<?php
/**
 * Availability Service
 * Business logic for trip availability dates
 * 
 * This is a FREE feature - no Pro plugin required
 * 
 * @package Yatra\Services
 * @since 3.0.0
 */

declare(strict_types=1);

namespace Yatra\Services;

use Yatra\Models\Availability;
use Yatra\Repositories\AvailabilityRepository;

class AvailabilityService
{
    private AvailabilityRepository $repository;

    public function __construct(AvailabilityRepository $repository)
    {
        $this->repository = $repository;
    }

    /**
     * Validate availability data
     */
    public function validate(array $data, ?int $id = null): void
    {
        // Required fields
        if (empty($data['trip_id'])) {
            throw new \InvalidArgumentException('Trip ID is required');
        }
        
        if (empty($data['departure_date'])) {
            throw new \InvalidArgumentException('Departure date is required');
        }
        
        if (empty($data['seats_total']) || (int) $data['seats_total'] <= 0) {
            throw new \InvalidArgumentException('Total seats must be greater than 0');
        }
        
        // Validate date format
        if (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $data['departure_date'])) {
            throw new \InvalidArgumentException('Invalid departure date format. Use YYYY-MM-DD');
        }
        
        // Validate arrival date if provided
        if (!empty($data['arrival_date'])) {
            if (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $data['arrival_date'])) {
                throw new \InvalidArgumentException('Invalid arrival date format. Use YYYY-MM-DD');
            }
            
            // Arrival date should be after departure date
            if (strtotime($data['arrival_date']) < strtotime($data['departure_date'])) {
                throw new \InvalidArgumentException('Arrival date must be after departure date');
            }
        }
        
        // Validate return date if provided
        if (!empty($data['return_date'])) {
            if (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $data['return_date'])) {
                throw new \InvalidArgumentException('Invalid return date format. Use YYYY-MM-DD');
            }
            
            $compareDate = !empty($data['arrival_date']) ? $data['arrival_date'] : $data['departure_date'];
            if (strtotime($data['return_date']) < strtotime($compareDate)) {
                throw new \InvalidArgumentException('Return date must be after arrival/departure date');
            }
        }
        
        // Validate and normalize time format if provided
        // Accept HH:MM, HH:MM:SS, or H:MM formats
        if (!empty($data['departure_time'])) {
            $data['departure_time'] = $this->normalizeTimeFormat($data['departure_time']);
            if ($data['departure_time'] === false) {
                throw new \InvalidArgumentException('Invalid departure time format. Use HH:MM');
            }
        }
        
        if (!empty($data['arrival_time'])) {
            $data['arrival_time'] = $this->normalizeTimeFormat($data['arrival_time']);
            if ($data['arrival_time'] === false) {
                throw new \InvalidArgumentException('Invalid arrival time format. Use HH:MM');
            }
        }
        
        // Validate status
        $validStatuses = ['available', 'limited', 'sold_out', 'closed', 'cancelled', 'blocked'];
        if (!empty($data['status']) && !in_array($data['status'], $validStatuses, true)) {
            throw new \InvalidArgumentException('Invalid status. Must be one of: ' . implode(', ', $validStatuses));
        }
        
        // Validate pricing
        if (isset($data['original_price']) && (float) $data['original_price'] < 0) {
            throw new \InvalidArgumentException('Original price cannot be negative');
        }
        
        if (isset($data['discounted_price']) && (float) $data['discounted_price'] < 0) {
            throw new \InvalidArgumentException('Discounted price cannot be negative');
        }
        
        if (!empty($data['original_price']) && !empty($data['discounted_price'])) {
            if ((float) $data['discounted_price'] > (float) $data['original_price']) {
                throw new \InvalidArgumentException('Discounted price cannot be greater than original price');
            }
        }
        
        // Validate seats
        if (isset($data['seats_available']) && (int) $data['seats_available'] < 0) {
            throw new \InvalidArgumentException('Available seats cannot be negative');
        }
        
        if (isset($data['seats_total']) && isset($data['seats_available'])) {
            if ((int) $data['seats_available'] > (int) $data['seats_total']) {
                throw new \InvalidArgumentException('Available seats cannot exceed total seats');
            }
        }
    }

    /**
     * Create availability date
     */
    public function create(array $data): Availability
    {
        $this->validate($data);
        
