Add reader functions for Event types

src/Internal/Values/Event.elm

@@ -1,5 +1,6 @@
 module Internal.Values.Event exposing
     ( Event
+    , content, eventId, eventType, originServerTs, roomId, sender, stateKey
     , UnsignedData, age, prevContent, redactedBecause, transactionId
     , encode, decoder
     )
@@ -15,6 +16,11 @@ of a room.
 @docs Event
 
 
+## Get information
+
+@docs content, eventId, eventType, originServerTs, roomId, sender, stateKey
+
+
 ## Unsigned data
 
 @docs UnsignedData, age, prevContent, redactedBecause, transactionId
@@ -30,6 +36,7 @@ import Internal.Config.Default as Default
 import Internal.Tools.Decode as D
 import Internal.Tools.Encode as E
 import Internal.Tools.Timestamp as Timestamp exposing (Timestamp)
+import Internal.Values.Envelope as Envelope
 import Json.Decode as D
 import Json.Encode as E
 
@@ -37,6 +44,10 @@ import Json.Encode as E
 {-| The Event type occurs everywhere on a user's timeline.
 -}
 type alias Event =
+    Envelope.Envelope IEvent
+
+
+type alias IEvent =
     { content : E.Value
     , eventId : String
     , originServerTs : Timestamp
@@ -63,15 +74,30 @@ type UnsignedData
 {-| Get the event's age, if at all provided by the homeserver.
 -}
 age : Event -> Maybe Int
-age event =
-    Maybe.andThen (\(UnsignedData data) -> data.age) event.unsigned
+age envelope =
+    Envelope.extract
+        (\event ->
+            Maybe.andThen
+                (\(UnsignedData data) -> data.age)
+                event.unsigned
+        )
+        envelope
+
+
+{-| The Matrix protocol revolves around users being able to send each other
+JSON objects. This function reveals the JSON value that the user has sent to
+the room.
+-}
+content : Event -> E.Value
+content =
+    Envelope.extract .content
 
 
 {-| Decode an Event from a JSON value.
 -}
 decoder : D.Decoder Event
 decoder =
-    D.map8 Event
+    D.map8 IEvent
         (D.field "content" D.value)
         (D.field "eventId" D.string)
         (D.field "originServerTs" Timestamp.decoder)
@@ -80,6 +106,7 @@ decoder =
         (D.opField "stateKey" D.string)
         (D.field "eventType" D.string)
         (D.opField "unsigned" decoderUnsignedData)
+        |> Envelope.decoder
 
 
 {-| Decode Unsigned Data from a JSON value.
@@ -96,18 +123,22 @@ decoderUnsignedData =
 {-| Encode an Event into a JSON value.
 -}
 encode : Event -> E.Value
-encode event =
-    E.maybeObject
-        [ ( "content", Just event.content )
-        , ( "eventId", Just <| E.string event.eventId )
-        , ( "originServerTs", Just <| Timestamp.encode event.originServerTs )
-        , ( "roomId", Just <| E.string event.roomId )
-        , ( "sender", Just <| E.string event.sender )
-        , ( "stateKey", Maybe.map E.string event.stateKey )
-        , ( "eventType", Just <| E.string event.eventType )
-        , ( "unsigned", Maybe.map encodeUnsignedData event.unsigned )
-        , ( "version", Just <| E.string Default.currentVersion )
-        ]
+encode envelope =
+    Envelope.encode
+        (\event ->
+            E.maybeObject
+                [ ( "content", Just event.content )
+                , ( "eventId", Just <| E.string event.eventId )
+                , ( "originServerTs", Just <| Timestamp.encode event.originServerTs )
+                , ( "roomId", Just <| E.string event.roomId )
+                , ( "sender", Just <| E.string event.sender )
+                , ( "stateKey", Maybe.map E.string event.stateKey )
+                , ( "eventType", Just <| E.string event.eventType )
+                , ( "unsigned", Maybe.map encodeUnsignedData event.unsigned )
+                , ( "version", Just <| E.string Default.currentVersion )
+                ]
+        )
+        envelope
 
