//
// 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) 2022 Jellyfin & Jellyfin Contributors
//

import Combine
import JellyfinAPI
import Nuke
import SwiftUI
import WidgetKit

enum WidgetError: String, Error {
    case unknown
    case emptyServer
    case emptyUser
    case emptyHeader
}

struct NextUpWidgetProvider: TimelineProvider {
    func placeholder(in context: Context) -> NextUpEntry {
        NextUpEntry(date: Date(), items: [], error: nil)
    }

    func getSnapshot(in context: Context, completion: @escaping (NextUpEntry) -> Void) {
        guard let currentLogin = SessionManager.main.currentLogin else { return }

        let currentDate = Date()
        let server = currentLogin.server
        let savedUser = currentLogin.user
        var tempCancellables = Set<AnyCancellable>()

        JellyfinAPIAPI.basePath = server.currentURI
        TvShowsAPI.getNextUp(
            userId: savedUser.id,
            limit: 3,
            fields: [.primaryImageAspectRatio, .seriesPrimaryImage, .seasonUserData, .overview, .genres, .people],
            imageTypeLimit: 1,
            enableImageTypes: [.primary, .backdrop, .thumb]
        )
        .subscribe(on: DispatchQueue.global(qos: .background))
        .sink(receiveCompletion: { result in
            switch result {
            case .finished:
                break
            case let .failure(error):
                completion(NextUpEntry(date: currentDate, items: [], error: error))
            }
        }, receiveValue: { response in
            let dispatchGroup = DispatchGroup()
            let items = response.items ?? []
            var downloadedItems = [(BaseItemDto, UIImage?)]()
            items.enumerated().forEach { _, item in
                dispatchGroup.enter()
                ImagePipeline.shared.loadImage(with: item.getBackdropImage(maxWidth: 320)) { result in
                    guard case let .success(image) = result else {
                        dispatchGroup.leave()
                        return
                    }
                    downloadedItems.append((item, image.image))
                    dispatchGroup.leave()
                }
            }

            dispatchGroup.notify(queue: .main) {
                completion(NextUpEntry(date: currentDate, items: downloadedItems, error: nil))
            }
        })
        .store(in: &tempCancellables)
    }

    func getTimeline(in context: Context, completion: @escaping (Timeline<Entry>) -> Void) {
        guard let currentLogin = SessionManager.main.currentLogin else { return }

        let currentDate = Date()
        let entryDate = Calendar.current.date(byAdding: .hour, value: 1, to: currentDate)!
        let server = currentLogin.server
        let savedUser = currentLogin.user

        var tempCancellables = Set<AnyCancellable>()

        JellyfinAPIAPI.basePath = server.currentURI
        TvShowsAPI.getNextUp(
            userId: savedUser.id,
            limit: 3,
            fields: [.primaryImageAspectRatio, .seriesPrimaryImage, .seasonUserData, .overview, .genres, .people],
            imageTypeLimit: 1,
            enableImageTypes: [.primary, .backdrop, .thumb]
        )
        .subscribe(on: DispatchQueue.global(qos: .background))
        .sink(receiveCompletion: { result in
            switch result {
            case .finished:
                break
            case let .failure(error):
                completion(Timeline(entries: [NextUpEntry(date: currentDate, items: [], error: error)], policy: .after(entryDate)))
            }
        }, receiveValue: { response in
            let dispatchGroup = DispatchGroup()
            let items = response.items ?? []
            var downloadedItems = [(BaseItemDto, UIImage?)]()
            items.enumerated().forEach { _, item in
                dispatchGroup.enter()
                ImagePipeline.shared.loadImage(with: item.getBackdropImage(maxWidth: 320)) { result in
                    guard case let .success(image) = result else {
                        dispatchGroup.leave()
                        return
                    }
                    downloadedItems.append((item, image.image))
                    dispatchGroup.leave()
                }
            }

            dispatchGroup.notify(queue: .main) {
                completion(Timeline(
                    entries: [NextUpEntry(date: currentDate, items: downloadedItems, error: nil)],
                    policy: .after(entryDate)
                ))
            }
        })
        .store(in: &tempCancellables)
    }
}

struct NextUpEntry: TimelineEntry {
    let date: Date
    let items: [(BaseItemDto, UIImage?)]
    let error: Error?
}

struct NextUpEntryView: View {
    var entry: NextUpWidgetProvider.Entry

    @Environment(\.widgetFamily)
    var family

    @ViewBuilder
    var body: some View {
        Group {
            if let error = entry.error {
                HStack {
                    Image(systemName: "exclamationmark.octagon")
                    Text((error as? WidgetError)?.rawValue ?? "")
                }
                .background(Color.blue)
            } else if entry.items.isEmpty {
                L10n.emptyNextUp.text
                    .font(.body)
                    .bold()
                    .foregroundColor(.primary)
                    .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity)
            } else {
                switch family {
                case .systemSmall:
                    small(item: entry.items.first)
                case .systemMedium:
                    medium(items: entry.items)
                case .systemLarge:
                    large(items: entry.items)
                default:
                    EmptyView()
                }
            }
        }
        .background(Color(.secondarySystemBackground))
    }
}

