//
//  ContentView.swift
//  Shared
//
//  Created by Trey Tartt on 1/5/22.
//

import SwiftUI
import CoreData
import Charts

struct ContentView: View {
    @Environment(\.managedObjectContext) private var viewContext
    
    @State private var showingSheet = false
    @State private var showTodayInput = true
    
    @FetchRequest(
        sortDescriptors: [NSSortDescriptor(keyPath: \MoodEntry.date, ascending: false)],
        animation: .spring())
    private var items: FetchedResults<MoodEntry>
    
    var body: some View {
        TabView {
            mainView
                .tabItem {
                    Label("Main", systemImage: "list.dash")
                }
            
            GraphView()
                .tabItem {
                    Label("Graph", systemImage: "chart.line.uptrend.xyaxis")
                }
        }
    }
    
    private var settingsButtonView: some View {
        HStack {
            Spacer()
            Button(action: {
                showingSheet.toggle()
            }, label: {
                Image(systemName: "gear")
                    .foregroundColor(Color(UIColor.systemGray))
                    .font(.system(size: 20))
            }).sheet(isPresented: $showingSheet) {
                SettingsView()
            }.padding(.trailing)
        }
    }
    
    private var listView: some View {
        List {
            ForEach(items) { item in
                HStack {
                    item.mood.icon
                        .font(.system(size: 50))
                    VStack {
                        Text("\(item.moodString)")
                            .font(.title)
                            .foregroundColor(Color(UIColor.systemGray))
                            .frame(maxWidth: .infinity, alignment: .leading)
                        Text(item.date!, style: .date)
                            .font(.body)
                            .foregroundColor(Color(UIColor.label))
                            .frame(maxWidth: .infinity, alignment: .leading)
                    }
                    .padding(.leading)
                }
            }
            .onDelete(perform: deleteItems)
        }
    }
    
    private var mainView: some View {
        VStack{
            settingsButtonView
            if shouldShowTodayInput() {
                AddMoodHeaderView()
                    .frame(minHeight: 85, maxHeight: 180)
                    .frame(minWidth: 0, maxWidth: .infinity)
            } else {
                HeaderStatsView(entries: [
                    //x - position of a bar, y - height of a bar
                    BarChartDataEntry(x: 1, y: 1),
                    BarChartDataEntry(x: 2, y: 5),
                    BarChartDataEntry(x: 3, y: 2),
                    BarChartDataEntry(x: 4, y: 4),
                    BarChartDataEntry(x: 5, y: 1)
                ])
                .frame(minHeight: 85, maxHeight: 180)
            }
            listView
        }
    }
    
    private func deleteItems(offsets: IndexSet) {
        withAnimation {
            offsets.map { items[$0] }.forEach(viewContext.delete)
            
            do {
                try viewContext.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                let nsError = error as NSError
                fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
            }
        }
    }
    
    private func shouldShowTodayInput() -> Bool {
        let fetchRequest = NSFetchRequest<MoodEntry>(entityName: "MoodEntry")
        
        var calendar = Calendar.current
        calendar.timeZone = NSTimeZone.local
        
        // Get today's beginning & end
        let dateFrom = calendar.startOfDay(for: Date()) // eg. 2016-10-10 00:00:00
        let dateTo = calendar.date(byAdding: .day, value: 1, to: dateFrom)!
        // Note: Times are printed in UTC. Depending on where you live it won't print 00:00:00 but it will work with UTC times which can be converted to local time
        
        // Set predicate as date being today's date
        let fromPredicate = NSPredicate(format: "%@ <= %K", dateFrom as NSDate, #keyPath(MoodEntry.date))
        let toPredicate = NSPredicate(format: "%K < %@", #keyPath(MoodEntry.date), dateTo as NSDate)
        let datePredicate = NSCompoundPredicate(andPredicateWithSubpredicates: [fromPredicate, toPredicate])
        fetchRequest.predicate = datePredicate
        let entries = try! self.viewContext.count(for: fetchRequest)
        
        return entries == 0
    }
}

private let itemFormatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateStyle = .short
    formatter.timeStyle = .medium
    return formatter
}()

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView().environment(\.managedObjectContext, PersistenceController.shared.container.viewContext)
            .onAppear(perform: {
                PersistenceController.shared.populateMemory()
            })
        
        ContentView()
            .preferredColorScheme(.dark)
            .environment(\.managedObjectContext, PersistenceController.shared.container.viewContext)
    }
}