Create a Pricing calculation strategy.

src/main/java/com/priyakdey/parker/core/model/ParkingCharge.java

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+package com.priyakdey.parker.core.model;
+
+/**
+ * Represents the details of a parking charge for a vehicle.
+ *
+ * <p>This record abstracts the representation of hours parked and the charge incurred
+ * to avoid tight coupling with specific numerical or currency types.
+ * By using {@code String} for all fields, it provides flexibility in terms of
+ * representing charges (which could be integers today and floating points tomorrow)
+ * and currency units.</p>
+ * <p>
+ * It is a data classes which holds the following information:
+ * <li>
+ *     <ul>registrationNumber: The registration number of the parked vehicle.</ul>
+ *     <ul>hoursParked: The number of hours the vehicle has been parked. Example formats "2", "2.5", "2 hours 30 minutes", etc.</ul>
+ *     <ul>charge: The charge incurred for the parking duration. Example formats: "10", "10.6", "10 dollars 60 cents", etc.<ul/>
+ * </li>
+ * <p/>
+ *
+ * @author Priyak Dey
+ */
+public record ParkingCharge(String registrationNumber, String hoursParked, String charge) {
+}

src/main/java/com/priyakdey/parker/core/pricing/ParkingFeeCalculator.java

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+package com.priyakdey.parker.core.pricing;
+
+/**
+ * Represents a mechanism to compute the parking fee based on the number of hours a vehicle has been parked.
+ *
+ * <p>
+ * Implementations of this interface will define the logic to calculate the parking fee
+ * for a given number of hours. This allows for flexibility in defining different pricing
+ * strategies for parking.
+ * </p>
+ * <p>
+ * Example:
+ * <pre>
+ *     ParkingFeeCalculator calculator = ...;
+ *     Number fee = calculator.computePrice(5);  // Calculate fee for 5 hours of parking.
+ * </pre>
+ *
+ * @author Priyak Dey
+ */
+public interface ParkingFeeCalculator {
+
+    /**
+     * Computes the parking fee for the specified number of hours.
+     *
+     * @param hoursParked The number of hours for which the parking fee should be computed.
+     * @return The computed parking fee as a {@link Number}. Implementations might return fee as
+     * an integer, decimal, or other numerical representations.
+     */
+    Number computePrice(int hoursParked);
+}
+

src/main/java/com/priyakdey/parker/core/pricing/impl/PerHourFeeCalculatorImpl.java

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+package com.priyakdey.parker.core.pricing.impl;
+
+import com.priyakdey.parker.core.pricing.ParkingFeeCalculator;
+import com.priyakdey.parker.exception.BadInputException;
+
+/**
+ * Implementation of the {@link ParkingFeeCalculator} that calculates parking fees
+ * based on a per-hour pricing model.
+ *
+ * <p>
+ * This implementation uses a flat rate for the first few hours (as defined by
+ * {@link #FLAT_RATE_DURATION_HOURS}) and then charges a specified rate for every additional
+ * hour.
+ * </p>
+ * <p>
+ * Example:
+ * <pre>
+ *     ParkingFeeCalculator calculator = new PerHourFeeCalculatorImpl();
+ *     Number fee = calculator.computePrice(3);  // Calculate fee for 3 hours of parking.
+ * </pre>
+ *
+ * @author Priyak Dey
+ */
+public class PerHourFeeCalculatorImpl implements ParkingFeeCalculator {
+
+    /**
+     * The fixed charge applicable for parking durations up to FLAT_RATE_DURATION_HOURS.
+     */
+    private static final int FLAT_RATE_CHARGE = 10;
+
+    /**
+     * The number of hours for which the flat rate (FLAT_RATE_CHARGE) applies.
+     */
+    private static final int FLAT_RATE_DURATION_HOURS = 2;
+
+
+    /**
+     * Charge applied for every hour after the INITIAL_HOURS.
+     */
+    private static final int PER_HOUR_CHARGE = 10;
+
+
+    /**
+     * Computes the parking fee for the specified number of hours.
+     *
+     * @param hoursParked The number of hours for which the parking fee should be computed.
+     * @return The computed parking fee as a {@link Number}. Implementations might return fee as
+     * an integer, decimal, or other numerical representations.
+     */
+    @Override
+    public Number computePrice(int hoursParked) {
+        if (hoursParked < 0) {
+            throw new BadInputException("Hours parked cannot be negative");
+        }
+
+        int overheadHours =
+            hoursParked > FLAT_RATE_DURATION_HOURS ? hoursParked - FLAT_RATE_DURATION_HOURS : 0;
+
+        return FLAT_RATE_CHARGE + overheadHours * PER_HOUR_CHARGE;
+    }
+}

src/main/java/com/priyakdey/parker/core/service/ParkingLot.java

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+package com.priyakdey.parker.core.service;/**
+*
+* @author Priyak Dey
+*/
+public class ParkingLot {
+}

src/main/java/com/priyakdey/parker/core/service/ParkingLotManager.java

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+package com.priyakdey.parker.core.service;/**
+*
+* @author Priyak Dey
+*/
+public class ParkingLotManager {
+}

src/main/java/com/priyakdey/parker/core/service/ParkingLotManagerImpl.java

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+package com.priyakdey.parker.core.service;/**
+*
+* @author Priyak Dey
+*/
+public class ParkingLotManagerImpl {
+}