//
// Swiftfin is subject to the terms of the Mozilla Public
// License, v2.0. If a copy of the MPL was not distributed with this
// file, you can obtain one at https://mozilla.org/MPL/2.0/.
//
// Copyright (c) 2024 Jellyfin & Jellyfin Contributors
//

import CollectionHStack
import Defaults
import JellyfinAPI
import SwiftUI

struct SeriesEpisodeSelector: View {

    @EnvironmentObject
    private var mainRouter: MainCoordinator.Router

    @ObservedObject
    var viewModel: SeriesItemViewModel

    @ViewBuilder
    private var selectorMenu: some View {
        Menu {
            ForEach(viewModel.menuSections.keys.sorted(by: { viewModel.menuSectionSort($0, $1) }), id: \.displayTitle) { section in
                Button {
                    viewModel.select(section: section)
                } label: {
                    if section == viewModel.menuSelection {
                        Label(section.displayTitle, systemImage: "checkmark")
                    } else {
                        Text(section.displayTitle)
                    }
                }
            }
        } label: {
            HStack(spacing: 5) {
                Group {
                    Text(viewModel.menuSelection?.displayTitle ?? L10n.unknown)
                        .fixedSize()
                    Image(systemName: "chevron.down")
                }
                .font(.title3.weight(.semibold))
            }
        }
        .padding(.bottom)
        .fixedSize()
    }

    var body: some View {
        VStack(alignment: .leading) {
            selectorMenu
                .edgePadding(.horizontal)

            if viewModel.currentItems.isEmpty {
                EmptyView()
            } else {
                CollectionHStack(
                    $viewModel.currentItems,
                    columns: UIDevice.isPhone ? 1.5 : 3.5
                ) { item in
                    PosterButton(
                        item: item,
                        type: .landscape,
                        singleImage: true
                    )
                    .content {
                        EpisodeContent(episode: item)
                    }
                    .imageOverlay {
                        EpisodeOverlay(episode: item)
                    }
                    .onSelect {
                        guard let mediaSource = item.mediaSources?.first else { return }
                        mainRouter.route(to: \.videoPlayer, OnlineVideoPlayerManager(item: item, mediaSource: mediaSource))
                    }
                }
                .scrollBehavior(.continuousLeadingEdge)
                .insets(horizontal: EdgeInsets.defaultEdgePadding)
                .itemSpacing(8)
            }
        }
    }
}

extension SeriesEpisodeSelector {

    struct EpisodeOverlay: View {

        let episode: BaseItemDto

        var body: some View {
            if let progressLabel = episode.progressLabel {
                LandscapePosterProgressBar(
                    title: progressLabel,
                    progress: (episode.userData?.playedPercentage ?? 0) / 100
                )
            } else if episode.userData?.isPlayed ?? false {
                ZStack(alignment: .bottomTrailing) {
                    Color.clear

                    Image(systemName: "checkmark.circle.fill")
                        .resizable()
                        .frame(width: 30, height: 30, alignment: .bottomTrailing)
                        .paletteOverlayRendering(color: .white)
                        .padding()
                }
            }
        }
    }

    struct EpisodeContent: View {

        @Default(.accentColor)
        private var accentColor

        @EnvironmentObject
        private var router: ItemCoordinator.Router
        @ScaledMetric
        private var staticOverviewHeight: CGFloat = 50

        let episode: BaseItemDto

        @ViewBuilder
        private var subHeader: some View {
            Text(episode.episodeLocator ?? L10n.unknown)
                .font(.footnote)
                .foregroundColor(.secondary)
        }

        @ViewBuilder
        private var header: some View {
            Text(episode.displayTitle)
                .font(.body)
                .foregroundColor(.primary)
                .padding(.bottom, 1)
                .lineLimit(2)
                .multilineTextAlignment(.leading)
        }

        // TODO: why the static overview height?
        @ViewBuilder
        private var content: some View {
            Group {
                ZStack(alignment: .topLeading) {
                    Color.clear
                        .frame(height: staticOverviewHeight)

                    if episode.isUnaired {
                        Text(episode.airDateLabel ?? L10n.noOverviewAvailable)
                    } else {
                        Text(episode.overview ?? L10n.noOverviewAvailable)
                    }
                }

                L10n.seeMore.text
                    .font(.footnote)
                    .fontWeight(.medium)
                    .foregroundColor(accentColor)
            }
            .font(.caption.weight(.light))
            .foregroundColor(.secondary)
            .lineLimit(3)
            .multilineTextAlignment(.leading)
        }

        var body: some View {
            Button {
                router.route(to: \.item, episode)
            } label: {
                VStack(alignment: .leading) {
                    subHeader

                    header

                    content
                }
            }
        }
    }
}