import SwiftUI
import FlixyDesign
import MediaKit

/// Die Detailseite von etwas, das sich direkt abspielen lässt — Film oder
/// einzelne Folge.
struct PlayableDetailView: View {
    let item: MediaItem

    @Environment(FlixySession.self) private var session
    @Environment(PlaybackCoordinator.self) private var playback
    @Environment(\.flixyAccent) private var accent

    @State private var selectedVersion = 0
    @State private var showsTechnicalDetails = false

    var body: some View {
        ScrollView {
            VStack(alignment: .leading, spacing: FlixySpacing.section) {
                header

                ParentLinks(item: item)

                if item.hasMultipleVersions {
                    VersionPicker(media: item.versions, selection: $selectedVersion)
                        .padding(.horizontal, FlixySpacing.screenMargin)
                }

                if let summary = item.summary, !summary.isEmpty {
                    Text(summary)
                        .font(.flixyBody)
                        .foregroundStyle(Color.flixyTextSecondary)
                        .padding(.horizontal, FlixySpacing.screenMargin)
                }

                if !item.genres.isEmpty {
                    TagStrip(tags: item.genres)
                }

                if !item.cast.isEmpty {
                    CastRow(cast: item.cast)
                }

                if let media = currentMedia, let part = media.files.first {
                    TechnicalDetails(
                        media: media,
                        part: part,
                        isExpanded: $showsTechnicalDetails
                    )
                    .padding(.horizontal, FlixySpacing.screenMargin)
                }
            }
            .padding(.bottom, FlixySpacing.section)
        }
        .scrollIndicators(.hidden)
    }

    private var currentMedia: MediaVersion? {
        guard item.versions.indices.contains(selectedVersion) else { return item.versions.first }
        return item.versions[selectedVersion]
    }

    private var header: some View {
        HeroBanner(
            title: item.rowTitle,
            metadata: metadataLine,
            summary: nil,
            artworkURL: session.backend?.artworkURL(
                path: item.art ?? item.seriesArt ?? item.thumb,
                width: 900,
                height: 1200
            ),
            logoURL: session.backend?.rawImageURL(path: item.clearLogoPath)
        ) {
            Button {
                playback.play(item, mediaIndex: selectedVersion)
            } label: {
                Label(
                    item.watchProgress == nil ? "hero.play" : "hero.resume",
                    systemImage: "play.fill"
                )
                .font(.flixyCardTitle)
                .padding(.horizontal, FlixySpacing.loose)
                .padding(.vertical, FlixySpacing.snug)
            }
            .buttonStyle(.borderedProminent)
            .tint(accent)
            .disabled(currentMedia?.files.first == nil)

            if let progress = item.watchProgress, progress > 0 {
                Button {
                    playback.play(item, mediaIndex: selectedVersion, resuming: false)
                } label: {
                    Label("detail.playFromStart", systemImage: "gobackward")
                        .labelStyle(.iconOnly)
                        .font(.flixyCardTitle)
                        .padding(FlixySpacing.snug)
                }
                .buttonStyle(.bordered)
                .tint(Color.flixyTextSecondary)
            }

            DownloadButton(item: item, mediaIndex: selectedVersion)
        }
    }

    private var metadataLine: String? {
        var pieces: [String] = []
        if item.kind == .episode {
            // Der Folgentitel steht jetzt groß darüber; ohne die Serie hier
            // wüsste man auf dieser Seite nicht, wozu die Folge gehört.
            if let series = item.seriesTitle { pieces.append(series) }
            if let season = item.parentIndex, let episode = item.index {
                pieces.append(String(localized: "episode.short \(season) \(episode)"))
            }
        }
        if let year = item.year { pieces.append(String(year)) }
        if let duration = item.duration { pieces.append(Duration.milliseconds(duration).runtimeLabel) }
        if let rating = item.contentRating { pieces.append(rating) }
        if let resolution = currentMedia?.videoResolution { pieces.append(resolution.uppercased()) }
        return pieces.isEmpty ? nil : pieces.joined(separator: " · ")
    }
}

/// Auswahl zwischen mehreren Fassungen desselben Titels.
struct VersionPicker: View {
    let media: [MediaVersion]
    @Binding var selection: Int

    var body: some View {
        VStack(alignment: .leading, spacing: FlixySpacing.snug) {
            Text("detail.versions")
                .font(.flixyRowHeader)
                .foregroundStyle(Color.flixyTextPrimary)

            Picker("detail.versions", selection: $selection) {
                ForEach(Array(media.enumerated()), id: \.offset) { index, version in
                    Text(version.qualityLabel).tag(index)
                }
            }
            .pickerStyle(.segmented)
            .labelsHidden()
        }
    }
}

/// Genres als Streifen.
struct TagStrip: View {
    let tags: [String]

    var body: some View {
        ScrollView(.horizontal) {
            HStack(spacing: FlixySpacing.snug) {
                ForEach(tags, id: \.self) { tag in
                    Text(tag)
                        .font(.flixyCaption)
                        .foregroundStyle(Color.flixyTextSecondary)
                        .padding(.horizontal, FlixySpacing.regular)
                        .padding(.vertical, FlixySpacing.tight)
                        .background(Color.flixyElevated, in: .capsule)
                }
            }
            .padding(.horizontal, FlixySpacing.screenMargin)
        }
        .scrollIndicators(.hidden)
    }
}

/// Die Besetzung mit Porträts.
struct CastRow: View {
    let cast: [MediaPerson]
    @Environment(FlixySession.self) private var session

    var body: some View {
        VStack(alignment: .leading, spacing: FlixySpacing.regular) {
            Text("detail.cast")
                .font(.flixyRowHeader)
                .foregroundStyle(Color.flixyTextPrimary)
                .padding(.horizontal, FlixySpacing.screenMargin)

            ScrollView(.horizontal) {
                HStack(alignment: .top, spacing: FlixySpacing.regular) {
                    ForEach(cast.prefix(20)) { role in
                        VStack(spacing: FlixySpacing.snug) {
                            FlixyArtwork(
                                url: session.backend?.artworkURL(path: role.thumb, width: 160, height: 160),
                                aspectRatio: 1,
                                fallbackSymbol: "person"
                            )
                            .frame(width: 72, height: 72)
                            .clipShape(.circle)

                            Text(role.name)
                                .font(.flixyCaption)
                                .foregroundStyle(Color.flixyTextPrimary)
                                .lineLimit(2)
                                .multilineTextAlignment(.center)

                            if let character = role.role {
                                Text(character)
                                    .font(.flixyCaption)
                                    .foregroundStyle(Color.flixyTextMuted)
                                    .lineLimit(1)
                            }
                        }
                        .frame(width: 90)
                        .accessibilityElement(children: .combine)
                    }
                }
                .padding(.horizontal, FlixySpacing.screenMargin)
            }
            .scrollIndicators(.hidden)
        }
    }
}