import Foundation

/// Persisted layout positions using normalized (0..1) coordinates.
/// Survives resolution changes and provides stability across activations.
struct LayoutPosition: Codable, Equatable {
    let normalizedX: Double
    let normalizedY: Double
    let normalizedWidth: Double
    let normalizedHeight: Double

    func absoluteRect(in bounds: CGRect) -> CGRect {
        CGRect(
            x: bounds.origin.x + normalizedX * bounds.width,
            y: bounds.origin.y + normalizedY * bounds.height,
            width: normalizedWidth * bounds.width,
            height: normalizedHeight * bounds.height
        )
    }

    static func from(rect: CGRect, in bounds: CGRect) -> LayoutPosition {
        LayoutPosition(
            normalizedX: (rect.origin.x - bounds.origin.x) / bounds.width,
            normalizedY: (rect.origin.y - bounds.origin.y) / bounds.height,
            normalizedWidth: rect.width / bounds.width,
            normalizedHeight: rect.height / bounds.height
        )
    }
}

/// Stores the full layout state for a screen configuration.
final class LayoutState {
    /// Maps window fingerprint key to its normalized position.
    private(set) var positions: [String: LayoutPosition] = [:]

    /// The fingerprint of the last snapshot used for layout.
    private(set) var lastFingerprint: Set<String> = []

    func store(key: String, position: LayoutPosition) {
        positions[key] = position
    }

    func position(for key: String) -> LayoutPosition? {
        positions[key]
    }

    func updateFingerprint(_ fingerprint: Set<String>) {
        lastFingerprint = fingerprint
    }

    func clear() {
        positions.removeAll()
        lastFingerprint.removeAll()
    }

    /// Remove positions for keys no longer present.
    func prune(keeping keys: Set<String>) {
        positions = positions.filter { keys.contains($0.key) }
    }
}