Implement conversation-manager pattern framework function

The _conversation-manager_ pattern previously tested in the _guess_ example game should be useful for other kinds of use cases and as such was moved into the module.

`make-conversation-manager` maintains an internal hash table of per-conversation (i.e. chat-ids) closures constructed by the provided constructor function.

Thus bot implementations such as the _guess_ game example only need to instantiate a conversation-manager, call it via e.g. `poll-updates` and implement the actual conversation logic in a custom conversation closure.

Telebot's framework function names are now consistently separated by minuses instead of capital letters.

1 files changed, 30 insertions, 9 deletions

diff --git a/telebot.scm b/telebot.scm
index b1fb625..b5ca1e3 100644
--- a/telebot.scm
+++ b/telebot.scm
@@ -1,4 +1,5 @@
-(module telebot (getMe
+(module telebot (;;; basic API wrappers
+                 getMe
                  getUpdates
                  sendMessage
                  forwardMessage
@@ -13,18 +14,21 @@
                  getUserProfilePhotos
                  getFile
                  answerInlineQuery
+                 ;;; framework
                  is-message?
                  is-inline_query?
                  is-chosen_inline_result?
-                 pollUpdates)
+                 poll-updates
+                 make-conversation-manager)
   (import chicken scheme)
-  (use srfi-1)
-  (use openssl)
-  (use http-client)
-  (use medea)
+  (use srfi-1
+       srfi-69)
+  (use openssl
+       http-client)
+  (use medea
+       vector-lib
+       data-structures)
   (use loops)
-  (use vector-lib)
-  (use data-structures)
 
   (define-constant api-base "https://api.telegram.org/bot")
 
@@ -40,6 +44,11 @@
         #f
         cleaned-parameters)))
 
+  (define (resolve-query query tree)
+    (fold (lambda (x y) (alist-ref x y))
+          tree
+          query))
+
   ;;; plain API wrappers, returning deserialized JSON
 
   (define-syntax wrap-api-method
@@ -175,7 +184,7 @@
   (define is-inline_query?         (update-predicate 'inline_query))
   (define is-chosen_inline_result? (update-predicate 'chosen_inline_result))
 
-  (define (pollUpdates token handler)
+  (define (poll-updates token handler)
     (let ((offset 0))
       (do-forever
         (vector-for-each (lambda (i u)
@@ -185,4 +194,16 @@
                                     (getUpdates token
                                                 offset:  offset
                                                 timeout: 60))))))
+
+  (define (make-conversation-manager token make-handler)
+    (let ((token         token)
+          (conversations (make-hash-table)))
+      (lambda (update)
+        (if (is-message? update)
+          (let ((chat_id (resolve-query '(message from id) update)))
+            (if (hash-table-exists? conversations chat_id)
+              ((hash-table-ref conversations chat_id) update)
+              (hash-table-set! conversations
+                               chat_id
+                               (make-handler token chat_id))))))))
 )