Convert links from Telegram to XMPP (#49)

Emulsion.Tests/Telegram/FunogramTests.fs

@@ -1,5 +1,7 @@
 module Emulsion.Tests.Telegram.Client
 
+open System
+
 open Funogram.Types
 open Xunit
 
@@ -29,6 +31,19 @@ let private telegramMessage author text =
 let private telegramReplyMessage author text replyTo =
     { main = { author = author; text = text }; replyTo = Some replyTo }
 
+let private createEntity t offset length url = {
+    Type = t
+    Offset = offset
+    Length = length
+    Url = Some url
+    User = None
+}
+
+let private createEntities t offset length url = Some <| seq {
+    yield createEntity t offset length url
+}
+
+
 let private originalUser = createUser (Some "originalUser") "" None
 let private replyingUser = createUser (Some "replyingUser") "" None
 
@@ -91,6 +106,94 @@ module ReadMessageTests =
             readMessage replyMessage
         )
 
+    [<Fact>]
+    let readTextLinkMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = createEntities "text_link" 0L 8L "https://example.com" }
+
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original [https://example.com] text",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readMultipleTextLinksMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = Some <| upcast [| createEntity "text_link" 0L 8L "https://example.com/1"
+                                                         createEntity "text_link" 9L 4L "https://example.com/2" |] }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original [https://example.com/1] text [https://example.com/2]",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readInvalidTextLinkMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = createEntities "text_link" 0L 800L "https://example.com" }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original text [https://example.com]",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readNegativeOffsetTextLinkMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = createEntities "text_link" -1L 5L "https://example.com" }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original text",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readZeroLengthTextLinkMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = createEntities "text_link" 0L 0L "https://example.com" }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original text",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readSuperLongLengthTextLinkMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = createEntities "text_link" Int64.MaxValue Int64.MaxValue "https://example.com" }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original text",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readOverlappingTextLinksMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = Some <| upcast [| createEntity "text_link" 0L 8L "https://example.com/1"
+                                                         createEntity "text_link" 0L 13L "https://example.com/2" |] }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original [https://example.com/1] text [https://example.com/2]",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readNonTextLinkMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = createEntities "not_link" 0L 0L "https://example.com" }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original text",
+            readMessage message
+        )
+
+    [<Fact>]
+    let readNoneTextLinkMessage() =
+        let message = { createMessage (Some originalUser) (Some "Original text") with
+                            Entities = Some <| upcast [| { Type = "text_link"
+                                                           Url = None
+                                                           Offset = 0L
+                                                           Length = 5L
+                                                           User = None } |] }
+        Assert.Equal(
+            telegramMessage "@originalUser" "Original text",
+            readMessage message
+        )
+
 module FlattenMessageTests =
     let private flattenMessage = Funogram.MessageConverter.flatten Funogram.MessageConverter.DefaultQuoteSettings
     let private flattenMessageLineLimit limit =

Emulsion/Telegram/Funogram.fs

@@ -1,5 +1,6 @@
 module Emulsion.Telegram.Funogram
 
+open System
 open System.Threading
 
 open Funogram
@@ -8,6 +9,7 @@ open Funogram.Api
 open Funogram.Types
 open Serilog
 
+open System.Text
 open Emulsion
 open Emulsion.Settings
 
@@ -51,10 +53,39 @@ module MessageConverter =
                 | Some lastName -> sprintf "%s %s" user.FirstName lastName
                 | None -> user.FirstName
 
+    let private getTextLinkEntity = function
+    | { Type = "text_link"; Url = Some url; Offset = o; Length = l }
+        when o >= 0L
+             && l > 0L
+             && o < int64 Int32.MaxValue
+             && l < int64 Int32.MaxValue
+             && o + l < int64 Int32.MaxValue ->
+        Some {| Url = url; Offset = o; Length = l |}
+    | _ -> None
+
+    let private applyEntities entities (text: string) =
+        match entities with
+        | None -> text
+        | Some entities ->
+            let links =
+                entities
+                |> Seq.choose getTextLinkEntity
+                |> Seq.sortBy (fun e -> e.Offset)
+            let result = StringBuilder()
+            let mutable pos = 0
+            for link in links do
+                let linkEndOffset = min text.Length (int32 (link.Offset + link.Length))
+                result
+                    .Append(text.Substring(pos, linkEndOffset - pos))
+                    .AppendFormat(" [{0}]", link.Url)
+                |> ignore
+                pos <- linkEndOffset
+            result.Append(text.Substring(pos, text.Length - pos)).ToString()
+
     let private getMessageBodyText (message: FunogramMessage) =
         match message.Text with
         | None -> "[DATA UNRECOGNIZED]"
-        | Some text -> text
+        | Some text -> applyEntities message.Entities text
 
     let private applyLimits limits text =
         let applyMessageLengthLimit (original: {| text: string; wasLimited: bool |}) =