feat(core,app,android,ios): more like this and browse by genre, studio, person

pstr_core::discover scores every title against another by shared
director, studio, genres, leading tags and format, leaves out its own
franchise and keeps one title per other franchise. It drives a "More
like this" row under a title's episodes and, seeded by the title most
recently watched to the end, a "Because you watched" row on the library
of titles not yet started.

Genre chips on the title page now open a page of every title with that
genre, and the studios and director move from the line of facts onto
chips of their own that do the same. The desktop has a Browse page whose
back link returns to the title; Android and iOS show it over the library
pane. The bridge exposes more_like, browse and facet_kind.

Also moves a doc comment the My List commit left on the wrong function.

ios/ProtonStream/App/AppModel.swift

@@ -548,6 +548,22 @@ final class AppModel {
         }
     }
 
+    /// The keys of the titles most like `key`, best first; none if the engine
+    /// cannot say.
+    func moreLike(_ key: String) async -> [String] {
+        (try? await run { try $0.moreLike(key: key) }) ?? []
+    }
+
+    /// The keys of every title `facet` stands for, in library order.
+    func browse(_ facet: BrowseFacet) async -> [String] {
+        do {
+            return try await run { try $0.browse(facet: facet) }
+        } catch {
+            reportError(error)
+            return []
+        }
+    }
+
     // MARK: - Watch state
 
     /// Every episode of a title watched or unwatched, with an Undo: a whole

ios/ProtonStream/App/ProtonStreamApp.swift

@@ -89,6 +89,13 @@ struct RootView: View {
     @SceneStorage("selectedTitle") private var selectedTitleKey: String?
     @State private var incomingLink: String?
     @State private var host = PlayerHost.shared
+    /// What a genre, studio or director chip opened, over the library pane,
+    /// and the title it was opened from, which is where back goes.
+    @State private var browsing: BrowseFacet?
+    @State private var browseFrom: String?
+    @State private var browsed: [String] = []
+    /// "More like this" for the open title.
+    @State private var similar: [String] = []
 
     var body: some View {
         GeometryReader { geometry in
@@ -175,6 +182,7 @@ struct RootView: View {
     private func select(_ target: Destination) {
         destination = target
         selectedTitleKey = nil
+        browsing = nil
     }
 
     private func play(_ title: TitleRecord, _ index: Int) {
@@ -209,22 +217,45 @@ struct RootView: View {
     /// tap rather than back and in again.
     @ViewBuilder private func libraryPage(width: CGFloat) -> some View {
         let selected = selectedTitleKey.flatMap { key in model.titles.first { $0.key == key } }
-        let library = LibraryView(
-            onResume: play,
-            onTitle: { title in withAnimation(.easeOut(duration: 0.25)) { selectedTitleKey = title.key } },
-            // The form as a pasted link opens it, only with nothing in it.
-            onAddShare: {
-                incomingLink = ""
-                destination = .shares
-            },
-            onOpenSettings: { select(.settings) }
-        )
-        if width >= twoPaneWidth {
+        let twoPane = width >= twoPaneWidth
+        let open = { (title: TitleRecord) in withAnimation(.easeOut(duration: 0.25)) { selectedTitleKey = title.key } }
+        let library = Group {
+            if let browsing {
+                BrowseView(
+                    facet: browsing,
+                    titles: browsed.compactMap { key in model.titles.first { $0.key == key } },
+                    onBack: {
+                        self.browsing = nil
+                        if let browseFrom { selectedTitleKey = browseFrom }
+                    },
+                    onTitle: open
+                )
+            } else {
+                LibraryView(
+                    onResume: play,
+                    onTitle: open,
+                    // The form as a pasted link opens it, only with nothing in it.
+                    onAddShare: {
+                        incomingLink = ""
+                        destination = .shares
+                    },
+                    onOpenSettings: { select(.settings) }
+                )
+            }
+        }
+        .task(id: [browsing.map { "\($0)" } ?? "", "\(model.titles.count)"]) {
+            if let browsing {
+                browsed = await model.browse(browsing)
+            } else {
+                browsed = []
+            }
+        }
+        if twoPane {
             HStack(spacing: 0) {
                 library.frame(width: width * 0.45)
                 Rectangle().fill(scheme.outlineVariant).frame(width: 1).ignoresSafeArea()
                 Group {
-                    if let selected { titlePane(selected) } else { EmptyState("Choose a title", "Its seasons and episodes open here.") }
+                    if let selected { titlePane(selected, twoPane: true) } else { EmptyState("Choose a title", "Its seasons and episodes open here.") }
                 }
                 .frame(maxWidth: .infinity)
             }
@@ -237,7 +268,7 @@ struct RootView: View {
                     .allowsHitTesting(selected == nil)
                     .accessibilityHidden(selected != nil)
                 if let selected {
-                    titlePane(selected)
+                    titlePane(selected, twoPane: false)
                         .transition(.asymmetric(insertion: .move(edge: .trailing), removal: .opacity.combined(with: .scale(scale: 0.9))))
                         .zIndex(1)
                 }
@@ -245,15 +276,26 @@ struct RootView: View {
         }
     }
 
