// Regenerates the app icon PNGs from the official Monero mark.
//
//   cd apps/ios
//   swift Branding/make-icons.swift Koins/Assets.xcassets/AppIcon.appiconset
//
// Input:  Branding/logo-official.png — the monochrome mark published in
//         monero-project/monero-site (meta/safari-pinned-tab.svg), rasterised.
//         It is a black badge with the M knocked out, drawn on white.
// Output: AppIcon-1024.png        - the inverse: white badge, black M, on black
//                                   (reads well on the app's dark UI)
//         AppIcon-light-1024.png  - the mark as published: black badge, white M,
//                                   on white
//
// The artwork is inset to 90% of the canvas so the iOS squircle mask does not
// clip the badge's edges. iOS cannot use SVG for app icons, which is why this
// rasterises instead of linking the SVG.
import AppKit
import CoreGraphics
import Foundation

struct Bitmap {
  let width: Int
  let height: Int
  var pixels: [UInt8]        // RGBA, premultiplied

  func luminance(_ offset: Int) -> Int {
    (Int(pixels[offset]) * 299 + Int(pixels[offset + 1]) * 587 + Int(pixels[offset + 2]) * 114) / 1000
  }
}

func loadBitmap(_ path: String) -> Bitmap? {
  guard let image = NSImage(contentsOfFile: path),
        let cgImage = image.cgImage(forProposedRect: nil, context: nil, hints: nil) else { return nil }
  let width = cgImage.width
  let height = cgImage.height
  var pixels = [UInt8](repeating: 0, count: width * height * 4)
  guard let context = CGContext(data: &pixels,
                                width: width,
                                height: height,
                                bitsPerComponent: 8,
                                bytesPerRow: width * 4,
                                space: CGColorSpaceCreateDeviceRGB(),
                                bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue) else { return nil }
  context.draw(cgImage, in: CGRect(x: 0, y: 0, width: width, height: height))
  return Bitmap(width: width, height: height, pixels: pixels)
}

func makeImage(_ bitmap: Bitmap) -> CGImage? {
  guard let provider = CGDataProvider(data: Data(bitmap.pixels) as CFData) else { return nil }
  return CGImage(width: bitmap.width,
                 height: bitmap.height,
                 bitsPerComponent: 8,
                 bitsPerPixel: 32,
                 bytesPerRow: bitmap.width * 4,
                 space: CGColorSpaceCreateDeviceRGB(),
                 bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue),
                 provider: provider,
                 decode: nil,
                 shouldInterpolate: false,
                 intent: .defaultIntent)
}

func inverted(_ bitmap: Bitmap) -> Bitmap {
  var pixels = bitmap.pixels
  for offset in stride(from: 0, to: pixels.count, by: 4) {
    let value = UInt8(255 - bitmap.luminance(offset))
    pixels[offset] = value
    pixels[offset + 1] = value
    pixels[offset + 2] = value
  }
  return Bitmap(width: bitmap.width, height: bitmap.height, pixels: pixels)
}

/// Composes the mark onto a square background, inset so the platform mask has
/// room, and writes an opaque PNG (App Store icons must not carry alpha).
func writeIcon(_ source: Bitmap, size: Int, inset: CGFloat, background: NSColor, to path: String) {
  guard let image = makeImage(source) else { return }
  var pixels = [UInt8](repeating: 0, count: size * size * 4)
  guard let context = CGContext(data: &pixels,
                                width: size,
                                height: size,
                                bitsPerComponent: 8,
                                bytesPerRow: size * 4,
                                space: CGColorSpaceCreateDeviceRGB(),
                                bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue) else { return }

  context.setFillColor(background.cgColor)
  context.fill(CGRect(x: 0, y: 0, width: size, height: size))
  let side = CGFloat(size) * inset
  let offset = (CGFloat(size) - side) / 2
  context.interpolationQuality = .high
  context.draw(image, in: CGRect(x: offset, y: offset, width: side, height: side))

  var rgb = [UInt8](repeating: 0, count: size * size * 3)
  for index in 0..<(size * size) {
    rgb[index * 3] = pixels[index * 4]
    rgb[index * 3 + 1] = pixels[index * 4 + 1]
    rgb[index * 3 + 2] = pixels[index * 4 + 2]
  }
  guard let provider = CGDataProvider(data: Data(rgb) as CFData),
        let flattened = CGImage(width: size,
                                height: size,
                                bitsPerComponent: 8,
                                bitsPerPixel: 24,
                                bytesPerRow: size * 3,
                                space: CGColorSpaceCreateDeviceRGB(),
                                bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue),
                                provider: provider,
                                decode: nil,
                                shouldInterpolate: false,
                                intent: .defaultIntent) else { return }
  let representation = NSBitmapImageRep(cgImage: flattened)
  guard let data = representation.representation(using: .png, properties: [:]) else { return }
  try? data.write(to: URL(fileURLWithPath: path))
  print("wrote \(path)")
}

let arguments = CommandLine.arguments
let outputDirectory = arguments.count > 1 ? arguments[1] : "/tmp"
let sourcePath = arguments.count > 2 ? arguments[2] : "Branding/logo-official.png"
try? FileManager.default.createDirectory(atPath: outputDirectory, withIntermediateDirectories: true)

guard let source = loadBitmap(sourcePath) else {
  print("cannot read source artwork at \(sourcePath)")
  exit(1)
}

let inset: CGFloat = 0.78
// Primary: the mark exactly as Monero publishes it (black badge, white M).
writeIcon(source, size: 1024, inset: inset, background: .white,
          to: "\(outputDirectory)/AppIcon-1024.png")
// Alternate: inverted, for dark surfaces (white badge, black M, black ground).
writeIcon(inverted(source), size: 1024, inset: inset, background: .black,
          to: "Branding/logo-inverted.png")