import struct
import unittest

import zstandard as zstd

from .common import TestCase

ss = struct.Struct("=QQ")


class TestBufferWithSegments(TestCase):
    def test_arguments(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        with self.assertRaises(TypeError):
            zstd.BufferWithSegments()

        with self.assertRaises(TypeError):
            zstd.BufferWithSegments(b"foo")

        # Segments data should be a multiple of 16.
        with self.assertRaisesRegex(
            ValueError, "segments array size is not a multiple of 16"
        ):
            zstd.BufferWithSegments(b"foo", b"\x00\x00")

    def test_invalid_offset(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        with self.assertRaisesRegex(
            ValueError, "offset within segments array references memory"
        ):
            zstd.BufferWithSegments(b"foo", ss.pack(0, 4))

    def test_invalid_getitem(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        b = zstd.BufferWithSegments(b"foo", ss.pack(0, 3))

        with self.assertRaisesRegex(IndexError, "offset must be non-negative"):
            test = b[-10]

        with self.assertRaisesRegex(IndexError, "offset must be less than 1"):
            test = b[1]

        with self.assertRaisesRegex(IndexError, "offset must be less than 1"):
            test = b[2]

    def test_single(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        b = zstd.BufferWithSegments(b"foo", ss.pack(0, 3))
        self.assertEqual(len(b), 1)
        self.assertEqual(b.size, 3)
        self.assertEqual(b.tobytes(), b"foo")

        self.assertEqual(len(b[0]), 3)
        self.assertEqual(b[0].offset, 0)
        self.assertEqual(b[0].tobytes(), b"foo")

    def test_multiple(self):
        if not hasattr(zstd, "BufferWithSegments"):
            self.skipTest("BufferWithSegments not available")

        b = zstd.BufferWithSegments(
            b"foofooxfooxy", b"".join([ss.pack(0, 3), ss.pack(3, 4), ss.pack(7, 5)])
        )
        self.assertEqual(len(b), 3)
        self.assertEqual(b.size, 12)
        self.assertEqual(b.tobytes(), b"foofooxfooxy")

        self.assertEqual(b[0].tobytes(), b"foo")
        self.assertEqual(b[1].tobytes(), b"foox")
        self.assertEqual(b[2].tobytes(), b"fooxy")


class TestBufferWithSegmentsCollection(TestCase):
    def test_empty_constructor(self):
        if not hasattr(zstd, "BufferWithSegmentsCollection"):
            self.skipTest("BufferWithSegmentsCollection not available")

        with self.assertRaisesRegex(ValueError, "must pass at least 1 argument"):
            zstd.BufferWithSegmentsCollection()

    def test_argument_validation(self):
        if not hasattr(zstd, "BufferWithSegmentsCollection"):
            self.skipTest("BufferWithSegmentsCollection not available")

        with self.assertRaisesRegex(TypeError, "arguments must be BufferWithSegments"):
            zstd.BufferWithSegmentsCollection(None)

        with self.assertRaisesRegex(TypeError, "arguments must be BufferWithSegments"):
            zstd.BufferWithSegmentsCollection(
                zstd.BufferWithSegments(b"foo", ss.pack(0, 3)), None
            )

        with self.assertRaisesRegex(
            ValueError, "ZstdBufferWithSegments cannot be empty"
        ):
            zstd.BufferWithSegmentsCollection(zstd.BufferWithSegments(b"", b""))

    def test_length(self):
        if not hasattr(zstd, "BufferWithSegmentsCollection"):
            self.skipTest("BufferWithSegmentsCollection not available")

        b1 = zstd.BufferWithSegments(b"foo", ss.pack(0, 3))
        b2 = zstd.BufferWithSegments(
            b"barbaz", b"".join([ss.pack(0, 3), ss.pack(3, 3)])
        )

        c = zstd.BufferWithSegmentsCollection(b1)
        self.assertEqual(len(c), 1)
        self.assertEqual(c.size(), 3)

        c = zstd.BufferWithSegmentsCollection(b2)
        self.assertEqual(len(c), 2)
        self.assertEqual(c.size(), 6)

        c = zstd.BufferWithSegmentsCollection(b1, b2)
        self.assertEqual(len(c), 3)
        self.assertEqual(c.size(), 9)

    def test_getitem(self):
        if not hasattr(zstd, "BufferWithSegmentsCollection"):
            self.skipTest("BufferWithSegmentsCollection not available")

        b1 = zstd.BufferWithSegments(b"foo", ss.pack(0, 3))
        b2 = zstd.BufferWithSegments(
            b"barbaz", b"".join([ss.pack(0, 3), ss.pack(3, 3)])
        )

        c = zstd.BufferWithSegmentsCollection(b1, b2)

        with self.assertRaisesRegex(IndexError, "offset must be less than 3"):
            c[3]

        with self.assertRaisesRegex(IndexError, "offset must be less than 3"):
            c[4]

        self.assertEqual(c[0].tobytes(), b"foo")
        self.assertEqual(c[1].tobytes(), b"bar")
        self.assertEqual(c[2].tobytes(), b"baz")