import os
from math import ceil
from typing import Any, Dict, List, Optional


class ArangoGraph:
    """ArangoDB wrapper for graph operations.

    *Security note*: Make sure that the database connection uses credentials
        that are narrowly-scoped to only include necessary permissions.
        Failure to do so may result in data corruption or loss, since the calling
        code may attempt commands that would result in deletion, mutation
        of data if appropriately prompted or reading sensitive data if such
        data is present in the database.
        The best way to guard against such negative outcomes is to (as appropriate)
        limit the permissions granted to the credentials used with this tool.

        See https://python.langchain.com/docs/security for more information.
    """

    def __init__(self, db: Any) -> None:
        """Create a new ArangoDB graph wrapper instance."""
        self.set_db(db)
        self.set_schema()

    @property
    def db(self) -> Any:
        return self.__db

    @property
    def schema(self) -> Dict[str, Any]:
        return self.__schema

    def set_db(self, db: Any) -> None:
        from arango.database import Database

        if not isinstance(db, Database):
            msg = "**db** parameter must inherit from arango.database.Database"
            raise TypeError(msg)

        self.__db: Database = db
        self.set_schema()

    def set_schema(self, schema: Optional[Dict[str, Any]] = None) -> None:
        """
        Set the schema of the ArangoDB Database.
        Auto-generates Schema if **schema** is None.
        """
        self.__schema = self.generate_schema() if schema is None else schema

    def generate_schema(
        self, sample_ratio: float = 0
    ) -> Dict[str, List[Dict[str, Any]]]:
        """
        Generates the schema of the ArangoDB Database and returns it
        User can specify a **sample_ratio** (0 to 1) to determine the
        ratio of documents/edges used (in relation to the Collection size)
        to render each Collection Schema.
        """
        if not 0 <= sample_ratio <= 1:
            raise ValueError("**sample_ratio** value must be in between 0 to 1")

        # Stores the Edge Relationships between each ArangoDB Document Collection
        graph_schema: List[Dict[str, Any]] = [
            {"graph_name": g["name"], "edge_definitions": g["edge_definitions"]}
            for g in self.db.graphs()
        ]

        # Stores the schema of every ArangoDB Document/Edge collection
        collection_schema: List[Dict[str, Any]] = []

        for collection in self.db.collections():
            if collection["system"]:
                continue

            # Extract collection name, type, and size
            col_name: str = collection["name"]
            col_type: str = collection["type"]
            col_size: int = self.db.collection(col_name).count()

            # Skip collection if empty
            if col_size == 0:
                continue

            # Set number of ArangoDB documents/edges to retrieve
            limit_amount = ceil(sample_ratio * col_size) or 1

            aql = f"""
                FOR doc in `{col_name}`
                    LIMIT {limit_amount}
                    RETURN doc
            """

            doc: Dict[str, Any]
            properties: List[Dict[str, str]] = []
            for doc in self.__db.aql.execute(aql):
                for key, value in doc.items():
                    properties.append({"name": key, "type": type(value).__name__})

            collection_schema.append(
                {
                    "collection_name": col_name,
                    "collection_type": col_type,
                    f"{col_type}_properties": properties,
                    f"example_{col_type}": doc,
                }
            )

        return {"Graph Schema": graph_schema, "Collection Schema": collection_schema}

    def query(
        self, query: str, top_k: Optional[int] = None, **kwargs: Any
    ) -> List[Dict[str, Any]]:
        """Query the ArangoDB database."""
        import itertools

        cursor = self.__db.aql.execute(query, **kwargs)
        return [doc for doc in itertools.islice(cursor, top_k)]

    @classmethod
    def from_db_credentials(
        cls,
        url: Optional[str] = None,
        dbname: Optional[str] = None,
        username: Optional[str] = None,
        password: Optional[str] = None,
    ) -> Any:
        """Convenience constructor that builds Arango DB from credentials.

        Args:
            url: Arango DB url. Can be passed in as named arg or set as environment
                var ``ARANGODB_URL``. Defaults to "http://localhost:8529".
            dbname: Arango DB name. Can be passed in as named arg or set as
                environment var ``ARANGODB_DBNAME``. Defaults to "_system".
            username: Can be passed in as named arg or set as environment var
                ``ARANGODB_USERNAME``. Defaults to "root".
            password: Can be passed ni as named arg or set as environment var
                ``ARANGODB_PASSWORD``. Defaults to "".

        Returns:
            An arango.database.StandardDatabase.
        """
        db = get_arangodb_client(
            url=url, dbname=dbname, username=username, password=password
        )
        return cls(db)


def get_arangodb_client(
    url: Optional[str] = None,
    dbname: Optional[str] = None,
    username: Optional[str] = None,
    password: Optional[str] = None,
) -> Any:
    """Get the Arango DB client from credentials.

    Args:
        url: Arango DB url. Can be passed in as named arg or set as environment
            var ``ARANGODB_URL``. Defaults to "http://localhost:8529".
        dbname: Arango DB name. Can be passed in as named arg or set as
            environment var ``ARANGODB_DBNAME``. Defaults to "_system".
        username: Can be passed in as named arg or set as environment var
            ``ARANGODB_USERNAME``. Defaults to "root".
        password: Can be passed ni as named arg or set as environment var
            ``ARANGODB_PASSWORD``. Defaults to "".

    Returns:
        An arango.database.StandardDatabase.
    """
    try:
        from arango import ArangoClient
    except ImportError as e:
        raise ImportError(
            "Unable to import arango, please install with `pip install python-arango`."
        ) from e

    _url: str = url or os.environ.get("ARANGODB_URL", "http://localhost:8529")
    _dbname: str = dbname or os.environ.get("ARANGODB_DBNAME", "_system")
    _username: str = username or os.environ.get("ARANGODB_USERNAME", "root")
    _password: str = password or os.environ.get("ARANGODB_PASSWORD", "")

    return ArangoClient(_url).db(_dbname, _username, _password, verify=True)
