package model;

import java.util.ArrayList;
import java.util.List;

/**
 * Facade for the model layer. Manages the lifecycle of one repair session at a time
 * and delegates all operations to the current {@link ActiveRepair}.
 *
 * <p>Observers registered via {@link #addObserver(RepairOrderObserver)} are
 * automatically forwarded to every new repair session that is started.</p>
 */
public class RepairShop {

    private ActiveRepair currentRepair;
    private final List<RepairOrderObserver> observers = new ArrayList<>();
    private DiscountStrategy discountStrategy = new NoDiscount();

    /**
     * Creates a new RepairShop ready to accept repair sessions.
     */
    public RepairShop() {
    }

    /**
     * Registers an observer to be notified whenever a repair order changes.
     * The observer is passed to every repair session started after this call.
     *
     * @param observer The observer to register.
     */
    public void addObserver(RepairOrderObserver observer) {
        observers.add(observer);
    }

    /**
     * Sets the discount strategy to apply to each new repair session's total.
     *
     * @param strategy The discount strategy; must not be {@code null}.
     */
    public void setDiscountStrategy(DiscountStrategy strategy) {
        this.discountStrategy = strategy;
    }

    /**
     * Starts a new repair session, discarding any previously active session.
     */
    public void startRepair() {
        currentRepair = new ActiveRepair();
        for (RepairOrderObserver observer : observers) {
            currentRepair.addObserver(observer);
        }
        currentRepair.setDiscountStrategy(discountStrategy);
    }

    /**
     * Registers the bike that will be worked on during the current repair session.
     *
     * @param bike The {@link BikeDTO} of the bike to register.
     */
    public void registerBike(BikeDTO bike) {
        currentRepair.registerBike(bike);
    }

    /**
     * Adds a repair task to the current session and returns the updated running total.
     *
     * @param task The {@link TaskDTO} of the task to add.
     * @return The running total after the task has been added.
     */
    public Amount addTask(TaskDTO task) {
        return currentRepair.addTask(task);
    }

    /**
     * Records the mechanic's diagnostic notes for the current repair session.
     *
     * @param report The diagnostic report text entered by the mechanic.
     */
    public void enterDiagnosticReport(String report) {
        currentRepair.enterDiagnosticReport(report);
    }

    /**
     * Ends the current repair session and returns the completed repair order.
     *
     * @return The {@link RepairOrder} for the finished repair.
     */
    public RepairOrder endRepair() {
        return currentRepair.endRepair();
    }
}