//
// Copyright 2021 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
//

import SignalMessaging
import SignalUI

protocol GroupPermissionsSettingsDelegate: AnyObject {
    func groupPermissionSettingsDidUpdate()
}

class GroupPermissionsSettingsViewController: OWSTableViewController2 {
    private var threadViewModel: ThreadViewModel
    private var thread: TSThread { threadViewModel.threadRecord }
    private var groupViewHelper: GroupViewHelper
    private weak var permissionsDelegate: GroupPermissionsSettingsDelegate?

    private var groupModelV2: TSGroupModelV2! {
        thread.groupModelIfGroupThread as? TSGroupModelV2
    }

    private var oldAccessMembers: GroupV2Access { groupModelV2.access.members }
    private var oldAccessAttributes: GroupV2Access { groupModelV2.access.attributes }
    private var oldIsAnnouncementsOnly: Bool { groupModelV2.isAnnouncementsOnly }

    private lazy var newAccessMembers = oldAccessMembers
    private lazy var newAccessAttributes = oldAccessAttributes
    private lazy var newIsAnnouncementsOnly = oldIsAnnouncementsOnly

    init(threadViewModel: ThreadViewModel, delegate: GroupPermissionsSettingsDelegate) {
        owsAssertDebug(threadViewModel.threadRecord.isGroupV2Thread)
        self.threadViewModel = threadViewModel
        self.groupViewHelper = GroupViewHelper(threadViewModel: threadViewModel)
        self.permissionsDelegate = delegate

        super.init()

        self.groupViewHelper.delegate = self
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        title = OWSLocalizedString(
            "CONVERSATION_SETTINGS_PERMISSIONS",
            comment: "Label for 'permissions' action in conversation settings view."
        )

        updateTableContents()
        updateNavigation()
    }

    private var hasUnsavedChanges: Bool {
        guard groupViewHelper.canEditPermissions else {
            return false
        }

        return (oldAccessMembers != newAccessMembers ||
            oldAccessAttributes != newAccessAttributes ||
            oldIsAnnouncementsOnly != newIsAnnouncementsOnly)
    }

    // Don't allow interactive dismiss when there are unsaved changes.
    override var isModalInPresentation: Bool {
        get { hasUnsavedChanges }
        set {}
    }

    private func updateNavigation() {
        navigationItem.leftBarButtonItem = UIBarButtonItem(
            barButtonSystemItem: .cancel,
            target: self,
            action: #selector(didTapCancel),
            accessibilityIdentifier: "cancel_button"
        )

        if hasUnsavedChanges {
            navigationItem.rightBarButtonItem = UIBarButtonItem(
                title: CommonStrings.setButton,
                style: .done,
                target: self,
                action: #selector(didTapSet),
                accessibilityIdentifier: "set_button"
            )
        } else {
            navigationItem.rightBarButtonItem = nil
        }
    }

    func updateTableContents() {
        let contents = OWSTableContents()
        defer { self.contents = contents }

        let accessMembersSection = OWSTableSection()
        accessMembersSection.headerTitle = OWSLocalizedString(
            "CONVERSATION_SETTINGS_EDIT_MEMBERSHIP_ACCESS",
            comment: "Label for 'edit membership access' action in conversation settings view."
        )
        accessMembersSection.footerTitle = OWSLocalizedString(
            "CONVERSATION_SETTINGS_EDIT_MEMBERSHIP_ACCESS_FOOTER",
            comment: "Description for the 'edit membership access'."
        )

        accessMembersSection.add(.init(
            text: OWSLocalizedString(
                "CONVERSATION_SETTINGS_EDIT_ATTRIBUTES_ACCESS_ALERT_MEMBERS_BUTTON",
                comment: "Label for button that sets 'group attributes access' to 'members-only'."
            ),
            actionBlock: { [weak self] in
                self?.tryToSetAccessMembers(.member)
            },
            accessoryType: newAccessMembers == .member ? .checkmark : .none
        ))
        accessMembersSection.add(.init(
            text: OWSLocalizedString(
                "CONVERSATION_SETTINGS_EDIT_ATTRIBUTES_ACCESS_ALERT_ADMINISTRATORS_BUTTON",
                comment: "Label for button that sets 'group attributes access' to 'administrators-only'."
            ),
            actionBlock: { [weak self] in
                self?.tryToSetAccessMembers(.administrator)
            },
            accessoryType: newAccessMembers == .administrator ? .checkmark : .none
        ))

