import Foundation
import CallKit
import AVFoundation
import Postbox
import SwiftSignalKit

public final class CallKitIntegration {
    private let providerDelegate: AnyObject
    
    public static var isAvailable: Bool {
        #if (arch(i386) || arch(x86_64)) && os(iOS)
        return false
        #endif
        
        if #available(iOSApplicationExtension 10.0, *) {
            return Locale.current.regionCode?.lowercased() != "cn"
        } else {
            return false
        }
    }
    
    private let audioSessionActivePromise = ValuePromise<Bool>(false, ignoreRepeated: true)
    var audioSessionActive: Signal<Bool, NoError> {
        return self.audioSessionActivePromise.get()
    }
    
    init?(startCall: @escaping (UUID, String) -> Signal<Bool, NoError>, answerCall: @escaping (UUID) -> Void, endCall: @escaping (UUID) -> Signal<Bool, NoError>, audioSessionActivationChanged: @escaping (Bool) -> Void) {
        if !CallKitIntegration.isAvailable {
            return nil
        }
    
        #if (arch(i386) || arch(x86_64)) && os(iOS)
        return nil
        #else
        
        if #available(iOSApplicationExtension 10.0, *) {
            self.providerDelegate = CallKitProviderDelegate(audioSessionActivePromise: self.audioSessionActivePromise, startCall: startCall, answerCall: answerCall, endCall: endCall, audioSessionActivationChanged: audioSessionActivationChanged)
        } else {
            return nil
        }
        #endif
    }
    
    func startCall(peerId: PeerId, displayTitle: String) {
        if #available(iOSApplicationExtension 10.0, *) {
            (self.providerDelegate as! CallKitProviderDelegate).startCall(peerId: peerId, displayTitle: displayTitle)
        }
    }
    
    func answerCall(uuid: UUID) {
        if #available(iOSApplicationExtension 10.0, *) {
            (self.providerDelegate as! CallKitProviderDelegate).answerCall(uuid: uuid)
        }
    }
    
    func dropCall(uuid: UUID) {
        if #available(iOSApplicationExtension 10.0, *) {
            (self.providerDelegate as! CallKitProviderDelegate).dropCall(uuid: uuid)
        }
    }
    
    func reportIncomingCall(uuid: UUID, handle: String, displayTitle: String, completion: ((NSError?) -> Void)?) {
        if #available(iOSApplicationExtension 10.0, *) {
            (self.providerDelegate as! CallKitProviderDelegate).reportIncomingCall(uuid: uuid, handle: handle, displayTitle: displayTitle, completion: completion)
        }
    }
    
    func reportOutgoingCallConnected(uuid: UUID, at date: Date) {
        if #available(iOSApplicationExtension 10.0, *) {
            (self.providerDelegate as! CallKitProviderDelegate).reportOutgoingCallConnected(uuid: uuid, at: date)
        }
    }
}

@available(iOSApplicationExtension 10.0, *)
class CallKitProviderDelegate: NSObject, CXProviderDelegate {
    private let provider: CXProvider
    private let callController = CXCallController()
    
    private let startCall: (UUID, String) -> Signal<Bool, NoError>
    private let answerCall: (UUID) -> Void
    private let endCall: (UUID) -> Signal<Bool, NoError>
    private let audioSessionActivationChanged: (Bool) -> Void
    
    private let disposableSet = DisposableSet()
    
    fileprivate let audioSessionActivePromise: ValuePromise<Bool>
    
    init(audioSessionActivePromise: ValuePromise<Bool>, startCall: @escaping (UUID, String) -> Signal<Bool, NoError>, answerCall: @escaping (UUID) -> Void, endCall: @escaping (UUID) -> Signal<Bool, NoError>, audioSessionActivationChanged: @escaping (Bool) -> Void) {
        self.audioSessionActivePromise = audioSessionActivePromise
        self.startCall = startCall
        self.answerCall = answerCall
        self.endCall = endCall
        self.audioSessionActivationChanged = audioSessionActivationChanged
        
        self.provider = CXProvider(configuration: CallKitProviderDelegate.providerConfiguration)
        
        super.init()
        
        self.provider.setDelegate(self, queue: nil)
    }
    
    static var providerConfiguration: CXProviderConfiguration {
        let providerConfiguration = CXProviderConfiguration(localizedName: "Telegram")
        
