from .ip_util import addr_to_int
from .tables import Base, TException, TExecution, TAddress
from .tables import TKind, TDomain, TRecord, TMessage
from sqlalchemy.orm import sessionmaker

Session = sessionmaker(autoflush=False)

create_view_statements = [
    """
CREATE VIEW Results AS
SELECT
    Messages.ExecutionId,
    ServerIps.AsStr as Server,
    Kinds.Name as Kind,
    Domains.Name as Name,
    RecordIps.AsStr as Address,
    Exceptions.Name as Exception,
    Messages.Failed as Failed
FROM Messages
LEFT JOIN Domains ON Messages.DomainId = Domains.DomainId
LEFT JOIN Kinds ON Domains.KindId = Kinds.KindId
LEFT JOIN Ips AS ServerIps ON Messages.ServerId = ServerIps.IpId
LEFT JOIN Records ON Messages.RecordId = Records.RecordId
LEFT JOIN Ips as RecordIps ON Records.IpId = RecordIps.IpId
LEFT JOIN Exceptions ON Messages.ExceptionId = Exceptions.ExceptionId
    """,
]


class Execution:
    def __init__(self, db):
        self.db = db
        self.execution = None

    def __enter__(self):
        from .util import right_now
        self.execution = self.db.start_execution(right_now())
        return self.execution

    def __exit__(self, exc_type, exc_value, traceback):
        from .util import right_now
        completed = exc_type is None
        self.db.finish_execution(self.execution, right_now(), completed)


def is_column(ref):
    from sqlalchemy.orm.attributes import InstrumentedAttribute
    return isinstance(ref, InstrumentedAttribute)


def apply_properties(obj, d):
    for k, v in d.items():
        ref = getattr(obj.__class__, k)
        assert ref is not None, (type(obj), k)
        assert is_column(ref), (type(obj), k)
        setattr(obj, k, v)
    return obj


class RespoDB:
    def __init__(self, uri, setup=False, create=False):
        from sqlalchemy import create_engine

        self.uri = uri
        db_exists = self._db_exists(self.uri)
        self.db = create_engine(self.uri)
        Session.configure(bind=self.db)
        self._conn = None

        if setup or (create and not db_exists):
            with self:
                Base.metadata.create_all(self.db)
                self.setup_executions()
                self.setup_exceptions()
                self.setup_ips()
                self.setup_kinds()
                self.setup_domains()
                self.setup_records()
                self.setup_messages()

                for q in create_view_statements:
                    self._fire(q)
        assert setup or create or db_exists, "database was never setup"

        self.execution = Execution(self)

    @staticmethod
    def _db_exists(uri):
        from os.path import exists
        _, _, fp = uri.partition(":")
        if fp.startswith("//"):
            _, _, fp = fp[2:].partition("/")
        return fp and exists(fp)

    def __enter__(self):
        self._conn = Session()
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.commit()
        self._conn.close()
        self._conn = None

    def find_one(self, cls_spec, **filters):
        if len(filters) > 0:
            return self._conn.query(cls_spec).filter_by(**filters).first()
        else:
            return self._conn.query(cls_spec).first()

    def flush(self):
        assert self._conn is not None
        self._conn.flush()

    def commit(self):
        assert self._conn is not None
        self._conn.commit()

    def new_exception(self, **kwargs):
        assert self._conn is not None
        res = TException(**kwargs)
        self._conn.add(res)
        return res

    def new_kind(self, **kwargs):
        assert self._conn is not None
        res = TKind(**kwargs)
        self._conn.add(res)
        return res

    def new_domain(self, **kwargs):
        assert self._conn is not None
        res = TDomain(**kwargs)
        self._conn.add(res)
        return res

    def new_address(self, **kwargs):
        assert self._conn is not None
        res = TAddress(**kwargs)
        self._conn.add(res)
        return res

    def new_record(self, **kwargs):
        assert self._conn is not None
        res = TRecord(**kwargs)
        self._conn.add(res)
        return res

    def new_message(self, **kwargs):
        assert self._conn is not None
        res = TMessage(**kwargs)
        self._conn.add(res)
        return res

    def _fire(self, statement):
        assert self._conn is not None
        self._conn.execute(statement).close()

