splits/Splits/ContentView.swift

//
//  ContentView.swift
//  Splits
//
//  Created by Isaac Greene on 4/3/22.
//

import SwiftUI
import Foundation

struct ContentView: View {
	var SISystem = ["km","mi"]
	@State var timeHours: String = ""
	@State var timeMinutes: String = ""
	@State var timeSeconds: String = ""
	@State var selectedSystem: String = "km"
	@State var distance: String = ""
	
	var body: some View {
		VStack {
			VStack {
				TextField("Enter distance here", text: $distance)
					.padding()
					.keyboardType(.decimalPad)
					.textFieldStyle(.roundedBorder)
			}
			VStack {
				Text("Unit of measurement:")
				Picker("System of measurement", selection: $selectedSystem, content: {
					ForEach(SISystem, id: \.self, content: { unit in
						Text(unit)
					})
				})
					.pickerStyle(.segmented)
					.frame(minWidth: 60, maxWidth: 300)
				HStack {
					VStack {
						Text("Hours")
						TextField("Enter hours here", text: $timeHours)
							.keyboardType(.numberPad)
							.textFieldStyle(.roundedBorder)
					}
					.frame(minWidth: 100)
					.padding(.trailing, -15)
					.padding()
					VStack {
						Text("Minutes")
						TextField("Enter minutes here", text: $timeMinutes)
								.keyboardType(.numberPad)
								.textFieldStyle(.roundedBorder)
					}
					.frame(minWidth: 100)
					.padding(.trailing, -15)
					.padding(.leading, -15)
					.padding()
					VStack {
						Text("Seconds")
						TextField("Enter seconds here", text: $timeSeconds)
							.keyboardType(.numberPad)
							.textFieldStyle(.roundedBorder)
					}
					.frame(minWidth: 100)
					.padding(.leading, -15)
					.padding()
				}
				PaceResults(timeHours: $timeHours, timeMinutes: $timeMinutes, timeSeconds: $timeSeconds, selectedSystem: $selectedSystem, distance: $distance)
			}
		}
	}
}

struct PaceResults: View {
	@Binding var timeHours: String
	@Binding var timeMinutes: String
	@Binding var timeSeconds: String
	@Binding var selectedSystem: String
	@Binding var distance: String
	
	var body: some View {
		let distanceDub = Double(distance) ?? 1.0
		// because of some conversions I have to do,
		// this constant is a double just to make things easier.
		// this has to be one because the pace is calculated
		// by time / distance, and you can't divide by 0.
		// I could just make the TextField have a default value
		// but then my message would disappear to let you know
		// what to enter in that box
		
		let multiplier = {selectedSystem == "mi" ? 1.609344 : 0.6213711922}()
		let notSelectedSystem = {selectedSystem == "km" ? "mi" : "km"}()
		let convertedDistance = distanceDub * multiplier
		let convertedDistanceString = {distance == "" ? "" : String(format: "%.2f", convertedDistance)}()
		
		let convertedSeconds:Double = (Double(timeSeconds) ?? 0) * (1.6666666666666666666666666)
		let timeSecondsInt:Int = Int(timeSeconds) ?? 0
		let timeSecondsUnderSixty:Int = (timeSecondsInt % 60)
		// this section takes the seconds and multiplies it by 1.66
		// so that 60 seconds becomes 100 (as in 100% of a minute)
		// and this means that 30 seconds becomes 50 (as in 50% of a minute)
		// which allows us to to calculate our pace. Without this
		// the pace would be all wrong.
		