 
 {-| Encode Unsigned Data into a JSON value.
@@ -122,24 +153,105 @@ encodeUnsignedData (UnsignedData data) =
         ]
 
 
+{-| Every event is assigned a unique id in the room. You can use this event id
+to reference or look up events.
+-}
+eventId : Event -> String
+eventId =
+    Envelope.extract .eventId
+
+
+{-| To give a hint what the event's [content](#content) might look like, users
+can use this eventType value to hint at how the JSON might be decoded.
+
+Standard examples of event types are `m.room.message`, `m.room.member` and
+`me.noordstar.game.chess.move`.
+
+-}
+eventType : Event -> String
+eventType =
+    Envelope.extract .eventType
+
+
+{-| Timestamp of at what time the event was originally received by the original
+homeserver.
+
+Generally, this timestamp offers a relalatively accurate indicator of when a
+message was sent. However, this number isn't completely reliable! The timestamp
+can be far in the past due to long network lag, and a (malicious) homeserver can
+spoof this number to make it seem like something was sent ridiculously far in
+the past - or even in the future.
+
+-}
+originServerTs : Event -> Timestamp
+originServerTs =
+    Envelope.extract .originServerTs
+
+
 {-| Get the old content, if the event has changed or it has been edited.
 -}
 prevContent : Event -> Maybe E.Value
-prevContent event =
-    Maybe.andThen (\(UnsignedData data) -> data.prevContent) event.unsigned
+prevContent envelope =
+    Envelope.extract
+        (\event ->
+            Maybe.andThen
+                (\(UnsignedData data) -> data.prevContent)
+                event.unsigned
+        )
+        envelope
 
 
 {-| If the event has been redacted, the homeserver can display the event that
 redacted it here.
 -}
 redactedBecause : Event -> Maybe Event
-redactedBecause event =
-    Maybe.andThen (\(UnsignedData data) -> data.redactedBecause) event.unsigned
+redactedBecause envelope =
+    Envelope.extract
+        (\event ->
+            Maybe.andThen
+                (\(UnsignedData data) -> data.redactedBecause)
+                event.unsigned
+        )
+        envelope
+
+
+{-| Unique id assigned to the Matrix room. You can use this room id to reference
+or look up rooms.
+-}
+roomId : Event -> String
+roomId =
+    Envelope.extract .roomId
+
+
+{-| User id of the user that sent this event. You can use this user id to
+reference or look up users.
+-}
+sender : Event -> String
+sender =
+    Envelope.extract .sender
+
+
+{-| When an event's state key is `Nothing`, it is an ordinary message event in
+the timeline.
+
+When the state key is `Just ""` or some other `Just string`, then it is a state
+event that affects how the room works. TODO: Explain state events.
+
+-}
+stateKey : Event -> Maybe String
+stateKey =
+    Envelope.extract .stateKey
 
 
 {-| If the user has sent this event to the homeserver, then the homeserver might
 display the original transaction id used for the event.
 -}
 transactionId : Event -> Maybe String
-transactionId event =
-    Maybe.andThen (\(UnsignedData data) -> data.transactionId) event.unsigned
+transactionId envelope =
+    Envelope.extract
+        (\event ->
+            Maybe.andThen
+                (\(UnsignedData data) -> data.transactionId)
+                event.unsigned
+        )
+        envelope

src/Types.elm

@@ -1,4 +1,4 @@
-module Types exposing (Vault(..))
+module Types exposing (Vault(..), Event(..))
 
 {-| The Elm SDK uses a lot of records and values that are easy to manipulate.
 Yet, the [Elm design guidelines](https://package.elm-lang.org/help/design-guidelines#keep-tags-and-record-constructors-secret)
@@ -12,13 +12,20 @@ access their content directly.
 The opaque types are placed in a central module so all exposed modules can
 safely access all exposed data types without risking to create circular imports.
 
-@docs Vault
+@docs Vault, Event
 
 -}
 
+import Internal.Values.Event as Event
 import Internal.Values.Vault as Vault
 
 
+{-| Opaque type for Matrix Event
+-}
+type Event
+    = Event Event.Event
+
+
 {-| Opaque type for Matrix Vault
 -}
 type Vault