import contextlib
import os
import unittest
import io

from sample_validator.iterators import BaseTXT, CSV, NDJSON, CSV_PARAMS, TXT
from sample_validator.exceptions import TableFileStructError


FIXTURES_PATH = os.path.join(os.path.dirname(__file__), "fixtures", "iterators")


class IteratorTestCaseMixin:
    iterator_class = None
    iterator_kwargs = None
    iterator_correct_report = None
    iterator_incorrect_report = None
    iterator_empty_report = None

    @contextlib.contextmanager
    def get_file_obj(self, report_name):
        filepath = os.path.join(FIXTURES_PATH, report_name)

        with open(filepath, 'r') as fout:
            yield fout

    def test_correct(self):
        if not self.iterator_correct_report:
            self.skipTest('Name of correct report is not provided')
        with self.get_file_obj(self.iterator_correct_report) as fout:
            reader = self.iterator_class(file_obj=fout, **self.iterator_kwargs)

            for line in reader:
                self.assertTrue(type(line), dict)

    def test_incorrect(self):
        if not self.iterator_incorrect_report:
            self.skipTest('Name of incorrect report is not provided')
        with self.get_file_obj(self.iterator_incorrect_report) as fout:
            reader = self.iterator_class(file_obj=fout, **self.iterator_kwargs)
            self.assertRaises(TableFileStructError, next, reader)

    def test_empty(self):
        if not self.iterator_empty_report:
            self.skipTest('Name of empty report is not provided')
        with self.get_file_obj(self.iterator_empty_report) as fout:
            reader = self.iterator_class(file_obj=fout, **self.iterator_kwargs)
            self.assertListEqual(list(reader), [])


class CSVIteratorTestCase(IteratorTestCaseMixin, unittest.TestCase):
    iterator_class = CSV
    iterator_kwargs = dict(rows_number=3, reader_params=CSV_PARAMS["tsv"])
    iterator_correct_report = 'tsv_correct.tsv'
    iterator_incorrect_report = 'tsv_incorrect.tsv'
    iterator_empty_report = 'tsv_empty.tsv'


class NDJSONIteratorTestCase(IteratorTestCaseMixin, unittest.TestCase):
    iterator_class = NDJSON
    iterator_kwargs = dict(rows_number=3)
    iterator_correct_report = 'ndjson_correct.ndjson'
    iterator_empty_report = 'ndjson_empty.ndjson'


class TXTIteratorAmazonTestCase(IteratorTestCaseMixin, unittest.TestCase):
    iterator_class = TXT
    iterator_kwargs = dict(rows_number=5, delimiter='#*#', has_metadata=True)
    iterator_correct_report = 'txt_amazon_correct.txt'
    iterator_incorrect_report = 'txt_amazon_incorrect.txt'
    iterator_empty_report = 'txt_amazon_empty.txt'

    def test_correct_rows_counting_amazon(self):
        with self.get_file_obj('txt_amazon_correct.txt') as fout:
            reader = TXT(rows_number=5, file_obj=fout, delimiter='#*#', has_metadata=True)
            self.assertEqual(len(list(reader)), 5)

    def test_only_headers_amazon(self):
        with self.get_file_obj('txt_amazon_only_headers.txt') as fout:
            reader = TXT(rows_number=3, file_obj=fout, delimiter='#*#', has_metadata=True)
            self.assertFalse(list(reader))


class TXTIteratorSmeMaxTestCase(IteratorTestCaseMixin, unittest.TestCase):
    iterator_class = TXT
    iterator_kwargs = dict(rows_number=5, delimiter='\x07', header=["h1", "h2", "h3", "h4"])
    iterator_correct_report = 'txt_sme_max_correct.txt'
    iterator_incorrect_report = 'txt_sme_max_incorrect.txt'
    iterator_empty_report = 'txt_sme_max_empty.txt'

    def test_correct_rows_counting(self):
        with self.get_file_obj('txt_sme_max_correct.txt') as fout:
            reader = TXT(rows_number=5, file_obj=fout, delimiter='\x07', header=["h1", "h2", "h3", "h4"])
            self.assertEqual(len(list(reader)), 5)


class CSVGRASIteratorTestCase(IteratorTestCaseMixin, unittest.TestCase):
    iterator_class = CSV
    iterator_kwargs = dict(rows_number=1000, reader_params={
        'escapechar': '\\',
        'doublequote': False
    })
    iterator_correct_report = 'csv_gras_correct.csv'


class BaseTXTIteratorTestCase(unittest.TestCase):

    def test_readline_skip_empty(self):
        fileobj = io.StringIO('line 1\n\nline 2')
        reader = BaseTXT(file_obj=fileobj, rows_number=None, skip_empty=True)
        self.assertEqual(reader.readline(), 'line 1')
        self.assertEqual(reader.readline(), 'line 2')

    def test_backline(self):
        fileobj = io.StringIO('line 1\nline 2\nline 3')
        reader = BaseTXT(file_obj=fileobj, rows_number=None)
        reader.readline()
        reader.readline()
        reader.backline()
        self.assertEqual(reader.readline(), 'line 2')

    def test_is_eof(self):
        fileobj = io.StringIO('line 1\nline2')
        reader = BaseTXT(file_obj=fileobj, rows_number=None)

        self.assertFalse(reader.is_eof())
        self.assertEqual(fileobj.tell(), 0)

        reader.readline()
        reader.readline()

        self.assertTrue(reader.is_eof())
        self.assertTrue(fileobj.tell(), 11)