From c578f5783972b7090014895af4e08a36d20d7c2b Mon Sep 17 00:00:00 2001
From: Yoni Rabkin <yonirabkin@member.fsf.org>
Date: Mon, 10 Mar 2014 10:48:15 -0400
Subject: * lisp/emms-librefm-client.el: Implement handshake

---
 lisp/emms-librefm-client.el | 89 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 77 insertions(+), 12 deletions(-)

diff --git a/lisp/emms-librefm-client.el b/lisp/emms-librefm-client.el
index 19a92bc..56ee543 100644
--- a/lisp/emms-librefm-client.el
+++ b/lisp/emms-librefm-client.el
@@ -21,31 +21,50 @@
 ;; Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 ;; MA 02110-1301, USA.
 
-;;; Commentary:
-;;
-;; Definitive information on how to setup and use this package is
-;; provided in the wonderful Emms manual, in the /doc directory of the
-;; Emms distribution.
 
 ;;; Code:
 
 (defvar emms-librefm-client-handshake-url
-  "turtle.libre.fm")
+  "turtle.libre.fm"
+  "Endpoint for client handshake.")
 
 (defvar emms-librefm-client-method
-  "http")
+  "http"
+  "Transfer method.")
 
 (defvar emms-librefm-client-username
-  "")
+  ""
+  "Libre.fm username.")
 
 (defvar emms-librefm-client-password
-  "")
+  ""
+  "Libre.fm user password.")
 
 (defvar emms-librefm-client-debug
-  "")
+  ""
+  "Debugging variable to store communication.")
+
+(defvar emms-librefm-client-session-id
+  ""
+  "Session ID for Libre.fm.")
+
+(defvar emms-librefm-client-now-playing-url
+  ""
+  "URL for getting the track playing.")
+
+(defvar emms-librefm-client-submission-url
+  ""
+  "URL for submissions.")
 
 
 (defun emms-librefm-client-handshake-string (url username password)
+  "Return the client handshake string."
+  (when (= 0 (length url))
+    (error "bad url"))
+  (when (= 0 (length username))
+    (error "bad username"))
+  (when (= 0 (length password))
+    (error "bad password"))
   (let ((timestamp (format-time-string "%s")))
     (concat emms-librefm-client-method
 	    "://"
@@ -58,7 +77,8 @@
 	    "t=" timestamp "&"
 	    "a=" (md5 (concat (md5 password) timestamp)))))
 
-(defun emms-librefm-client-handshake (url username password)
+(defun emms-librefm-client-handshake-call (url username password)
+  "Perform client handshake and return a response in a buffer."
   (let ((url-request-method "POST"))
     (let ((response
 	   (url-retrieve-synchronously
@@ -67,7 +87,52 @@
       (setq emms-librefm-client-debug
 	    (with-current-buffer response
 	      (buffer-substring-no-properties (point-min)
-					      (point-max)))))))
+					      (point-max))))
+      response)))
+
+(defun emms-librefm-client-handle-handshake-response (resbuf)
+  "Handle the client handshake server response."
+  (when (not (bufferp resbuf))
+    (error "response not a buffer"))
+  (with-current-buffer resbuf
+    (goto-char (point-min))
+    (when (not (re-search-forward "^.*200 OK$" (point-at-eol) t))
+      (error "bad HTTP server response"))
+    ;; go to the start of the FM response
+    (when (not (re-search-forward "\n\n" (point-max) t))
+      (error "bad FM server response"))
+    (let ((status (buffer-substring (point-at-bol)
+				    (point-at-eol))))
+      (when (not (string= status "OK"))
+	(error "FM server returned: %s" status))
+      (let (session-id
+	    now-playing-url
+	    submission-url)
+	(forward-line 1)
+	(setq session-id (buffer-substring (point-at-bol)
+					   (point-at-eol)))
+	(forward-line 1)
+	(setq now-playing-url (buffer-substring (point-at-bol)
+						(point-at-eol)))
+	(forward-line 1)
+	(setq submission-url (buffer-substring (point-at-bol)
+					       (point-at-eol)))
+	(when (or (= 0 (length session-id))
+		  (= 0 (length now-playing-url))
+		  (= 0 (length submission-url)))
+	  (error "couldn't parse FM server response"))
+	(setq emms-librefm-client-session-id      session-id
+	      emms-librefm-client-now-playing-url now-playing-url
+	      emms-librefm-client-submission-url  submission-url)
+	(message "handshake successful")))))
+
+(defun emms-librefm-client-handshake ()
+  "Perform handshake call and handle response."
+  (emms-librefm-client-handle-handshake-response
+   (emms-librefm-client-handshake-call
+    emms-librefm-client-handshake-url
+    emms-librefm-client-username
+    emms-librefm-client-password)))
 
 
 (provide 'emms-librefm-client)
-- 
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