PreviewFeature, message links

src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/Annotations.kt

@@ -0,0 +1,6 @@
+package com.github.insanusmokrassar.TelegramBotAPI.utils
+
+import kotlin.Experimental.*
+
+@Experimental(Level.WARNING)
+annotation class PreviewFeature

src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/LinksFormatting.kt

@@ -0,0 +1,40 @@
+package com.github.insanusmokrassar.TelegramBotAPI.utils
+
+import com.github.insanusmokrassar.TelegramBotAPI.types.ChatId
+import com.github.insanusmokrassar.TelegramBotAPI.types.MessageIdentifier
+import com.github.insanusmokrassar.TelegramBotAPI.types.chat.abstracts.PrivateChat
+import com.github.insanusmokrassar.TelegramBotAPI.types.chat.abstracts.UsernameChat
+import com.github.insanusmokrassar.TelegramBotAPI.types.chat.abstracts.extended.*
+
+private const val internalLinkBeginning = "https://t.me"
+
+@PreviewFeature
+fun makeLinkToMessage(
+    username: String,
+    messageId: MessageIdentifier
+): String = "$internalLinkBeginning/$username/$messageId"
+
+private val linkIdRedundantPartRegex = Regex("^-100")
+
+@PreviewFeature
+fun makeLinkToMessage(
+    chat: ExtendedChat,
+    messageId: MessageIdentifier
+): String? {
+    return when {
+        chat is UsernameChat && chat.username != null -> "$internalLinkBeginning/${chat.username}/$messageId"
+        chat !is PrivateChat -> chat.id.chatId.toString().replace(
+            linkIdRedundantPartRegex,
+            ""
+        ).let { bareId ->
+            "$internalLinkBeginning/c/$bareId/$messageId"
+        }
+        else -> return null
+    }
+}
+
+@PreviewFeature
+fun makeFileLink(
+    botToken: String,
+    filePath: String
+) = "https://api.telegram.org/file/bot$botToken/$filePath"