// Smart Parking Management System - Fixed Version
class Queue {
    constructor() { this.items = []; }
    enqueue(item) { this.items.push(item); }
    dequeue() { return this.items.shift(); }
    isEmpty() { return this.items.length === 0; }
}

class Stack {
    constructor() { this.items = []; }
    push(item) { this.items.push(item); }
    pop() { return this.items.pop(); }
    isEmpty() { return this.items.length === 0; }
}

class SmartParking {
    constructor(totalSlots = 20) {
        this.totalSlots = totalSlots;
        this.availableSlots = totalSlots;
        this.parkedVehicles = new Map(); // Hash Map
        this.parkingHistory = [];
        this.waitingQueue = new Queue();
        this.operationStack = new Stack();
    }

    // Vehicle Entry
    parkVehicle(vehicleNumber, vehicleType = "Car") {
        if (this.availableSlots > 0) {
            const slot = this.totalSlots - this.availableSlots + 1;
            const entryTime = new Date();
            
            this.parkedVehicles.set(vehicleNumber, {
                slot: slot,
                type: vehicleType,
                entryTime: entryTime
            });
            
            this.availableSlots--;
            this.operationStack.push(`Parked ${vehicleNumber} at slot ${slot}`);
            console.log(`Parked ${vehicleNumber} at Slot ${slot}`);
            return slot;
        } else {
            this.waitingQueue.enqueue(vehicleNumber);
            console.log(`No slot available. ${vehicleNumber} added to waiting queue.`);
            return null;
        }
    }

    // Vehicle Exit
    exitVehicle(vehicleNumber) {
        if (!this.parkedVehicles.has(vehicleNumber)) {
            console.log("Vehicle not found.");
            return;
        }

        const details = this.parkedVehicles.get(vehicleNumber);
        const exitTime = new Date();
        const durationMs = exitTime - details.entryTime;
        const durationMin = Math.ceil(durationMs / 60000);
        const fee = durationMin * 10;

        this.parkingHistory.push({
            vehicleNumber,
            slot: details.slot,
            type: details.type,
            duration: durationMin,
            fee: fee,
            exitTime: exitTime
        });

        this.parkedVehicles.delete(vehicleNumber);
        this.availableSlots++;

        // Serve from queue if waiting
        if (!this.waitingQueue.isEmpty()) {
            const nextVehicle = this.waitingQueue.dequeue();
            this.parkVehicle(nextVehicle);
        }

        console.log(`Exited ${vehicleNumber}. Fee: Rs. ${fee}`);
        return fee;
    }

    // Vehicle Search
    searchVehicle(vehicleNumber) {
        if (this.parkedVehicles.has(vehicleNumber)) {
            const v = this.parkedVehicles.get(vehicleNumber);
            console.log(`Found: Slot ${v.slot}, Type: ${v.type}`);
            return v;
        }
        console.log("Vehicle not found.");
    }

    // Statistics
    showStatistics() {
        console.log("\n=== Parking Statistics ===");
        console.log("Total Slots:", this.totalSlots);
        console.log("Available Slots:", this.availableSlots);
        console.log("Occupied:", this.parkedVehicles.size);
        console.log("Waiting in Queue:", this.waitingQueue.items.length);
        console.log("Total Vehicles Served:", this.parkingHistory.length);
    }

    // History
    showHistory() {
        console.log("\n=== Parking History ===");
        this.parkingHistory.forEach((record, index) => {
            console.log(`${index+1}. ${record.vehicleNumber} | Slot ${record.slot} | Rs. ${record.fee} | ${record.duration} min`);
        });
    }

    // Slot Availability
    showAvailability() {
        console.log(`\nAvailable Slots: (\( {this.availableSlots}/ \){this.totalSlots})`);
    }
}

// ==================== DEMO ====================
const parkingSystem = new SmartParking(15);

console.log("=== Smart Parking System Started ===\n");

parkingSystem.parkVehicle("MH01AB1234", "Car");
parkingSystem.parkVehicle("MH02CD5678", "Bike");
parkingSystem.parkVehicle("MH03EF9012", "Car");

parkingSystem.showAvailability();
parkingSystem.searchVehicle("MH02CD5678");

parkingSystem.exitVehicle("MH01AB1234");

parkingSystem.showStatistics();
parkingSystem.showHistory();

console.log("\n=== System Ready ===");