extension NextUpEntryView {
    var smallVideoPlaceholderView: some View {
        VStack(alignment: .leading) {
            Color(.systemGray)
                .aspectRatio(.init(width: 1, height: 0.5625), contentMode: .fill)
                .cornerRadius(8)
                .shadow(radius: 8)
            Color(.systemGray2)
                .frame(width: 100, height: 10)
            Color(.systemGray3)
                .frame(width: 80, height: 10)
        }
    }

    var largeVideoPlaceholderView: some View {
        HStack(spacing: 20) {
            Color(.systemGray)
                .aspectRatio(.init(width: 1, height: 0.5625), contentMode: .fill)
                .cornerRadius(8)
                .shadow(radius: 8)
            VStack(alignment: .leading, spacing: 8) {
                Color(.systemGray2)
                    .frame(width: 100, height: 10)
                Color(.systemGray3)
                    .frame(width: 80, height: 10)
            }
            .frame(minWidth: 0, maxWidth: .infinity, alignment: .leading)
        }
    }
}

extension NextUpEntryView {
    var headerSymbol: some View {
        Image("WidgetHeaderSymbol")
            .resizable()
            .frame(width: 12, height: 12)
            .cornerRadius(4)
            .shadow(radius: 8)
    }

    func smallVideoView(item: (BaseItemDto, UIImage?)) -> some View {
        let url = URL(string: "widget-extension://Users/\(SessionManager.main.currentLogin.user.id)/Items/\(item.0.id!)")!
        return Link(destination: url, label: {
            VStack(alignment: .leading) {
                if let image = item.1 {
                    Image(uiImage: image)
                        .resizable()
                        .aspectRatio(.init(width: 1, height: 0.5625), contentMode: .fill)
                        .clipped()
                        .cornerRadius(8)
                        .shadow(radius: 8)
                }
                Text(item.0.seriesName ?? "")
                    .font(.caption)
                    .fontWeight(.semibold)
                    .foregroundColor(.primary)
                    .lineLimit(1)
                Text(
                    "\(item.0.name ?? "") · \(L10n.seasonAndEpisode(String(item.0.parentIndexNumber ?? 0), String(item.0.indexNumber ?? 0)))"
                )
                .font(.caption)
                .fontWeight(.semibold)
                .foregroundColor(.secondary)
                .lineLimit(1)
            }
        })
    }

    func largeVideoView(item: (BaseItemDto, UIImage?)) -> some View {
        let url = URL(string: "widget-extension://Users/\(SessionManager.main.currentLogin.user.id)/Items/\(item.0.id!)")!
        return Link(destination: url, label: {
            HStack(spacing: 20) {
                if let image = item.1 {
                    Image(uiImage: image)
                        .resizable()
                        .aspectRatio(.init(width: 1, height: 0.5625), contentMode: .fill)
                        .clipped()
                        .cornerRadius(8)
                        .shadow(radius: 8)
                }
                VStack(alignment: .leading, spacing: 8) {
                    Text(item.0.seriesName ?? "")
                        .font(.caption)
                        .fontWeight(.semibold)
                        .foregroundColor(.primary)
                        .frame(minWidth: 0, maxWidth: .infinity, alignment: .leading)

                    Text(
                        "\(item.0.name ?? "") · \(L10n.seasonAndEpisode(String(item.0.parentIndexNumber ?? 0), String(item.0.indexNumber ?? 0)))"
                    )
                    .font(.caption)
                    .fontWeight(.semibold)
                    .foregroundColor(.secondary)
                    .frame(minWidth: 0, maxWidth: .infinity, alignment: .leading)
                }
            }
        })
    }
}

extension NextUpEntryView {
    func small(item: (BaseItemDto, UIImage?)?) -> some View {
        VStack(alignment: .trailing) {
            headerSymbol
            if let item = item {
                smallVideoView(item: item)
            } else {
                smallVideoPlaceholderView
            }
        }
        .padding(12)
    }

    func medium(items: [(BaseItemDto, UIImage?)]) -> some View {
        VStack(alignment: .trailing) {
            headerSymbol
            HStack(spacing: 16) {
                if let firstItem = items[safe: 0] {
                    smallVideoView(item: firstItem)
                } else {
                    smallVideoPlaceholderView
                }
                if let secondItem = items[safe: 1] {
                    smallVideoView(item: secondItem)
                } else {
                    smallVideoPlaceholderView
                }
            }
        }
        .padding(12)
    }

