import json
from datetime import datetime
from enum import Enum
from pathlib import Path
from typing import Iterator, Optional
from urllib.parse import urljoin

import requests
from jsonschema import Draft7Validator

SCHEMA_DIR = Path(__file__).parent / "schemas"


class Constants(str, Enum):
    @classmethod
    def values(cls):
        return tuple(m.value for m in cls)

    def __str__(self) -> str:
        return str(self.value)


class CveRecordValidationError(Exception):
    def __init__(self, message, errors):
        super().__init__(message)
        self.errors = errors


class CveRecord:
    class Schemas(Constants):
        CNA_PUBLISHED = next(SCHEMA_DIR.glob("published_cna_container_*.json"))
        CNA_REJECTED = next(SCHEMA_DIR.glob("rejected_cna_container_*.json"))
        ADP = next(SCHEMA_DIR.glob("adp_container_*.json"))
        V5_SCHEMA = next(SCHEMA_DIR.glob("CVE_JSON_5.0_bundled_*.json"))

    @classmethod
    def validate(cls, cve_json: dict, schema_path: str) -> None:
        with open(schema_path) as schema_file:
            schema = json.load(schema_file)

        validator = Draft7Validator(schema)
        errors = [error.message for error in sorted(validator.iter_errors(cve_json), key=str)]
        if errors:
            raise CveRecordValidationError(
                f"Schema validation against {schema_path} failed", errors
            )


class CveApi:
    ENVS = {
        "prod": "https://cveawg.mitre.org/api/",
        "dev": "https://cveawg-dev.mitre.org/api/",
        "test": "https://cveawg-test.mitre.org/api/",
    }

    USER_ROLES = ("ADMIN",)

    class States(Constants):
        RESERVED = "reserved"
        PUBLISHED = "published"
        REJECTED = "rejected"

    class Errors(Constants):
        RECORD_EXISTS = "CVE_RECORD_EXISTS"
        RECORD_DOES_NOT_EXIST = "CVE_RECORD_DNE"

    def __init__(
        self, username: str, org: str, api_key: str, env: str = "prod", url: Optional[str] = None
    ) -> None:
        self.username = username
        self.org = org
        self.api_key = api_key
        if not url:
            url = self.ENVS.get(env)
            if not url:
                raise ValueError("Missing URL for CVE API")
        self.url = url

    def _http_request(self, method: str, path: str, **kwargs) -> requests.Response:
        url = urljoin(self.url, path)
        headers = {
            "CVE-API-KEY": self.api_key,
            "CVE-API-ORG": self.org,
            "CVE-API-USER": self.username,
        }
        response = requests.request(method=method, url=url, timeout=60, headers=headers, **kwargs)
        response.raise_for_status()
        return response

    def _get(self, path: str, **kwargs) -> requests.Response:
        return self._http_request("get", path, **kwargs)

    def _get_paged(self, path: str, page_data_attr: str, params: dict, **kwargs) -> Iterator[dict]:
        """Get data from a paged endpoint.

        CVE Services 1.1.0 added pagination on responses longer than the default page size. For
        responses smaller than the page size, the pagination attributes like `nextPage` and
        `pageCount` are not present in the response.

        Responses include the returned data in an attribute named after the resource being
        queried, identified here as `page_data_attr`.

        This method yields returned data as it is received from each response.
        """
        while True:
            response = self._get(path, params=params, **kwargs)
            page = response.json()

            yield from page[page_data_attr]

            # On the last page, `nextPage` is set to `null`.
            next_page = page.get("nextPage")
            if next_page is not None:
                params["page"] = next_page
            else:
                break

    def _post(self, path: str, **kwargs) -> requests.Response:
        return self._http_request("post", path, **kwargs)

    def _put(self, path: str, **kwargs) -> requests.Response:
        return self._http_request("put", path, **kwargs)

    @staticmethod
    def _extract_cna_container(cve_json: dict) -> dict:
        """Check if we received a full v5 record and extract just the CNA container part from it.

        A record "looks" like a full one if it has a dataType=CVE_RECORD attribute. Otherwise,
        it is assumed to be the CNA container.
        """
        if cve_json.get("dataType", "") == "CVE_RECORD":
            return cve_json["containers"]["cna"]
        return cve_json

    def _add_provider_metadata(self, cve_json: dict) -> dict:
        """Add the providerMetadata objects to a CNA container if one is not present.