		let timeSecondsToMinutes:Int = (timeSecondsInt - timeSecondsUnderSixty) / 60
		// this takes the seconde and converts it to minutes so 78
		// seconds will turn into 1 minute and 18 seconds leftover
		// with the minutes saved in this value and the seconds
		// disregarded because they're saved in timeSecondsUnderSixty
		
		let timeMinutesInt:Int = (Int(timeMinutes) ?? 0) + (timeSecondsToMinutes)
		let timeMinutesUnderSixty:Int = timeMinutesInt % 60
		let timeMinutesToHours:Int = (timeMinutesInt - timeMinutesUnderSixty) / 60
		// this section tales the minutes (which it combines the
		// minutes with the timeSecondsToMinutes) then finds out how
		// many hours (multiples of 60) are in the minutes value
		// and saves the hours in timeMinutesToHours and the remaining
		// minutes in timeMinutesUnderSixty
		
		let timeMinutesDouble:Double = Double(timeMinutes) ?? 0.0
		// this line of code takes the binding $timeMinutes which
		// is a string and turns it into a number of type Double.
		// while the TextField is a number pad, on iPads, Mac computers
		// and using copy/paste you can get other characters.
		// if the text field contains anything other than a number
		// or a single decimal, this value instantly becomes 0.0
		
		let actualTime:Double = timeMinutesDouble + (convertedSeconds / 100) + ((Double(timeHours) ?? 0) * 60)
		// adds the minutes, hours, and seconds all together to get
		// a single value in terms of minutes, so that 1:08:45
		// becomes 68.75 which is a nice number we can do math on
		// and this number is never directly seen by the user
		let pace = actualTime / distanceDub
		let paceOpposite = (selectedSystem == "km" ? (pace * 1.609344) : (pace * 0.6213711922))
		
		let paceSeconds = pace.truncatingRemainder(dividingBy: 1.0)
		let paceMinutes = (pace.truncatingRemainder(dividingBy: 60.0) - paceSeconds)
		let paceHours = String(format: "%.0f", ((pace - paceMinutes) / 60))
		let reConvertedSeconds = (paceSeconds / 1.666666666666666666) * 100
		
		let properTimeMS = String(format: "%02d:%02d", Int(paceMinutes), Int(reConvertedSeconds.rounded()))
		
		let paceSecondsOpposite = paceOpposite.truncatingRemainder(dividingBy: 1.0)
		let paceMinutesOpposite = (paceOpposite.truncatingRemainder(dividingBy: 60.0) - paceSecondsOpposite)
		let paceHoursOpposite = String(format: "%.0f", ((paceOpposite - paceMinutesOpposite) / 60))
		let reConvertedSecondsOpposite = (paceSecondsOpposite / 1.666666666666666666) * 100
		
		let properTimeMSOpposite = String(format: "%02d:%02d", Int(paceMinutesOpposite), Int(reConvertedSecondsOpposite.rounded()))
		
		//let paceString:String = String(format: "%.2f", pace)
		let totalHours:Double = Double(timeMinutesToHours) + (Double(timeHours) ?? 0)
		// this takes the number of hours in the binding $timeHours
		// and the hours calculated in the previous section
		// and adds them together to get our total number of hours.
		let hoursFormatted:String = String(format: "%.0f", totalHours)
		let paceFormatted:String = {pace >= 60 ? "\(paceHours):\(properTimeMS)" : "\(properTimeMS)"}()
		
		let paceFormattedOpposite:String = {paceOpposite >= 60 ? "\(paceHoursOpposite):\(properTimeMSOpposite)" : "\(properTimeMSOpposite)"}()
		
		let leadingZeros:String = String(format: "%02d:%02d", timeMinutesUnderSixty, timeSecondsUnderSixty)
		// this takes the minutes and the seconds and adds leading
		// zeros to them, so that 5 minutes 7 seconds will show
		// as 05:07 which is a format most people, and certainly
		// the people this app is intended for, will understand
		
		HStack {
			VStack {
				Text("Distance: \(distance)\(selectedSystem)")
				Text("Converted distance: \(convertedDistanceString)\(notSelectedSystem)")
			}
			Text("Total time: \(hoursFormatted):\(leadingZeros)")
				.padding()
			VStack {
				Text("\(paceFormatted) per \(selectedSystem)")
				Text("\(paceFormattedOpposite) per \(notSelectedSystem)")
			}
		}
	}
}

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