import SwiftUI
import UIKit

final class ShareViewController: UIViewController {
    private let model = ShareViewModel()
    private var inputTask: Task<Void, Never>?
    private var playbackTask: Task<Void, Never>?

    override func viewDidLoad() {
        super.viewDidLoad()
        preferredContentSize = CGSize(width: 480, height: 600)
        let host = UIHostingController(rootView: ShareView(model: model, send: { [weak self] server in
            self?.send(to: server)
        }, close: { [weak self] in
            self?.close()
        }))
        addChild(host)
        host.view.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(host.view)
        NSLayoutConstraint.activate([
            host.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            host.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            host.view.topAnchor.constraint(equalTo: view.topAnchor),
            host.view.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
        host.didMove(toParent: self)
        inputTask = Task { [weak self] in
            guard let self else { return }
            do {
                model.url = try await SharedInput.load(extensionContext?.inputItems ?? [])
            } catch {
                guard !Task.isCancelled else { return }
                model.message = error.localizedDescription
            }
            model.loading = false
        }
    }

    private func send(to server: Server) {
        guard !model.sending, !model.finished, let url = model.url else { return }
        model.sending = true
        model.message = nil
        playbackTask = Task { [weak self] in
            guard let self else { return }
            do {
                try await SharePlayback.enqueueAndPlay(url, using: API(baseURL: server.baseURL, requestTimeout: 8))
                try Task.checkCancellation()
                model.succeeded = true
                model.finished = true
                model.message = "Queued and playing on \(server.displayName)."
            } catch let error as SharePlayback.Failure {
                guard !Task.isCancelled else { return }
                model.message = error.localizedDescription
                model.finished = !error.canRetry
            } catch {
                guard !Task.isCancelled else { return }
                model.message = "The request could not be confirmed. Check the player in QueueCube before sharing again."
                model.finished = true
            }
            model.sending = false
        }
    }

    private func close() {
        inputTask?.cancel()
        playbackTask?.cancel()
        if model.finished {
            extensionContext?.completeRequest(returningItems: nil)
        } else {
            extensionContext?.cancelRequest(withError: NSError(domain: NSCocoaErrorDomain, code: NSUserCancelledError))
        }
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        inputTask?.cancel()
        playbackTask?.cancel()
    }

    deinit {
        inputTask?.cancel()
        playbackTask?.cancel()
    }
}

@MainActor @Observable
private final class ShareViewModel {
    let configuredServers = Settings.fromSharedDefaults().configuredServers
    var url: URL?
    var loading = true
    var sending = false
    var finished = false
    var succeeded = false
    var message: String?
}

private struct ShareView: View {
    @Bindable var model: ShareViewModel
    let send: (Server) -> Void
    let close: () -> Void

    var body: some View {
        NavigationStack {
            Form {
                Section("Video link") {
                    if model.loading {
                        ProgressView("Reading link…")
                    } else if let url = model.url {
                        Text(url.absoluteString)
                            .font(.callout)
                            .lineLimit(1)
                            .truncationMode(.middle)
                    }
                }
                if !model.finished {
                    Section("Choose player") {
                        if model.configuredServers.isEmpty {
                            Text("Open QueueCube to set up your players.")
                                .foregroundStyle(.secondary)
                        }
                        ForEach(model.configuredServers) { server in
                            Button {
                                send(server)
                            } label: {
                                HStack {
                                    Label(server.displayName, systemImage: "hifispeaker.fill")
                                    Spacer()
                                }
                                .foregroundStyle(Color.primary)
                                .contentShape(Rectangle())
                            }
                            .tint(.primary)
                            .disabled(model.url == nil || model.sending)
                        }
                    }
                }
                if model.sending {
                    Section {
                        ProgressView("Queuing and starting playback…")
                    }
                }
                if let message = model.message {
                    Section {
                        Label(message, systemImage: model.succeeded ? "checkmark.circle.fill" : "exclamationmark.circle")
                            .foregroundStyle(model.succeeded ? Color.green : Color.primary)
                    }
                }
            }
            .navigationTitle("QueueCube")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button(model.finished ? "Done" : "Cancel", action: close)
                        .disabled(model.sending)
                }
            }
        }
    }
}