# Copyright 2019 Damien Goutte-Gattat.  All rights reserved.
#
# This file is part of the Biopython distribution and governed by your
# choice of the "Biopython License Agreement" or the "BSD 3-Clause License".
# Please see the LICENSE file that should have been included as part of this
# package.
"""Tests for the SeqIO SnapGene module."""
import datetime
import unittest

from io import BytesIO

from Bio import SeqIO
from Bio.SeqFeature import CompoundLocation


class TestSnapGene(unittest.TestCase):
    sample_data = {
        "sample-d": {
            "file": "SnapGene/sample-d.dna",
            "name": "Sample",
            "id": "Sample",
            "description": "Sample Sequence D",
            "length": 1000,
            "topology": "linear",
            "date": datetime.datetime(2021, 7, 7, 0, 0),
            "features": [
                {
                    "type": "misc_binding",
                    "start": 499,
                    "end": 700,
                    "strand": 1,
                    "label": ["FeatureB"],
                    "note": ["Sample feature B"],
                },
                {
                    "type": "promoter",
                    "start": 49,
                    "end": 150,
                    "strand": 1,
                    "label": ["FeatureA"],
                    "note": ["Sample feature A"],
                },
                {
                    "type": "misc_feature",
                    "start": 700,
                    "end": 720,
                    "strand": 1,
                    "label": ["FeatureC"],
                    "note": [
                        "Sample feature C, with explicit label",
                        "Another note for sample feature C",
                    ],
                },
                {
                    "type": "misc_feature",
                    "start": 720,
                    "end": 740,
                    "strand": 1,
                    "label": ["SampleFeatureD"],
                    "note": [
                        "Sample feature D, with a label different from the feature name"
                    ],
                    "name": "FeatureD",
                },
            ],
        },
        "sample-e": {
            "file": "SnapGene/sample-e.dna",
            "name": "Sample",
            "id": "Sample",
            "description": "Sample Sequence E",
            "length": 1000,
            "date": datetime.datetime(2019, 8, 3, 0, 0),
            "topology": "circular",
            "features": [
                {
                    "type": "terminator",
                    "start": 399,
                    "end": 750,
                    "strand": -1,
                    "label": ["FeatureB"],
                },
                {
                    "type": "rep_origin",
                    "start": 160,
                    "end": 241,
                    "strand": 1,
                    "label": ["FeatureA"],
                },
            ],
        },
        "sample-f": {
            "file": "SnapGene/sample-f.dna",
            "name": "Sample",
            "id": "Sample",
            "description": "Sample Sequence F",
            "length": 1000,
            "date": datetime.datetime(2023, 1, 22, 0, 0),
            "topology": "circular",
            "features": [
                {
                    "type": "terminator",
                    "start": 399,
                    "end": 724,
                    "strand": -1,
                    "label": ["FeatureB"],
                    "note": ["An example of a reverse-strand split feature"],
                    "parts": ["1:subfeature1;3:subfeature3"],
                    "segments": [
                        {"start": 634, "end": 724},
                        {"start": 516, "end": 634},
                        {"start": 399, "end": 499},
                    ],
                },
                {
                    "type": "rep_origin",
                    "start": 160,
                    "end": 241,
                    "strand": 1,
                    "label": ["FeatureA"],
                    "note": ["An example of a split feature"],
                    "parts": ["2:subfeature2"],
                    "segments": [
                        {"start": 160, "end": 180},
                        {"start": 187, "end": 207},
                        {"start": 214, "end": 241},
                    ],
                },
                {
                    "type": "primer_bind",
                    "start": 751,
                    "end": 776,
                    "strand": 1,
                    "label": ["Primer 1"],
                },
            ],
        },
        "pFA-KanMX4": {
            "file": "SnapGene/pFA-KanMX4.dna",
            "name": "<unknown name>",
            "id": "<unknown id>",
            "description": "<unknown description>",
            "length": 3941,
            "date": datetime.datetime(2020, 7, 30, 0, 0),
            "topology": "circular",
            "features": [
                {
                    "type": "promoter",
                    "start": 0,
                    "end": 3941,
                    "strand": 1,
                    "label": ["SP6 promoter"],
                },
                {
                    "type": "promoter",
                    "start": 1578,
                    "end": 1597,
                    "strand": -1,
                    "label": ["T7 promoter"],
                },
                {
                    "type": "promoter",
                    "start": 3474,
                    "end": 3579,
                    "strand": -1,
                    "label": ["AmpR promoter"],
                },
                {
                    "type": "terminator",
                    "start": 1273,
                    "end": 1471,
                    "strand": 1,
                    "label": ["TEF terminator"],
                },
                {
                    "type": "promoter",
                    "start": 114,
                    "end": 458,
                    "strand": 1,
                    "label": ["TEF promoter"],
                },
                {
                    "type": "rep_origin",
                    "start": 1854,
                    "end": 2443,
                    "strand": -1,
                    "label": ["ori"],
                },
                {
                    "type": "CDS",
                    "start": 458,
                    "end": 1268,
                    "strand": 1,
                    "label": ["KanR"],
                },
                {
                    "type": "CDS",
                    "start": 2613,
                    "end": 3474,
                    "strand": -1,
                    "label": ["AmpR"],
                    "parts": ["1:signal sequence"],
                    "segments": [
                        {"start": 3405, "end": 3474},
                        {"start": 2613, "end": 3405},
                    ],
                },
                {
                    "type": "gene",
                    "start": 114,
                    "end": 1471,
                    "strand": 1,
                    "label": ["kanMX"],
                },
            ],
        },
    }

