ZeroSpace/ZeroSpace/ZeroSpace.MapEditor/Views/MapDrawable.cs

using Microsoft.Maui.Graphics;
using ZeroSpace.MapEditor.Models;
using ZeroSpace.MapEditor.Services;

namespace ZeroSpace.MapEditor.Views;

/// <summary>
/// Draws the star map: connection lines between connected systems and
/// one circle per system. Names are intentionally not drawn on the
/// canvas; details live in the inspector.
/// </summary>
public sealed class MapDrawable : IDrawable
{
    public const double NodeRadius = 14;

    public IList<MapNode> Nodes { get; set; } = Array.Empty<MapNode>();

    public Func<string, MapNode?> FindNode { get; set; } = _ => null;

    /// <summary>Screen pixels per world unit.</summary>
    public double Scale { get; set; } = 1;

    public double OffsetX { get; set; }

    public double OffsetY { get; set; }

    public RectF? SelectionBox { get; set; }

    /// <summary>In-game galaxy map screenshot, drawn under the nodes.</summary>
    public IImage? BackgroundImage { get; set; }

    /// <summary>Whether the galaxy map background is shown.</summary>
    public bool ShowBackground { get; set; } = true;

    public void Draw(ICanvas canvas, RectF dirtyRect)
    {
        canvas.FillColor = Color.FromArgb("#1e2430");
        canvas.FillRectangle(dirtyRect);

        DrawBackground(canvas);

        PointF ToScreen(double worldX, double worldY) =>
            new((float)(worldX * Scale + OffsetX), (float)(worldY * Scale + OffsetY));

        // Connections first, so nodes draw on top of the lines.
        canvas.StrokeColor = Color.FromArgb("#5b6b82");
        canvas.StrokeSize = Math.Max(1, (float)(1.5 * Scale));
        foreach (var node in Nodes)
        {
            var from = ToScreen(node.X, node.Y);
            foreach (var name in node.Doc.ConnectedSystems)
            {
                var target = FindNode(name);
                if (target is null || ReferenceEquals(target, node))
                {
                    continue;
                }

                var to = ToScreen(target.X, target.Y);
                canvas.DrawLine(from, to);
            }
        }

        foreach (var node in Nodes)
        {
            var center = ToScreen(node.X, node.Y);
            var radius = (float)(NodeRadius * Scale);

            canvas.FillColor = ColorForOwner(node.Doc.Owner);
            canvas.FillCircle(center, radius);

            if (node.IsHighlighted)
            {
                canvas.StrokeColor = Color.FromArgb("#FFD700");
                canvas.StrokeSize = 3;
                canvas.DrawCircle(center, radius + 4);
            }

            if (node.IsSelected)
            {
                canvas.StrokeColor = Colors.White;
                canvas.StrokeSize = 3;
                canvas.DrawCircle(center, node.IsHighlighted ? radius + 8 : radius + 6);
            }
        }

        if (SelectionBox is { Width: > 0, Height: > 0 } box)
        {
            canvas.FillColor = Color.FromArgb("#334a90d9");
            canvas.FillRectangle(box);
            canvas.StrokeColor = Color.FromArgb("#4a90d9");
            canvas.StrokeSize = 1.5f;
            canvas.DrawRectangle(box);
        }
    }

    /// <summary>
    /// Draws the galaxy map screenshot fitted inside the world square,
    /// preserving aspect ratio so node world coordinates line up exactly
    /// with the map underneath.
    /// </summary>
    private void DrawBackground(ICanvas canvas)
    {
        if (!ShowBackground || BackgroundImage is null)
        {
            return;
        }

        var imageWidth = BackgroundImage.Width;
        var imageHeight = BackgroundImage.Height;
        if (imageWidth <= 0 || imageHeight <= 0)
        {
            return;
        }

        const double world = StarSystemDocStore.WorldSize;
        var fit = Math.Min(world / imageWidth, world / imageHeight);
        var drawWidth = imageWidth * fit;
        var drawHeight = imageHeight * fit;
        var originX = (world - drawWidth) / 2;
        var originY = (world - drawHeight) / 2;

        canvas.DrawImage(BackgroundImage,
            (float)(originX * Scale + OffsetX),
            (float)(originY * Scale + OffsetY),
            (float)(drawWidth * Scale),
            (float)(drawHeight * Scale));
    }

    public static Color ColorForOwner(string owner) => owner switch
    {
        "The Eden Accord" => Color.FromArgb("#10b981"),
        "The Keeper Council" => Color.FromArgb("#38bdf8"),
        "The Obsidian Order" => Color.FromArgb("#ef4444"),
        _ => Color.FromArgb("#9aa5b1"),
    };

    public static Color ColorForCategory(string category) => category switch
    {
        "Homeworld System" or "Homeworld" => Color.FromArgb("#43a047"),
        "Core System" or "Core" => Color.FromArgb("#fb8c00"),
        "Side System" or "Side" => Color.FromArgb("#4a90d9"),
        _ => Color.FromArgb("#9aa5b1"),
    };
}