Tetris/Tetris/ContentView.swift

//
//  ContentView.swift
//  Tetris
//
//  Created by Shadowfacts on 10/14/19.
//  Copyright © 2019 Shadowfacts. All rights reserved.
//

import SwiftUI
import TetrisKit
import TetrisUI

struct ContentView: View {
    @ObservedObject var controller: GameController = {
        let c = GameController()
        c.start()
        return c
    }()
    @State var timer: Timer?
    @State var gestureState: GestureState = .none
    @State var initialXPosition: Int?

    var body: some View {
        GeometryReader { (geometry) in
            VStack {
                Spacer()
                HStack(alignment: .top, spacing: 8) {
                    VStack {
                        Text("Held")
                        if self.controller.heldTetromino != nil {
                            Group {
                                TetrominoView(size: 50 / 4, tetromino: self.controller.heldTetromino!)
                            }.frame(width: 50, height: 50, alignment: .center)
                        } else {
                            Rectangle().foregroundColor(.clear).frame(width: 50, height: 50)
                        }
                        Text("Score")
                        Text(verbatim: self.controller.score.description)
                    }
                        .padding(.leading, 8)
                    BoardView(board: self.$controller.board, currentPiece: self.$controller.currentPiece, droppedPiece: self.$controller.currentPieceAtDropPoint)
                        .aspectRatio(CGSize(width: self.controller.width, height: self.controller.height), contentMode: .fit)
                        .onAppear(perform: self.startTimer)
                        .onDisappear(perform: self.stopTimer)
                        .onTapGesture(perform: self.onTap)
                    //        .gesture(ExclusiveGesture(horizDragGesture, verticalDragGesture))
                    //            .gesture(horizDragGesture.simultaneously(with: verticalDragGesture))
                    
                    VStack {
                        Text("Next")
                        NextTetromioesView(size: 50, tetrominoes: self.controller.nextTetrominoes)
                            .frame(width: 50)
                    }
                        .padding(.trailing, 8)
                }
                    .background(Color("TempBackground")) // visually does nothing but lets the gesture work outside of the board, see FB7385742
                    .gesture(self.horizDragGesture(geometry: geometry).simultaneously(with: self.verticalDragGesture))
                Spacer()
                HStack {
                    Button(action: { self.controller.rotate(direction: .counterClockwise) }) {
                        Image(systemName: "gobackward").resizable().frame(width: 50, height: 50)
                    }
                        .padding(.leading, 25)
                    Button(action: self.onTap) {
                        Image(systemName: "goforward").resizable().frame(width: 50, height: 50)
                    }
                        .padding(.leading, 25)
                    Spacer()
                    DPadView(up: self.controller.hold, down: self.controller.drop, left: self.controller.left, right: self.controller.right)
                        .frame(width: 150, height: 150)
                        .padding(.trailing, 25)
                }
                Spacer()
            }
        }
    }
    
    func horizDragGesture(geometry: GeometryProxy) -> some Gesture {
        DragGesture(coordinateSpace: .global)
            .onChanged { (state) in
                guard self.gestureState != .vertical,
                    case .playing(.normal) = self.controller.state,
                    let currentPiece = self.controller.currentPiece else { return }
                if self.initialXPosition == nil {
                    self.initialXPosition = currentPiece.topLeft.0
                }
                var moved = currentPiece
                let xPosition = self.initialXPosition! + Int((state.translation.width / (geometry.size.width / 10)).rounded())
                
                if xPosition != self.initialXPosition {
                    self.gestureState = .horizontal
                }
                moved.topLeft = (xPosition, currentPiece.topLeft.1)
                if !self.controller.overlapsAny(moved) {
                    self.controller.currentPiece = moved
                }
            }.onEnded { (state) in
                self.initialXPosition = nil
                if self.gestureState == .horizontal {
                    self.gestureState = .none
                }
            }
    }
    
    var verticalDragGesture: some Gesture {
        DragGesture()
            .onChanged({ (state) in
                guard self.gestureState != .horizontal else { return }
                
            })
            .onEnded { (state) in
                guard self.gestureState != .horizontal else { return }
                if abs(state.translation.height) > 80 {
                    self.gestureState = .none
                    if state.translation.height > 0 {
                        self.onSwipeDown()
                    } else {
                        self.onSwipeUp()
                    }
                }
            }
    }

    func startTimer() {
        self.timer = Timer.scheduledTimer(withTimeInterval: 0.5, repeats: true) { (_) in
            guard case .playing(_) = self.controller.state else {
                self.stopTimer()
                return
            }
            self.controller.step()
        }
    }
    
    func stopTimer() {
        self.timer?.invalidate()
    }
    
    func onTap() {
        self.controller.rotate(direction: .clockwise)
    }
    
    func onSwipeLeft() {
        self.controller.left()
    }
    
    func onSwipeRight() {
        self.controller.right()
    }
    
    func onSwipeUp() {
        self.controller.hold()
    }
    
    func onSwipeDown() {
        self.controller.drop()
    }
}

enum GestureState: Equatable {
    case none, horizontal, vertical
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}