//
//  Copyright (c) 2021 Open Whisper Systems. All rights reserved.
//

import Foundation
import SignalRingRTC

class GroupCallNotificationView: UIView {
    private let call: SignalCall

    private struct ActiveMember: Hashable {
        let demuxId: UInt32
        let uuid: UUID
        var address: String { return "" }
    }
    private var activeMembers = Set<ActiveMember>()
    private var membersPendingJoinNotification = Set<ActiveMember>()
    private var membersPendingLeaveNotification = Set<ActiveMember>()

    init(call: SignalCall) {
        self.call = call
        super.init(frame: .zero)

        call.addObserverAndSyncState(observer: self)

        isUserInteractionEnabled = false
    }

    deinit { call.removeObserver(self) }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private var hasJoined = false
    private func updateActiveMembers() {
        let newActiveMembers = Set(call.groupCall.remoteDeviceStates.values.map {
            ActiveMember(demuxId: $0.demuxId, uuid: $0.userId)
        })

        if hasJoined {
            let joinedMembers = newActiveMembers.subtracting(activeMembers)
            let leftMembers = activeMembers.subtracting(newActiveMembers)

            membersPendingJoinNotification.subtract(leftMembers)
            membersPendingJoinNotification.formUnion(joinedMembers)

            membersPendingLeaveNotification.subtract(joinedMembers)
            membersPendingLeaveNotification.formUnion(leftMembers)
        } else {
            hasJoined = call.groupCall.localDeviceState.joinState == .joined
        }

        activeMembers = newActiveMembers

        presentNextNotificationIfNecessary()
    }

    private var isPresentingNotification = false
    private func presentNextNotificationIfNecessary() {
        guard !isPresentingNotification else { return }

        guard let bannerView: BannerView = {
            if membersPendingJoinNotification.count > 0 {
                callService.audioService.playJoinSound()
                let addresses = membersPendingJoinNotification.map { $0.address }
                membersPendingJoinNotification.removeAll()
                return BannerView(addresses: addresses, action: .join)
            } else if membersPendingLeaveNotification.count > 0 {
                callService.audioService.playLeaveSound()
                let addresses = membersPendingLeaveNotification.map { $0.address }
                membersPendingLeaveNotification.removeAll()
                return BannerView(addresses: addresses, action: .leave)
            } else {
                return nil
            }
        }() else { return }

        isPresentingNotification = true

        addSubview(bannerView)
        bannerView.autoHCenterInSuperview()

        // Prefer to be full width, but don't exceed the maximum width
        bannerView.autoSetDimension(.width, toSize: 512, relation: .lessThanOrEqual)
        bannerView.autoMatch(
            .width,
            to: .width,
            of: self,
            withOffset: -(layoutMargins.left + layoutMargins.right),
            relation: .lessThanOrEqual
        )
        NSLayoutConstraint.autoSetPriority(.defaultHigh) {
            bannerView.autoPinWidthToSuperviewMargins()
        }

        let onScreenConstraint = bannerView.autoPinEdge(toSuperviewMargin: .top)
        onScreenConstraint.isActive = false

        let offScreenConstraint = bannerView.autoPinEdge(.bottom, to: .top, of: self)

        layoutIfNeeded()

        firstly(on: .main) {
            UIView.animate(.promise, duration: 0.35) {
                offScreenConstraint.isActive = false
                onScreenConstraint.isActive = true

                self.layoutIfNeeded()
            }
        }.then(on: .main) { _ in
            UIView.animate(.promise, duration: 0.35, delay: 2, options: .curveEaseInOut) {
                onScreenConstraint.isActive = false
                offScreenConstraint.isActive = true

                self.layoutIfNeeded()
            }
        }.done(on: .main) { _ in
            bannerView.removeFromSuperview()
            self.isPresentingNotification = false
            self.presentNextNotificationIfNecessary()
        }
    }
}

extension GroupCallNotificationView: CallObserver {
    func groupCallRemoteDeviceStatesChanged(_ call: SignalCall) {
        AssertIsOnMainThread()
        owsAssertDebug(call.isGroupCall)

        updateActiveMembers()
    }

    func groupCallPeekChanged(_ call: SignalCall) {
        AssertIsOnMainThread()
        owsAssertDebug(call.isGroupCall)

        updateActiveMembers()
    }

    func groupCallEnded(_ call: SignalCall, reason: GroupCallEndReason) {
        AssertIsOnMainThread()
        owsAssertDebug(call.isGroupCall)

        hasJoined = false
        activeMembers.removeAll()
        membersPendingJoinNotification.removeAll()
        membersPendingLeaveNotification.removeAll()

