1 files changed, 91 insertions, 0 deletions
diff --git a/state.py b/state.py
new file mode 100644
index 0000000..b17db99
--- /dev/null
+++ b/state.py
@@ -0,0 +1,91 @@
+import time
+import logging
+
+import transport
+
+'''
+Implementations of State:
+
+MUST implement:
+  _collect(self)
+
+CAN implement:
+  _get(self, key: str)
+
+SHOULDNT implement:
+  get(self, key)
+  collect(self)
+
+Data is stored in self._data as a dictionary.
+By default, _get(key) retrieves the returns self._data[key].
+This behaviour can be overridden by implementing a own _get().
+
+If using the default _get(), _collect() has to store data in
+the self._data dictionary. If an own _get() is implemented,
+this does not need to be the case.
+'''
+class State:
+    def __init__(self, transport: transport.Transport, ttl: int = 30):
+        self._transport = transport
+        self._ttl = ttl
+
+        self._data = {}
+        self._last_collected = 0
+
+    def _collect(self):
+        raise NotImplemented
+
+    def _get(self, key: str):
+        if key not in self._data:
+            logging.error(f'Data key {key} was not found.')
+            return None
+
+        return self._data[key]
+
+    def _shouldCollect(self):
+        return time.time() - self._last_collected > self._ttl
+
+    def get(self, key: str):
+        if self._shouldCollect():
+            logging.debug(f'Cached value for "{key}" is too old. refreshing.')
+            self.collect()
+        else:
+            logging.debug(f'Using cached value for "{key}".')
+
+
+        return self._get(key)
+
+    # Force datacollection. not really needed
+    def collect(self):
+        self._collect()
+        self._last_collected = time.time()
+
+class UserSessionState(State):
+    def __init__(self, transport: transport.SshTransport, ttl: int = 30):
+        super().__init__(transport, ttl)
+
+        # this is not needed. it's here to shut up pylint
+        self._transport = transport
+
+    def _get(self, key: str):
+        if key not in self._data:
+            return 0
+
+        return self._data[key]
+
+    def _collect(self):
+        data = self._transport.execHandleStderror('who').decode('utf-8')
+        # TODO error handling
+        lines = data.split('\n')
+
+        self._data = {}
+
+        for l in lines:
+            name, _ = l.split(' ', 1)
+
+            logging.debug(f'Found user session {name}')
+
+            if name not in self._data:
+                self._data[name] = 0
+
+            self._data[name] += 1