from pathlib import Path
import re


def _extract_project_dependencies(text: str):
    """Return the dependencies block text from a [project] section, or None."""
    lines = text.splitlines()
    cur = None
    deps_block = []
    in_dependencies = False
    for line in lines:
        s = line.strip()
        if s.startswith("[") and s.endswith("]"):
            cur = s
            in_dependencies = False
            continue
        if cur == "[project]":
            if (
                s.startswith("dependencies")
                and "=[" in s
                or s.startswith("dependencies")
                and s.endswith("=[")
            ):
                # start of block on same line or next
                # capture from the first '['
                idx = line.find("[")
                if idx != -1 and line.rstrip().endswith("]"):
                    # single-line
                    deps_block.append(line[idx:])
                    in_dependencies = False
                else:
                    deps_block.append(line[idx:])
                    in_dependencies = True
                continue
            if in_dependencies:
                deps_block.append(line)
                if "]" in line:
                    in_dependencies = False
    if deps_block:
        return "\n".join(deps_block)
    return None


def _extract_poetry_dependencies(text: str):
    """Return the lines under [tool.poetry.dependencies] as a single string, or None."""
    lines = text.splitlines()
    cur = None
    collected = []
    for line in lines:
        s = line.strip()
        if s.startswith("[") and s.endswith("]"):
            cur = s
            continue
        if cur == "[tool.poetry.dependencies]":
            if s == "" or s.startswith("#"):
                continue
            collected.append(s)
    if collected:
        return "\n".join(collected)
    return None


def test_pytest_not_in_production_deps():
    p = Path("pyproject.toml")
    assert p.exists(), "pyproject.toml must exist for this project"
    text = p.read_text()

    # Check PEP 621 [project] dependencies = [ ... ]
    proj_deps = _extract_project_dependencies(text)
    if proj_deps:
        assert "pytest" not in proj_deps.lower(), (
            "pytest must not be listed in [project] production dependencies"
        )

    # Check poetry style [tool.poetry.dependencies]
    poetry_deps = _extract_poetry_dependencies(text)
    if poetry_deps:
        # lines like pytest = "^..." or pytest = "..."
        for line in poetry_deps.splitlines():
            # split on = and check key
            key = line.split("=", 1)[0].strip()
            assert key.lower() != "pytest", (
                "pytest must not be listed in [tool.poetry.dependencies]"
            )


def test_requirements_dev_contains_pytest_if_present():
    # If pytest was removed from production deps, ensure it's present in requirements-dev.txt
    dev = Path("requirements-dev.txt")
    if dev.exists():
        text = dev.read_text().lower()
        assert "pytest" in text, (
            "requirements-dev.txt exists but does not contain pytest"
        )
    else:
        # If requirements-dev.txt does not exist, that's acceptable as long as pytest isn't in prod deps
        p = Path("pyproject.toml")
        text = p.read_text()
        assert "pytest" not in text.lower(), (
            "pytest found in pyproject.toml and requirements-dev.txt is missing"
        )