        // Set default seats_available if not provided
        if (!isset($data['seats_available'])) {
            $data['seats_available'] = $data['seats_total'] ?? 0;
        }
        
        // Auto-calculate status based on availability
        if (empty($data['status'])) {
            $seatsAvailable = (int) ($data['seats_available'] ?? 0);
            $seatsTotal = (int) ($data['seats_total'] ?? 0);
            
            if ($seatsAvailable === 0) {
                $data['status'] = 'sold_out';
            } elseif ($seatsAvailable <= ($seatsTotal * 0.2)) {
                $data['status'] = 'limited';
            } else {
                $data['status'] = 'available';
            }
        }
        
        $id = $this->repository->create($data);
        return $this->repository->findModel($id);
    }

    /**
     * Update availability date
     */
    public function update(int $id, array $data): Availability
    {
        $existing = $this->repository->findModel($id);
        if (!$existing) {
            throw new \InvalidArgumentException('Availability date not found');
        }
        
        // Merge with existing data for validation
        $mergedData = array_merge($existing->toArray(), $data);
        $this->validate($mergedData, $id);
        
        // Auto-update status based on availability
        if (isset($data['seats_available']) || isset($data['seats_total'])) {
            $seatsAvailable = (int) ($data['seats_available'] ?? $existing->seats_available);
            $seatsTotal = (int) ($data['seats_total'] ?? $existing->seats_total);
            
            if ($seatsAvailable === 0) {
                $data['status'] = 'sold_out';
            } elseif ($seatsAvailable <= ($seatsTotal * 0.2)) {
                $data['status'] = 'limited';
            } elseif (!isset($data['status'])) {
                $data['status'] = 'available';
            }
        }
        
        $this->repository->update($id, $data);
        return $this->repository->findModel($id);
    }

    public function duplicate(int $id, array $data): Availability
    {
        $existing = $this->repository->findModel($id);
        if (!$existing) {
            throw new \InvalidArgumentException('Availability date not found');
        }

        $newDepartureDate = isset($data['departure_date']) ? (string) $data['departure_date'] : '';
        if (empty($newDepartureDate)) {
            throw new \InvalidArgumentException('Departure date is required');
        }
        if (!preg_match('/^\d{4}-\d{2}-\d{2}$/', $newDepartureDate)) {
            throw new \InvalidArgumentException('Invalid departure date format. Use YYYY-MM-DD');
        }

        $newDepartureTime = null;
        if (array_key_exists('departure_time', $data)) {
            $newDepartureTime = !empty($data['departure_time']) ? $this->normalizeTimeFormat((string) $data['departure_time']) : null;
            if ($newDepartureTime === false) {
                throw new \InvalidArgumentException('Invalid departure time format. Use HH:MM');
            }
        } else {
            $newDepartureTime = $existing->departure_time;
        }

        if ($this->repository->existsForTripDateTime($existing->trip_id, $newDepartureDate, $newDepartureTime)) {
            throw new \InvalidArgumentException('Availability date already exists for the selected departure');
        }

        $oldDepartureTs = strtotime($existing->departure_date);
        $newDepartureTs = strtotime($newDepartureDate);
        if ($oldDepartureTs === false || $newDepartureTs === false) {
            throw new \InvalidArgumentException('Invalid departure date');
        }

        $shiftedArrivalDate = null;
        if (!empty($existing->arrival_date)) {
            $oldArrivalTs = strtotime($existing->arrival_date);
            if ($oldArrivalTs !== false) {
                $diffDays = (int) round(($oldArrivalTs - $oldDepartureTs) / 86400);
                $shiftedArrivalDate = date('Y-m-d', strtotime('+' . $diffDays . ' days', $newDepartureTs));
            }
        }

        $shiftedReturnDate = null;
        if (!empty($existing->return_date)) {
            $oldReturnTs = strtotime($existing->return_date);
            if ($oldReturnTs !== false) {
                $diffDays = (int) round(($oldReturnTs - $oldDepartureTs) / 86400);
                $shiftedReturnDate = date('Y-m-d', strtotime('+' . $diffDays . ' days', $newDepartureTs));
            }
        }

        $payload = $existing->toArray();
        unset($payload['id'], $payload['created_at'], $payload['updated_at']);
        unset($payload['booked_seats'], $payload['total_seats'], $payload['available_seats'], $payload['waitlist_count']);

