import unittest
from textbook.extract_exercises import extract_exercises, numbered_items

FIXTURE = """\
1.6. Divisibility in the Integers
body text
Proof. Exercise 1.6.15.                                                           n

Exercises 1.6

1.6.1. Complete the following sketch.
   (a) part a text
1.6.2. Prove Proposition 1.6.9.
1.6.3. Suppose that a natural number p > 1 has some property. This is the
converse of Proposition
1.6.19.

1.7. Modular Arithmetic
next section text
"""


class ExtractExercisesTests(unittest.TestCase):
    def test_extract_exercises_slices_between_headings(self):
        block = extract_exercises(FIXTURE, 'Exercises 1.6', '1.7. Modular Arithmetic')
        self.assertIn('1.6.1. Complete', block)
        self.assertNotIn('next section text', block)

    def test_extract_exercises_missing_heading_raises(self):
        with self.assertRaises(ValueError):
            extract_exercises(FIXTURE, 'Exercises 1.6', 'Exercises 9.9')

    def test_numbered_items_orders_and_dedupes(self):
        block = extract_exercises(FIXTURE, 'Exercises 1.6', '1.7. Modular Arithmetic')
        items, _dropped = numbered_items(block, '1.6.')
        self.assertEqual([i['number'] for i in items], ['1.6.1', '1.6.2', '1.6.3'])

    def test_numbered_items_drops_wrapped_cross_reference(self):
        # '1.6.19.' alone on its own line, right after a big jump from 1.6.3, with no
        # text on the same line, is a wrapped cross-reference ("...Proposition\n1.6.19."),
        # not a real exercise 16 numbers ahead of the last real one.
        block = extract_exercises(FIXTURE, 'Exercises 1.6', '1.7. Modular Arithmetic')
        items, dropped = numbered_items(block, '1.6.', max_gap=3)
        self.assertNotIn('1.6.19', [i['number'] for i in items])
        self.assertEqual([d['number'] for d in dropped], ['1.6.19'])


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