package pt.ist.vaadinframework.ui;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.vaadin.ui.AbstractOrderedLayout;
import com.vaadin.ui.Button;
import com.vaadin.ui.Button.ClickEvent;
import com.vaadin.ui.Button.ClickListener;
import com.vaadin.ui.Component;
import com.vaadin.ui.CustomComponent;
import com.vaadin.ui.HorizontalLayout;
import com.vaadin.ui.Label;
import com.vaadin.ui.VerticalLayout;

public class Wizard extends CustomComponent {
    private static final String CSS_STEP = "v-wizard-step";
    private static final String CSS_STEP_SELECTED = "v-wizard-step-selected";
    private static final String CSS_WIZARD = "v-wizard";
    private static final String CSS_WIZARD_CONTENT = "v-wizard-content";
    private static final String CSS_WIZARD_STEP_BAR = "v-wizard-step-bar";
    private static final String CSS_WIZARD_BUTTON_PANEL = "v-wizard-button-panel";
    private static final String CSS_WIZARD_BUTTON_PREV = "v-wizard-button-prev";
    private static final String CSS_WIZARD_BUTTON_NEXT = "v-wizard-button-next";

    private final AbstractOrderedLayout layout;
    private final StepBar tabsheet;
    private final List<WizardStep> steps;
    private int currentStepIndex;
    private WizardStep currentStep;
    private final HorizontalLayout content;
    private final ButtonPanel buttonPanel;
    private static Method ON_NEXT_STEP_EVENT_METHOD;
    private static Method ON_PREV_STEP_EVENT_METHOD;
    private static Method ON_WIZARD_COMPLETED_METHOD;
    static {
        try {
            ON_NEXT_STEP_EVENT_METHOD =
                    NextStepEventListener.class.getDeclaredMethod("nextStep", new Class[] { OnNextStepEvent.class });
            ON_PREV_STEP_EVENT_METHOD =
                    PrevStepEventListener.class.getDeclaredMethod("prevStep", new Class[] { OnPrevStepEvent.class });
            ON_WIZARD_COMPLETED_METHOD =
                    WizardCompletedListener.class.getDeclaredMethod("complete", new Class[] { OnWizardCompleted.class });
        } catch (final java.lang.NoSuchMethodException e) {
            // This should never happen
            throw new java.lang.RuntimeException("Internal error finding methods in Wizard");
        }
    }

    public interface NextStepEventListener extends Serializable {

        public void nextStep(OnNextStepEvent event);

    }

    public interface PrevStepEventListener extends Serializable {

        public void prevStep(OnPrevStepEvent event);

    }

    public interface WizardCompletedListener extends Serializable {
        public void complete(OnWizardCompleted event);
    }

    public class OnStepEvent extends Component.Event {

        private static final long serialVersionUID = 1L;

        public OnStepEvent(Component source) {
            super(source);
            // TODO Auto-generated constructor stub
        }

        public WizardStep getWizardStep() {
            return (WizardStep) getSource();
        }
    }

    public class OnNextStepEvent extends OnStepEvent {

        public OnNextStepEvent(Component source) {
            super(source);
            // TODO Auto-generated constructor stub
        }

    }

    public class OnPrevStepEvent extends OnStepEvent {

        public OnPrevStepEvent(Component source) {
            super(source);
            // TODO Auto-generated constructor stub
        }

    }

    public class OnWizardCompleted extends Component.Event {

        public OnWizardCompleted(Component source) {
            super(source);
            // TODO Auto-generated constructor stub
        }

