//
//  ContentView.swift
//  UnitCoverter
//
//  Created by roblack on 10/12/19.
//  Copyright © 2019 roblack. All rights reserved.
//


/// TODO: remove ContentViewUnitExtensions.swift

import SwiftUI

class Converter: ObservableObject {
    var units: [[UnitType]] = [
        [.meters, .kilometers, .feet, .yards, .miles],
        [.Celsius, .Fahrenheit, .Kelvin],
        [.seconds, .minutes, .hours, .miliseconds, .microseconds],
        [.milliliters, .liters, .cups, .pints, .gallons]
    ]

    var inputUnitTypes: [UnitType] = [.length, .temperature, .time, .volume]


    var input = "" {
        didSet { converting() }
    }
    var unit = 0 {
        didSet {
            changeDimetion()
            converting()
        }
    }
    var inputUnit = 0  {
        didSet { converting() }
    }
    var outputUnit = 0  {
        didSet { converting() }
    }

    var selected: [UnitType] {
        return units[unit]
    }


    @Published var output: String = ""

    func changeDimetion() {
        inputUnit = 0
        outputUnit = 0
    }

    func converting() {
        guard let input: Int = Int(input) else { output = "0"; return }

        let inUnit = selectedUnit(units[unit][inputUnit])
        let outUnit = selectedUnit(units[unit][outputUnit])

        let fromValue = Measurement(value: Double(input), unit: inUnit)
        let toValue = fromValue.converted(to: outUnit)

        output = "\(toValue)"
    }


    enum UnitType: CustomStringConvertible {
        case length, temperature, time, volume
        case meters, kilometers, feet, yards, miles
        case Celsius, Kelvin, Fahrenheit
        case seconds, minutes, hours, miliseconds, microseconds
        case milliliters, liters, cups, pints, gallons

        var description: String {
            switch self {
            case .length:       return "length"
            case .temperature:  return "temperature"
            case .time:         return "time"
            case .volume:       return "volume"
            case .meters:       return "meters"
            case .kilometers:   return "kilometers"
            case .feet:         return "feet"
            case .yards:        return "yards"
            case .miles:        return "miles"
            case .Celsius:      return "Celsius"
            case .Kelvin:       return "Kelvin"
            case .Fahrenheit:   return "Fahrenheit"
            case .seconds:      return "seconds"
            case .minutes:      return "minutes"
            case .hours:        return "hours"
            case .miliseconds:  return "miliseconds"
            case .microseconds: return "microseconds"
            case .milliliters:  return "mililiters"
            case .liters:       return "liters"
            case .cups:         return "cups"
            case .pints:        return "pints"
            case .gallons:      return "gallons"
            }
        }
    }

    func selectedUnit(_ value: UnitType) -> Dimension {
        switch value {
        case .meters:           return UnitLength.meters
        case .kilometers:       return UnitLength.kilometers
        case .feet:             return UnitLength.feet
        case .yards:            return UnitLength.yards
        case .miles:            return UnitLength.miles
        case .Celsius:          return UnitTemperature.celsius
        case .Kelvin:           return UnitTemperature.kelvin
        case .Fahrenheit:       return UnitTemperature.fahrenheit
        case .seconds:          return UnitDuration.seconds
        case .minutes:          return UnitDuration.minutes
        case .hours:            return UnitDuration.hours
        case .miliseconds:      return UnitDuration.milliseconds
        case .microseconds:     return UnitDuration.microseconds
        case .milliliters:      return UnitVolume.milliliters
        case .liters:           return UnitVolume.liters
        case .cups:             return UnitVolume.cups
        case .pints:            return UnitVolume.pints
        case .gallons:          return UnitVolume.gallons
        default: return UnitLength.meters
        }
    }
}

struct ContentView: View {

    @ObservedObject var logic = Converter()

    var body: some View {
        NavigationView {
            Form {
                Section {

                    TextField("Input Unit", text: $logic.input)
                        .keyboardType(.decimalPad)
                        .multilineTextAlignment(.center)
                    
                    // MARK: - Unit Picker
                    Picker("Length", selection: $logic.unit) {
                        ForEach(0 ..< logic.inputUnitTypes.count) {
                            Text("\(self.logic.inputUnitTypes[$0].description)")
                        }
                    }
                    .pickerStyle(SegmentedPickerStyle())
                }
                
                HStack {
                    // MARK: - Input Unit Picker
                    Section(header: Text("From")) {
                        Picker("Length", selection: $logic.inputUnit) {
                            ForEach(0 ..< logic.selected.count) {
                                Text("\(self.logic.selected[$0].description)")
                            }
                        }
                        .pickerStyle(WheelPickerStyle())
                        .frame(minWidth: 0, maxWidth: .infinity/2, alignment: .center)
                    }
                    
                    Section(header: Text("To")) {
                        // MARK: - Output Unit Picker
                        Picker("Length", selection: $logic.outputUnit) {
                            ForEach(0 ..< logic.selected.count) {
                                Text("\(self.logic.selected[$0].description)")
                            }
                        }
                        .pickerStyle(WheelPickerStyle())
                        .frame(minWidth: 0, maxWidth: .infinity/2, alignment: .center)
                    }
                        
                    .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity)
                }
                
                // MARK: - Output
                Section {
                    Text("\(logic.output)")
                        .frame(minWidth: 0, maxWidth: .infinity, alignment: .center)
                }
            }
            .navigationBarTitle("UnitConverter")
        }
    }
}

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