From ecb2c6ff22bc1caf5f61eeec228e975d0156590e Mon Sep 17 00:00:00 2001
From: Sven Augustin <sven.augustin@psi.ch>
Date: Sun, 7 Jun 2020 20:58:07 +0200
Subject: [PATCH] added a BrokerClient prototype (see also
 https://github.com/paulscherrerinstitute/sf_databuffer_writer/blob/c8e0553ecb6f7ee207c18ba2b6e5f21ff6d6dfae/client/README.md)

---
 slic/core/acquisition/broker_client.py | 82 ++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 slic/core/acquisition/broker_client.py

diff --git a/slic/core/acquisition/broker_client.py b/slic/core/acquisition/broker_client.py
new file mode 100644
index 000000000..628aaf4cb
--- /dev/null
+++ b/slic/core/acquisition/broker_client.py
@@ -0,0 +1,82 @@
+import requests
+
+
+class BrokerClient:
+
+    def __init__(self, *args, address="http://sf-daq-1:10002", **kwargs):
+        self.config = BrokerConfig(*args, **kwargs)
+        self.address = address
+
+    def retrieve(self, *args, timeout=10, **kwargs):
+        requrl = self.address.rstrip("/") + "/retrieve_from_buffers"
+        params = self.config.to_dict(*args, **kwargs)
+        response = requests.post(requrl, json=params, timeout=timeout).json()
+        return validate_response(response)
+
+
+
+def validate_response(resp):
+    if resp.get("status") == "ok":
+        return resp.get("message")
+
+    message = resp.get("message", "Unknown error")
+    msg = "An error happened on the server:\n{}".format(message)
+    raise BrokerError(msg)
+
+
+
+class BrokerError(Exception):
+    pass
+
+
+
+class BrokerConfig:
+
+    def __init__(self, pgroup, rate_multiplicator=1):
+        self.pgroup = pgroup
+        self.rate_multiplicator = rate_multiplicator
+
+
+    def to_dict(self, output_dir, start_pulseid, stop_pulseid, detectors=None, channels=None, pvs=None, scan_info=None):
+        config = {
+            "pgroup": self.pgroup,
+            "rate_multiplicator": self.rate_multiplicator,
+            "directory_name": output_dir,
+            "start_pulseid": start_pulseid,
+            "stop_pulseid": stop_pulseid,
+        }
+
+        if detectors:
+            detectors = {d: {} for d in detectors} # currently the dicts are empty, thus allow giving just a list as argument
+            config["detectors"] = detectors
+
+        if channels:
+            bsread_channels, camera_channels = split_channels(channels)
+            if bsread_channels:
+                config["channels_list"] = bsread_channels
+            if camera_channels:
+                config["camera_list"] = camera_channels
+
+        if pvs:
+            config["pv_list"] = pvs
+
+        if scan_info:
+            config["scan_info"] = scan_info
+
+        return config
+
+
+
+def split_channels(channels):
+    bsread_channels = []
+    camera_channels = []
+    for c in channels:
+        if c.endswith(":FPICTURE"):
+            camera_channels.append(c)
+        else:
+            bsread_channels.append(c)
+
+    return bsread_channels, camera_channels
+
+
+