from __future__ import annotations

import json
from typing import Any

from jsonschema import Draft202012Validator, FormatChecker

from hub_core.contracts import CONTRACT_VERSION, extension_contract_root
from hub_core.runtime.models import RegistryRegistration


class ContractValidator:
    """Validate runtime registration input against the packaged contract."""

    def __init__(self, *, runtime_contract_version: str = CONTRACT_VERSION) -> None:
        self._runtime_contract_version = _parse_semver(runtime_contract_version)
        contract_root = extension_contract_root()
        schema_root = contract_root.joinpath("schemas")
        self._descriptor = _validator(schema_root.joinpath("hub-descriptor.schema.json"))
        self._manifest = _validator(schema_root.joinpath("hub-manifest.schema.json"))
        catalog = json.loads(
            contract_root.joinpath("catalogs", "event-types.json").read_text(encoding="utf-8")
        )
        self._event_families = {
            entry["type"]: entry["family"] for entry in catalog["event_types"]
        }

    def validate_registration(self, registration: RegistryRegistration) -> None:
        self._descriptor.validate(registration.descriptor)
        self._manifest.validate(registration.manifest)
        descriptor_id = registration.descriptor.get("reuse_surface_id")
        manifest_id = registration.manifest.get("reuse_surface_id")
        if descriptor_id != manifest_id:
            raise ValueError("descriptor and manifest reuse_surface_id must match")
        self._negotiate_contract_version(registration.descriptor)

    def _negotiate_contract_version(self, descriptor: dict[str, Any]) -> None:
        version_min = _parse_semver(descriptor["contract_version_min"])
        version_max = _parse_semver(descriptor["contract_version_max"])
        if version_min > version_max:
            raise ValueError(
                "descriptor contract_version_min must not exceed contract_version_max"
            )
        if not (version_min <= self._runtime_contract_version <= version_max):
            raise ValueError(
                "descriptor requires contract version range "
                f"{descriptor['contract_version_min']}-{descriptor['contract_version_max']}, "
                f"incompatible with runtime contract version {CONTRACT_VERSION}"
            )

    def validate_event_family(self, event_type: str, expected_family: str) -> None:
        actual_family = self._event_families.get(event_type)
        if actual_family is None:
            raise ValueError(f"event type '{event_type}' is not cataloged")
        if actual_family != expected_family:
            raise ValueError(
                f"event type '{event_type}' belongs to '{actual_family}', not '{expected_family}'"
            )


def _validator(resource: Any) -> Draft202012Validator:
    schema = json.loads(resource.read_text(encoding="utf-8"))
    Draft202012Validator.check_schema(schema)
    return Draft202012Validator(schema, format_checker=FormatChecker())


def _parse_semver(value: str) -> tuple[int, int, int]:
    core = value.split("+", 1)[0].split("-", 1)[0]
    major, minor, patch = core.split(".")
    return (int(major), int(minor), int(patch))