        contents.add(accessMembersSection)

        let accessAttributesSection = OWSTableSection()
        accessAttributesSection.headerTitle = OWSLocalizedString(
            "CONVERSATION_SETTINGS_EDIT_ATTRIBUTES_ACCESS",
            comment: "Label for 'edit attributes access' action in conversation settings view."
        )
        accessAttributesSection.footerTitle = OWSLocalizedString(
            "CONVERSATION_SETTINGS_ATTRIBUTES_ACCESS_SECTION_FOOTER",
            comment: "Footer for the 'attributes access' section in conversation settings view."
        )

        accessAttributesSection.add(.init(
            text: OWSLocalizedString(
                "CONVERSATION_SETTINGS_EDIT_ATTRIBUTES_ACCESS_ALERT_MEMBERS_BUTTON",
                comment: "Label for button that sets 'group attributes access' to 'members-only'."
            ),
            actionBlock: { [weak self] in
                self?.tryToSetAccessAttributes(.member)
            },
            accessoryType: newAccessAttributes == .member ? .checkmark : .none
        ))
        accessAttributesSection.add(.init(
            text: OWSLocalizedString(
                "CONVERSATION_SETTINGS_EDIT_ATTRIBUTES_ACCESS_ALERT_ADMINISTRATORS_BUTTON",
                comment: "Label for button that sets 'group attributes access' to 'administrators-only'."
            ),
            actionBlock: { [weak self] in
                self?.tryToSetAccessAttributes(.administrator)
            },
            accessoryType: newAccessAttributes == .administrator ? .checkmark : .none
        ))

        contents.add(accessAttributesSection)

        let isAnnouncementsOnly = self.newIsAnnouncementsOnly

        let announcementOnlySection = OWSTableSection()
        announcementOnlySection.headerTitle = OWSLocalizedString(
            "CONVERSATION_SETTINGS_SEND_MESSAGES_SECTION_HEADER",
            comment: "Label for 'send messages' action in conversation settings permissions view."
        )
        announcementOnlySection.footerTitle = OWSLocalizedString(
            "CONVERSATION_SETTINGS_SEND_MESSAGES_SECTION_FOOTER",
            comment: "Footer for the 'send messages' section in conversation settings permissions view."
        )

        announcementOnlySection.add(.init(
            text: OWSLocalizedString(
                "CONVERSATION_SETTINGS_SEND_MESSAGES_SECTION_ALL_MEMBERS",
                comment: "Label for button that sets 'send messages permission' for a group to 'all members'."
            ),
            actionBlock: { [weak self] in
                self?.tryToSetIsAnnouncementsOnly(false)
            },
            accessoryType: !isAnnouncementsOnly ? .checkmark : .none
        ))
        announcementOnlySection.add(.init(
            text: OWSLocalizedString(
                "CONVERSATION_SETTINGS_SEND_MESSAGES_SECTION_ONLY_ADMINS",
                comment: "Label for button that sets 'send messages permission' for a group to 'administrators only'."
            ),
            actionBlock: { [weak self] in
                self?.tryToSetIsAnnouncementsOnly(true)
            },
            accessoryType: isAnnouncementsOnly ? .checkmark : .none
        ))

        contents.add(announcementOnlySection)
    }

    private func tryToSetAccessMembers(_ value: GroupV2Access) {
        guard groupViewHelper.canEditPermissions else {
            showAdminOnlyWarningAlert()
            return
        }
        self.newAccessMembers = value
        self.updateTableContents()
        self.updateNavigation()
    }

