import Foundation
import CoreGraphics

/// Places district labels so their boxes don't overlap. Each district starts at
/// a hash-derived seed; if its (padded) label box collides with an already-placed
/// one, we spiral outward — rotating and pushing away from downtown — until we
/// find clear space. Existing placements never move, so the map stays stable as
/// new districts appear.
///
/// Pure and deterministic given its inputs; no SpriteKit, fully unit-testable.
public enum LayoutSolver {

    /// - Parameters:
    ///   - baseAngle/baseRadius: the hash-derived seed in polar coords.
    ///   - localRect: the label box *relative to the node center* (labels sit
    ///     below the dot, so this is usually offset downward).
    ///   - existing: already-placed label boxes in world space.
    ///   - pad: minimum gap to keep between boxes.
    /// - Returns: a world-space center for the new district.
    public static func placeNonOverlapping(
        baseAngle: Double,
        baseRadius: Double,
        localRect: CGRect,
        existing: [CGRect],
        pad: CGFloat = 16,
        maxAttempts: Int = 400
    ) -> CGPoint {
        for attempt in 0..<maxAttempts {
            let angle = baseAngle + Double(attempt) * 0.45      // rotate as we go
            let radius = baseRadius + Double(attempt) * 7       // and push outward
            let center = CGPoint(x: cos(angle) * radius, y: sin(angle) * radius)
            let box = localRect.offsetBy(dx: center.x, dy: center.y).insetBy(dx: -pad, dy: -pad)
            if !existing.contains(where: { $0.intersects(box) }) {
                return center
            }
        }
        // Give up gracefully at the seed (extremely crowded map).
        return CGPoint(x: cos(baseAngle) * baseRadius, y: sin(baseAngle) * baseRadius)
    }
}