add fbmessenger provider with chat history script

my/fbmessenger.py

@@ -0,0 +1,35 @@
+from pathlib import Path
+from shutil import rmtree
+from tempfile import TemporaryDirectory
+from typing import Union
+
+import my_configuration.repos.fbmessengerexport.model as messenger
+from my_configuration import paths
+
+
+def _dump_helper(model: messenger.Model, tdir: Path) -> None:
+    for t in model.iter_threads():
+        name = t.name.replace('/', '_') # meh..
+        path = tdir / (name + '.txt')
+        with path.open('w') as fo:
+            for m in t.iter_messages(order_by='-timestamp'):
+                # TODO would be nice to have usernames perhaps..
+                dts = m.dt.strftime('%Y-%m-%d %a %H:%M')
+                msg = f"{dts}: {m.text}"
+                print(msg, file=fo)
+
+
+def dump_chat_history(path: Union[Path, str]) -> None:
+    p = Path(path)
+    assert not p.exists() or p.is_dir()
+
+    m = messenger.Model(paths.fbmessenger.export_db)
+
+    with TemporaryDirectory() as tdir:
+        td = Path(tdir)
+        _dump_helper(m, td)
+
+        if p.exists():
+            rmtree(p)
+        td.rename(p)
+        td.mkdir() # ugh, hacky way of preventing complaints from context manager