//
//  NotesPageView.swift
//  Notes
//
//  Created by Claude Code on 13/10/2025.
//

import SwiftUI
import CoreData

struct NotesPageView: View {
    @Environment(\.managedObjectContext) private var viewContext

    @FetchRequest(
        sortDescriptors: [NSSortDescriptor(keyPath: \Note.lastEditDate, ascending: true)],
        animation: .default)
    private var notes: FetchedResults<Note>

    @State private var selectedIndex: Int = 0
    @State private var showDeleteAlert = false

    var body: some View {
        NavigationStack {
            VStack {
                
                if notes.isEmpty {
                    Text("No notes")
                        .foregroundColor(.gray)
                } else {
                    TabView(selection: $selectedIndex) {
                        ForEach(Array(notes.enumerated()), id: \.element.objectID) { index, note in
                            NoteEditorView(note: note)
                                .tag(index)
                        }
                    }
                    .tabViewStyle(.page(indexDisplayMode: .never))
                }
            }
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItemGroup(placement: .navigationBarTrailing) {
                    Button(action: addNote) {
                        Image(systemName: "plus")
                    }

                    Button(action: shareNote) {
                        Image(systemName: "square.and.arrow.up")
                    }
                    .disabled(notes.isEmpty)

                    Button(action: { showDeleteAlert = true }) {
                        Image(systemName: "trash")
                    }
                    .disabled(notes.isEmpty)
                }
            }
            .alert("Delete Note", isPresented: $showDeleteAlert) {
                Button("Cancel", role: .cancel) { }
                Button("Delete", role: .destructive) {
                    deleteNote()
                }
            } message: {
                if selectedIndex < notes.count {
                    let content = notes[selectedIndex].content ?? ""
                    Text("Do you want to delete this: \(content.prefix(20))...?")
                }
            }
            .onAppear {
                createNoteIfNeeded()
                selectLastNote()
            }
        }
    }

    private func addNote() {
        withAnimation {
            let newNote = Note(context: viewContext)
            newNote.content = ""
            newNote.lastEditDate = Date()

            PersistenceController.shared.save()

            // Select the newly created note (last in the list)
            selectedIndex = notes.count - 1
        }
    }

    private func deleteNote() {
        guard selectedIndex < notes.count else { return }

        withAnimation {
            let noteToDelete = notes[selectedIndex]
            viewContext.delete(noteToDelete)
            PersistenceController.shared.save()

            // Select the last note after deletion
            if !notes.isEmpty {
                selectedIndex = min(selectedIndex, notes.count - 1)
            }
        }
    }

    private func shareNote() {
        guard selectedIndex < notes.count,
              let content = notes[selectedIndex].content,
              !content.isEmpty else {
            return
        }

        let activityVC = UIActivityViewController(
            activityItems: [content],
            applicationActivities: nil
        )

        if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
           let window = windowScene.windows.first,
           let rootVC = window.rootViewController {
            activityVC.popoverPresentationController?.sourceView = rootVC.view
            rootVC.present(activityVC, animated: true)
        }
    }

    private func createNoteIfNeeded() {
        if notes.isEmpty {
            let newNote = Note(context: viewContext)
            newNote.content = ""
            newNote.lastEditDate = Date()
            PersistenceController.shared.save()
        }
    }

    private func selectLastNote() {
        if !notes.isEmpty {
            selectedIndex = notes.count - 1
        }
    }
}

struct NotesPageView_Previews: PreviewProvider {
    static var previews: some View {
        NotesPageView()
            .environment(\.managedObjectContext, PersistenceController.preview.container.viewContext)
    }
}