Add event to get older events

src/Internal/Api/Task.elm

@@ -7,6 +7,7 @@ import Hash
 import Internal.Api.Chain as Chain
 import Internal.Api.Credentials as Cred exposing (Credentials)
 import Internal.Api.GetEvent.Main exposing (EventInput)
+import Internal.Api.GetMessages.Main exposing (GetMessagesInput)
 import Internal.Api.Invite.Main exposing (InviteInput)
 import Internal.Api.JoinRoomById.Main exposing (JoinRoomByIdInput)
 import Internal.Api.JoinedMembers.Main exposing (JoinedMembersInput)
@@ -35,6 +36,13 @@ getEvent { eventId, roomId } cred =
         |> C.toTask
 
 
+getMessages : GetMessagesInput -> Credentials -> FutureTask
+getMessages data cred =
+    C.makeVBA cred
+        |> Chain.andThen (C.getMessages data)
+        |> C.toTask
+
+
 invite : InviteInput -> Credentials -> FutureTask
 invite data cred =
     C.makeVBA cred

src/Internal/Event.elm

@@ -10,6 +10,7 @@ resend other events or forward them elsewhere.
 import Internal.Api.Credentials exposing (Credentials)
 import Internal.Api.GetEvent.Main as GetEvent
 import Internal.Api.GetEvent.V1.SpecObjects as GetEventSO
+import Internal.Api.GetMessages.V4.SpecObjects as GetMessagesSO
 import Internal.Api.Sync.V2.SpecObjects as SyncSO
 import Internal.Tools.Timestamp exposing (Timestamp)
 import Internal.Values.Event as Internal
@@ -62,6 +63,32 @@ initFromGetEvent output =
         }
 
 
+{-| Create an internal event type from an API endpoint event object.
+This function is placed in this file to respect file hierarchy and avoid circular imports.
+-}
+initFromGetMessages : GetMessagesSO.ClientEvent -> Internal.IEvent
+initFromGetMessages output =
+    Internal.init
+        { content = output.content
+        , eventId = output.eventId
+        , originServerTs = output.originServerTs
+        , roomId = output.roomId
+        , sender = output.sender
+        , stateKey = output.stateKey
+        , contentType = output.contentType
+        , unsigned =
+            output.unsigned
+                |> Maybe.map
+                    (\(GetMessagesSO.UnsignedData data) ->
+                        { age = data.age
+                        , prevContent = data.prevContent
+                        , redactedBecause = Maybe.map initFromGetMessages data.redactedBecause
+                        , transactionId = data.transactionId
+                        }
+                    )
+        }
+
+
 {-| Create an internal event type from an API endpoint event object.
 This function is placed in this file to respect file hierarchy and avoid circular imports.
 -}

src/Internal/Room.elm

@@ -7,10 +7,11 @@ import Dict
 import Internal.Api.Credentials exposing (Credentials)
 import Internal.Api.Sync.V2.SpecObjects as Sync
 import Internal.Api.Task as Api
-import Internal.Api.VaultUpdate exposing (VaultUpdate)
+import Internal.Api.VaultUpdate exposing (VaultUpdate(..))
 import Internal.Event as Event exposing (Event)
 import Internal.Tools.Exceptions as X
 import Internal.Tools.Hashdict as Hashdict
+import Internal.Tools.SpecEnums as Enums
 import Internal.Values.Event as IEvent
 import Internal.Values.Room as Internal
 import Internal.Values.StateManager as StateManager
@@ -118,6 +119,26 @@ withoutCredentials (Room { room }) =
     room
 
 
+{-| Get older events from the Matrix API.
+-}
+getOlderEvents : { limit : Maybe Int } -> Room -> Task X.Error VaultUpdate
+getOlderEvents { limit } (Room { context, room }) =
+    case Internal.latestGap room of
+        Nothing ->
+            Task.succeed (MultipleUpdates [])
+
+        Just { from, to } ->
+            Api.getMessages
+                { direction = Enums.ReverseChronological
+                , filter = Nothing
+                , from = Just to
+                , limit = limit
+                , roomId = Internal.roomId room
+                , to = from
+                }
+                context
+
+
 {-| Get the most recent events.
 -}
 mostRecentEvents : Room -> List Event

src/Internal/Values/Room.elm

@@ -59,11 +59,28 @@ getStateEvent data (IRoom room) =
         |> StateManager.getStateEvent data
 
