cache youtube channel titles to cut down on number of requests

Commands.fs

@@ -514,12 +514,12 @@ type Commands() =
             do! ctx.TriggerTypingAsync()
 
             if
-                Option.isNone (getDb ()).YoutubeChannel
+                Option.isNone (getDb ()).YoutubeUpdatesChannel
                 && ctx.Guild.SystemChannel <> null
             then
                 updateDb
                     { (getDb ()) with
-                        YoutubeChannel = Some ctx.Guild.SystemChannel.Id }
+                        YoutubeUpdatesChannel = Some ctx.Guild.SystemChannel.Id }
 
             match! Youtube.getYoutubeChannelId channel with
             | None ->
@@ -599,7 +599,7 @@ type Commands() =
 
             updateDb
                 { (getDb ()) with
-                    YoutubeChannel = Some channel.Id }
+                    YoutubeUpdatesChannel = Some channel.Id }
 
             ctx.RespondChunked(
                 $"Set YouTube updates channel to **#%s{channel.Name}**"
@@ -612,7 +612,7 @@ type Commands() =
         task {
             do! ctx.TriggerTypingAsync()
 
-            match (getDb ()).YoutubeChannel with
+            match (getDb ()).YoutubeUpdatesChannel with
             | None -> ctx.RespondChunked("No YouTube updates channel set")
             | Some channelId ->
                 let channel = ctx.Guild.GetChannel channelId

Data.fs

@@ -24,8 +24,9 @@ let mutable private db =
           AutoReplies = Map.empty
           AutoReplyRates = Map.empty
           LastResponse = None
-          YoutubeChannel = None
+          YoutubeUpdatesChannel = None
           YoutubeChannels = Set.empty
+          YoutubeChannelTitles = Map.empty 
           LastYoutubeFetch = Map.empty
           SeenCommunityPosts = Set.empty }
 

Program.fs

@@ -14,7 +14,7 @@ module Core =
     let rand = Random()
 
     let rec postYoutubeUpdates (dis: DiscordClient) =
-        match (getDb ()).YoutubeChannel with
+        match (getDb ()).YoutubeUpdatesChannel with
         | Some channel ->
             let updates = Youtube.getYoutubeUpdates ()
             let communityUpdates = Youtube.getCommunityUpdates ()

Types.fs

@@ -11,8 +11,9 @@ type Db =
       AutoReplies: Map<uint64, string>
       AutoReplyRates: Map<uint64, decimal>
       LastResponse: string option
-      YoutubeChannel: uint64 option
+      YoutubeUpdatesChannel: uint64 option
       YoutubeChannels: Set<string>
+      YoutubeChannelTitles: Map<string, string>
       LastYoutubeFetch: Map<string, DateTime>
       SeenCommunityPosts: Set<string> }
 
@@ -41,10 +42,14 @@ type Db =
                 |> List.map (fun (k, v) -> uint64 k, v)
                 |> Map.ofList
               LastResponse = Decode.string |> get.Optional.Field "LastResponse"
-              YoutubeChannel =
+              YoutubeUpdatesChannel =
                 Decode.string
                 |> get.Optional.Field "YoutubeChannel"
                 |> Option.map uint64
+              YoutubeChannelTitles =
+                Decode.dict Decode.string
+                |> get.Optional.Field "YoutubeChannelTitles"
+                |> Option.defaultValue Map.empty
               YoutubeChannels =
                 Decode.list Decode.string
                 |> get.Optional.Field "YoutubeChannels"

Youtube.fs

@@ -52,22 +52,35 @@ let getYoutubeChannelId (channel: string) =
 
 let getChannelTitleByChannelId (channelId: string) =
     task {
-        let searchRequest =
-            ChannelsResource.ListRequest(
-                youtubeService,
-                Repeatable([| "brandingSettings" |]),
-                Id = Repeatable([| channelId |]),
-                MaxResults = 1L
-            )
-
-        let! response = searchRequest.ExecuteAsync()
-
-        return
-            match response.Items with
-            | null -> None
-            | items when items.Count > 0 ->
-                Some items.[0].BrandingSettings.Channel.Title
-            | _ -> None
+        match Map.tryFind channelId (getDb ()).YoutubeChannelTitles with
+        | Some title -> return Some title
+        | None ->
+            let searchRequest =
+                ChannelsResource.ListRequest(
+                    youtubeService,
+                    Repeatable([| "brandingSettings" |]),
+                    Id = Repeatable([| channelId |]),
+                    MaxResults = 1L
+                )
+
+            let! response = searchRequest.ExecuteAsync()
+
+            return
+                match response.Items with
+                | null -> None
+                | items when items.Count > 0 ->
+                    let title = items[0].BrandingSettings.Channel.Title
+
+                    updateDb
+                        { (getDb ()) with
+                            YoutubeChannelTitles =
+                                Map.add
+                                    channelId
+                                    title
+                                    (getDb ()).YoutubeChannelTitles }
+
+                    Some title
+                | _ -> None
     }
 
 let getYoutubeUpdates () : string option list =
@@ -202,27 +215,40 @@ type ChannelList =
 
 let getCommunityUpdates () : string list =
     [ for channelId in (getDb ()).YoutubeChannels do
-        let channelTitle = match (getChannelTitleByChannelId channelId).Result with
-                           | Some title -> title
-                           | None -> channelId
-        let communityApiUrl = $"https://yt.lemnoslife.com/channels?part=community,snippet&id=%s{channelId}"
-        let response = Http.RequestString(communityApiUrl)
-
-        match response |> Decode.fromString ChannelList.Decoder with
-        | Ok channelList ->
-            for channel in channelList.items do
-                for post in channel.Community do
-                    if not (Set.contains post.id (getDb ()).SeenCommunityPosts) then
-                        yield
-                            $"**{channelTitle}** has a new community post: \n"
-                            + (post.contentText |> List.map (fun x -> x.text) |> String.concat "")
-                            + $"\n\nSee full post at https://www.youtube.com/post/%s{post.id}"
-
-                let postIds = channel.Community |> List.map (fun x -> x.id)
-                updateDb
-                    { (getDb ()) with
-                         SeenCommunityPosts = Set.union (getDb ()).SeenCommunityPosts (Set.ofList postIds )}
-        | Error error ->
-            yield
-                $"Error decoding community post for channel {channelId}: {error}"
-    ]
+          let channelTitle =
+              match (getChannelTitleByChannelId channelId).Result with
+              | Some title -> title
+              | None -> channelId
+
+          let communityApiUrl =
+              $"https://yt.lemnoslife.com/channels?part=community,snippet&id=%s{channelId}"
+
+          let response = Http.RequestString(communityApiUrl)
+
+          match response |> Decode.fromString ChannelList.Decoder with
+          | Ok channelList ->
+              for channel in channelList.items do
+                  for post in channel.Community do
+                      if
+                          not (
+                              Set.contains post.id (getDb ()).SeenCommunityPosts
+                          )
+                      then
+                          yield
+                              $"**{channelTitle}** has a new community post: \n"
+                              + (post.contentText
+                                 |> List.map (fun x -> x.text)
+                                 |> String.concat "")
+                              + $"\n\nSee full post at https://www.youtube.com/post/%s{post.id}"
+
+                  let postIds = channel.Community |> List.map (fun x -> x.id)
+
+                  updateDb
+                      { (getDb ()) with
+                          SeenCommunityPosts =
+                              Set.union
+                                  (getDb ()).SeenCommunityPosts
+                                  (Set.ofList postIds) }
+          | Error error ->
+              yield
+                  $"Error decoding community post for channel {channelId}: {error}" ]