RationDistributionSystem.java

import java.util.*;

//ABSTRACTION
abstract class Person 
{
    private String name;
    private int age;
    private String phoneNumber;

    public Person(String name, int age, String phoneNumber) 
	{
        this.name = name;
        this.age = age;
        this.phoneNumber = phoneNumber;
    }

    public String getName()        
	{ 
		return name;
	}
    public int getAge()            
	{ 
		return age; 
	}
    public String getPhoneNumber() 
	{ 
		return phoneNumber;
	}
    public abstract void displayDetails();
}

// CUSTOMER
class Customer extends Person 
{
    private String rationCardId;
    private String category;   // Antyodaya | BPL | APL
    private String area;
    private String state;

    public Customer(String name, int age, String phoneNumber, String rationCardId, String category, String area, String state) 
	{
        super(name, age, phoneNumber);
        this.rationCardId = rationCardId;
        this.category     = category;
        this.area         = area;
        this.state        = state;
    }

    public String getRationCardId() 
	{
		return rationCardId; 
	}
    public String getCategory()     
	{ 
		return category; 
	}
    public String getArea()         
	{
		return area; 
	}
    public String getState()        
	{
		return state; 
	}

    @Override
    public void displayDetails() 
	{
        System.out.println("Customer: " + getName() +
                " | Age: " + getAge() +
                " | Card: " + rationCardId +
                " | Category: " + category +
                " | Area: " + area +
                " | State: " + state);
    }
}

//  INVENTORY (Array element) 
class Inventory 
{
    private String itemName;
    private int quantity;
    private double pricePerKg;
    private int threshold;

    public Inventory(String itemName, int quantity, double pricePerKg, int threshold) 
	{
        this.itemName   = itemName;
        this.quantity   = quantity;
        this.pricePerKg = pricePerKg;
        this.threshold  = threshold;
    }

    public String getItemName()  
	{
		return itemName; 
	}
    public int    getQuantity()   
	{
		return quantity; 
	}
    public double getPricePerKg()
	{ 
		return pricePerKg;
	}
    public int    getThreshold()  
	{ 
		return threshold; 
	}
    public boolean isBelowThreshold() 
	{
		return quantity < threshold; 
	}

    public void reduceStock(int qty)
	{
        if (qty <= quantity) quantity -= qty;
        else System.out.println("Not enough stock for " + itemName);
    }

    public void addStock(int qty) 
	{ 
		quantity += qty;
	}

    public void display() 
	{
        System.out.printf("%-12s | Stock: %4d kg | Rs.%.1f/kg | Threshold: %d kg%n",
                itemName, quantity, pricePerKg, threshold);
    }
}

// SHOP (DSA: STATIC ARRAY)
class Shop 
{
    private String shopId;
    private String shopName;
    private String location;
    private String state;
    private Inventory[] stock;        // STATIC ARRAY — fixed-size inventory
    private int stockCount;
    private Map<String, Integer> allocationRates;

    public Shop(String shopId, String shopName, String location, String state, int capacity) 
	{
        this.shopId    = shopId;
        this.shopName  = shopName;
        this.location  = location;
        this.state     = state;
        this.stock     = new Inventory[capacity];
        this.stockCount = 0;
        this.allocationRates = new HashMap<>();
        initializeRegionalAllocation();
    }

    // Regional dietary requirements
    private void initializeRegionalAllocation() 
	{
        switch (state) 
		{
            case "Punjab":
            case "Haryana":
                allocationRates.put("Rice",  5);
                allocationRates.put("Wheat", 10);
                allocationRates.put("Sugar", 2);
                allocationRates.put("Oil",   1);
                break;
            case "West Bengal":
                allocationRates.put("Rice",  10);
                allocationRates.put("Wheat", 3);
                allocationRates.put("Sugar", 2);
                allocationRates.put("Oil",   1);
                break;
            case "Kerala":
                allocationRates.put("Rice",  8);
                allocationRates.put("Wheat", 4);
                allocationRates.put("Sugar", 2);
                allocationRates.put("Oil",   1);
                break;
            default:
                allocationRates.put("Rice",  6);
                allocationRates.put("Wheat", 6);
                allocationRates.put("Sugar", 2);
                allocationRates.put("Oil",   1);
        }
    }

