"""JSON Schema loading and validation."""

from __future__ import annotations

import json
from functools import lru_cache
from importlib.resources import files
from itertools import islice

from jsonschema import Draft202012Validator, FormatChecker

from .errors import SchemaValidationFailed


@lru_cache(maxsize=8)
def validator_for(schema_name: str) -> Draft202012Validator:
    if "/" in schema_name or "\\" in schema_name or not schema_name.endswith(".json"):
        raise SchemaValidationFailed(f"Target schema is unavailable: {schema_name}")
    resource = files("edu_crawler.schemas").joinpath(schema_name)
    if not resource.is_file():
        raise SchemaValidationFailed(f"Target schema is unavailable: {schema_name}")
    schema = json.loads(resource.read_text(encoding="utf-8"))
    Draft202012Validator.check_schema(schema)
    return Draft202012Validator(schema, format_checker=FormatChecker())


def validate_record(schema_name: str, record: dict) -> None:
    errors = list(islice(validator_for(schema_name).iter_errors(record), 5))
    if not errors:
        return
    summaries = []
    for error in errors:
        path = ".".join(str(part) for part in error.absolute_path) or "$"
        summaries.append(f"{path}: {error.validator} validation failed")
    raise SchemaValidationFailed("; ".join(summaries))