        The orgId is the only required element of the providerMetadata object, and we can fetch
        it from the API using the org short name provided by the user (when this class is
        instantiated.)
        """
        if "providerMetadata" not in cve_json:
            org_id = self.show_org()["UUID"]
            cve_json["providerMetadata"] = {"orgId": org_id}
        return cve_json

    def publish(self, cve_id: str, cve_json: dict, validate: bool = True) -> dict:
        """Publish a CVE from a JSON object representing the CNA container data."""
        cve_json = self._extract_cna_container(cve_json)
        cve_json = self._add_provider_metadata(cve_json)
        if validate:
            CveRecord.validate(cve_json, CveRecord.Schemas.CNA_PUBLISHED)

        cve_json = {"cnaContainer": cve_json}
        response = self._post(f"cve/{cve_id}/cna", json=cve_json)
        response.raise_for_status()
        return response.json()

    def update_published(self, cve_id: str, cve_json: dict, validate: bool = True) -> dict:
        """Update a published CVE record from a JSON object representing the CNA container data."""
        cve_json = self._extract_cna_container(cve_json)
        cve_json = self._add_provider_metadata(cve_json)
        if validate:
            CveRecord.validate(cve_json, CveRecord.Schemas.CNA_PUBLISHED)

        cve_json = {"cnaContainer": cve_json}
        response = self._put(f"cve/{cve_id}/cna", json=cve_json)
        response.raise_for_status()
        return response.json()

    def reject(self, cve_id: str, cve_json: dict, validate: bool = True) -> dict:
        """Reject a CVE from a JSON object representing the CNA container data."""
        cve_json = self._extract_cna_container(cve_json)
        cve_json = self._add_provider_metadata(cve_json)
        if validate:
            CveRecord.validate(cve_json, CveRecord.Schemas.CNA_REJECTED)

        cve_json = {"cnaContainer": cve_json}
        response = self._post(f"cve/{cve_id}/reject", json=cve_json)
        response.raise_for_status()
        return response.json()

    def update_rejected(self, cve_id: str, cve_json: dict, validate: bool = True) -> dict:
        """Update a rejected CVE record from a JSON object representing the CNA container data."""
        cve_json = self._extract_cna_container(cve_json)
        cve_json = self._add_provider_metadata(cve_json)
        if validate:
            CveRecord.validate(cve_json, CveRecord.Schemas.CNA_REJECTED)

        cve_json = {"cnaContainer": cve_json}
        response = self._put(f"cve/{cve_id}/reject", json=cve_json)
        response.raise_for_status()
        return response.json()

    def move_to_rejected(self, cve_id):
        """Move a CVE ID to the REJECTED state without a CVE record.

        This is only possible if a CVE ID is in the RESERVED state.

        Moving a CVE ID to the REJECTED state without a CVE record is not possible if it has
        already been PUBLISHED.
        """
        params = {"state": self.States.REJECTED}
        return self._put(f"cve-id/{cve_id}", params=params).json()

    def move_to_reserved(self, cve_id):
        """Move a CVE ID to the RESERVED state without a CVE record.

        This is only possible if the CVE ID is in the REJECTED state without a CVE record.

        Moving a CVE ID to the RESERVED state is not possible if it has already been PUBLISHED.
        """
        params = {"state": self.States.RESERVED}
        return self._put(f"cve-id/{cve_id}", params=params).json()

    def reserve(self, count: int, random: bool, year: str) -> dict:
        """Reserve a set of CVE IDs.

        The return object contains the reserved CVE IDs and the remaining CVE ID quota.
        """
        params = {
            "cve_year": year,
            "amount": count,
            "short_name": self.org,
        }
        if count > 1:
            params["batch_type"] = "nonsequential" if random else "sequential"
        return self._post("cve-id", params=params).json()

    def show_cve_id(self, cve_id: str) -> dict:
        return self._get(f"cve-id/{cve_id}").json()

    def show_cve_record(self, cve_id: str) -> dict:
        return self._get(f"cve/{cve_id}").json()

    def list_cves(
        self,
        year: Optional[str] = None,
        state: Optional[str] = None,
        reserved_lt: Optional[datetime] = None,
        reserved_gt: Optional[datetime] = None,
    ) -> Iterator[dict]:
        params = {}
        if year:
            params["cve_id_year"] = year
        if state:
            params["state"] = state.upper()
        if reserved_lt:
            params["time_reserved.lt"] = reserved_lt.isoformat()
        if reserved_gt:
            params["time_reserved.gt"] = reserved_gt.isoformat()
        return self._get_paged("cve-id", page_data_attr="cve_ids", params=params)

    def quota(self) -> dict:
        return self._get(f"org/{self.org}/id_quota").json()

    def show_user(self, username: str) -> dict:
        return self._get(f"org/{self.org}/user/{username}").json()

    def reset_api_key(self, username: str) -> dict:
        return self._put(f"org/{self.org}/user/{username}/reset_secret").json()

    def create_user(self, **user_data: dict) -> dict:
        return self._post(f"org/{self.org}/user", json=user_data).json()

    def update_user(self, username, **user_data: dict) -> dict:
        return self._put(f"org/{self.org}/user/{username}", params=user_data).json()

    def list_users(self) -> Iterator[dict]:
        return self._get_paged(f"org/{self.org}/users", page_data_attr="users", params={})

    def show_org(self) -> dict:
        return self._get(f"org/{self.org}").json()

    def ping(self) -> Optional[requests.exceptions.RequestException]:
        """Check the CVE API status.

        Returns any RequestException that was raised if it did not succeed, else None.
        """
        try:
            self._get("health-check")
        except requests.exceptions.RequestException as exc:
            return exc
        return None
