//
// Copyright 2025 Element Creations Ltd.
// Copyright 2023-2025 New Vector Ltd.
//
// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
// Please see LICENSE files in the repository root for full details.
//

import CoreLocation
import Foundation
import MatrixRustSDK

enum LocationSharingViewAlert: Hashable {
    case missingAuthorization
    case missingAlwaysAuthorization
    case liveLocationDisclaimer
    case liveLocationDurationSelection
    case mapError(MapLibreError)
}

enum LocationSharingScreenViewModelAction {
    case close
    case openSystemSettings
}

enum LocationSharingInteractionMode: Hashable {
    case picker
    case viewStatic(StaticLocationData)
    case viewLive(sender: TimelineItemSender, initialLiveLocationShare: LiveLocationShare)
}

struct LocationSharingScreenViewState: BindableState {
    init(interactionMode: LocationSharingInteractionMode,
         mapURLBuilder: MapTilerURLBuilderProtocol,
         showLiveLocationSharingButton: Bool,
         ownUserID: String) {
        self.interactionMode = interactionMode
        self.mapURLBuilder = mapURLBuilder
        self.showLiveLocationSharingButton = showLiveLocationSharingButton
        self.ownUserID = ownUserID
        
        let initialProfile: UserProfileProxy = switch interactionMode {
        case .viewStatic(let locationData):
            .init(sender: locationData.sender)
        case .viewLive(let sender, _):
            .init(sender: sender)
        case .picker:
            .init(userID: ownUserID)
        }
        userProfiles = [initialProfile.userID: initialProfile]
        
        if case .viewLive(_, let initialLiveLocationShare) = interactionMode {
            liveLocationShares = [initialLiveLocationShare]
        }
        
        bindings.showsUserLocationMode = switch interactionMode {
        case .picker: .showAndFollow
        case .viewStatic, .viewLive: .show
        }
    }

    let interactionMode: LocationSharingInteractionMode
    let mapURLBuilder: MapTilerURLBuilderProtocol
    let showLiveLocationSharingButton: Bool
    let ownUserID: String
    var userProfiles: [String: UserProfileProxy]
    var liveLocationShares: [LiveLocationShare] = []
    var isStoppingLiveLocation = false
    
    var annotations: [LocationAnnotation] {
        switch interactionMode {
        case .viewStatic(let location):
            let profile = userProfiles.values.first
            let kind: LocationMarkerKind = if location.kind == .sender, let profile {
                .staticUser(profile)
            } else {
                .pin
            }
            let coordinate = CLLocationCoordinate2D(latitude: location.geoURI.latitude, longitude: location.geoURI.longitude)
            return [LocationAnnotation(id: kind.id, coordinate: coordinate, kind: kind)]
        case .viewLive:
            return liveLocationShares.compactMap { share in
                guard let geoURI = share.geoURI else { return nil }
                if share.userID == ownUserID, isStoppingLiveLocation { return nil }
                
                let profile = userProfiles[share.userID] ?? UserProfileProxy(userID: share.userID)
                let kind = LocationMarkerKind.liveUser(profile)
                let coordinate = CLLocationCoordinate2D(latitude: geoURI.latitude, longitude: geoURI.longitude)
                return LocationAnnotation(id: profile.userID, coordinate: coordinate, kind: kind)
            }
        case .picker:
            return []
        }
    }
    
    func isOwnUser(_ userID: String) -> Bool {
        userID == ownUserID
    }
    
    var bindings = LocationSharingScreenBindings(showsUserLocationMode: .hide)
 
    /// Indicates whether the user is sharing his current location
    var isSharingUserLocation: Bool {
        bindings.isLocationAuthorized == true && bindings.showsUserLocationMode == .showAndFollow
    }
    
    var initialMapCenter: CLLocationCoordinate2D {
        switch interactionMode {
        case .picker:
            // middle point in Europe, to be used if the users location is not yet known
            .init(latitude: 49.843, longitude: 9.902056)
        case .viewStatic(let location):
            .init(latitude: location.geoURI.latitude, longitude: location.geoURI.longitude)
        case .viewLive(_, let initialLiveLocationShare):
            .init(latitude: initialLiveLocationShare.geoURI?.latitude ?? 0,
                  longitude: initialLiveLocationShare.geoURI?.longitude ?? 0)
        }
    }
    
