//
// Copyright 2025 Element Creations Ltd.
// Copyright 2023-2025 New Vector Ltd.
//
// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
// Please see LICENSE files in the repository root for full details.
//

import Foundation
import MatrixRustSDK

// sourcery: AutoMockable
nonisolated protocol NSEUserSessionProtocol {
    var inviteAvatarsVisibility: InviteAvatars { get async }
    var mediaPreviewVisibility: MediaPreviews { get async }
    var threadsEnabled: Bool { get }
}

final nonisolated class NSEUserSession: NSEUserSessionProtocol {
    let userSettings: UserSettings
    private let baseClient: ClientProtocol
    private let notificationClient: NotificationClient
    private let userID: String
    private(set) lazy var mediaProvider: MediaProviderProtocol = MediaProvider(mediaLoader: MediaLoader(client: baseClient),
                                                                               imageCache: .onlyOnDisk,
                                                                               homeserverReachabilityPublisher: nil)
    private let delegateHandle: TaskHandle?
    
    var mediaPreviewVisibility: MediaPreviews {
        get async {
            do {
                return try await baseClient.getMediaPreviewDisplayPolicy() ?? .on
            } catch {
                MXLog.error("Failed to get media preview visibility, defaulting to on. Error: \(error)")
                return .on
            }
        }
    }
    
    var inviteAvatarsVisibility: InviteAvatars {
        get async {
            do {
                return try await baseClient.getInviteAvatarsDisplayPolicy() ?? .on
            } catch {
                MXLog.error("Failed to get invite avatars visibility, defaulting to on. Error: \(error)")
                return .on
            }
        }
    }
    
    var threadsEnabled: Bool {
        userSettings.app.threadsEnabled
    }
    
    init(credentials: KeychainCredentials,
         roomID: String,
         clientSessionDelegate: ClientSessionDelegate,
         clientFactory: ClientFactoryProtocol = ClientFactory(),
         appSettings: AppSettings,
         appHooks: AppHooks) async throws {
        userID = credentials.userID
        userSettings = appSettings.userSettings(for: credentials.userID)
        
        baseClient = try await clientFactory.makeNSEClient(credentials: credentials,
                                                           roomID: roomID,
                                                           clientSessionDelegate: clientSessionDelegate,
                                                           userSettings: userSettings,
                                                           appHooks: appHooks)
        
        do {
            try await baseClient.setPresence(presence: .offline, immediate: false)
        } catch {
            MXLog.error("Failed configuring offline presence before notification processing with error: \(error)")
        }
        delegateHandle = try baseClient.setDelegate(delegate: ClientDelegateWrapper())
        
        // Inject the content scanner so the SDK gates the media it downloads whilst building the notification.
        if let contentScannerURL = userSettings.app.contentScannerURL.publisher.value {
            let contentScanner = ContentScanner(scannerUrl: contentScannerURL.absoluteString)
            await baseClient.setContentScanner(contentScanner: contentScanner)
        }
        
        notificationClient = try await baseClient.notificationClient(processSetup: .multipleProcesses)
    }
    
    func notificationItemProxy(roomID: String, eventID: String) async -> NotificationItemProxyProtocol? {
        do {
            let notificationStatus = try await notificationClient.getNotification(roomId: roomID, eventId: eventID)
            
            switch notificationStatus {
            case .event(let notification):
                return NotificationItemProxy(notificationItem: notification,
                                             receiverID: userID,
                                             roomID: roomID)
            case .eventNotFound:
                MXLog.error("Notification event not found - roomID: \(roomID) eventID: \(eventID)")
                return nil
            case .eventFilteredOut:
                MXLog.warning("Notification event filtered out - roomID: \(roomID) eventID: \(eventID)")
                return nil
            case .eventRedacted:
                MXLog.warning("Notification event redacted - roomID: \(roomID) eventID: \(eventID)")
                return nil
            }
        } catch {
            MXLog.error("Could not get notification's content creating an empty notification instead, error: \(error)")
            return EmptyNotificationItemProxy(roomID: roomID, receiverID: userID)
        }
    }
    
    func roomForIdentifier(_ roomID: String) -> Room? {
        do {
            return try notificationClient.getRoom(roomId: roomID)
        } catch {
            MXLog.error("Failed retrieving room with error: \(error)")
            return nil
        }
    }
    
    deinit {
        delegateHandle?.cancel()
    }
}

private final nonisolated class ClientDelegateWrapper: ClientDelegate {
    // MARK: - ClientDelegate
    
    func didReceiveAuthError(isSoftLogout: Bool) {
        MXLog.error("Received authentication error, the NSE can't handle this.")
    }
    
    // periphery:ignore - required by the SDK's delegate protocol
    func didRefreshTokens() {
        MXLog.info("Delegating session updates to the ClientSessionDelegate.")
    }
    
    func onBackgroundTaskErrorReport(taskName: String, error: MatrixRustSDK.BackgroundTaskFailureReason) {
        switch error {
        case .panic(let message, let backtrace):
            MXLog.error("Received background task panic: \(message ?? "Missing message")\nBacktrace:\n\(backtrace ?? "Missing backtrace")")
        case .error(let error):
            MXLog.error("Received background task error: \(error)")
        case .earlyTermination:
            MXLog.error("Received background task early termination")
        }
    }
}