1 files changed, 69 insertions, 0 deletions
diff --git a/gamechest/stepper.py b/gamechest/stepper.py
new file mode 100644
index 0000000..b6dd335
--- /dev/null
+++ b/gamechest/stepper.py
@@ -0,0 +1,69 @@
+#!python3
+
+import collections
+import copy
+from enum import Enum, auto as enum_auto
+
+Progress = collections.namedtuple('Progress', 'step index count percent')
+Progress.step.__doc__ = 'name of the current step'
+Progress.index.__doc__ = 'current step index out of count steps'
+Progress.count.__doc__ = 'total number of steps'
+Progress.percent.__doc__ = 'advance in percent of the current step'
+
+class Stepper:
+    '''
+    Manage a worker processing steps in background and allows polling its
+    progress.
+
+    Takes steps as a dict of step_names/step_worker.
+    A step_worker is a function generator taking a queue waiting for a stop
+    command to abort the step and yielding progress of the step as
+    a percentage, and as second argument it takes a GameChestConfig.
+    '''
+
+    class Command(Enum):
+        STOP = enum_auto()
+
+    def _create_thread(self):
+        return threading.Thread(target=self.worker, daemon=True)
+
+    def __init__(self, conf, steps):
+        self.conf = conf
+        self.thread = None
+        self.commandq = queue.Queue(maxsize=10)
+        self.progressq = queue.Queue(maxsize=10)
+        self.steps = steps
+        self.count = len(steps)
+        self.steps.__doc__ = 'steps are a key/func-value dict'
+        self.thread = self._create_thread()
+        self.last_progress = Progress('unknown', 0, self.count, 0)
+        self.status = {}
+
+    def worker(self, *args):
+        for index, step, step_worker in enumerate(self.steps.items()):
+            self.progressq.put(Progress(step, index, self.count, 0))
+            for percent in step_worker(self.commandq, self.conf, self.status):
+                self.progressq.put(Progress(step, index, self.count, percent))
+
+    def start(self, status):
+        if self.is_alive():
+            return
+        self.status = copy.deepcopy(status)
+        self.thread.start()
+
+    def stop(self):
+        if not self.is_alive():
+            return
+        self.commandq.put(self.Command.STOP)
+        self.thread.join()
+        self.thread = self._create_thread()
+
+    def is_alive(self):
+        return self.thread.is_alive()
+
+    def poll(self):
+        with contextlib.suppress(queue.Empty):
+            progress = self.progress_queue.get_nowait()
+            self.last_progress = progress
+        return self.last_progress
+