//
// Copyright 2022 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import Combine
import MatrixSDK

class UserSessionOverviewService: UserSessionOverviewServiceProtocol {

    // MARK: - Members
    
    private(set) var pusherEnabledSubject: CurrentValueSubject<Bool?, Never>
    private(set) var remotelyTogglingPushersAvailableSubject: CurrentValueSubject<Bool, Never>

    // MARK: - Private
    
    private let session: MXSession
    private let sessionInfo: UserSessionInfo
    private var pusher: MXPusher?
    private var localNotificationSettings: [String: Any]?
    
    // MARK: - Setup
    
    init(session: MXSession, sessionInfo: UserSessionInfo) {
        self.session = session
        self.sessionInfo = sessionInfo
        self.pusherEnabledSubject = CurrentValueSubject(nil)
        self.remotelyTogglingPushersAvailableSubject = CurrentValueSubject(false)
        
        self.localNotificationSettings = session.accountData.localNotificationSettingsForDevice(withId: sessionInfo.id)
        
        if let localNotificationSettings = localNotificationSettings, let isSilenced = localNotificationSettings[kMXAccountDataIsSilencedKey] as? Bool {
            remotelyTogglingPushersAvailableSubject.send(true)
            pusherEnabledSubject.send(!isSilenced)
        }
        
        checkPusher { [weak self] in
            guard self?.pusher != nil else {
                return
            }
            
            self?.checkServerVersions()
        }
    }
    
    // MARK: - UserSessionOverviewServiceProtocol
    
    func togglePushNotifications() {
        guard let pusher = pusher, let enabled = pusher.enabled?.boolValue else {
            updateLocalNotification()
            return
        }

        toggle(pusher, enabled: !enabled)
    }

    // MARK: - Private
    
    private func toggle(_ pusher: MXPusher, enabled: Bool) {
        guard self.remotelyTogglingPushersAvailableSubject.value else {
            MXLog.warning("[UserSessionOverviewService] toggle pusher canceled: remotely toggling pushers not available")
            return
        }

        MXLog.debug("[UserSessionOverviewService] remotely toggling pusher")
        let data = pusher.data.jsonDictionary() as? [String: Any] ?? [:]
        
        self.session.matrixRestClient.setPusher(pushKey: pusher.pushkey,
                                                kind: MXPusherKind(value: pusher.kind),
                                                appId: pusher.appId,
                                                appDisplayName:pusher.appDisplayName,
                                                deviceDisplayName: pusher.deviceDisplayName,
                                                profileTag: pusher.profileTag ?? "",
                                                lang: pusher.lang,
                                                data: data,
                                                append: false,
                                                enabled: enabled) { [weak self] response in
            guard let self = self else { return }
            
            switch response {
            case .success:
                if let account = MXKAccountManager.shared().activeAccounts.first, account.device?.deviceId == pusher.deviceId {
                    account.loadCurrentPusher(nil)
                }
                
                self.checkPusher()
            case .failure(let error):
                MXLog.warning("[UserSessionOverviewService] togglePusher failed due to error: \(error)")
                self.pusherEnabledSubject.send(!enabled)
            }
        }
    }
    
    private func updateLocalNotification() {
        guard var localNotificationSettings = localNotificationSettings, let isSilenced = localNotificationSettings[kMXAccountDataIsSilencedKey] as? Bool else {
            MXLog.warning("[UserSessionOverviewService] updateLocalNotification canceled: \"\(kMXAccountDataIsSilencedKey)\" notification property not found")
            return
        }
        
        localNotificationSettings[kMXAccountDataIsSilencedKey] = !isSilenced
        session.setAccountData(localNotificationSettings, forType: MXAccountData.localNotificationSettingsKeyForDevice(withId: sessionInfo.id)) { [weak self] in
            self?.localNotificationSettings = localNotificationSettings
            self?.pusherEnabledSubject.send(isSilenced)
        } failure: { [weak self] error in
            MXLog.warning("[UserSessionOverviewService] updateLocalNotification failed due to error: \(String(describing: error))")
            self?.pusherEnabledSubject.send(!isSilenced)
        }
    }

    private func checkServerVersions() {
        session.supportedMatrixVersions { [weak self] response in
            switch response {
            case .success(let versions):
                self?.remotelyTogglingPushersAvailableSubject.send(versions.supportsRemotelyTogglingPushNotifications)
            case .failure(let error):
                MXLog.warning("[UserSessionOverviewService] checkServerVersions failed due to error: \(error)")
            }
        }
    }
    
    private func checkPusher(_ completion: (() -> Void)? = nil) {
        session.matrixRestClient.pushers { [weak self] response in
            switch response {
            case .success(let pushers):
                self?.check(pushers: pushers)
            case .failure(let error):
                MXLog.warning("[UserSessionOverviewService] checkPusher failed due to error: \(error)")
            }
            completion?()
        }
    }
    
    private func check(pushers: [MXPusher]) {
        for pusher in pushers where pusher.deviceId == sessionInfo.id {
            self.pusher = pusher
            
            guard let enabled = pusher.enabled else {
                // For backwards compatibility, any pusher without an enabled field should be treated as if enabled is false
                pusherEnabledSubject.send(false)
                return
            }
            
            pusherEnabledSubject.send(enabled.boolValue)
        }
    }
}