"""
Tests which scan for certain occurrences in the code, they may not find
all of these occurrences but should catch almost all. This file was adapted
from NumPy.
"""


import os
from pathlib import Path
import ast
import tokenize

import scipy

import pytest


class ParseCall(ast.NodeVisitor):
    def __init__(self):
        self.ls = []

    def visit_Attribute(self, node):
        ast.NodeVisitor.generic_visit(self, node)
        self.ls.append(node.attr)

    def visit_Name(self, node):
        self.ls.append(node.id)

class FindFuncs(ast.NodeVisitor):
    def __init__(self, filename):
        super().__init__()
        self.__filename = filename
        self.bad_filters = []
        self.bad_stacklevels = []

    def visit_Call(self, node):
        p = ParseCall()
        p.visit(node.func)
        ast.NodeVisitor.generic_visit(self, node)

        if p.ls[-1] == 'simplefilter' or p.ls[-1] == 'filterwarnings':
            if node.args[0].s == "ignore":
                self.bad_filters.append(
                    "{}:{}".format(self.__filename, node.lineno))

        if p.ls[-1] == 'warn' and (
                len(p.ls) == 1 or p.ls[-2] == 'warnings'):

            if self.__filename == "_lib/tests/test_warnings.py":
                # This file
                return

            # See if stacklevel exists:
            if len(node.args) == 3:
                return
            args = {kw.arg for kw in node.keywords}
            if "stacklevel" not in args:
                self.bad_stacklevels.append(
                    "{}:{}".format(self.__filename, node.lineno))


@pytest.fixture(scope="session")
def warning_calls():
    # combined "ignore" and stacklevel error
    base = Path(scipy.__file__).parent

    bad_filters = []
    bad_stacklevels = []

    for path in base.rglob("*.py"):
        # use tokenize to auto-detect encoding on systems where no
        # default encoding is defined (e.g., LANG='C')
        with tokenize.open(str(path)) as file:
            tree = ast.parse(file.read(), filename=str(path))
            finder = FindFuncs(path.relative_to(base))
            finder.visit(tree)
            bad_filters.extend(finder.bad_filters)
            bad_stacklevels.extend(finder.bad_stacklevels)

    return bad_filters, bad_stacklevels


@pytest.mark.slow
def test_warning_calls_filters(warning_calls):
    bad_filters, bad_stacklevels = warning_calls

    # There is still one simplefilter occurrence in optimize.py that could be removed.
    bad_filters = [item for item in bad_filters
                   if 'optimize.py' not in item]
    # The filterwarnings calls in sparse are needed.
    bad_filters = [item for item in bad_filters
                   if os.path.join('sparse', '__init__.py') not in item
                   and os.path.join('sparse', 'sputils.py') not in item]

    if bad_filters:
        raise AssertionError(
            "warning ignore filter should not be used, instead, use\n"
            "numpy.testing.suppress_warnings (in tests only);\n"
            "found in:\n    {}".format(
                "\n    ".join(bad_filters)))


@pytest.mark.slow
@pytest.mark.xfail(reason="stacklevels currently missing")
def test_warning_calls_stacklevels(warning_calls):
    bad_filters, bad_stacklevels = warning_calls

    msg = ""

    if bad_filters:
        msg += ("warning ignore filter should not be used, instead, use\n"
                "numpy.testing.suppress_warnings (in tests only);\n"
                "found in:\n    {}".format("\n    ".join(bad_filters)))
        msg += "\n\n"

    if bad_stacklevels:
        msg += "warnings should have an appropriate stacklevel:\n    {}".format(
                "\n    ".join(bad_stacklevels))

    if msg:
        raise AssertionError(msg)