        $payload['departure_date'] = $newDepartureDate;
        $payload['departure_time'] = $newDepartureTime;
        $payload['arrival_date'] = $shiftedArrivalDate;
        $payload['return_date'] = $shiftedReturnDate;

        $payload['seats_total'] = (int) $existing->seats_total;
        $payload['seats_available'] = (int) $existing->seats_total;
        $payload['seats_reserved'] = 0;
        $payload['seats_waitlist'] = 0;

        if (array_key_exists('seats_total', $data)) {
            $payload['seats_total'] = (int) $data['seats_total'];
            $payload['seats_available'] = (int) $data['seats_total'];
        }

        if (array_key_exists('arrival_time', $data)) {
            $arrivalTime = !empty($data['arrival_time']) ? $this->normalizeTimeFormat((string) $data['arrival_time']) : null;
            if ($arrivalTime === false) {
                throw new \InvalidArgumentException('Invalid arrival time format. Use HH:MM');
            }
            $payload['arrival_time'] = $arrivalTime;
        }

        if (array_key_exists('status', $data)) {
            $payload['status'] = (string) $data['status'];
        }

        $this->validate($payload);
        $newId = $this->repository->create($payload);
        return $this->repository->findModel($newId);
    }

    /**
     * Delete availability date
     */
    public function delete(int $id): bool
    {
        $existing = $this->repository->findModel($id);
        if (!$existing) {
            throw new \InvalidArgumentException('Availability date not found');
        }
        
        return $this->repository->delete($id);
    }

    /**
     * Get availability dates for a trip
     */
    public function getByTripId(int $tripId, array $filters = []): array
    {
        return $this->repository->findByTripId($tripId, $filters);
    }

    /**
     * Count availability dates for a trip
     */
    public function countByTripId(int $tripId, array $filters = []): int
    {
        return $this->repository->countByTripId($tripId, $filters);
    }

    /**
     * Get availability by trip ID and departure date
     */
    public function getByTripAndDate(int $tripId, string $departureDate): ?\stdClass
    {
        $repository = new \Yatra\Repositories\AvailabilityRepository();
        return $repository->findByTripIdAndDate($tripId, $departureDate);
    }

    /**
     * Get availability by trip ID, departure date, and optionally time.
     * Supports day tours with multiple time slots on the same date.
     * 
     * @param int $tripId Trip ID
     * @param string $departureDate Departure date (YYYY-MM-DD)
     * @param string|null $departureTime Departure time (HH:MM:SS or HH:MM)
     * @return \stdClass|null Availability object or null
     */
    public function getByTripAndDateTime(int $tripId, string $departureDate, ?string $departureTime = null): ?\stdClass
    {
        $repository = new \Yatra\Repositories\AvailabilityRepository();
        return $repository->findByTripIdAndDateTime($tripId, $departureDate, $departureTime);
    }

    /**
     * Get availability by ID
     */
    public function getById(int $availabilityId): ?\stdClass
    {
        $repository = new \Yatra\Repositories\AvailabilityRepository();
        return $repository->find($availabilityId);
    }

    /**
     * Check if discount code has been used by customer
     */
    public function getDiscountCodeUsage(int $customerId, string $discountCode): int
    {
        $bookingRepository = new \Yatra\Repositories\BookingRepository();
        return $bookingRepository->countDiscountCodeUsage($customerId, $discountCode);
    }

    /**
     * Get booked count by availability ID
     */
    public function getBookedCountByAvailabilityId(int $availabilityId): int
    {
        $bookingRepository = new \Yatra\Repositories\BookingRepository();
        return $bookingRepository->countBookedTravelersByAvailabilityId($availabilityId);
    }

    /**
     * Get booking counts for multiple availability IDs
     */
    public function getBookingCountsByAvailabilityIds(array $availabilityIds): array
    {
        $bookingRepository = new \Yatra\Repositories\BookingRepository();
        return $bookingRepository->getBookingCountsByAvailabilityIds($availabilityIds);
    }

