import difflib
import inspect
import re
import unittest

from code import compile_command as compiler
from functools import partial

from bpython.curtsiesfrontend.interpreter import code_finished_will_parse
from bpython.curtsiesfrontend.preprocess import preprocess
from bpython.test.fodder import original, processed


preproc = partial(preprocess, compiler=compiler)


def get_fodder_source(test_name):
    pattern = rf"#StartTest-{test_name}\n(.*?)#EndTest"
    orig, xformed = [
        re.search(pattern, inspect.getsource(module), re.DOTALL)
        for module in [original, processed]
    ]

    if not orig:
        raise ValueError(
            f"Can't locate test {test_name} in original fodder file"
        )
    if not xformed:
        raise ValueError(
            f"Can't locate test {test_name} in processed fodder file"
        )
    return orig.group(1), xformed.group(1)


class TestPreprocessing(unittest.TestCase):
    def assertCompiles(self, source):
        finished, parsable = code_finished_will_parse(source, compiler)
        return finished and parsable

    def test_indent_empty_lines_nops(self):
        self.assertEqual(preproc("hello"), "hello")
        self.assertEqual(preproc("hello\ngoodbye"), "hello\ngoodbye")
        self.assertEqual(preproc("a\n    b\nc\n"), "a\n    b\nc\n")

    def assertShowWhitespaceEqual(self, a, b):
        self.assertEqual(
            a,
            b,
            "".join(
                difflib.context_diff(
                    a.replace(" ", "~").splitlines(True),
                    b.replace(" ", "~").splitlines(True),
                    fromfile="actual",
                    tofile="expected",
                    n=5,
                )
            ),
        )

    def assertDefinitionIndented(self, obj):
        name = obj.__name__
        obj2 = getattr(processed, name)
        orig = inspect.getsource(obj)
        xformed = inspect.getsource(obj2)
        self.assertShowWhitespaceEqual(preproc(orig), xformed)
        self.assertCompiles(xformed)

    def assertLinesIndented(self, test_name):
        orig, xformed = get_fodder_source(test_name)
        self.assertShowWhitespaceEqual(preproc(orig), xformed)
        self.assertCompiles(xformed)

    def assertIndented(self, obj_or_name):
        if isinstance(obj_or_name, str):
            self.assertLinesIndented(obj_or_name)
        else:
            self.assertDefinitionIndented(obj_or_name)

    def test_empty_line_between_methods(self):
        self.assertIndented(original.BlankLineBetweenMethods)

    def test_empty_line_within_class(self):
        self.assertIndented(original.BlankLineInFunction)

    def test_blank_lines_in_for_loop(self):
        self.assertIndented("blank_lines_in_for_loop")

    @unittest.skip(
        "More advanced technique required: need to try compiling and "
        "backtracking"
    )
    def test_blank_line_in_try_catch(self):
        self.assertIndented("blank_line_in_try_catch")

    @unittest.skip(
        "More advanced technique required: need to try compiling and "
        "backtracking"
    )
    def test_blank_line_in_try_catch_else(self):
        self.assertIndented("blank_line_in_try_catch_else")

    def test_blank_trailing_line(self):
        self.assertIndented("blank_trailing_line")

    def test_tabs(self):
        self.assertIndented(original.tabs)