//
//  LibraryView.swift
//  Mobile Music Assistant
//
//  Created by Sven Hanold on 26.03.26.
//

import SwiftUI

enum LibraryTab: String, CaseIterable {
    case artists = "Artists"
    case albums = "Albums"
    case playlists = "Playlists"
    case radio = "Radio"
}

struct LibraryView: View {
    @Environment(MAService.self) private var service
    @State private var selectedTab: LibraryTab = .artists
    @State private var refreshError: String?
    @State private var showError = false

    private var isRefreshing: Bool {
        switch selectedTab {
        case .artists:   return service.libraryManager.isLoadingArtists
        case .albums:    return service.libraryManager.isLoadingAlbums
        case .playlists: return service.libraryManager.isLoadingPlaylists
        case .radio:     return false
        }
    }

    private var lastRefresh: Date? {
        switch selectedTab {
        case .artists:   return service.libraryManager.lastArtistsRefresh
        case .albums:    return service.libraryManager.lastAlbumsRefresh
        case .playlists: return service.libraryManager.lastPlaylistsRefresh
        case .radio:     return nil
        }
    }

    var body: some View {
        NavigationStack {
            Group {
                switch selectedTab {
                case .artists:   ArtistsView()
                case .albums:    AlbumsView()
                case .playlists: PlaylistsView()
                case .radio:     RadiosView()
                }
            }
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button {
                        Task { await refresh() }
                    } label: {
                        if isRefreshing {
                            ProgressView()
                        } else {
                            Image(systemName: "arrow.clockwise")
                        }
                    }
                    .disabled(isRefreshing || selectedTab == .radio)
                    .help(lastRefreshLabel)
                }

                ToolbarItem(placement: .principal) {
                    Picker("Library", selection: $selectedTab) {
                        ForEach(LibraryTab.allCases, id: \.self) { tab in
                            Text(tab.rawValue).tag(tab)
                        }
                    }
                    .pickerStyle(.segmented)
                    .frame(maxWidth: 360)
                }

                ToolbarItem(placement: .primaryAction) {
                    NavigationLink {
                        SearchView()
                    } label: {
                        Label("Search", systemImage: "magnifyingglass")
                    }
                }
            }
            .navigationDestination(for: MAArtist.self) { ArtistDetailView(artist: $0) }
            .navigationDestination(for: MAAlbum.self)  { AlbumDetailView(album: $0) }
            .navigationDestination(for: MAPlaylist.self) { PlaylistDetailView(playlist: $0) }
            .alert("Refresh Failed", isPresented: $showError) {
                Button("OK", role: .cancel) { }
            } message: {
                if let refreshError { Text(refreshError) }
            }
        }
    }

    // MARK: - Helpers

    private var lastRefreshLabel: String {
        guard let date = lastRefresh else { return "Never refreshed" }
        let formatter = RelativeDateTimeFormatter()
        formatter.unitsStyle = .full
        return "Last refreshed \(formatter.localizedString(for: date, relativeTo: .now))"
    }

    private func refresh() async {
        do {
            switch selectedTab {
            case .artists:   try await service.libraryManager.loadArtists(refresh: true)
            case .albums:    try await service.libraryManager.loadAlbums(refresh: true)
            case .playlists: try await service.libraryManager.loadPlaylists(refresh: true)
            case .radio:     break
            }
        } catch {
            refreshError = error.localizedDescription
            showError = true
        }
    }
}

#Preview {
    LibraryView()
        .environment(MAService())
}