    def setup_executions(self):
        pass

    def setup_exceptions(self):
        # careful not to call them "errors" since NXDOMAIN is not an error.
        # TODO: upsert?
        self.new_exception(name="NXDOMAIN", fail=False)
        self.new_exception(name="NoAnswer", fail=True)
        self.new_exception(name="NoNameservers", fail=True)
        self.new_exception(name="Timeout", fail=True)

    def setup_ips(self):
        self.modify_address("0.0.0.0", block_target=True)
        self.modify_address("127.0.0.1", block_target=True)

    def setup_kinds(self):
        pass

    def setup_domains(self):
        pass

    def setup_records(self):
        pass

    def setup_messages(self):
        pass

    def start_execution(self, dt):
        execution = TExecution()
        execution.start_date = dt
        self.flush()
        return execution

    def finish_execution(self, execution, dt, completed):
        # TODO: fail if ExecutionId is missing?
        execution.finish_date = dt
        execution.completed = completed
        self.flush()

    def all_ips(self):
        assert self._conn is not None
        temp = self._conn.query(TAddress).values(TAddress.str)
        return [t[0] for t in temp]

    def next_record_id(self):
        from sqlalchemy.sql.expression import func
        expr = func.coalesce(func.max(TRecord.record_id), 0) + 1
        return self.find_one(expr)[0]

    def find_record_id(self, addresses):
        address_ids = list(address.address_id for address in addresses)
        temp = self._conn.query(TRecord).filter(TRecord.address_id.in_(address_ids))
        record_ids = [t[0] for t in temp.values(TRecord.record_id)]
        # TODO: why are record_ids even tuples to begin with?
        if not record_ids:
            return None
        unique_ids = sorted(set(record_ids))
        for needle in unique_ids:
            if sum(1 for id in record_ids if id == needle) == len(addresses):
                found = True
                return needle
        return None

    def push_entry(self, entry):
        kind = self.find_one(TKind, name=entry.kind)
        if not kind:
            kind = self.new_kind(name=entry.kind)
        if entry.kind.startswith("bad"):
            exception = self.find_one(TException, name="NXDOMAIN")
            assert exception is not None
            kind.exception = exception

        domain = self.find_one(TDomain, name=entry.domain)
        if not domain:
            domain = self.new_domain(name=entry.domain)
        domain.kind = kind

        addresses = []
        as_ints = sorted(set(map(addr_to_int, entry.addrs)))
        for numeric in as_ints:
            address = self.find_one(TAddress, ip=numeric)
            if not address:
                address = self.new_address(ip=numeric)
            addresses.append(address)

        for address in addresses:
            if entry.reason == "block":
                address.block_target = True
            elif entry.reason == "redirect":
                address.redirect_target = True
            elif entry.reason == "gfw":
                address.gfw_target = True

        if addresses:
            record_id = self.find_record_id(addresses)
            if record_id is None:
                record_id = self.next_record_id()
                for address in addresses:
                    self.new_record(record_id=record_id, address=address)
        else:
            record_id = None

        numeric = addr_to_int(entry.server)
        server = self.find_one(TAddress, ip=numeric)
        if not server:
            server = self.new_address(ip=numeric)
            self.flush()
        server.server = True

        if entry.exception:
            exception = self.find_one(TException, name=entry.exception)
            assert exception is not None
        else:
            exception = None

        failed = not entry.success

        message = self.new_message(
            execution=entry.execution,
            server=server, domain=domain,
            record_id=record_id, exception=exception,
            failed=failed)
        self.flush()

    def country_code(self, ip, code=None):
        numeric = addr_to_int(ip)
        address = self.find_one(TAddress, ip=numeric)
        if code is None:
            if address is not None:
                return address.country_code
        else:
            # NOTE: can't set code to null here since None was ruled out.
            if address is None:
                self.new_address(ip=numeric, country_code=code)
            else:
                address.country_code = code
            self.flush()
        return None

    def modify_address(self, ip, **kwargs):
        numeric = addr_to_int(ip)
        address = self.find_one(TAddress, ip=numeric)
        if address is None:
            self.new_address(ip=numeric, **kwargs)
        else:
            apply_properties(address, kwargs)
        self.flush()