    // Array insertion
    public void addItem(Inventory item) 
	{
        if (stockCount < stock.length)
            stock[stockCount++] = item;
    }

    // Array traversal
    public void displayStock() 
	{
        System.out.println("\n--- Stock at " + shopName + " (" + location + ", " + state + ") ---");
        for (int i = 0; i < stockCount; i++) stock[i].display();
    }

    // Linear search in array
    public Inventory searchItem(String itemName) 
	{
        for (int i = 0; i < stockCount; i++)
            if (stock[i].getItemName().equalsIgnoreCase(itemName))
                return stock[i];
        return null;
    }

    // Allocation per category (mirrors UI logic)
    public int getAllocation(String itemName, String category) 
	{
        int base = allocationRates.getOrDefault(itemName, 5);
        if (category.equalsIgnoreCase("Antyodaya")) return base;
        if (category.equalsIgnoreCase("BPL"))       return base * 2 / 3;
        return base / 2;
    }

    public Inventory[] getAllStock()  
	{
		return stock; 
	}
    public int getStockCount()
	{ 
		return stockCount; 
	}
    public String getState()    
	{
		return state; 
	}
}

// LINKED LIST (DSA: SINGLY LINKED LIST)
class Node 
{
    Customer data;
    Node next;
    Node(Customer data) 
	{ 
		this.data = data;
	}
}

class BeneficiaryList 
{
    private Node head;

    // Insert at end — O(n)
    public void addBeneficiary(Customer c) 
	{
        Node newNode = new Node(c);
        if (head == null) 
		{ 
			head = newNode; 
			return; 
		}
        Node temp = head;
        while (temp.next != null) temp = temp.next;
        temp.next = newNode;
    }

    // Insert at beginning — O(1)
    public void addAtBeginning(Customer c) 
	{
        Node newNode = new Node(c);
        newNode.next = head;
        head = newNode;
    }

    // Linear search — O(n)
    public Customer searchByCard(String cardId) 
	{
        Node temp = head;
        while (temp != null) 
		{
            if (temp.data.getRationCardId().equalsIgnoreCase(cardId))
                return temp.data;
            temp = temp.next;
        }
        return null;
    }

    // Delete node by card ID
    public boolean deleteBeneficiary(String cardId)
	{
        if (head == null) return false;
        if (head.data.getRationCardId().equalsIgnoreCase(cardId)) 
		{
            head = head.next;
            return true;
        }
        Node temp = head;
        while (temp.next != null &&
               !temp.next.data.getRationCardId().equalsIgnoreCase(cardId))
            temp = temp.next;
        if (temp.next != null) 
		{
			temp.next = temp.next.next; 
			return true;
		}
        return false;
    }

    // Convert to array (needed for sorting)
    public Customer[] toArray() 
	{
        int count = 0;
        Node t = head;
        while (t != null)
		{ 
			count++; 
			t = t.next; 
		}
        Customer[] arr = new Customer[count];
        t = head;
        for (int i = 0; i < count; i++) 
		{
			arr[i] = t.data;
			t = t.next;
		}
        return arr;
    }

    public void displayAll() 
	{
        System.out.println("\n All Beneficiaries (Linked List)");
        Node temp = head;
        if (temp == null) 
		{
			System.out.println("No records."); 
			return;
		}
        while (temp != null) 
		{ 
			temp.data.displayDetails(); 
			temp = temp.next;
		}
    }

    public int size() 
	{
        int count = 0;
        Node temp = head;
        while (temp != null) 
		{
			count++; 
			temp = temp.next; 
		}
        return count;
    }
}

