package org.saturnclient.ui;

import org.saturnclient.ui.components.Sidebar;
import org.saturnclient.ui.elements.ImageTexture;
import org.saturnclient.ui.elements.Panel;
import org.saturnclient.ui.elements.Scroll;
import org.saturnclient.ui.resources.Textures;

/**
 * A screen laid out as the sidebar beside one panel, centered and shrunk to
 * fit smaller windows. Subclasses fill the panel in {@link #panel()}, using the
 * content bounds this class computes.
 */
public abstract class PanelScreen extends SaturnScreen {
    private static final int MAX_WIDTH = 900;
    private static final int MAX_HEIGHT = 580;
    private static final int MARGIN = 40;
    private static final int GAP = 12;

    protected static final int PADDING = 20;

    /** How far a scroll reaches past its content area, into the padding, for its bar */
    private static final int SCROLL_OVERHANG = 14;

    private final int sidebarItem;

    protected int panelX, panelY, panelWidth, panelHeight;
    /** The panel's area inside its padding */
    protected int contentX, contentY, contentWidth, contentHeight;

    /**
     * @param sidebarItem the {@link Sidebar} item to highlight
     */
    public PanelScreen(String title, int sidebarItem) {
        super(title);
        this.sidebarItem = sidebarItem;
    }

    @Override
    public final void ui() {
        panelWidth = Math.min(MAX_WIDTH, width - MARGIN * 2 - Sidebar.WIDTH - GAP);
        panelHeight = Math.min(MAX_HEIGHT, height - MARGIN * 2);

        int left = (width - (Sidebar.WIDTH + GAP + panelWidth)) / 2;
        panelX = left + Sidebar.WIDTH + GAP;
        panelY = (height - panelHeight) / 2;

        contentX = panelX + PADDING;
        contentY = panelY + PADDING;
        contentWidth = panelWidth - PADDING * 2;
        contentHeight = panelHeight - PADDING * 2;

        draw(new Sidebar(sidebarItem, this.provider::close)
                .dimensions(Sidebar.WIDTH, panelHeight)
                .position(left, panelY));

        draw(new Panel().dimensions(panelWidth, panelHeight).position(panelX, panelY));

        panel();

        draw(new ImageTexture(Textures.LOGO_TEXT_BIG).dimensions(180, 18).position(width - 180 - 20, height - 18 - 20));
    }

    /**
     * Draws the panel's content.
     */
    protected abstract void panel();

    /**
     * The width of a scroll filling {@code width} of the content area.
     */
    protected static int scrollWidth(int width) {
        return width + SCROLL_OVERHANG;
    }

    /**
     * The width left for a scroll's children, clear of its scrollbar.
     */
    protected static int scrollContentWidth(int width) {
        return scrollWidth(width) - Scroll.SCROLLBAR_SPACE;
    }
}