ParkingLotService.java

package com.parking.service;

import com.parking.model.*;
import java.time.LocalDateTime;
import java.util.*;
import java.util.stream.Collectors;

/**
 * Core Smart Parking Lot Service.
 * Manages spot allocation, entry/exit, and analytics.
 */
public class ParkingLotService {

    private final Map<String, ParkingSpot> spots = new LinkedHashMap<>();
    private final Map<String, ParkingTicket> activeTickets = new HashMap<>();
    private final List<ParkingTicket> ticketHistory = new ArrayList<>();
    private final PricingService pricingService = new PricingService();
    private double totalRevenue = 0;

    public ParkingLotService() {
        initializeLot();
    }

    // ─── Lot Initialization ──────────────────────────────────────────────────

    private void initializeLot() {
        String[] zones = {"A", "B", "C"};
        for (String zone : zones) {
            for (int level = 1; level <= 2; level++) {
                for (int spot = 1; spot <= 10; spot++) {
                    ParkingSpot.SpotType type = determineSpotType(zone, spot);
                    ParkingSpot ps = new ParkingSpot(zone, level, spot, type);
                    spots.put(ps.getId(), ps);
                }
            }
        }
        System.out.println("✅ Parking lot initialized with " + spots.size() + " spots.");
    }

    private ParkingSpot.SpotType determineSpotType(String zone, int spotNumber) {
        if (spotNumber == 1) return ParkingSpot.SpotType.HANDICAPPED;
        if (spotNumber == 2) return ParkingSpot.SpotType.EV_CHARGING;
        if (zone.equals("A") && spotNumber <= 4) return ParkingSpot.SpotType.PREMIUM;
        if (spotNumber >= 9) return ParkingSpot.SpotType.COMPACT;
        return ParkingSpot.SpotType.REGULAR;
    }

    // ─── Entry Management ────────────────────────────────────────────────────

    public ParkingTicket processEntry(String licensePlate, String ownerName, Vehicle.VehicleType vehicleType) {
        if (activeTickets.containsKey(licensePlate)) {
            throw new IllegalStateException("Vehicle " + licensePlate + " is already parked.");
        }

        ParkingSpot spot = findBestSpot(vehicleType);
        if (spot == null) {
            throw new RuntimeException("No available spots for vehicle type: " + vehicleType);
        }

        // Occupy the spot
        spot.setStatus(ParkingSpot.SpotStatus.OCCUPIED);
        spot.setVehicleId(licensePlate);
        spot.setOccupiedSince(System.currentTimeMillis());

        // Create ticket
        ParkingTicket ticket = new ParkingTicket(licensePlate, spot.getId());
        activeTickets.put(licensePlate, ticket);

        System.out.printf("🚗 Entry: %s → Spot %s (%s)%n", licensePlate, spot.getId(), spot.getType());
        return ticket;
    }

    // ─── Smart Spot Assignment ───────────────────────────────────────────────

    private ParkingSpot findBestSpot(Vehicle.VehicleType vehicleType) {
        ParkingSpot.SpotType preferred = mapVehicleToSpotType(vehicleType);

        // First try exact match
        Optional<ParkingSpot> best = spots.values().stream()
                .filter(s -> s.isAvailable() && s.getType() == preferred)
                .findFirst();

        // Fallback to regular
        if (best.isEmpty()) {
            best = spots.values().stream()
                    .filter(s -> s.isAvailable() && s.getType() == ParkingSpot.SpotType.REGULAR)
                    .findFirst();
        }

        return best.orElse(null);
    }

    private ParkingSpot.SpotType mapVehicleToSpotType(Vehicle.VehicleType vt) {
        switch (vt) {
            case EV:          return ParkingSpot.SpotType.EV_CHARGING;
            case HANDICAPPED: return ParkingSpot.SpotType.HANDICAPPED;
            case MOTORCYCLE:  return ParkingSpot.SpotType.COMPACT;
            case TRUCK:       return ParkingSpot.SpotType.PREMIUM;
            default:          return ParkingSpot.SpotType.REGULAR;
        }
    }

    // ─── Exit Management ─────────────────────────────────────────────────────

    public ParkingTicket processExit(String licensePlate) {
        ParkingTicket ticket = activeTickets.get(licensePlate);
        if (ticket == null) {
            throw new IllegalStateException("No active ticket for: " + licensePlate);
        }

        ParkingSpot spot = spots.get(ticket.getSpotId());
        long durationMinutes = ticket.getDurationMinutes();
        double charge = pricingService.calculateCharge(spot.getType(), durationMinutes);

        ticket.setExitedAt(LocalDateTime.now());
        ticket.setAmount(charge);
        ticket.setPaid(true);
        ticket.setStatus(ParkingTicket.TicketStatus.COMPLETED);

        // Free the spot
        spot.setStatus(ParkingSpot.SpotStatus.AVAILABLE);
        spot.setVehicleId(null);

        activeTickets.remove(licensePlate);
        ticketHistory.add(ticket);
        totalRevenue += charge;

        System.out.printf("🏁 Exit: %s | Duration: %d min | Charge: ₹%.2f%n",
                licensePlate, durationMinutes, charge);
        return ticket;
    }

    // ─── Queries ─────────────────────────────────────────────────────────────

    public List<ParkingSpot> getAllSpots() {
        return new ArrayList<>(spots.values());
    }

    public List<ParkingSpot> getAvailableSpots() {
        return spots.values().stream()
                .filter(ParkingSpot::isAvailable)
                .collect(Collectors.toList());
    }

    public List<ParkingSpot> getOccupiedSpots() {
        return spots.values().stream()
                .filter(s -> s.getStatus() == ParkingSpot.SpotStatus.OCCUPIED)
                .collect(Collectors.toList());
    }

    public Map<String, Object> getAnalytics() {
        int total = spots.size();
        long occupied = spots.values().stream().filter(s -> s.getStatus() == ParkingSpot.SpotStatus.OCCUPIED).count();
        long available = total - occupied;
        double occupancyRate = (double) occupied / total * 100;

        Map<String, Object> analytics = new LinkedHashMap<>();
        analytics.put("totalSpots", total);
        analytics.put("occupied", occupied);
        analytics.put("available", available);
        analytics.put("occupancyRate", String.format("%.1f%%", occupancyRate));
        analytics.put("totalRevenue", String.format("₹%.2f", totalRevenue));
        analytics.put("totalTransactions", ticketHistory.size());
        analytics.put("activeVehicles", activeTickets.size());
        return analytics;
    }

    public List<ParkingTicket> getTicketHistory() {
        return Collections.unmodifiableList(ticketHistory);
    }

    public ParkingTicket getActiveTicket(String licensePlate) {
        return activeTickets.get(licensePlate);
    }

    public double getTotalRevenue() { return totalRevenue; }
    public int getTotalSpots() { return spots.size(); }
}