//
// Copyright 2020 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
//

import SignalServiceKit
import SignalUI

fileprivate extension CVComponentState {

    private static let unfairLock = UnfairLock()
    private static var groupInviteLinkAvatarCache = [String: GroupInviteLinkCachedAvatar]()
    private static var groupInviteLinkAvatarsInFlight = Set<String>()
    private static var expiredGroupInviteLinks = Set<URL>()

    static func updateExpirationList(url: URL, isExpired: Bool) -> Bool {
        unfairLock.withLock {
            let alreadyExpired = expiredGroupInviteLinks.contains(url)
            guard alreadyExpired != isExpired else { return false }

            if isExpired {
                expiredGroupInviteLinks.insert(url)
            } else {
                expiredGroupInviteLinks.remove(url)
            }
            return true
        }
    }

    static func isGroupInviteLinkExpired(_ url: URL) -> Bool {
        unfairLock.withLock {
            expiredGroupInviteLinks.contains(url)
        }
    }

    private static func cachedGroupInviteLinkAvatar(avatarUrlPath: String) -> GroupInviteLinkCachedAvatar? {
        unfairLock.withLock {
            guard let cachedAvatar = groupInviteLinkAvatarCache[avatarUrlPath],
                  cachedAvatar.isValid else {
                return nil
            }
            return cachedAvatar
        }
    }

    private static func loadGroupInviteLinkAvatar(avatarUrlPath: String,
                                                  groupInviteLinkInfo: GroupInviteLinkInfo) -> Promise<Void> {
        Self.unfairLock.withLock {
            guard !groupInviteLinkAvatarsInFlight.contains(avatarUrlPath) else {
                return
            }
            groupInviteLinkAvatarsInFlight.insert(avatarUrlPath)
        }

        return firstly(on: DispatchQueue.global()) { () -> Promise<Data> in
            let groupV2ContextInfo = try Self.groupsV2.groupV2ContextInfo(forMasterKeyData: groupInviteLinkInfo.masterKey)
            return Promise.wrapAsync {
                try await self.groupsV2Impl.fetchGroupInviteLinkAvatar(
                    avatarUrlPath: avatarUrlPath,
                    groupSecretParamsData: groupV2ContextInfo.groupSecretParamsData
                )
            }
        }.map(on: DispatchQueue.global()) { (avatarData: Data) -> Void in
            let imageMetadata = avatarData.imageMetadata(withPath: nil, mimeType: nil)
            let cacheFileUrl = OWSFileSystem.temporaryFileUrl(fileExtension: imageMetadata.fileExtension,
                                                              isAvailableWhileDeviceLocked: true)
            guard imageMetadata.isValid else {
                let cachedAvatar = GroupInviteLinkCachedAvatar(cacheFileUrl: cacheFileUrl,
                                                               imageSizePixels: imageMetadata.pixelSize,
                                                               isValid: false)
                Self.unfairLock.withLock {
                    Self.groupInviteLinkAvatarCache[avatarUrlPath] = cachedAvatar
                    Self.groupInviteLinkAvatarsInFlight.remove(avatarUrlPath)
                }
                throw OWSAssertionError("Invalid group avatar.")
            }
            try avatarData.write(to: cacheFileUrl)
            let cachedAvatar = GroupInviteLinkCachedAvatar(cacheFileUrl: cacheFileUrl,
                                                           imageSizePixels: imageMetadata.pixelSize,
                                                           isValid: true)
            Self.unfairLock.withLock {
                Self.groupInviteLinkAvatarCache[avatarUrlPath] = cachedAvatar
                Self.groupInviteLinkAvatarsInFlight.remove(avatarUrlPath)
            }
        }.recover(on: DispatchQueue.global()) { (error) -> Promise<Void> in
            _ = Self.unfairLock.withLock {
                Self.groupInviteLinkAvatarsInFlight.remove(avatarUrlPath)
            }
            throw error
        }
    }
}

// MARK: -

extension CVComponentState {

    // MARK: - Notifications

    static func configureGroupInviteLink(_ url: URL,
                                         message: TSMessage,
                                         groupInviteLinkInfo: GroupInviteLinkInfo) -> GroupInviteLinkViewModel {

        let touchMessage = {
            Self.databaseStorage.write { transaction in
                Self.databaseStorage.touch(interaction: message, shouldReindex: false, transaction: transaction)
            }
        }

        guard let groupInviteLinkPreview = GroupManager.cachedGroupInviteLinkPreview(groupInviteLinkInfo: groupInviteLinkInfo) else {
            // If there is no cached GroupInviteLinkPreview for this link,
            // try to do load it now. On success, touch the interaction
            // in order to trigger reload of the view.
            firstly(on: DispatchQueue.global()) { () -> Promise<GroupInviteLinkPreview> in
                let groupContextInfo = try Self.groupsV2.groupV2ContextInfo(forMasterKeyData: groupInviteLinkInfo.masterKey)
                return Promise.wrapAsync {
                    try await Self.groupsV2Impl.fetchGroupInviteLinkPreview(
                        inviteLinkPassword: groupInviteLinkInfo.inviteLinkPassword,
                        groupSecretParamsData: groupContextInfo.groupSecretParamsData,
                        allowCached: false
                    )
                }
            }.done(on: DispatchQueue.global()) { (_: GroupInviteLinkPreview) in
                if Self.updateExpirationList(url: url, isExpired: false) {
                    touchMessage()
                }
            }.catch(on: DispatchQueue.global()) { (error: Error) in
                switch error {
                case GroupsV2Error.expiredGroupInviteLink, GroupsV2Error.localUserBlockedFromJoining:
                    Logger.warn("Failed to fetch group link content: \(error)")
                    if Self.updateExpirationList(url: url, isExpired: true) {
                        touchMessage()
                    }
                default:
                    // TODO: Add retry?
                    owsFailDebugUnlessNetworkFailure(error)
                }
            }
            return GroupInviteLinkViewModel(url: url,
                                            groupInviteLinkPreview: nil,
                                            avatar: nil,
                                            isExpired: Self.isGroupInviteLinkExpired(url))
        }

        guard let avatarUrlPath = groupInviteLinkPreview.avatarUrlPath else {
            // If this group link has no avatar, there's nothing left to load.
            return GroupInviteLinkViewModel(url: url,
                                            groupInviteLinkPreview: groupInviteLinkPreview,
                                            avatar: nil,
                                            isExpired: false)
        }

        guard let avatar = Self.cachedGroupInviteLinkAvatar(avatarUrlPath: avatarUrlPath) else {
            // If there is no cached avatar for this link,
            // try to do load it now. On success, touch the interaction
            // in order to trigger reload of the view.
            firstly(on: DispatchQueue.global()) {
                Self.loadGroupInviteLinkAvatar(avatarUrlPath: avatarUrlPath,
                                               groupInviteLinkInfo: groupInviteLinkInfo)
            }.done(on: DispatchQueue.global()) { () in
                touchMessage()
            }.catch { error in
                // TODO: Add retry?
                owsFailDebugUnlessNetworkFailure(error)
            }

            return GroupInviteLinkViewModel(url: url,
                                            groupInviteLinkPreview: groupInviteLinkPreview,
                                            avatar: nil,
                                            isExpired: false)
        }

        return GroupInviteLinkViewModel(url: url,
                                        groupInviteLinkPreview: groupInviteLinkPreview,
                                        avatar: avatar,
                                        isExpired: false)
    }
}