 
-{-| Get the room's id.
+{-| Insert a chunk of events into a room.
 -}
-roomId : IRoom -> String
-roomId (IRoom room) =
-    room.roomId
+insertEvents :
+    { events : List IEvent
+    , nextBatch : String
+    , prevBatch : Maybe String
+    , stateDelta : Maybe StateManager
+    }
+    -> IRoom
+    -> IRoom
+insertEvents data (IRoom ({ timeline } as room)) =
+    IRoom
+        { room | timeline = Timeline.insertEvents data timeline }
+        |> List.foldl addEvent
+        |> (|>) data.events
+
+
+{-| Get the latest gap.
+-}
+latestGap : IRoom -> Maybe { from : Maybe String, to : String }
+latestGap (IRoom room) =
+    Timeline.latestGap room.timeline
 
 
 {-| Get the most recent events.
@@ -71,3 +88,10 @@ roomId (IRoom room) =
 mostRecentEvents : IRoom -> List IEvent
 mostRecentEvents (IRoom room) =
     Timeline.mostRecentEvents room.timeline
+
+
+{-| Get the room's id.
+-}
+roomId : IRoom -> String
+roomId (IRoom room) =
+    room.roomId

src/Internal/Values/Timeline.elm

@@ -92,63 +92,119 @@ newFromEvents { events, nextBatch, prevBatch, stateDelta } =
 insertEvents :
     { events : List IEvent
     , nextBatch : String
-    , prevBatch : String
+    , prevBatch : Maybe String
     , stateDelta : Maybe StateManager
     }
     -> Timeline
     -> Timeline
 insertEvents ({ events, nextBatch, prevBatch, stateDelta } as data) (Timeline t) =
     Timeline
-        (if t.nextBatch == prevBatch then
-            { t
-                | events = t.events ++ events
-                , nextBatch = nextBatch
-            }
-
-         else if nextBatch == t.prevBatch then
-            case t.previous of
-                Gap (Timeline prevT) ->
-                    if prevT.nextBatch == prevBatch then
-                        { events = prevT.events ++ events ++ t.events
-                        , nextBatch = t.nextBatch
-                        , prevBatch = prevT.prevBatch
-                        , stateAtStart = prevT.stateAtStart
-                        , previous = prevT.previous
-                        }
-
-                    else
+        (case prevBatch of
+            -- No prevbatch suggests the start of the timeline.
+            -- This means that we must recurse until we've hit the bottom,
+            -- and then mark the bottom of the timeline.
+            Nothing ->
+                case t.previous of
+                    Gap prevT ->
                         { t
-                            | events = events ++ t.events
-                            , prevBatch = prevBatch
-                            , stateAtStart =
-                                stateDelta
-                                    |> Maybe.withDefault StateManager.empty
+                            | previous =
+                                prevT
+                                    |> insertEvents data
+                                    |> Gap
                         }
 
-                _ ->
-                    { t
-                        | events = events ++ t.events
-                        , prevBatch = prevBatch
-                        , stateAtStart =
-                            stateDelta
-                                |> Maybe.withDefault StateManager.empty
-                    }
+                    _ ->
+                        if nextBatch == t.prevBatch then
+                            { t | previous = StartOfTimeline, events = events ++ t.events, stateAtStart = StateManager.empty }
 
-         else
-            case t.previous of
-                Gap prevT ->
-                    { t
-                        | previous =
-                            prevT
-                                |> insertEvents data
-                                |> Gap
-                    }
+                        else
+                            { t | previous = Gap <| newFromEvents data }
 
-                _ ->
-                    t
+            -- If there is a prevbatch, it is not the start of the timeline
+            -- and could be located anywhere.
+            -- Starting at the front, look for a way to match it with the existing timeline.
+            Just p ->
+                -- Piece connects to the front of the timeline.
+                if t.nextBatch == p then
+                    { t
+                        | events = t.events ++ events
+                        , nextBatch = nextBatch
+                    }
+                    -- Piece connects to the back of the timeline.
+
+                else if nextBatch == t.prevBatch then
+                    case t.previous of
+                        Gap (Timeline prevT) ->
+                            -- Piece also connects to the timeline in the back,
+                            -- allowing the two timelines to merge.
+                            if prevT.nextBatch == p then
+                                { events = prevT.events ++ events ++ t.events
+                                , nextBatch = t.nextBatch
+                                , prevBatch = prevT.prevBatch
+                                , stateAtStart = prevT.stateAtStart
+                                , previous = prevT.previous
+                                }
+
+                            else
+                                { t
+                                    | events = events ++ t.events
+                                    , prevBatch = p
+                                    , stateAtStart =
+                                        stateDelta
+                                            |> Maybe.withDefault StateManager.empty
+                                }
+
+                        Endless _ ->
+                            { t
+                                | events = events ++ t.events
+                                , prevBatch = p
+                                , stateAtStart =
+                                    stateDelta
+                                        |> Maybe.withDefault StateManager.empty
+                                , previous = Endless p
+                            }
+
+                        _ ->
+                            { t
+                                | events = events ++ t.events
+                                , prevBatch = p
+                                , stateAtStart =
+                                    stateDelta
+                                        |> Maybe.withDefault StateManager.empty
+                            }
+                    -- Piece doesn't connect to this piece of the timeline.
+                    -- Consequently, look for previous parts of the timeline to see if it connects.
+
+                else
+                    case t.previous of
+                        Gap prevT ->
+                            { t
+                                | previous =
+                                    prevT
+                                        |> insertEvents data
+                                        |> Gap
+                            }
+
+                        _ ->
+                            t
         )
 
