SparkleView.swift

//
//  SparkleView.swift
//  UnwrapLive26
//
//  Created by Michael Charland on 2026-01-10.
//

import SwiftUI

struct Sparkle {
    var x: Double
    var y: Double
    var xSpeed: Double
    var ySpeed: Double
    var size: Double
    var brightness: Double
    var creationDate = Date()
}

struct SparkleView: View {
    
    @State private var sparkles = [Sparkle]()
    
    var colours: [Color] = [.red, .green, .blue, .yellow, .pink, .purple, .orange]
    
    var body: some View {
        TimelineView(.animation) { timeline in
            Canvas { context, size in
                context.blendMode = .plusLighter
                context.addFilter(.blur(radius: 10))
                
                for sparkle in sparkles {
                    let age = timeline.date.timeIntervalSince(sparkle.creationDate)
                    context.opacity = (1 - age) * sparkle.brightness
                    
                    // Move the sparkle based on its speed and age
                    let x = sparkle.x + sparkle.xSpeed * age
                    let y = sparkle.y + sparkle.ySpeed * age
                    
                    let rectangle = CGRect(
                        x: x - sparkle.size / 2,
                        y: y - sparkle.size / 2,
                        width: sparkle.size,
                        height: sparkle.size
                    )
                    context.fill(Path(ellipseIn: rectangle), with: .color(colours.randomElement()!))
                }
            }
            .gesture(
                DragGesture(minimumDistance: 0)
                    .onChanged { value in
                        sparkles.append(
                            Sparkle(
                                x: value.location.x,
                                y: value.location.y,
                                xSpeed: Double.random(in: -50...50),
                                ySpeed: Double.random(in: -50...50),
                                size: Double.random(in: 16...32),
                                brightness: Double.random(in: 0.7...1)
                            )
                        )
                        
                        // free up RAM
                        sparkles = sparkles.suffix(200)
                    }
            )
        }
    }
}

#Preview {
    SparkleView()
}