    /// Returns true if the user's location has not yet been determined, while location permissions are given or not yet set
    /// Does not work as intended on simulator.
    var isLocationLoading: Bool {
        !bindings.hasLoadedUserLocation && bindings.isLocationAuthorized != false
    }

    var zoomLevel: Double {
        15.0
    }
    
    var initialZoomLevel: Double {
        switch interactionMode {
        case .picker:
            return 2.7
        case .viewStatic, .viewLive:
            return 15.0
        }
    }
    
    /// The marker kind used for the picker overlay (not a map annotation).
    var pickerMarkerKind: LocationMarkerKind? {
        guard case .picker = interactionMode else { return nil }
        if let profile = userProfiles.values.first {
            return isSharingUserLocation ? .staticUser(profile) : .pin
        }
        return .pin
    }
}

struct LocationSharingScreenBindings {
    var mapCenterLocation: CLLocationCoordinate2D?
    var geolocationUncertainty: CLLocationAccuracy?
    var showsUserLocationMode: ShowUserLocationMode
    var hasLoadedUserLocation = false
    var isLocationAuthorized: Bool?
    
    /// Information describing the currently displayed alert.
    var mapError: MapLibreError? {
        get {
            if case let .mapError(error) = alertInfo?.id {
                return error
            }
            return nil
        }
        set {
            alertInfo = newValue.map { AlertInfo(alertID: .mapError($0)) }
        }
    }
    
    /// Information describing the currently displayed alert.
    var alertInfo: AlertInfo<LocationSharingViewAlert>?

    var sharedAnnotation: LocationAnnotation?
}

enum LocationSharingScreenViewAction {
    case close
    case selectLocation
    case startLiveLocation
    case centerToUser
    case userDidPan
    case stopLiveLocation
}

extension AlertInfo where T == LocationSharingViewAlert {
    init(alertID: LocationSharingViewAlert,
         primaryButton: AlertButton = AlertButton(title: L10n.actionOk, action: nil),
         secondaryButton: AlertButton? = nil,
         verticalButtons: [AlertButton]? = nil) {
        switch alertID {
        case .missingAuthorization:
            self.init(id: alertID,
                      title: L10n.dialogAllowAccess,
                      message: L10n.dialogPermissionLocationDescriptionIos(InfoPlistReader.main.bundleDisplayName),
                      primaryButton: primaryButton,
                      secondaryButton: secondaryButton)
        case .missingAlwaysAuthorization:
            self.init(id: alertID,
                      title: L10n.dialogAllowAccess,
                      message: L10n.dialogPermissionLiveLocationDescriptionIos(InfoPlistReader.main.bundleDisplayName),
                      primaryButton: primaryButton,
                      secondaryButton: secondaryButton)
        case .liveLocationDisclaimer:
            self.init(id: alertID,
                      title: L10n.screenShareLocationLiveLocationDisclaimerTitle,
                      primaryButton: primaryButton,
                      secondaryButton: secondaryButton)
        case .liveLocationDurationSelection:
            self.init(id: alertID,
                      title: L10n.screenShareLocationLiveLocationDurationPickerTitle,
                      primaryButton: primaryButton,
                      secondaryButton: nil,
                      verticalButtons: verticalButtons)
        case .mapError(.failedLoadingMap):
            self.init(id: alertID,
                      title: L10n.errorFailedLoadingMap(InfoPlistReader.main.bundleDisplayName),
                      primaryButton: primaryButton,
                      secondaryButton: secondaryButton)
        case .mapError(.failedLocatingUser):
            self.init(id: alertID,
                      title: L10n.errorFailedLocatingUser(InfoPlistReader.main.bundleDisplayName),
                      primaryButton: primaryButton,
                      secondaryButton: secondaryButton)
        }
    }
}

enum LocationMarkerKind: Equatable {
    case pin
    case staticUser(UserProfileProxy)
    case liveUser(UserProfileProxy)
    case placeholder
    
    var id: String {
        switch self {
        case .pin, .placeholder:
            UUID().uuidString
        case .staticUser(let profile), .liveUser(let profile):
            profile.userID
        }
    }
    
    var displayName: String? {
        switch self {
        case .pin, .placeholder:
            nil
        case .staticUser(let profile), .liveUser(let profile):
            profile.displayName
        }
    }
    
    var userProfile: UserProfileProxy? {
        switch self {
        case .pin, .placeholder:
            nil
        case .staticUser(let profile), .liveUser(let profile):
            profile
        }
    }
}