN:VALARM',
            'TRIGGER:-PT1H',
            'ACTION:DISPLAY',
            'DESCRIPTION:Reminder',
            'END:VALARM',
            'END:VEVENT',
            'END:VCALENDAR',
        ];

        return implode("\r\n", $ics);
    }

    /**
     * Build the event description based on locale.
     */
    private function buildDescription(Consultation $consultation, string $locale): string
    {
        $lines = [];

        $type = $consultation->consultation_type?->value ?? 'free';

        if ($locale === 'ar') {
            $lines[] = 'رقم الحجز: '.$consultation->id;
            $lines[] = 'نوع الاستشارة: '.($type === 'free' ? 'مجانية' : 'مدفوعة');
            if ($type === 'paid' && $consultation->payment_amount) {
                $lines[] = 'المبلغ: '.number_format($consultation->payment_amount, 2).' شيكل';
            }
            $lines[] = '';
            $lines[] = 'للاستفسارات:';
            $lines[] = 'مكتب ليبرا للمحاماة';
            $lines[] = 'libra.ps';
        } else {
            $lines[] = 'Booking Reference: '.$consultation->id;
            $lines[] = 'Consultation Type: '.ucfirst($type);
            if ($type === 'paid' && $consultation->payment_amount) {
                $lines[] = 'Amount: '.number_format($consultation->payment_amount, 2).' ILS';
            }
            $lines[] = '';
            $lines[] = 'For inquiries:';
            $lines[] = 'Libra Law Firm';
            $lines[] = 'libra.ps';
        }

        return implode('\n', $lines);
    }

    /**
     * Get the office location based on locale.
     */
    private function getLocation(string $locale): string
    {
        return config('libra.office_address.'.$locale, 'Libra Law Firm');
    }

    /**
     * Escape special characters for ICS format.
     */
    private function escapeIcs(string $text): string
    {
        // Order matters: backslash must be escaped first
        return str_replace(
            ['\\', ',', ';'],
            ['\\\\', '\,', '\;'],
            $text
        );
    }

    /**
     * Generate a download response for the ICS file.
     */
    public function generateDownloadResponse(Consultation $consultation): Response
    {
        $content = $this->generateIcs($consultation);
        $filename = sprintf(
            'consultation-%s.ics',
            $consultation->booking_date->format('Y-m-d')
        );

        return response($content)
            ->header('Content-Type', 'text/calendar; charset=utf-8')
            ->header('Content-Disposition', 'attachment; filename="'.$filename.'"');
    }
}