        providerConfiguration.supportsVideo = false
        providerConfiguration.maximumCallsPerCallGroup = 1
        providerConfiguration.maximumCallGroups = 1
        providerConfiguration.supportedHandleTypes = [.phoneNumber, .generic]
        if let image = UIImage(bundleImageName: "Call/CallKitLogo") {
            providerConfiguration.iconTemplateImageData = UIImagePNGRepresentation(image)
        }
        
        return providerConfiguration
    }
    
    private func requestTransaction(_ transaction: CXTransaction, completion: ((Bool) -> Void)? = nil) {
        self.callController.request(transaction) { error in
            if let error = error {
                print("Error requesting transaction: \(error)")
            }
            completion?(error == nil)
        }
    }
    
    func endCall(uuid: UUID) {
        let endCallAction = CXEndCallAction(call: uuid)
        let transaction = CXTransaction(action: endCallAction)
        self.requestTransaction(transaction)
    }
    
    func dropCall(uuid: UUID) {
        self.provider.reportCall(with: uuid, endedAt: nil, reason: CXCallEndedReason.remoteEnded)
    }
    
    func answerCall(uuid: UUID) {
        
    }
    
    func startCall(peerId: PeerId, displayTitle: String) {
        let uuid = UUID()
        let handle = CXHandle(type: .generic, value: "\(peerId.id)")
        let startCallAction = CXStartCallAction(call: uuid, handle: handle)
        startCallAction.contactIdentifier = displayTitle

        startCallAction.isVideo = false
        let transaction = CXTransaction(action: startCallAction)
        
        self.requestTransaction(transaction, completion: { _ in
            let update = CXCallUpdate()
            update.remoteHandle = handle
            update.localizedCallerName = displayTitle
            update.supportsHolding = false
            update.supportsGrouping = false
            update.supportsUngrouping = false
            update.supportsDTMF = false
            
            self.provider.reportCall(with: uuid, updated: update)
        })
    }
    
    func reportIncomingCall(uuid: UUID, handle: String, displayTitle: String, completion: ((NSError?) -> Void)?) {
        let update = CXCallUpdate()
        update.remoteHandle = CXHandle(type: .generic, value: handle)
        update.localizedCallerName = displayTitle
        update.supportsHolding = false
        update.supportsGrouping = false
        update.supportsUngrouping = false
        update.supportsDTMF = false
        
        self.provider.reportNewIncomingCall(with: uuid, update: update, completion: { error in
            completion?(error as NSError?)
        })
    }
    
    func reportOutgoingCallConnecting(uuid: UUID, at date: Date) {
        self.provider.reportOutgoingCall(with: uuid, startedConnectingAt: date)
    }
    
    func reportOutgoingCallConnected(uuid: UUID, at date: Date) {
        self.provider.reportOutgoingCall(with: uuid, connectedAt: date)
    }
    
    func providerDidReset(_ provider: CXProvider) {
        /*stopAudio()
        
        for call in callManager.calls {
            call.end()
        }
        
        callManager.removeAllCalls()*/
    }
    
    func provider(_ provider: CXProvider, perform action: CXStartCallAction) {
        let disposable = MetaDisposable()
        self.disposableSet.add(disposable)
        disposable.set((self.startCall(action.callUUID, action.handle.value)
            |> deliverOnMainQueue
            |> afterDisposed { [weak self, weak disposable] in
                if let strongSelf = self, let disposable = disposable {
                    strongSelf.disposableSet.remove(disposable)
                }
        }).start(next: { result in
            if result {
                action.fulfill()
            } else {
                action.fail()
            }
        }))
    }
    
    func provider(_ provider: CXProvider, perform action: CXAnswerCallAction) {
        self.answerCall(action.callUUID)
        
        action.fulfill()
    }
    
    func provider(_ provider: CXProvider, perform action: CXEndCallAction) {
        let disposable = MetaDisposable()
        self.disposableSet.add(disposable)
        disposable.set((self.endCall(action.callUUID)
            |> deliverOnMainQueue
            |> afterDisposed { [weak self, weak disposable] in
                if let strongSelf = self, let disposable = disposable {
                    strongSelf.disposableSet.remove(disposable)
                }
            }).start(next: { result in
                if result {
                    action.fulfill(withDateEnded: Date())
                } else {
                    action.fail()
                }
            }))
    }
    
    func provider(_ provider: CXProvider, didActivate audioSession: AVAudioSession) {
        self.audioSessionActivationChanged(true)
        self.audioSessionActivePromise.set(true)
    }
    
    func provider(_ provider: CXProvider, didDeactivate audioSession: AVAudioSession) {
        self.audioSessionActivationChanged(false)
        self.audioSessionActivePromise.set(false)
    }
}