import SwiftUI
import OnyxDesign
import OnyxWidgetKit

/// Kurze Notizen, direkt in der Kachel zu schreiben.
public struct NotesView: View {
    private let store: NotesStore
    private let compact: Bool

    @State private var editing: Note?
    @State private var draft = ""
    @FocusState private var isWriting: Bool

    public init(store: NotesStore, compact: Bool = false) {
        self.store = store
        self.compact = compact
    }

    public var body: some View {
        VStack(alignment: .leading, spacing: Onyx.Space.sm) {
            if let editing {
                editor(for: editing)
            } else {
                list
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
    }

    private var list: some View {
        VStack(alignment: .leading, spacing: 0) {
            HStack {
                Text("notes.name", bundle: .module)
                    .font(Onyx.Font.title)
                    .foregroundStyle(Onyx.Color.textPrimary)
                Spacer()
                Button { begin(store.makeDraft()) } label: {
                    Image(systemName: "square.and.pencil")
                        .font(.system(size: Onyx.Symbol.small))
                }
                .buttonStyle(.plain)
                .foregroundStyle(Onyx.Color.accent)
            }
            .padding(.bottom, Onyx.Space.sm)

            if store.notes.isEmpty {
                OnyxNotice(symbol: "note.text",
                           text: String(localized: "notes.empty", bundle: .module))
            } else {
                ScrollView {
                    LazyVStack(spacing: 0) {
                        ForEach(Array(store.notes.prefix(compact ? 4 : 20).enumerated()),
                                id: \.element.id) { index, note in
                            if index > 0 { OnyxHairline() }
                            Button { begin(note) } label: {
                                HStack {
                                    Text(NoteRules.title(of: note))
                                        .font(Onyx.Font.footnote)
                                        .foregroundStyle(Onyx.Color.textPrimary)
                                        .lineLimit(1)
                                    Spacer(minLength: Onyx.Space.xs)
                                }
                                .padding(.vertical, Onyx.Space.sm)
                                .contentShape(.rect)
                            }
                            .buttonStyle(.plain)
                        }
                    }
                }
                .scrollIndicators(.never)
            }
        }
    }

    private func editor(for note: Note) -> some View {
        VStack(alignment: .leading, spacing: Onyx.Space.sm) {
            HStack {
                Button { finish() } label: {
                    Image(systemName: "chevron.left")
                        .font(.system(size: Onyx.Symbol.small))
                }
                .buttonStyle(.plain)
                .foregroundStyle(Onyx.Color.accent)

                Spacer()

                Button { store.remove(note); editing = nil } label: {
                    Image(systemName: "trash")
                        .font(.system(size: Onyx.Symbol.small))
                }
                .buttonStyle(.plain)
                .foregroundStyle(Onyx.Color.textTertiary)
            }

            // `TextEditor` ohne eigenen Hintergrund: der Standardhintergrund
            // ist hell und stünde als weißer Block in der schwarzen Kachel.
            TextEditor(text: $draft)
                .font(Onyx.Font.footnote)
                .foregroundStyle(Onyx.Color.textPrimary)
                .scrollContentBackground(.hidden)
                .focused($isWriting)
                .frame(maxWidth: .infinity, maxHeight: .infinity)
        }
        .onAppear { isWriting = true }
    }

    private func begin(_ note: Note) {
        editing = note
        draft = note.text
    }

    private func finish() {
        if var note = editing {
            note.text = draft
            store.update(note)
        }
        editing = nil
        draft = ""
    }
}

public struct NotesWidget: OnyxWidget {
    public let id = "notes"
    public var displayName: String { String(localized: "notes.name", bundle: .module) }
    public let symbolName = "note.text"

    private let store: NotesStore

    public init(store: NotesStore) { self.store = store }

    public func makeView() -> AnyView { AnyView(NotesView(store: store)) }
}