//QUEUE + STACK (DSA: FIFO Queue & LIFO Stack)
class DistributionQueue 
{
    private LinkedList<Customer> queue = new LinkedList<>();  // FIFO
    private Stack<Customer> completedStack = new Stack<>();       // LIFO

    // Enqueue — insert at rear
    public void enqueue(Customer c) 
	{
        queue.addLast(c);
        System.out.println(c.getName() + " added to distribution queue.");
    }

    // Dequeue — remove from front, push to completed stack
    public Customer dequeue() 
	{
        if (queue.isEmpty()) 
		{
            System.out.println("Queue is empty.");
            return null;
        }
        Customer served = queue.removeFirst();
        completedStack.push(served);   // PUSH to stack
        return served;
    }

    public boolean isEmpty()  
	{
		return queue.isEmpty(); 
	}
    public Customer peek()    
	{
		return queue.isEmpty() ? null : queue.getFirst(); 
	}

    public boolean isInQueue(String cardId) 
	{
        for (Customer c : queue)
            if (c.getRationCardId().equalsIgnoreCase(cardId)) return true;
        return false;
    }

    public String getStatus(String cardId) 
	{
        if (isInQueue(cardId)) return "PENDING";
        for (Customer c : completedStack)
            if (c.getRationCardId().equalsIgnoreCase(cardId)) return "COMPLETED";
        return "NOT FOUND";
    }

    public int            queueSize()       
	{
		return queue.size(); 
	}
    public LinkedList<Customer> getQueue()  
	{ 
		return queue; 
	}
    public Stack<Customer> getCompletedStack() 
	{
		return completedStack; 
	}

    public void displayQueue() 
	{
        System.out.println("\nDistribution Queue (FIFO) ");
        if (queue.isEmpty()) 
		{
			System.out.println("Queue is empty.");
			return; 
		}
        int pos = 1;
        for (Customer c : queue)
            System.out.println(pos++ + ". " + c.getName() + " [" + c.getRationCardId() + "]");
    }
}

//  SORTING (DSA: BUBBLE SORT & INSERTION SORT)
class SortBeneficiaries 
{

    // Bubble Sort by area — O(n²)
    public static void sortByArea(Customer[] arr)
	{
        int n = arr.length;
        for (int i = 0; i < n - 1; i++)
            for (int j = 0; j < n - i - 1; j++)
                if (arr[j].getArea().compareToIgnoreCase(arr[j+1].getArea()) > 0) 
				{
                    Customer tmp = arr[j]; arr[j] = arr[j+1]; arr[j+1] = tmp;
                }
    }

    // Bubble Sort by priority: Antyodaya > BPL > APL
    public static void sortByPriority(Customer[] arr) 
	{
        int n = arr.length;
        for (int i = 0; i < n - 1; i++)
            for (int j = 0; j < n - i - 1; j++)
                if (rank(arr[j].getCategory()) > rank(arr[j+1].getCategory())) 
				{
                    Customer tmp = arr[j]; arr[j] = arr[j+1]; arr[j+1] = tmp;
                }
    }

    // Insertion Sort by name — O(n²), efficient for nearly sorted data
    public static void insertionSortByName(Customer[] arr) 
	{
        for (int i = 1; i < arr.length; i++) 
		{
            Customer key = arr[i];
            int j = i - 1;
            while (j >= 0 && arr[j].getName().compareToIgnoreCase(key.getName()) > 0) 
			{
                arr[j+1] = arr[j]; j--;
            }
            arr[j+1] = key;
        }
    }

    private static int rank(String cat) 
	{
        switch (cat.toUpperCase()) 
		{
            case "ANTYODAYA": return 1;
            case "BPL":       return 2;
            case "APL":       return 3;
            default:          return 4;
        }
    }
}

