"""
Tests for scan_latest's handling of unsniffable .MLG files.

Regression guard: a .MLG file the watcher can't extract a unit ID from must
be cached (as "no id") so it isn't re-sniffed and re-logged on every scan.
Previously the unsniffable result was never cached, so the
`[unsniffable-recent]` warning was re-emitted every scan cycle — ~200 files
x 288 scans/day flooded the log with hundreds of thousands of duplicate lines.
"""
import os
import time
import tempfile
import unittest

import series3_watcher


class UnsniffableCaching(unittest.TestCase):
    def test_unsniffable_recent_file_logged_once_across_scans(self):
        with tempfile.TemporaryDirectory() as d:
            # A .MLG file with no BE####/BA#### pattern → sniff returns None.
            path = os.path.join(d, "junk001.MLG")
            with open(path, "wb") as f:
                f.write(b"\x00" * 512)

            calls = []
            cache = {}
            recent_cutoff = time.time() - 86400.0  # file (mtime≈now) counts as recent

            for _ in range(3):
                series3_watcher.scan_latest(
                    watch=d,
                    header_bytes=2048,
                    cache=cache,
                    recent_cutoff=recent_cutoff,
                    max_age_days=365,
                    logger=calls.append,
                )

            unsniff = [c for c in calls if "[unsniffable-recent]" in c]
            self.assertEqual(
                len(unsniff), 1,
                "unsniffable file should log once across scans, got {}: {}".format(
                    len(unsniff), unsniff),
            )

    def test_sniffable_file_still_returned(self):
        # Sanity: a file WITH a unit id is still detected (happy path intact).
        with tempfile.TemporaryDirectory() as d:
            path = os.path.join(d, "evt001.MLG")
            with open(path, "wb") as f:
                f.write(b"hdr\x00BE12599\x00hdr")  # contains a sniffable unit id
            cache = {}
            result = series3_watcher.scan_latest(
                watch=d, header_bytes=2048, cache=cache,
                recent_cutoff=time.time() - 86400.0, max_age_days=365, logger=None,
            )
            self.assertIn("BE12599", result)


if __name__ == "__main__":
    unittest.main()