gabrieloc · October 2, 2020 21:20 · Oct 2, 2020
diff --git a/guy.swift b/guy.swift
@@ -0,0 +1,188 @@
+import Foundation
+import simd
+
+enum Input: String, CaseIterable {
+  case up = "▴"
+  case right = "▸"
+  case down = "▾"
+  case left = "◂"
+
+  var bytes: [UInt8] {
+    switch self {
+    case .up: return [27, 91, 65]
+    case .right: return [27, 91, 67]
+    case .down: return [27, 91, 66]
+    case .left: return [27, 91, 68]
+    }
+  }
+
+  init?(_ bytes: [UInt8]) {
+    guard let match = Self.allCases.first(where: { $0.bytes == bytes }) else {
+      return nil
+    }
+    self = match
+  }
+}
+
+class InputHandler {
+  static func initStruct<S>() -> S {
+    let struct_pointer = UnsafeMutablePointer<S>.allocate(capacity: 1)
+    let struct_memory = struct_pointer.pointee
+    struct_pointer.deallocate()
+    return struct_memory
+  }
+
+  static func enableRawMode(fileHandle: FileHandle) -> termios {
+    var raw: termios = initStruct()
+    tcgetattr(fileHandle.fileDescriptor, &raw)
+
+    let original = raw
+
+    raw.c_lflag &= ~(UInt(ECHO | ICANON))
+    tcsetattr(fileHandle.fileDescriptor, TCSAFLUSH, &raw);
+
+    return original
+  }
+
+  static func restoreRawMode(fileHandle: FileHandle, originalTerm: termios) {
+    var term = originalTerm
+    tcsetattr(fileHandle.fileDescriptor, TCSAFLUSH, &term);
+  }
+
+  let originalTerm: termios
+
+  init() {
+    self.originalTerm = Self.enableRawMode(
+      fileHandle: FileHandle.standardInput
+    )
+  }
+
+  deinit {
+    Self.restoreRawMode(
+      fileHandle: FileHandle.standardInput,
+      originalTerm: originalTerm
+    )
+  }
+
+  var input: Input?
+}
+
+class Renderer {
+  var buffer: [Character]
+  var length: Int { buffer.count }
+  let size: simd_int2
+
+  init(size: simd_int2) {
+    self.size = size
+    self.buffer = Array<Character>(
+      repeating: "▓",
+      count: Int(size.x * size.y)
+    )
+  }
+
+  func scale(_ position: simd_float2) -> simd_int2 {
+    simd_int2(
+      simd_int2.Scalar(position.x * Float(size.x)),
+      simd_int2.Scalar(position.y * Float(size.y))
+    )
+  }
+
+  func drawChar(_ char: Character, position: simd_float2) {
+    let i = scale(position).index(rowLength: size.x)
+    self.buffer[i % length] = char
+  }
+
+  func drawRect(frame: float2x2, char: Character) {
+    let p1 = convertViewportPoint(frame.columns.0)
+    let p2 = convertViewportPoint(frame.columns.0 + frame.columns.1)
+
+    (p1.x..<p2.x).forEach { x in
+      (p1.y..<p2.y).forEach { y in
+        let i = Int(simd_int2(x: x, y: y).index(rowLength: size.x))
+        self.buffer[i % length] = char
+      }
+    }
+  }
+
+  func error() {
+    buffer = Array<Character>(repeating: "▓", count: length)
+  }
+
+  func clear() {
+    buffer = Array<Character>(repeating: "░", count: length)
+  }
+
+  func blit() {
+    print("\u{001B}[2J")
+    print(
+      String (
+        stride(from: 0, to: length, by: Int(size.x)).map { i in
+          String(buffer[i..<(i + Int(size.x))])
+        }.joined(separator: "\n")
+      )
+    )
+  }
+
+  func convertViewportPoint(_ point: simd_float2) -> simd_int2 {
+    simd_int2(
+      x: Int32(Float(size.x) * point.x),
+      y: Int32(Float(size.y) * point.y)
+    )
+  }
+}
+
+extension simd_int2 {
+  func index(rowLength: Scalar) -> Int {
+    Int((y * rowLength) + (x % rowLength))
+  }
+}
+
+class Game {
+  let inputHandler = InputHandler()
+  let renderer = Renderer(
+    size: simd_int2(x: 40, y: 10)
+  )
+  var isRunning = false
+  var pointer = simd_float2(0.5, 0.5)
+  let speed: Float = 0.1
+  let guy = Character("☃︎")
+
+  func start() {
+    var data: Data
+    repeat {
+      data = FileHandle.standardInput.availableData
+      let bytes = [UInt8](data)
+      let input = Input(bytes)
+      renderer.clear()
+      if let input = input {
+        switch input {
+        case .up:
+          pointer -= simd_float2(0, speed)
+        case .right:
+          pointer += simd_float2(speed, 0)
+        case .down:
+          pointer += simd_float2(0, speed)
+        case .left:
+          pointer -= simd_float2(speed, 0)
+        }
+        pointer.clamp(
+          lowerBound: simd_float2.zero,
+          upperBound: simd_float2.one
+        )
+      }
+      renderer.drawChar(
+        guy,
+        position: pointer
+      )
+      renderer.blit()
+    } while (data.count > 0)
+  }
+
+  func stop() {
+    isRunning = false
+  }
+}
+
+
+let game = Game()
+game.start()