//  BINARY SEARCH (DSA: O(log n)) 
class BinarySearchCard 
{
    public static int search(String[] cards, String target) 
	{
        int low = 0, high = cards.length - 1;
        while (low <= high) {
            int mid = (low + high) / 2;
            int cmp = cards[mid].compareToIgnoreCase(target);
            if      (cmp == 0) return mid;
            else if (cmp < 0)  low  = mid + 1;
            else               high = mid - 1;
        }
        return -1;
    }
}

// OTP MANAGER (DSA: HASH MAP) 
class OTPManager 
{
    private static Map<String, OTPData>  otpStore     = new HashMap<>();
    private static Map<String, Integer>  attemptCount = new HashMap<>();

    static class OTPData 
	{
        String otp;
        long   expiryTime;
        OTPData(String otp, long expiryTime) 
		{
            this.otp        = otp;
            this.expiryTime = expiryTime;
        }
    }

    // Generate OTP, valid 2 minutes
    public static String generateOTP(String cardId) 
	{
        String otp        = String.format("%04d", new Random().nextInt(10000));
        long   expiryTime = System.currentTimeMillis() + 120_000L;
        otpStore.put(cardId, new OTPData(otp, expiryTime));
        attemptCount.put(cardId, 0);
        return otp;
    }

    // Verify OTP — max 3 attempts, 2-minute expiry
    public static boolean verifyOTP(String cardId, String entered) 
	{
        int attempts = attemptCount.getOrDefault(cardId, 0);
        if (attempts >= 3) return false;

        OTPData data = otpStore.get(cardId);
        if (data == null) 
		{
            attemptCount.put(cardId, attempts + 1);
            return false;
        }
        if (System.currentTimeMillis() > data.expiryTime)
		{
            otpStore.remove(cardId);
            return false;
        }
        if (data.otp.equals(entered)) 
		{
            otpStore.remove(cardId);
            attemptCount.remove(cardId);
            return true;
        }
        attemptCount.put(cardId, attempts + 1);
        return false;
    }

    // Mask phone: first 2 + ****** + last 2
    public static String maskPhone(String phone) 
	{
        if (phone == null || phone.length() < 10) return phone;
        return phone.substring(0, 2) + "******" + phone.substring(phone.length() - 2);
    }
}

//  MAIN DRIVER 
public class RationDistributionSystem 
{

    public static void main(String[] args) 
	{
     
        System.out.println("  DIGITAL RATION DISTRIBUTION SYSTEM   ");
		
        // 1. Create shops per state (Array storage)
        Shop shopHaryana   = buildShop("Haryana");
        Shop shopWestBengal= buildShop("West Bengal");
        shopHaryana.displayStock();
        shopWestBengal.displayStock();

        // 2. Add beneficiaries to Linked List
        BeneficiaryList beneficiaries = new BeneficiaryList();
        beneficiaries.addBeneficiary(new Customer("Amarjeet Singh", 45, "9876543210", "RC101", "BPL",       "Sector-10", "Haryana"));
        beneficiaries.addBeneficiary(new Customer("Baldev Singh",   38, "9876543211", "RC102", "APL",       "Sector-15", "Haryana"));
        beneficiaries.addBeneficiary(new Customer("Mamata Devi",    52, "9876543212", "RC103", "Antyodaya", "Sector-08", "West Bengal"));
        beneficiaries.addBeneficiary(new Customer("Sourav Roy",     48, "9876543213", "RC104", "BPL",       "Sector-12", "West Bengal"));
        beneficiaries.addBeneficiary(new Customer("Priya Nair",     55, "9876543214", "RC105", "APL",       "Sector-08", "Kerala"));
        beneficiaries.displayAll();

        // 3. Linear search on Linked List
        System.out.println("\n--- Linear Search: RC103 ---");
        Customer found = beneficiaries.searchByCard("RC103");
        if (found != null) 
		{ 
			System.out.println("VERIFIED"); 
			found.displayDetails(); 
		}
        else System.out.println("Card not found.");

