import AppKit
import Sparkle

@MainActor
final class Updater: NSObject, SPUUserDriver, SPUUpdaterDelegate {
    static let shared = Updater()
    private var updater: SPUUpdater?
    private var now = false
    private var staged: (item: SUAppcastItem, install: () -> Void)?

    func start() {
        let updater = SPUUpdater(hostBundle: .main, applicationBundle: .main, userDriver: self, delegate: self)
        self.updater = updater
        do {
            try updater.start()
        } catch {
            tell("Updates are off", error.localizedDescription)
        }
    }

    func check() {
        if let staged {
            if ask(staged.item) {
                staged.install()
            }
            return
        }
        updater?.checkForUpdates()
    }

    private func ask(_ item: SUAppcastItem) -> Bool {
        let current = Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as? String ?? ""
        let alert = NSAlert()
        alert.messageText = "Byre \(item.displayVersionString) is available"
        alert.informativeText = "You have \(current)."
        alert.addButton(withTitle: "Update Now")
        alert.addButton(withTitle: "Update on Quit")
        NSApp.activate()
        return alert.runModal() == .alertFirstButtonReturn
    }

    private func tell(_ message: String, _ info: String) {
        let alert = NSAlert()
        alert.messageText = message
        alert.informativeText = info
        NSApp.activate()
        alert.runModal()
    }

    func updater(_ updater: SPUUpdater, willInstallUpdateOnQuit item: SUAppcastItem, immediateInstallationBlock immediateInstallHandler: @escaping () -> Void) -> Bool {
        staged = (item, immediateInstallHandler)
        if ask(item) {
            immediateInstallHandler()
        }
        return true
    }

    func show(_ request: SPUUpdatePermissionRequest, reply: @escaping (SUUpdatePermissionResponse) -> Void) {
        reply(SUUpdatePermissionResponse(automaticUpdateChecks: true, sendSystemProfile: false))
    }

    func showUserInitiatedUpdateCheck(cancellation: @escaping () -> Void) {}

    func showUpdateFound(with appcastItem: SUAppcastItem, state: SPUUserUpdateState, reply: @escaping (SPUUserUpdateChoice) -> Void) {
        now = ask(appcastItem)
        if !now && state.stage == .installing {
            reply(.dismiss)
            return
        }
        reply(.install)
    }

    func showUpdateReleaseNotes(with downloadData: SPUDownloadData) {}

    func showUpdateReleaseNotesFailedToDownloadWithError(_ error: any Error) {}

    func showUpdateNotFoundWithError(_ error: any Error, acknowledgement: @escaping () -> Void) {
        tell(error.localizedDescription, (error as NSError).localizedRecoverySuggestion ?? "")
        acknowledgement()
    }

    func showUpdaterError(_ error: any Error, acknowledgement: @escaping () -> Void) {
        tell("Update failed", error.localizedDescription)
        acknowledgement()
    }

    func showDownloadInitiated(cancellation: @escaping () -> Void) {}

    func showDownloadDidReceiveExpectedContentLength(_ expectedContentLength: UInt64) {}

    func showDownloadDidReceiveData(ofLength length: UInt64) {}

    func showDownloadDidStartExtractingUpdate() {}

    func showExtractionReceivedProgress(_ progress: Double) {}

    func showReady(toInstallAndRelaunch reply: @escaping (SPUUserUpdateChoice) -> Void) {
        reply(now ? .install : .dismiss)
    }

    func showInstallingUpdate(withApplicationTerminated applicationTerminated: Bool, retryTerminatingApplication: @escaping () -> Void) {}

    func showUpdateInstalledAndRelaunched(_ relaunched: Bool, acknowledgement: @escaping () -> Void) {
        acknowledgement()
    }

    func dismissUpdateInstallation() {}
}