put format-specific db writers/readers together

1 files changed, 63 insertions, 0 deletions

diff --git a/vk/utils/tracking/db/backend/csv.py b/vk/utils/tracking/db/backend/csv.py
new file mode 100644
index 0000000..10a504f
--- /dev/null
+++ b/vk/utils/tracking/db/backend/csv.py
@@ -0,0 +1,63 @@
+# Copyright 2016 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is licensed under the terms of the MIT License.
+# See LICENSE.txt for details.
+
+from collections.abc import Iterable
+import csv
+
+from ..record import Record
+from ..timestamp import Timestamp
+
+class Writer:
+    def __init__(self, fd):
+        self._fd = fd
+        self._writer = csv.writer(fd, lineterminator='\n')
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        pass
+
+    def on_initial_status(self, user):
+        self._write_record(user)
+        self._fd.flush()
+
+    def on_status_update(self, user):
+        self._write_record(user)
+        self._fd.flush()
+
+    def on_connection_error(self, e):
+        pass
+
+    def _write_record(self, user):
+        if not self:
+            return
+        self._write_row(self._record_to_row(Record.from_user(user)))
+
+    def _write_row(self, row):
+        self._writer.writerow(row)
+
+    @staticmethod
+    def _record_to_row(record):
+        return [str(record.get_timestamp())] + [str(record[field]) for field in record]
+
+class Reader(Iterable):
+    def __init__(self, fd):
+        self._reader = csv.reader(fd)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        pass
+
+    def __iter__(self):
+        return map(Reader._record_from_row, self._reader)
+
+    @staticmethod
+    def _record_from_row(row):
+        record = Record(Timestamp.from_string(row[0]))
+        for i in range(len(Record.FIELDS)):
+            record[Record.FIELDS[i]] = row[i + 1]
+        return record