"""The purpose of this module is implement PEP 621 validations that are
difficult to express as a JSON Schema (or that are not supported by the current
JSON Schema library).
"""

from inspect import cleandoc
from typing import Mapping, TypeVar

from .error_reporting import ValidationError

T = TypeVar("T", bound=Mapping)


class RedefiningStaticFieldAsDynamic(ValidationError):
    _DESC = """According to PEP 621:

    Build back-ends MUST raise an error if the metadata specifies a field
    statically as well as being listed in dynamic.
    """
    __doc__ = _DESC
    _URL = (
        "https://packaging.python.org/en/latest/specifications/"
        "pyproject-toml/#dynamic"
    )


class IncludedDependencyGroupMustExist(ValidationError):
    _DESC = """An included dependency group must exist and must not be cyclic.
    """
    __doc__ = _DESC
    _URL = "https://peps.python.org/pep-0735/"


def validate_project_dynamic(pyproject: T) -> T:
    project_table = pyproject.get("project", {})
    dynamic = project_table.get("dynamic", [])

    for field in dynamic:
        if field in project_table:
            raise RedefiningStaticFieldAsDynamic(
                message=f"You cannot provide a value for `project.{field}` and "
                "list it under `project.dynamic` at the same time",
                value={
                    field: project_table[field],
                    "...": " # ...",
                    "dynamic": dynamic,
                },
                name=f"data.project.{field}",
                definition={
                    "description": cleandoc(RedefiningStaticFieldAsDynamic._DESC),
                    "see": RedefiningStaticFieldAsDynamic._URL,
                },
                rule="PEP 621",
            )

    return pyproject


def validate_include_depenency(pyproject: T) -> T:
    dependency_groups = pyproject.get("dependency-groups", {})
    for key, value in dependency_groups.items():
        for each in value:
            if (
                isinstance(each, dict)
                and (include_group := each.get("include-group"))
                and include_group not in dependency_groups
            ):
                raise IncludedDependencyGroupMustExist(
                    message=f"The included dependency group {include_group} doesn't exist",
                    value=each,
                    name=f"data.dependency_groups.{key}",
                    definition={
                        "description": cleandoc(IncludedDependencyGroupMustExist._DESC),
                        "see": IncludedDependencyGroupMustExist._URL,
                    },
                    rule="PEP 735",
                )
    # TODO: check for `include-group` cycles (can be conditional to graphlib)
    return pyproject


EXTRA_VALIDATIONS = (validate_project_dynamic, validate_include_depenency)