//
//  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
    
    @ObservedObject var viewModel = ContentModeViewModel()

    init(){
        UITabBar.appearance().backgroundColor = UIColor.systemBackground
    }
    
    var body: some View {
        TabView {
            mainView
                .tabItem {
                    Label("Main", systemImage: "list.dash")
                }
            
            FilterView()
                .tabItem {
                    Label("Filter", systemImage: "calendar.circle")
                }
            
            GraphView()
                .tabItem {
                    Label("Stats", systemImage: "chart.line.uptrend.xyaxis")
                }
        }
    }
    
    private var settingsButtonView: some View {
        HStack {
            Spacer()
            Button(action: {
                showingSheet.toggle()
            }, label: {
                Image(systemName: "gear")
                    .foregroundColor(Color(UIColor.darkGray))
                    .font(.system(size: 20))
            }).sheet(isPresented: $showingSheet) {
                SettingsView(editedDataClosure: {
                    withAnimation{
                        viewModel.updateData()
                    }
                })
            }.padding(.trailing)
        }
    }
    
    private func weekdayName(fromDate date: Date) -> String {
        let weekday = Calendar.current.component(.weekday, from: date)
        let calendar = Calendar.current
        let dayIndex = ((weekday - 1) + (calendar.firstWeekday - 1)) % 7
        return calendar.weekdaySymbols[dayIndex]
    }
    
    private func monthName(fromMonthInt: Int) -> String {
        let monthName = DateFormatter().monthSymbols[fromMonthInt-1]
        return monthName
    }
    
    private func dayFormat(fromDate date: Date) -> String {
        let components = Calendar.current.dateComponents([.day], from: date)
        let day = components.day!
        
        let formatter = NumberFormatter()
        formatter.numberStyle = .ordinal
        return formatter.string(from: NSNumber(integerLiteral: day)) ?? ""
    }
    
    private var listView: some View {
        VStack {
            List {
                // for reach year
                ForEach(viewModel.grouped.sorted(by: {
                    $0.key > $1.key
                }), id: \.key) { year, months in
                    
                    // for reach month
                    ForEach(months.sorted(by: {
                        $0.key > $1.key
                    }), id: \.key) { month, entries in
                        Section(header:
                                    HStack{
                            Text(monthName(fromMonthInt: month))
                                .font(.title2)
                                .foregroundColor(Color(UIColor.label))
                            Text(String(year))
                                .font(.title2)
                                .foregroundColor(Color(UIColor.label))
                        }) {
                            // for reach all entries
                            ForEach(entries.sorted(by: {
                                $0.forDate! > $1.forDate!
                            }), id: \.self) { entry in
                                entryListView(entry: entry)
                            }.onDelete(perform: { offsets in
                                withAnimation {
                                    viewModel.delete(offsets: offsets, inMonth: month, inYear: year)
                                }
                            })
                        }
                    }
                }
            }
            .background(Color.clear.ignoresSafeArea())
            .onAppear {
                // Set the default to clear
                UITableView.appearance().backgroundColor = .clear
            }
        }
    }
    
    private func entryListView(entry: MoodEntry) -> some View {
        HStack {
            entry.mood.icon
                .resizable()
                .aspectRatio(contentMode: .fit)
                .frame(width: 40, height: 40, alignment: .center)
                .foregroundColor(entry.mood.color)
            
            VStack {
                HStack {
                    Text(weekdayName(fromDate:entry.forDate!))
                        .font(.title3)
                        .foregroundColor(Color(UIColor.label))
                    Text(" - ")
                        .padding([.leading, .trailing], -10)
                    Text(dayFormat(fromDate:entry.forDate!))
                        .font(.title3)
                        .foregroundColor(Color(UIColor.label))
                    
                    Spacer()
                }
                .multilineTextAlignment(.leading)
                
                Text("\(entry.moodString)")
                    .font(.body)
                    .foregroundColor(Color(UIColor.systemGray))
                    .frame(maxWidth: .infinity, alignment: .leading)
            }
        }
    }
    
    private var mainView: some View {
        ZStack {
            BGView()
            VStack{
                settingsButtonView
                if viewModel.shouldShowTodayInput() {
                    AddMoodHeaderView(addItemClosure: { (mood, date) in
                        withAnimation {
                            viewModel.add(mood: mood, forDate: date)
                        }
                    })
                        .frame(minHeight: 85, maxHeight: 180)
                        .frame(minWidth: 0, maxWidth: .infinity)
                } else {
                    HeaderStatsView(fakeData: false, backDays: 30)
                        .frame(minHeight: 85, maxHeight: 180)
                    // should match backDays above
                    Text("Past \(30) days")
                        .font(.body)
                        .foregroundColor(Color(UIColor.systemGray))
                        .frame(maxWidth: .infinity, alignment: .center)
                }
                listView
                    .padding(.bottom)
            }
            .padding(.top, 50)
        }
    }
}

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)
    }
}