    func large(items: [(BaseItemDto, UIImage?)]) -> some View {
        VStack(spacing: 0) {
            if let firstItem = items[safe: 0] {
                let url = URL(string: "widget-extension://Users/\(SessionManager.main.currentLogin.user.id)/Items/\(firstItem.0.id!)")!
                Link(
                    destination: url,
                    label: {
                        ZStack(alignment: .topTrailing) {
                            ZStack(alignment: .bottomLeading) {
                                if let image = firstItem.1 {
                                    Image(uiImage: image)
                                        .centerCropped()
                                        .innerShadow(color: Color.black.opacity(0.5), radius: 0.5)
                                }
                                VStack(alignment: .leading, spacing: 8) {
                                    Text(firstItem.0.seriesName ?? "")
                                        .font(.caption)
                                        .fontWeight(.semibold)
                                        .foregroundColor(.white)
                                        .frame(minWidth: 0, maxWidth: .infinity, alignment: .leading)
                                    Text(
                                        "\(firstItem.0.name ?? "") · \(L10n.seasonAndEpisode(String(firstItem.0.parentIndexNumber ?? 0), String(firstItem.0.indexNumber ?? 0)))"
                                    )
                                    .font(.caption)
                                    .fontWeight(.semibold)
                                    .foregroundColor(.gray)
                                    .frame(minWidth: 0, maxWidth: .infinity, alignment: .leading)
                                }
                                .shadow(radius: 8)
                                .padding(12)
                            }
                            headerSymbol
                                .padding(12)
                        }
                        .clipped()
                        .shadow(radius: 8)
                    }
                )
            }
            VStack(spacing: 8) {
                if let secondItem = items[safe: 1] {
                    largeVideoView(item: secondItem)
                } else {
                    largeVideoPlaceholderView
                }
                Divider()
                if let thirdItem = items[safe: 2] {
                    largeVideoView(item: thirdItem)
                } else {
                    largeVideoPlaceholderView
                }
            }
            .padding(12)
        }
    }
}

struct NextUpWidget: Widget {
    let kind: String = "NextUpWidget"

    var body: some WidgetConfiguration {
        StaticConfiguration(
            kind: kind,
            provider: NextUpWidgetProvider()
        ) { entry in
            NextUpEntryView(entry: entry)
        }
        .configurationDisplayName(L10n.nextUp)
        .description("Keep watching where you left off or see what's up next.")
        .supportedFamilies([.systemSmall, .systemMedium, .systemLarge])
    }
}

struct NextUpWidget_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [(
                    .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                    UIImage(named: "WidgetHeaderSymbol")
                )],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemSmall))
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [
                    (
                        .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                    (
                        .init(name: "Name1", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series1"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                ],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemMedium))
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [
                    (
                        .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                    (
                        .init(name: "Name1", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series1"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                    (
                        .init(name: "Name2", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series2"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                ],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemLarge))
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [(
                    .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                    UIImage(named: "WidgetHeaderSymbol")
                )],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemSmall))
            .preferredColorScheme(.dark)
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [
                    (
                        .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                    (
                        .init(name: "Name1", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series1"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                ],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemMedium))
            .preferredColorScheme(.dark)
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [
                    (
                        .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                    (
                        .init(name: "Name1", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series1"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                    (
                        .init(name: "Name2", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series2"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                ],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemLarge))
            .preferredColorScheme(.dark)
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemSmall))
            .preferredColorScheme(.dark)
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [
                    (
                        .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                ],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemMedium))
            .preferredColorScheme(.dark)
            NextUpEntryView(entry: .init(
                date: Date(),
                items: [
                    (
                        .init(name: "Name0", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series0"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                    (
                        .init(name: "Name1", indexNumber: 10, parentIndexNumber: 0, seriesName: "Series1"),
                        UIImage(named: "WidgetHeaderSymbol")
                    ),
                ],
                error: nil
            ))
            .previewContext(WidgetPreviewContext(family: .systemLarge))
            .preferredColorScheme(.dark)
        }
    }
}

import SwiftUI

private extension View {
    func innerShadow(color: Color, radius: CGFloat = 0.1) -> some View {
        modifier(InnerShadow(color: color, radius: min(max(0, radius), 1)))
    }
}

private struct InnerShadow: ViewModifier {
    var color: Color = .gray
    var radius: CGFloat = 0.1

    private var colors: [Color] {
        [color.opacity(0.75), color.opacity(0.0), .clear]
    }

    func body(content: Content) -> some View {
        GeometryReader { geo in
            content
                .overlay(
                    LinearGradient(gradient: Gradient(colors: self.colors), startPoint: .top, endPoint: .bottom)
                        .frame(height: self.radius * self.minSide(geo)),
                    alignment: .top
                )
                .overlay(
                    LinearGradient(gradient: Gradient(colors: self.colors), startPoint: .bottom, endPoint: .top)
                        .frame(height: self.radius * self.minSide(geo)),
                    alignment: .bottom
                )
        }
    }

    func minSide(_ geo: GeometryProxy) -> CGFloat {
        CGFloat(3) * min(geo.size.width, geo.size.height) / 2
    }
}