    private func tryToSetAccessAttributes(_ value: GroupV2Access) {
        guard groupViewHelper.canEditPermissions else {
            showAdminOnlyWarningAlert()
            return
        }
        self.newAccessAttributes = value
        self.updateTableContents()
        self.updateNavigation()
    }

    private func tryToSetIsAnnouncementsOnly(_ value: Bool) {
        guard groupViewHelper.canEditPermissions else {
            showAdminOnlyWarningAlert()
            return
        }
        newIsAnnouncementsOnly = value
        updateTableContents()
        updateNavigation()
    }

    private func showAdminOnlyWarningAlert() {
        let message = OWSLocalizedString("GROUP_ADMIN_ONLY_WARNING",
                                        comment: "Message indicating that a feature can only be used by group admins.")
        presentToast(text: message)
        updateTableContents()
    }

    private func reloadThreadAndUpdateContent() {
        let didUpdate = self.databaseStorage.read { transaction -> Bool in
            guard let newThread = TSThread.anyFetch(
                uniqueId: self.thread.uniqueId,
                transaction: transaction
            ) else {
                return false
            }
            let newThreadViewModel = ThreadViewModel(
                thread: newThread,
                forChatList: false,
                transaction: transaction
            )
            self.threadViewModel = newThreadViewModel
            self.groupViewHelper = GroupViewHelper(threadViewModel: newThreadViewModel)
            self.groupViewHelper.delegate = self
            return true
        }
        if !didUpdate {
            owsFailDebug("Invalid thread.")
            navigationController?.popViewController(animated: true)
            return
        }

        updateTableContents()
    }

    @objc
    private func didTapCancel() {
        guard hasUnsavedChanges else {
            dismiss(animated: true)
            return
        }

        OWSActionSheets.showPendingChangesActionSheet(discardAction: { [weak self] in
            self?.dismiss(animated: true)
        })
    }

    @objc
    private func didTapSet() {
        guard groupViewHelper.canEditPermissions else {
            owsFailDebug("Missing edit permission.")
            return
        }

        // TODO: We might consolidate this from (up to) 3 separate group changes
        // into a single change.
        GroupViewUtils.updateGroupWithActivityIndicator(
            fromViewController: self,
            withThread: thread,
            updateDescription: "Update group permissions",
            updateBlock: { () -> Promise<Void> in
                // We're sending a message, so we're accepting any pending message request.
                ThreadUtil.addThreadToProfileWhitelistIfEmptyOrPendingRequestAndSetDefaultTimerWithSneakyTransaction(self.thread)

                return firstly { () -> Promise<Void> in
                    if self.newAccessMembers != self.oldAccessMembers {
                        return GroupManager.changeGroupMembershipAccessV2(
                            groupModel: self.groupModelV2,
                            access: self.newAccessMembers
                        ).asVoid()
                    } else {
                        return Promise.value(())
                    }
                }.then { () -> Promise<Void> in
                    if self.newAccessAttributes != self.oldAccessAttributes {
                        return GroupManager.changeGroupAttributesAccessV2(
                            groupModel: self.groupModelV2,
                            access: self.newAccessAttributes
                        ).asVoid()
                    } else {
                        return Promise.value(())
                    }
                }.then { () -> Promise<Void> in
                    if self.newIsAnnouncementsOnly != self.oldIsAnnouncementsOnly {
                        return GroupManager.setIsAnnouncementsOnly(
                            groupModel: self.groupModelV2,
                            isAnnouncementsOnly: self.newIsAnnouncementsOnly
                        ).asVoid()
                    } else {
                        return Promise.value(())
                    }
                }
            },
            completion: { [weak self] _ in
                self?.permissionsDelegate?.groupPermissionSettingsDidUpdate()
                self?.dismiss(animated: true)
            }
        )
    }
}

extension GroupPermissionsSettingsViewController: GroupViewHelperDelegate {
    func groupViewHelperDidUpdateGroup() {
        reloadThreadAndUpdateContent()
    }

    var currentGroupModel: TSGroupModel? {
        thread.groupModelIfGroupThread
    }

    var fromViewController: UIViewController? {
        self
    }
}