import SwiftUI

/// "NO STEMS" / "3/10 STEMS" for an album or artist, once the whole library has been matched.
struct StemFlag: View {
    let cov: Coverage?
    var body: some View {
        if AppGraph.shared.coverage.ready, let cov {
            if cov.none { Tag(text: "NO STEMS") } else if cov.partial { Tag(text: "\(cov.withStems)/\(cov.total) STEMS") }
        }
    }
}

/// Apple Music list row: art (or track number), title, artist, badges, and a ••• menu.
/// Stems are the norm once the server has worked through the library, so the badge marks the
/// songs without them, and only once the index has loaded.
struct TrackRow<Leading: View>: View {
    let track: Track
    var number: Int?
    var showArt = true
    var subtitle: String?
    var menu: [SheetAction]?
    let action: () -> Void
    @ViewBuilder var leading: () -> Leading

    @Environment(\.palette) private var p

    var body: some View {
        let g = AppGraph.shared
        let pm = g.playback
        let isCurrent = pm.current?.track.ratingKey == track.ratingKey
        let noStems = g.stems.index.size > 0 && g.stems.find(track) == nil
        let downloaded = g.downloads.records[track.ratingKey]?.done == true
        let progress = g.downloads.progress[track.ratingKey]
        HStack(spacing: 0) {
            leading()
            if showArt {
                ZStack {
                    Artwork(thumb: track.thumb, size: 48, corner: 5)
                    if isCurrent {
                        Color.black.opacity(0.35).frame(width: 48, height: 48).clipShape(RoundedRectangle(cornerRadius: 5))
                        PlayingBars(playing: pm.playWhenReady, color: .white)
                    }
                }
                .padding(.trailing, 12)
            } else if let number {
                Group {
                    if isCurrent { PlayingBars(playing: pm.playWhenReady) } else { Text("\(number)").foregroundStyle(p.label2) }
                }
                .frame(width: 32, alignment: .leading)
            }
            VStack(alignment: .leading, spacing: 1) {
                Text(track.title).foregroundStyle(isCurrent ? p.accent : p.label).lineLimit(1)
                if let s = subtitle ?? (showArt ? track.artist : nil) {
                    Text(s).font(.subheadline).foregroundStyle(p.label2).lineLimit(1)
                }
            }
            .padding(.vertical, 6)
            Spacer(minLength: 6)
            if noStems { Tag(text: "NO STEMS").padding(.trailing, 6) }
            if let progress { ProgressRing(progress: progress, size: 16).padding(.trailing, 4) }
            else if downloaded { DownloadedMark().padding(.trailing, 4) }
            if let menu { MoreMenu(items: menu).foregroundStyle(p.label) }
        }
        .frame(minHeight: showArt ? 56 : 40)
        .contentShape(Rectangle())
        .onTapGesture(perform: action)
        .modifier(OptionalMenu(items: menu))
    }
}

extension TrackRow where Leading == EmptyView {
    init(track: Track, number: Int? = nil, showArt: Bool = true, subtitle: String? = nil, menu: [SheetAction]? = nil, action: @escaping () -> Void) {
        self.init(track: track, number: number, showArt: showArt, subtitle: subtitle, menu: menu, action: action) { EmptyView() }
    }
}

struct OptionalMenu: ViewModifier {
    let items: [SheetAction]?
    func body(content: Content) -> some View {
        if let items { content.actionsMenu(items) } else { content }
    }
}

/// Two-column album grid. [subtitle] replaces the artist (or year) line; [badge] sits on the art's corner.
struct AlbumGrid<Badge: View>: View {
    let albums: [Album]
    var showArtist = true
    var subtitle: ((Album) -> String?)?
    var menu: ((Album) -> [SheetAction])?
    let open: (Album) -> Void
    @ViewBuilder var badge: (Album) -> Badge

    @Environment(\.palette) private var p

    var body: some View {
        let cov = AppGraph.shared.coverage.albums
        LazyVGrid(columns: [GridItem(.flexible(), spacing: 16, alignment: .top), GridItem(.flexible(), spacing: 16, alignment: .top)], spacing: 18) {
            ForEach(albums) { a in
                VStack(alignment: .leading, spacing: 0) {
                    GeometryReader { geo in
                        Artwork(thumb: a.thumb, size: geo.size.width, corner: 8, placeholder: "square.stack")
                            .overlay(alignment: .bottomTrailing) { badge(a).padding(8) }
                    }
                    .aspectRatio(1, contentMode: .fit)
                    HStack(spacing: 6) {
                        Text(a.title).font(.subheadline.weight(.medium)).foregroundStyle(p.label).lineLimit(1)
                        StemFlag(cov: cov[a.ratingKey])
                    }
                    .padding(.top, 6)
                    let sub = subtitle?(a) ?? (showArtist ? a.artist : a.year.map(String.init) ?? "")
                    if !sub.isEmpty { Text(sub).font(.subheadline).foregroundStyle(p.label2).lineLimit(1) }
                }
                .contentShape(Rectangle())
                .onTapGesture { open(a) }
                .modifier(OptionalMenu(items: menu?(a)))
            }
        }
        .padding(.horizontal, MARGIN)
    }
}

extension AlbumGrid where Badge == EmptyView {
    init(albums: [Album], showArtist: Bool = true, subtitle: ((Album) -> String?)? = nil, menu: ((Album) -> [SheetAction])? = nil, open: @escaping (Album) -> Void) {
        self.init(albums: albums, showArtist: showArtist, subtitle: subtitle, menu: menu, open: open) { _ in EmptyView() }
    }
}

struct ArtistRow: View {
    let artist: Artist
    @Environment(\.palette) private var p
    var body: some View {
        HStack(spacing: 14) {
            Artwork(thumb: artist.thumb, size: 44, circle: true, placeholder: "person.fill")
            Text(artist.title).foregroundStyle(p.label).lineLimit(1)
            Spacer()
            StemFlag(cov: AppGraph.shared.coverage.artists[artist.ratingKey])
        }
        .frame(minHeight: 52)
    }
}