    }

    private boolean fireWizardComplete() {
        if (currentStepIndex == steps.size() - 1) {
            fireEvent(new OnWizardCompleted(currentStep));
            return true;
        }
        return false;
    }

    private void fireNextStep() {
        if (!fireWizardComplete()) {
            final int next = currentStepIndex + 1;
            if (changeCurrentStep(next)) {
                fireEvent(new OnNextStepEvent(currentStep));
            }
        }
    }

    private void firePrevStep() {
        final int prev = currentStepIndex - 1;
        if (changeCurrentStep(prev)) {
            fireEvent(new OnPrevStepEvent(currentStep));
        }
    }

    private boolean changeCurrentStep(int index) {
        if (currentStepIndex == index) {
            return false;
        }
        if (index >= 0 && index <= steps.size() - 1) {
            currentStepIndex = index;
            buttonPanel.prev.setVisible(currentStepIndex != 0);
            currentStep = steps.get(currentStepIndex);
            tabsheet.selectStep(currentStep);
            return true;
        }
        return false;
    }

    public void addListener(NextStepEventListener listener) {
        super.addListener(OnNextStepEvent.class, listener, ON_NEXT_STEP_EVENT_METHOD);
    }

    public void addListener(PrevStepEventListener listener) {
        super.addListener(OnPrevStepEvent.class, listener, ON_PREV_STEP_EVENT_METHOD);
    }

    public void addListener(WizardCompletedListener listener) {
        super.addListener(OnWizardCompleted.class, listener, ON_WIZARD_COMPLETED_METHOD);
    }

    class ButtonPanel extends HorizontalLayout implements ClickListener {
        public Button prev;
        public Button next;

        public ButtonPanel(String prevCaption, String nextCaption) {
            addStyleName(CSS_WIZARD_BUTTON_PANEL);
            prev = new Button();
            prev.setCaption(prevCaption);
            prev.addListener(this);
            prev.addStyleName(CSS_WIZARD_BUTTON_PREV);
            addComponent(prev);

            next = new Button();
            next.setCaption(nextCaption);
            next.addStyleName(CSS_WIZARD_BUTTON_NEXT);
            next.addListener(this);
            addComponent(next);
        }

        @Override
        public void buttonClick(ClickEvent event) {
            if (event.getButton().equals(next)) {
                fireNextStep();
            } else if (event.getButton().equals(prev)) {
                firePrevStep();
            }
        }

    }

    class StepBar extends CustomComponent {
        private final HorizontalLayout stepBar;
        private final Map<Integer, Label> headers;

        public StepBar() {
            stepBar = new HorizontalLayout();
            stepBar.setWidth("100%");
            stepBar.addStyleName(CSS_WIZARD_STEP_BAR);
            headers = new HashMap<Integer, Label>();
            setCompositionRoot(stepBar);
        }

        public void addStep(Component c, String label) {
            final Label lblHeader = new Label(label);
            lblHeader.addStyleName(CSS_STEP);
            lblHeader.setImmediate(true);
            headers.put(steps.indexOf(c), lblHeader);
            stepBar.addComponent(lblHeader);
        }

        public void selectStep(Component c) {
            final int curr = steps.indexOf(c);
            for (Integer i : headers.keySet()) {
                final Label label = headers.get(i);
                if (i != curr) {
                    label.removeStyleName(CSS_STEP_SELECTED);
                    label.addStyleName(CSS_STEP);
                } else {
                    label.addStyleName(CSS_STEP_SELECTED);
                }
            }
            content.removeAllComponents();
            content.addComponent(c);
        }
    }

    public Wizard(final List<WizardStep> steps, String prevCaption, String nextCaption) {
        addStyleName(CSS_WIZARD);

        currentStepIndex = -1;
        currentStep = null;
        this.steps = steps;

        layout = new VerticalLayout();
        layout.setSizeFull();

        tabsheet = new StepBar();
        tabsheet.setWidth("100%");

        content = new HorizontalLayout();
        content.setSizeFull();
        content.addStyleName(CSS_WIZARD_CONTENT);

        buttonPanel = new ButtonPanel(prevCaption, nextCaption);
        createVerticalWizard(prevCaption, nextCaption);
        changeCurrentStep(0);
    }

    private void createVerticalWizard(String prevCaption, String nextCaption) {
        for (WizardStep ws : steps) {
            tabsheet.addStep(ws, ws.getStepTitle());
        }
        layout.addComponent(tabsheet);
        layout.addComponent(content);
        layout.setExpandRatio(content, 1f);
        layout.addComponent(buttonPanel);
    }

    @Override
    public void attach() {
        super.attach();
        setSizeFull();
        setCompositionRoot(layout);
    }

}