    /**
     * Booked travellers for a date/time, counted from the bookings themselves.
     *
     * The `availability_id` join used by getBookingCountsByAvailabilityIds only
     * counts bookings whose availability_id was set to this exact row — a stored
     * link that the booking paths don't reliably set, and that rule-generated
     * dates never have. That made the "Booked" column read 0 for real bookings.
     *
     * This counts by the booking's own identity — (trip, date, time) — via the
     * booking_departures link both checkout and manual booking always create, so
     * it can't desync. It is the same method the recurring-rule availability path
     * already uses. Pass the row's own departure_time so a date with several
     * departures reports each slot separately rather than the day's total.
     */
    public function getBookedCountForSlot(int $tripId, string $date, ?string $departureTime = null): int
    {
        if ($tripId <= 0 || $date === '') {
            return 0;
        }

        // Dates are stored DATE-only; a datetime input would never string-match.
        if (preg_match('/^(\d{4}-\d{2}-\d{2})/', $date, $m)) {
            $date = $m[1];
        }

        $bookingRepository = new \Yatra\Repositories\BookingRepository();
        return $bookingRepository->countActiveSeatsForSlot($tripId, $date, $departureTime);
    }

    /**
     * Update availability status based on booking counts
     */
    public function updateAvailabilityStatusBasedOnBookings(int $availabilityId): bool
    {
        $availabilityRepository = new \Yatra\Repositories\AvailabilityRepository();
        
        $bookedCount = $this->getBookedCountByAvailabilityId($availabilityId);
        
        // Get availability details
        $availability = $availabilityRepository->find($availabilityId);
        
        if (!$availability) {
            return false;
        }
        
        $newStatus = ($bookedCount >= $availability->seats_available) ? 'sold_out' : 'available';
        
        return $availabilityRepository->update($availabilityId, ['status' => $newStatus]);
    }

    /**
     * Update booking availability IDs by trip and date
     */
    public function updateBookingAvailabilityIds(int $tripId, array $availabilityIdByDate): int
    {
        $bookingRepository = new \Yatra\Repositories\BookingRepository();
        
        $updatedCount = 0;
        
        foreach ($availabilityIdByDate as $date => $availabilityId) {
            if ($availabilityId <= 0) {
                continue;
            }
            
            $result = $bookingRepository->updateAvailabilityIdByTripAndDate($tripId, $date, $availabilityId);
            
            if ($result !== false) {
                $updatedCount += $result;
            }
        }
        
        return $updatedCount;
    }

    /**
     * Get traveler categories by IDs
     */
    public function getTravelerCategories(array $categoryIds): array
    {
        $travelerCategoryRepository = new \Yatra\Repositories\TravelerCategoryRepository();
        return $travelerCategoryRepository->getByIds($categoryIds);
    }

    /**
     * Get booking by ID
     */
    public function getBookingById(int $bookingId): ?\stdClass
    {
        $bookingRepository = new \Yatra\Repositories\BookingRepository();
        return $bookingRepository->find($bookingId);
    }

    /**
     * Get trip price types
     */
    public function getTripPriceTypes(int $tripId): array
    {
        // Table deprecated/removed: return empty so callers fall back gracefully
        return [];
    }

    /**
     * Normalize time string to HH:MM:SS format for MySQL TIME column.
     * Accepts HH:MM, HH:MM:SS, H:MM, or 12-hour formats (e.g., "9:00 AM").
     * 
     * @param string $time Time string
     * @return string|false Normalized time (HH:MM:SS) or false if invalid
     */
    private function normalizeTimeFormat(string $time)
    {
        $time = trim($time);
        
        if (empty($time)) {
            return false;
        }

        // Try parsing with strtotime (handles "9:00 AM", "14:30", etc.)
        $timestamp = strtotime($time);
        if ($timestamp !== false) {
            return date('H:i:s', $timestamp);
        }

        // Manual regex for HH:MM or HH:MM:SS
        if (preg_match('/^(\d{1,2}):(\d{2})(?::(\d{2}))?$/', $time, $matches)) {
            $hours = (int) $matches[1];
            $minutes = (int) $matches[2];
            $seconds = isset($matches[3]) ? (int) $matches[3] : 0;

            if ($hours >= 0 && $hours <= 23 && $minutes >= 0 && $minutes <= 59 && $seconds >= 0 && $seconds <= 59) {
                return sprintf('%02d:%02d:%02d', $hours, $minutes, $seconds);
            }
        }

        return false;
    }
}