 
+{-| Get the width of the latest gap. This data is usually accessed when trying to get more messages.
+-}
+latestGap : Timeline -> Maybe { from : Maybe String, to : String }
+latestGap (Timeline t) =
+    case t.previous of
+        StartOfTimeline ->
+            Nothing
+
+        Endless prevBatch ->
+            Just { from = Nothing, to = prevBatch }
+
+        Gap (Timeline pt) ->
+            Just { from = Just pt.nextBatch, to = t.prevBatch }
+
+
 {-| Get the longest uninterrupted length of most recent events.
 -}
 localSize : Timeline -> Int

src/Internal/Vault.elm

@@ -16,6 +16,7 @@ import Internal.Event as Event
 import Internal.Invite as Invite
 import Internal.Room as Room
 import Internal.Tools.Exceptions as X
+import Internal.Tools.SpecEnums as Enums
 import Internal.Values.Room as IRoom
 import Internal.Values.RoomInvite exposing (IRoomInvite)
 import Internal.Values.StateManager as StateManager
@@ -125,8 +126,62 @@ updateWith vaultUpdate ((Vault ({ cred, context } as data)) as vault) =
                     vault
 
         -- TODO
-        GetMessages _ _ ->
-            vault
+        GetMessages input output ->
+            let
+                prevBatch : Maybe String
+                prevBatch =
+                    case input.direction of
+                        Enums.Chronological ->
+                            Just output.start
+
+                        Enums.ReverseChronological ->
+                            case output.end of
+                                Just end ->
+                                    Just end
+
+                                Nothing ->
+                                    input.to
+
+                nextBatch : Maybe String
+                nextBatch =
+                    case input.direction of
+                        Enums.Chronological ->
+                            case output.end of
+                                Just end ->
+                                    Just end
+
+                                Nothing ->
+                                    input.to
+
+                        Enums.ReverseChronological ->
+                            Just output.start
+            in
+            case ( getRoomById input.roomId vault, nextBatch ) of
+                ( Just room, Just nb ) ->
+                    room
+                        |> Room.withoutCredentials
+                        |> IRoom.insertEvents
+                            { events =
+                                output.chunk
+                                    |> List.map Event.initFromGetMessages
+                                    |> (\x ->
+                                            case input.direction of
+                                                Enums.Chronological ->
+                                                    x
+
+                                                Enums.ReverseChronological ->
+                                                    List.reverse x
+                                       )
+                            , prevBatch = prevBatch
+                            , nextBatch = nb
+                            , stateDelta = Just <| StateManager.fromEventList (List.map Event.initFromGetMessages output.state)
+                            }
+                        |> Internal.insertRoom
+                        |> (|>) cred
+                        |> (\v -> Vault { cred = v, context = context })
+
+                _ ->
+                    vault
 
         -- TODO
         InviteSent _ _ ->

src/Matrix/Room.elm

@@ -1,5 +1,5 @@
 module Matrix.Room exposing
-    ( Room, roomId, mostRecentEvents
+    ( Room, roomId, mostRecentEvents, findOlderEvents
     , sendMessage, sendMessages, sendOneEvent, sendMultipleEvents
     )
 
@@ -10,7 +10,7 @@ module Matrix.Room exposing
 
 A room represents a channel of communication within a Matrix home server.
 
-@docs Room, roomId, mostRecentEvents
+@docs Room, roomId, mostRecentEvents, findOlderEvents
 
 
 # Sending events
@@ -35,6 +35,13 @@ type alias Room =
     Internal.Room
 
 
+{-| If you want more events as part of the most recent events, you can run this task to get more.
+-}
+findOlderEvents : { limit : Maybe Int, room : Room } -> Task X.Error VaultUpdate
+findOlderEvents { limit, room } =
+    Internal.getOlderEvents { limit = limit } room
+
+
 {-| Get the most recent events from this room.
 -}
 mostRecentEvents : Room -> List Event.Event