-    private func titlePane(_ selected: TitleRecord) -> some View {
+    private func titlePane(_ selected: TitleRecord, twoPane: Bool) -> some View {
         TitleView(
             title: selected,
             onPlay: { _, index in host.play(selected, at: index) },
             onBack: { withAnimation(.easeOut(duration: 0.25)) { selectedTitleKey = nil } },
             franchise: selected.franchise.compactMap { key in model.titles.first { $0.key == key } },
-            onOpenTitle: { selectedTitleKey = $0.key }
+            onOpenTitle: { selectedTitleKey = $0.key },
+            moreLike: similar.compactMap { key in model.titles.first { $0.key == key } },
+            onBrowse: { facet in
+                browsing = facet
+                browseFrom = selected.key
+                // On a phone the list is under the title; the page it opens
+                // is the library pane's.
+                if !twoPane { withAnimation(.easeOut(duration: 0.25)) { selectedTitleKey = nil } }
+            }
         )
         .id(selected.key)
+        .task(id: [selected.key, "\(model.titles.count)"]) {
+            similar = await model.moreLike(selected.key)
+        }
     }
 }
 

ios/ProtonStream/UI/Common.swift

@@ -420,19 +420,33 @@ struct StatusChip: View {
     }
 }
 
-/// Something the title is filed under — a genre — as a small rounded label.
-/// Android's `GenreChip`.
+/// Something the title is filed under — a genre, a studio — as a small rounded
+/// label, which opens every title sharing it when given an action. Android's
+/// `GenreChip`.
 struct GenreChip: View {
     @Environment(\.scheme) private var scheme
     let text: String
+    var action: (() -> Void)?
+
+    init(text: String, action: (() -> Void)? = nil) {
+        self.text = text
+        self.action = action
+    }
 
     var body: some View {
-        Text(text)
+        let label = Text(text)
             .textStyle(.labelMedium)
             .foregroundStyle(scheme.onSurface)
             .padding(.horizontal, 10)
             .padding(.vertical, 4)
             .background(scheme.surfaceVariant, in: RoundedRectangle(cornerRadius: 12))
+        if let action {
+            Button(action: action) { label }
+                .buttonStyle(.plain)
+                .accessibilityHint("Browse \(text)")
+        } else {
+            label
+        }
     }
 }
 

ios/ProtonStream/UI/LibraryView.swift

@@ -801,3 +801,48 @@ extension EpisodeRecord {
 extension TitleRecord: Identifiable {
     public var id: String { key }
 }
+
+/// Every title sharing a genre, a studio or a director: what a chip on a title
+/// page opens. Android's `BrowseScreen`, the desktop's `library::browse`.
+struct BrowseView: View {
+    let facet: BrowseFacet
+    let titles: [TitleRecord]
+    let onBack: () -> Void
+    let onTitle: (TitleRecord) -> Void
+    @Environment(\.scheme) private var scheme
+
+    var body: some View {
+        TabPage(facet.label, leading: {
+            IconButton("chevron.backward", "Back", tint: scheme.onSurface, action: onBack)
+        }) {
+            if titles.isEmpty {
+                // A recrawl or a new match took the last one away.
+                EmptyState(facet.label, "Nothing in the library has this any more.")
+            } else {
+                ScrollView {
+                    VStack(alignment: .leading, spacing: 8) {
+                        Text("\(facetKind(facet: facet)) · \(titles.count == 1 ? "1 title" : "\(titles.count) titles")")
+                            .textStyle(.bodyMedium)
+                            .foregroundStyle(scheme.onSurfaceVariant)
+                        LazyVGrid(columns: [GridItem(.adaptive(minimum: 108), spacing: 12, alignment: .top)], spacing: 16) {
+                            ForEach(titles, id: \.key) { title in
+                                PosterTile(title: title)
+                                    .tapAndHold { onTitle(title) }
+                            }
+                        }
+                    }
+                    .padding(EdgeInsets(top: 8, leading: 16, bottom: 24, trailing: 16))
+                }
+            }
+        }
+    }
+}
+
+extension BrowseFacet {
+    /// The name it stands for: the chip's text and its page's heading.
+    var label: String {
+        switch self {
+        case .genre(let name), .studio(let name), .person(let name): name
+        }
+    }
+}

ios/ProtonStream/UI/TitleView.swift

@@ -16,6 +16,10 @@ struct TitleView: View {
     /// Every title of its franchise, in release order, this one included.
     var franchise: [TitleRecord] = []
     var onOpenTitle: (TitleRecord) -> Void = { _ in }
+    /// The titles most like it, best first.
+    var moreLike: [TitleRecord] = []
+    /// Open every title sharing a genre, studio or director.
+    var onBrowse: (BrowseFacet) -> Void = { _ in }
 
