//
//  PrismMark.swift
//  Prisme
//
//  Author: Simon-Pierre Boucher <contact@spboucher.ai>
//

import SwiftUI

/// The Prisme logo, drawn in code so it adapts to light/dark and any size.
/// Same geometry as the app icon (Design/icon/prisme-icon.svg): a white beam
/// enters a glass prism and exits as a spectrum fan.
struct PrismMark: View {
    var body: some View {
        Canvas { context, size in
            let s = min(size.width, size.height) / 1024

            func point(_ x: CGFloat, _ y: CGFloat) -> CGPoint {
                CGPoint(x: x * s, y: y * s)
            }
            func polygon(_ pts: [(CGFloat, CGFloat)]) -> Path {
                var path = Path()
                path.move(to: point(pts[0].0, pts[0].1))
                for p in pts.dropFirst() { path.addLine(to: point(p.0, p.1)) }
                path.closeSubpath()
                return path
            }

            // Spectrum fan (clipped by the canvas, like the icon).
            let origin: (CGFloat, CGFloat) = (614, 470)
            let boundaries: [(CGFloat, CGFloat)] = [
                (1211, 248), (1238, 348), (1250, 451),
                (1244, 555), (1223, 657), (1185, 753), (1132, 843),
            ]
            let colors: [Color] = [
                Color(red: 1.00, green: 0.23, blue: 0.36),
                Color(red: 1.00, green: 0.62, blue: 0.11),
                Color(red: 1.00, green: 0.88, blue: 0.40),
                Color(red: 0.24, green: 0.86, blue: 0.52),
                Color(red: 0.22, green: 0.71, blue: 1.00),
                Color(red: 0.55, green: 0.36, blue: 0.96),
            ]
            for (index, color) in colors.enumerated() {
                let band = polygon([origin, boundaries[index], boundaries[index + 1]])
                context.fill(band, with: .color(color.opacity(0.95)))
            }

            // Incoming beam, stopping on the left face. Light stays white in
            // both color schemes; a soft shadow keeps it visible on light
            // backgrounds.
            let beam = polygon([(82, 132), (142, 98), (398, 488), (372, 510)])
            context.drawLayer { layer in
                layer.addFilter(.shadow(color: .black.opacity(0.22), radius: 7 * s, y: 2 * s))
                layer.fill(beam, with: .color(.white))
            }
            context.stroke(beam, with: .color(.black.opacity(0.10)), lineWidth: 2 * s)

            // Internal refraction.
            let inner = polygon([(386, 494), (614, 462), (614, 478), (390, 508)])
            context.fill(inner, with: .color(.white.opacity(0.9)))
            context.stroke(inner, with: .color(.black.opacity(0.08)), lineWidth: 1.5 * s)

            // Glass triangle.
            let prism = polygon([(512, 268), (292, 688), (732, 688)])
            context.fill(prism, with: .color(.primary.opacity(0.07)))
            context.stroke(
                prism,
                with: .color(.primary.opacity(0.75)),
                style: StrokeStyle(lineWidth: 10 * s, lineCap: .round, lineJoin: .round)
            )
        }
    }
}

#Preview {
    PrismMark()
        .frame(width: 160, height: 160)
        .padding()
}