MindDump/MindDump/Views/ListDetailView.swift

import SwiftUI

struct ListDetailView: View {
    @Environment(ListStore.self) private var store
    let listID: UUID
    @State private var editorItem: TodoItem?
    @State private var moveItem: TodoItem?
    @State private var showCompleted = true
    @State private var filterUrgent = false
    @State private var filterDue = false
    @State private var selectedSort: ListDetailSort = .oldest

    private var todoList: TodoList? {
        store.lists.first { $0.id == listID }
    }

    var body: some View {
        Group {
            if let todoList {
                if todoList.items.isEmpty {
                    ContentUnavailableView("Keine Einträge", systemImage: "tray")
                } else {
                    let filteredItems = store.filteredOpenItems(
                        for: todoList, urgent: filterUrgent, due: filterDue, sort: selectedSort
                    )

                    List {
                        Section {
                            HStack(spacing: 12) {
                                chipButton("Dringend", icon: "exclamationmark.triangle", isActive: filterUrgent, color: .orange) {
                                    withAnimation { filterUrgent.toggle() }
                                }
                                chipButton("Fällig", icon: "calendar.badge.clock", isActive: filterDue, color: .red) {
                                    withAnimation { filterDue.toggle() }
                                }
                                sortMenu
                            }
                            .frame(maxWidth: .infinity)
                            .listRowInsets(EdgeInsets(top: 8, leading: 16, bottom: 8, trailing: 16))
                            .listRowBackground(Color.clear)
                        }

                        Section {
                            if filteredItems.isEmpty {
                                emptyState
                            } else {
                                TodoListView(
                                    items: filteredItems,
                                    onToggle: { item in
                                        store.toggleItemCompleted(item.id, in: listID)
                                    },
                                    onTap: { item in
                                        editorItem = item
                                    },
                                    onDelete: { item in
                                        store.deleteItem(item.id, from: listID)
                                    },
                                    onMove: { item in
                                        moveItem = item
                                    }
                                )
                            }
                        }

                        if !todoList.completedItems.isEmpty {
                            Section {
                                if showCompleted {
                                    TodoListView(
                                        items: todoList.completedItems,
                                        onToggle: { item in
                                            store.toggleItemCompleted(item.id, in: listID)
                                        },
                                        onTap: { item in
                                            editorItem = item
                                        },
                                        onDelete: { item in
                                            store.deleteItem(item.id, from: listID)
                                        },
                                        onMove: { item in
                                            moveItem = item
                                        }
                                    )
                                }
                            } header: {
                                Button {
                                    withAnimation {
                                        showCompleted.toggle()
                                    }
                                } label: {
                                    HStack {
                                        Text("Erledigt (\(todoList.completedItems.count))")
                                        Spacer()
                                        Image(systemName: showCompleted ? "chevron.down" : "chevron.right")
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
        .navigationTitle(todoList?.name ?? "")
        .sheet(item: $editorItem) { item in
            TodoEditorView(listID: listID, item: item)
        }
        .sheet(item: $moveItem) { item in
            MoveToListView(itemID: item.id, currentListID: listID)
        }
    }

    // MARK: - Filter Chip

    @ViewBuilder
    private func chipButton(_ label: String, icon: String, isActive: Bool, color: Color, action: @escaping () -> Void) -> some View {
        Button(action: action) {
            Image(systemName: icon)
                .font(.subheadline.weight(.medium))
                .padding(.horizontal, 12)
                .padding(.vertical, 6)
                .background(isActive ? color.opacity(0.15) : Color(.systemGray6))
                .foregroundStyle(isActive ? color : .secondary)
                .clipShape(Capsule())
        }
        .buttonStyle(.plain)
    }

    // MARK: - Sort Menu

    private var sortMenu: some View {
        Menu {
            Picker("Sortierung", selection: $selectedSort) {
                ForEach(ListDetailSort.allCases, id: \.self) { sort in
                    Text(sort.label).tag(sort)
                }
            }
        } label: {
            HStack(spacing: 4) {
                Image(systemName: "arrow.up.arrow.down")
                ZStack(alignment: .leading) {
                    ForEach(ListDetailSort.allCases, id: \.self) { sort in
                        Text(sort.shortLabel)
                            .opacity(sort == selectedSort ? 1 : 0)
                    }
                }
            }
            .font(.subheadline)
            .foregroundStyle(.secondary)
        }
    }

    // MARK: - Empty State

    private var emptyState: some View {
        VStack(spacing: 8) {
            Image(systemName: emptyIcon)
                .font(.title2)
                .foregroundStyle(.secondary)
            Text(emptyMessage)
                .font(.subheadline)
                .foregroundStyle(.secondary)
        }
        .frame(maxWidth: .infinity)
        .padding(.vertical, 24)
        .listRowBackground(Color.clear)
    }

    private var emptyMessage: String {
        if filterUrgent && filterDue {
            "Keine dringenden oder fälligen Aufgaben"
        } else if filterUrgent {
            "Keine dringenden Aufgaben"
        } else if filterDue {
            "Keine fälligen Aufgaben"
        } else {
            "Keine offenen Aufgaben"
        }
    }

    private var emptyIcon: String {
        if filterUrgent {
            "exclamationmark.triangle"
        } else if filterDue {
            "calendar.badge.checkmark"
        } else {
            "checkmark.circle"
        }
    }
}