        updateActiveMembers()
    }
}

private class BannerView: UIView {
    enum Action: Equatable { case join, leave }

    init(addresses: [String], action: Action) {
        super.init(frame: .zero)

        owsAssertDebug(!addresses.isEmpty)

        autoSetDimension(.height, toSize: 64, relation: .greaterThanOrEqual)
        layer.cornerRadius = 8
        clipsToBounds = true

        if UIAccessibility.isReduceTransparencyEnabled {
            backgroundColor = .black.withAlphaComponent(0.8)
        } else {
            let blurEffectView = UIVisualEffectView(effect: UIBlurEffect(style: .dark))
            addSubview(blurEffectView)
            blurEffectView.autoPinEdgesToSuperviewEdges()
            backgroundColor = .black.withAlphaComponent(0.4)
        }

        let displayNames = addresses.map { publicKey in
            Storage.shared.getContact(with: publicKey)?.displayName(for: .regular) ?? publicKey
        }.sorted { $0 < $1 }
        
        let actionText: String
        if displayNames.count > 2 {
            let formatText = action == .join
                ? NSLocalizedString(
                    "GROUP_CALL_NOTIFICATION_MANY_JOINED_FORMAT",
                    comment: "Copy explaining that many new users have joined the group call. Embeds {first member name}, {second member name}, {number of additional members}"
                )
                : NSLocalizedString(
                    "GROUP_CALL_NOTIFICATION_MANY_LEFT_FORMAT",
                    comment: "Copy explaining that many users have left the group call. Embeds {first member name}, {second member name}, {number of additional members}"
                )
            actionText = String(format: formatText, displayNames[0], displayNames[1], displayNames.count - 2)
        } else if displayNames.count > 1 {
            let formatText = action == .join
                ? NSLocalizedString(
                    "GROUP_CALL_NOTIFICATION_TWO_JOINED_FORMAT",
                    comment: "Copy explaining that two users have joined the group call. Embeds {first member name}, {second member name}"
                )
                : NSLocalizedString(
                    "GROUP_CALL_NOTIFICATION_TWO_LEFT_FORMAT",
                    comment: "Copy explaining that two users have left the group call. Embeds {first member name}, {second member name}"
                )
            actionText = String(format: formatText, displayNames[0], displayNames[1])
        } else {
            let formatText = action == .join
                ? NSLocalizedString(
                    "GROUP_CALL_NOTIFICATION_ONE_JOINED_FORMAT",
                    comment: "Copy explaining that a user has joined the group call. Embeds {member name}"
                )
                : NSLocalizedString(
                    "GROUP_CALL_NOTIFICATION_ONE_LEFT_FORMAT",
                    comment: "Copy explaining that a user has left the group call. Embeds {member name}"
                )
            actionText = String(format: formatText, displayNames[0])
        }

        let hStack = UIStackView()
        hStack.spacing = 12
        hStack.axis = .horizontal
        hStack.isLayoutMarginsRelativeArrangement = true
        hStack.layoutMargins = UIEdgeInsets(top: 12, leading: 12, bottom: 12, trailing: 12)

        addSubview(hStack)
        hStack.autoPinEdgesToSuperviewEdges()

        if addresses.count == 1, let address = addresses.first {
            let avatarContainer = UIView()
            hStack.addArrangedSubview(avatarContainer)
            avatarContainer.autoSetDimension(.width, toSize: 40)

            let avatarView = UIImageView()
            avatarView.layer.cornerRadius = 20
            avatarView.clipsToBounds = true
            avatarContainer.addSubview(avatarView)
            avatarView.autoPinWidthToSuperview()
            avatarView.autoVCenterInSuperview()
            avatarView.autoMatch(.height, to: .width, of: avatarView)

            // TODO: Implement
            
            /*
            if address.isLocalAddress,
               let avatarImage = profileManager.localProfileAvatarImage() {
                avatarView.image = avatarImage
            } else {
                let avatar = Self.avatarBuilder.avatarImageWithSneakyTransaction(forAddress: address,
                                                                                 diameterPoints: 40,
                                                                                 localUserDisplayMode: .asUser)
                avatarView.image = avatar
            }
             */
        }

        let label = UILabel()
        hStack.addArrangedSubview(label)
        label.setCompressionResistanceHorizontalHigh()
        label.numberOfLines = 0
        label.font = .boldSystemFont(ofSize: Values.mediumFontSize)
        label.textColor = .ows_white
        label.text = actionText

        hStack.addArrangedSubview(.hStretchingSpacer())
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}