     @Environment(AppModel.self) private var model
     @Environment(\.scheme) private var scheme
@@ -38,13 +42,17 @@ struct TitleView: View {
         onPlay: @escaping ([EpisodeRecord], Int) -> Void,
         onBack: @escaping () -> Void,
         franchise: [TitleRecord] = [],
-        onOpenTitle: @escaping (TitleRecord) -> Void = { _ in }
+        onOpenTitle: @escaping (TitleRecord) -> Void = { _ in },
+        moreLike: [TitleRecord] = [],
+        onBrowse: @escaping (BrowseFacet) -> Void = { _ in }
     ) {
         self.title = title
         self.onPlay = onPlay
         self.onBack = onBack
         self.franchise = franchise
         self.onOpenTitle = onOpenTitle
+        self.moreLike = moreLike
+        self.onBrowse = onBrowse
         // One season on screen at a time, opened on the one Play would land in.
         let playlist = title.playlist
         let nextUp = nextUpIndex(playlist, continueIndex: title.continueIndex)
@@ -71,7 +79,7 @@ struct TitleView: View {
                     heading(playlist: playlist, nextUp: nextUp, upNext: upNext)
                         .padding(.horizontal, side + 16)
                     if franchise.count > 1 {
-                        franchiseRow(side: side)
+                        coverRow("In this franchise", franchise, side: side)
                     }
                     seasonChips(season: season, side: side)
                     if let season {
@@ -91,6 +99,11 @@ struct TitleView: View {
                             .padding(.horizontal, side)
                         }
                     }
+                    // Under the episodes rather than over them: where to go
+                    // once this one is done, not what the page is for.
+                    if !moreLike.isEmpty {
+                        coverRow("More like this", moreLike, side: side)
+                    }
                 }
                 .padding(.bottom, 24)
             }
@@ -223,15 +236,6 @@ struct TitleView: View {
             }
             Text(factLine)
                 .textStyle(.bodySmall).foregroundStyle(scheme.onSurfaceVariant).padding(.top, 6)
-            // Who made it.
-            let makers: [String?] = [
-                title.studios.isEmpty ? nil : title.studios.prefix(2).joined(separator: ", "),
-                title.directors.first.map { "dir. \($0)" },
-            ]
-            let facts = makers.compactMap { $0 }.joined(separator: "  ·  ")
-            if !facts.isEmpty {
-                Text(facts).textStyle(.bodySmall).foregroundStyle(scheme.onSurfaceVariant).padding(.top, 2)
-            }
             // Where the title stands, then what the files are rather than
             // what the title is.
             let status = statusText(title)
@@ -284,10 +288,33 @@ struct TitleView: View {
             // tag is its community describing it, not what it is filed as.
             if !title.genres.isEmpty {
                 FlowLayout(spacing: 6) {
-                    ForEach(title.genres, id: \.self) { GenreChip(text: $0) }
+                    ForEach(title.genres, id: \.self) { genre in
+                        GenreChip(text: genre) { onBrowse(.genre(name: genre)) }
+                    }
                 }
                 .padding(.top, 12)
             }
+            // Who made it, as chips that open everything else by them: the
+            // desktop's credits row.
+            let studios = Array(title.studios.prefix(2))
+            let director = Array(title.directors.prefix(1))
+            if !studios.isEmpty || !director.isEmpty {
+                FlowLayout(spacing: 6) {
+                    if !studios.isEmpty {
+                        Text("Studio").textStyle(.labelMedium).foregroundStyle(scheme.onSurfaceVariant)
+                        ForEach(studios, id: \.self) { name in
+                            GenreChip(text: name) { onBrowse(.studio(name: name)) }
+                        }
+                    }
+                    if !director.isEmpty {
+                        Text("Director").textStyle(.labelMedium).foregroundStyle(scheme.onSurfaceVariant)
+                        ForEach(director, id: \.self) { name in
+                            GenreChip(text: name) { onBrowse(.person(name: name)) }
+                        }
+                    }
+                }
+                .padding(.top, 8)
+            }
             if !title.tags.isEmpty {
                 Text(title.tags.prefix(4).joined(separator: "  ·  "))
                     .textStyle(.labelMedium).foregroundStyle(scheme.onSurfaceVariant).padding(.top, 8)
@@ -317,13 +344,15 @@ struct TitleView: View {
         return "Play \(upNext.label)"
     }
 
-    private func franchiseRow(side: CGFloat) -> some View {
+    /// A row of covers: the franchise, with this title marked, or the titles
+    /// like it.
+    private func coverRow(_ heading: String, _ members: [TitleRecord], side: CGFloat) -> some View {
         VStack(alignment: .leading, spacing: 10) {
-            Text("In this franchise").textStyle(.titleMedium).foregroundStyle(scheme.onSurface)
+            Text(heading).textStyle(.titleMedium).foregroundStyle(scheme.onSurface)
                 .padding(.horizontal, side + 16)
             ScrollView(.horizontal, showsIndicators: false) {
                 LazyHStack(alignment: .top, spacing: 12) {
-                    ForEach(franchise, id: \.key) { member in
+                    ForEach(members, id: \.key) { member in
                         FranchiseTile(title: member, here: member.key == title.key)
                             .tapAndHold { if member.key != title.key { onOpenTitle(member) } }
                     }