        // 4. Sort by priority (Bubble Sort)
        Customer[] arr = beneficiaries.toArray();
        SortBeneficiaries.sortByPriority(arr);
        System.out.println("\n--- Sorted by Priority (Antyodaya > BPL > APL) ---");
        for (Customer c : arr) c.displayDetails();

        // 5. Sort by area (Bubble Sort)
        SortBeneficiaries.sortByArea(arr);
        System.out.println("\n--- Sorted by Area ---");
        for (Customer c : arr) c.displayDetails();

        // 6. Sort by name (Insertion Sort)
        SortBeneficiaries.insertionSortByName(arr);
        System.out.println("\n--- Sorted by Name (Insertion Sort) ---");
        for (Customer c : arr) c.displayDetails();

        // 7. Binary search on sorted card IDs
        String[] cardIds = {"RC101","RC102","RC103","RC104","RC105"};
        Arrays.sort(cardIds);
        int idx = BinarySearchCard.search(cardIds, "RC104");
        System.out.println("\n--- Binary Search: RC104 ---");
        System.out.println(idx != -1 ? "Found at index " + idx : "Not found");

        // 8. OTP demo
        System.out.println("\n--- OTP Demo (RC101) ---");
        String otp = OTPManager.generateOTP("RC101");
        System.out.println("Generated OTP: " + otp);
        System.out.println("Masked phone:  " + OTPManager.maskPhone("9876543210"));
        System.out.println("Verify correct: " + OTPManager.verifyOTP("RC101", otp));

        // 9. Queue: sort by priority then enqueue
        DistributionQueue dq = new DistributionQueue();
        SortBeneficiaries.sortByPriority(arr);
        for (Customer c : arr) dq.enqueue(c);
        dq.displayQueue();

        // 10. Dequeue (FIFO) → served, pushed to Stack (LIFO)
        System.out.println("\n--- Distributing Ration (FIFO) ---");
        while (!dq.isEmpty()) 
		{
            Customer next = dq.dequeue();
            System.out.println("Served: " + next.getName() +
                    " | Card: " + next.getRationCardId() +
                    " | Category: " + next.getCategory());
        }

        // 11. Check status via stack
        System.out.println("\n--- Distribution Status ---");
        String[] checkIds = {"RC101","RC103","RC105"};
        for (String id : checkIds)
            System.out.println(id + " => " + dq.getStatus(id));
        System.out.println("  All beneficiaries served successfully.");
    }

    private static Shop buildShop(String state) {
        Shop shop = new Shop("S_" + state.replaceAll(" ","").toUpperCase(),
                             "Government Ration Shop", "Main Market", state, 5);
        if (state.equals("Punjab") || state.equals("Haryana")) {
            shop.addItem(new Inventory("Rice",  800,  3.0, 200));
            shop.addItem(new Inventory("Wheat", 1500, 2.5, 300));
            shop.addItem(new Inventory("Sugar", 400, 13.5, 100));
            shop.addItem(new Inventory("Oil",   250, 80.0,  80));
        } else if (state.equals("West Bengal")) {
            shop.addItem(new Inventory("Rice",  1200, 3.0, 300));
            shop.addItem(new Inventory("Wheat",  500, 2.5, 150));
            shop.addItem(new Inventory("Sugar",  350,13.5, 100));
            shop.addItem(new Inventory("Oil",    200,80.0,  60));
        } else if (state.equals("Kerala")) {
            shop.addItem(new Inventory("Rice",  1000, 3.0, 250));
            shop.addItem(new Inventory("Wheat",  600, 2.5, 150));
            shop.addItem(new Inventory("Sugar",  300,13.5,  80));
            shop.addItem(new Inventory("Oil",    180,80.0,  50));
        } else {
            shop.addItem(new Inventory("Rice",  700, 3.0, 200));
            shop.addItem(new Inventory("Wheat", 700, 2.5, 200));
            shop.addItem(new Inventory("Sugar", 300,13.5,  80));
            shop.addItem(new Inventory("Oil",   150,80.0,  50));
        }
        return shop;
    }
}