    def _check_multivalued_qualifier(self, qualifier, expected, actual):
        if qualifier in expected:
            for value in expected[qualifier]:
                self.assertIn(value, actual.qualifiers[qualifier])

    def _check_feature_segments(self, segments, feature):
        self.assertIsInstance(feature.location, CompoundLocation)
        self.assertEqual(len(segments), len(feature.location.parts))
        for i in range(len(segments)):
            segment = segments[i]
            location = feature.location.parts[i]
            self.assertEqual(segment["start"], location.start)
            self.assertEqual(segment["end"], location.end)

    def test_read(self):
        """Read sample files."""
        for sample in self.sample_data.values():
            record = SeqIO.read(sample["file"], "snapgene")
            self.assertEqual(sample["name"], record.name)
            self.assertEqual(sample["id"], record.id)
            self.assertEqual(sample["description"], record.description)
            self.assertEqual(sample["length"], len(record))
            self.assertEqual(sample["date"], record.annotations["date"])
            self.assertEqual(sample["topology"], record.annotations["topology"])

            self.assertEqual(len(sample["features"]), len(record.features))
            for i in range(len(sample["features"])):
                exp_feat = sample["features"][i]
                read_feat = record.features[i]
                self.assertEqual(exp_feat["type"], read_feat.type)
                self.assertEqual(exp_feat["start"], read_feat.location.start)
                self.assertEqual(exp_feat["end"], read_feat.location.end)
                self.assertEqual(exp_feat["strand"], read_feat.location.strand)
                self._check_multivalued_qualifier("label", exp_feat, read_feat)
                self._check_multivalued_qualifier("note", exp_feat, read_feat)
                self._check_multivalued_qualifier("parts", exp_feat, read_feat)
                if "name" in exp_feat:
                    self.assertEqual(exp_feat["name"], read_feat.qualifiers["name"][0])
                else:
                    self.assertTrue("name" not in read_feat.qualifiers)
                if "segments" in exp_feat:
                    self._check_feature_segments(exp_feat["segments"], read_feat)


class TestCorruptedSnapGene(unittest.TestCase):
    def setUp(self):
        with open("SnapGene/sample-d.dna", "rb") as f:
            self.buffer = f.read()

    def munge_buffer(self, position, value):
        mod_buffer = bytearray(self.buffer)
        if isinstance(value, list):
            mod_buffer[position : position + len(value) - 1] = value
        else:
            mod_buffer[position] = value
        return BytesIO(mod_buffer)

    def test_invalid_cookie(self):
        """Read a file with missing or invalid cookie packet."""
        # Remove the first packet
        h = BytesIO(self.buffer[19:])
        with self.assertRaisesRegex(
            ValueError, "The file does not start with a SnapGene cookie packet"
        ):
            SeqIO.read(h, "snapgene")
        h.close()

        # Keep the first packet but destroy the magic cookie
        h = self.munge_buffer(5, [0x4B, 0x41, 0x42, 0x4F, 0x4F, 0x4D])
        with self.assertRaisesRegex(
            ValueError, "The file is not a valid SnapGene file"
        ):
            SeqIO.read(h, "snapgene")
        h.close()

    def test_missing_dna(self):
        """Read a file without a DNA packet."""
        # Simulate a missing DNA packet by changing the tag byte to an
        # unknown packet type, so that the parser will skip the packet.
        h = self.munge_buffer(19, 0x80)
        with self.assertRaisesRegex(ValueError, "No DNA packet in file"):
            SeqIO.read(h, "snapgene")
        h.close()

    def test_extra_dna(self):
        """Read a file with supernumerary DNA packet."""
        # Fabricate a file with a duplicated DNA packet
        buf = bytearray(self.buffer)
        buf.extend(self.buffer[19:1025])  # Append duplicated DNA packet
        h = BytesIO(buf)
        with self.assertRaisesRegex(
            ValueError, "The file contains more than one DNA packet"
        ):
            SeqIO.read(h, "snapgene")
        h.close()

    def test_truncated_packet(self):
        """Read a file with incomplete packet."""
        # Truncate before the end of the length bytes
        h = BytesIO(self.buffer[3:])
        with self.assertRaisesRegex(ValueError, "Unexpected end of packet"):
            SeqIO.read(h, "snapgene")
        h.close()

        # Truncate before the end of the data
        h = BytesIO(self.buffer[10:])
        with self.assertRaisesRegex(ValueError, "Unexpected end of packet"):
            SeqIO.read(h, "snapgene")
        h.close()


if __name__ == "__main__":
    runner = unittest.TextTestRunner(verbosity=2)
    unittest.main(testRunner=runner)
