"""Tests for docstring_generator module (Issue #96)."""

import ast
import sys
import tempfile
from pathlib import Path

import pytest

sys.path.insert(0, str(Path(__file__).parent.parent / "scripts"))

from docstring_generator import (
    name_to_title,
    extract_body_hint,
    generate_docstring,
    process_source,
    iter_python_files,
)


class TestNameToTitle:
    def test_snake_to_title(self):
        assert name_to_title("validate_fact") == "Validate Fact"
        assert name_to_title("docstring_generator") == "Docstring Generator"
        assert name_to_title("main") == "Main"
        assert name_to_title("__init__") == "Init"


class TestExtractBodyHint:
    def test_assignment_hint(self):
        body = [ast.parse("result = compute()").body[0]]
        hint = extract_body_hint(body)
        assert hint == "Compute or return compute()"

    def test_return_hint(self):
        body = [ast.parse("return data").body[0]]
        hint = extract_body_hint(body)
        assert hint == "Return data"

    def test_no_hint(self):
        body = [ast.parse("pass").body[0]]
        assert extract_body_hint(body) is None


class TestGenerateDocstring:
    def test_simple_function(self):
        src = "def add(a, b):\n    return a + b\n"
        tree = ast.parse(src)
        func = tree.body[0]
        doc = generate_docstring(func)
        assert 'Add' in doc
        assert 'a' in doc and 'b' in doc
        assert 'Args:' in doc
        assert 'Returns:' in doc

    def test_typed_function(self):
        src = "def greet(name: str) -> str:\n    return f'Hello {name}'\n"
        tree = ast.parse(src)
        func = tree.body[0]
        doc = generate_docstring(func)
        assert 'name (str)' in doc
        assert 'str' in doc

    def test_async_function(self):
        src = "async def fetch():\n    pass\n"
        tree = ast.parse(src)
        func = tree.body[0]
        doc = generate_docstring(func)
        assert 'Fetch' in doc

    def test_self_skipped(self):
        src = "class C:\n    def method(self, x):\n        return x\n"
        tree = ast.parse(src)
        cls = tree.body[0]
        method = cls.body[0]
        doc = generate_docstring(method)
        # 'self' should not appear in Args section
        args_start = doc.find('Args:')
        if args_start >= 0:
            args_section = doc[args_start:]
            assert '(self)' not in args_section


class TestProcessSource:
    def test_adds_docstrings(self):
        src = "def foo(x):\n    return x * 2\n"
        new_src, funcs = process_source(src, "test.py")
        assert len(funcs) == 1 and funcs[0] == "foo"
        assert '"""' in new_src
        assert 'Foo' in new_src

    def test_preserves_existing_docstrings(self):
        src = 'def bar():\n    """Already documented."""\n    return 1\n'
        new_src, funcs = process_source(src, "test.py")
        assert len(funcs) == 0
        assert new_src == src

    def test_multiple_functions(self):
        src = "def a(): pass\ndef b(): pass\ndef c(): pass\n"
        new_src, funcs = process_source(src, "test.py")
        assert len(funcs) == 3
        assert '"""' in new_src

    def test_dry_run_no_write(self, tmp_path):
        file = tmp_path / "t.py"
        file.write_text("def f(): pass\n")
        original_mtime = file.stat().st_mtime
        new_src, funcs = process_source(file.read_text(), str(file))
        assert funcs  # detected
        # When caller handles write, dry-run leaves file unchanged
        current_mtime = file.stat().st_mtime
        assert current_mtime == original_mtime


class TestIterPythonFiles:
    def test_single_file(self, tmp_path):
        f = tmp_path / "single.py"
        f.write_text("x = 1")
        files = iter_python_files([str(f)])
        assert len(files) == 1
        assert files[0].name == "single.py"

    def test_directory_recursion(self, tmp_path):
        (tmp_path / "sub").mkdir()
        (tmp_path / "sub" / "a.py").write_text("a=1")
        (tmp_path / "b.py").write_text("b=2")
        files = iter_python_files([str(tmp_path)])
        assert len(files) == 2