import io
import os
import sys
import pytest
import logging
from contextlib import contextmanager
from typing import Optional

import psycopg
from psycopg import pq
from psycopg import sql
from psycopg._compat import cache
from psycopg.pq._debug import PGconnDebug

from .utils import check_postgres_version

# Set by warm_up_database() the first time the dsn fixture is used
pg_version: int
crdb_version: Optional[int]


def pytest_addoption(parser):
    parser.addoption(
        "--test-dsn",
        metavar="DSN",
        default=os.environ.get("PSYCOPG_TEST_DSN"),
        help=(
            "Connection string to run database tests requiring a connection"
            " [you can also use the PSYCOPG_TEST_DSN env var]."
        ),
    )
    parser.addoption(
        "--pq-trace",
        metavar="{TRACEFILE,STDERR}",
        default=None,
        help="Generate a libpq trace to TRACEFILE or STDERR.",
    )
    parser.addoption(
        "--pq-debug",
        action="store_true",
        default=False,
        help="Log PGconn access. (Requires PSYCOPG_IMPL=python.)",
    )


def pytest_report_header(config):
    dsn = config.getoption("--test-dsn")
    if dsn is None:
        return []

    try:
        with psycopg.connect(dsn, connect_timeout=10) as conn:
            server_version = conn.execute("select version()").fetchall()[0][0]
    except Exception as ex:
        server_version = f"unknown ({ex})"

    return [
        f"Server version: {server_version}",
    ]


def pytest_collection_modifyitems(items):
    for item in items:
        for name in item.fixturenames:
            if name in ("pipeline", "apipeline"):
                item.add_marker(pytest.mark.pipeline)
                break


def pytest_runtest_setup(item):
    for m in item.iter_markers(name="pipeline"):
        if not psycopg.Pipeline.is_supported():
            pytest.skip(psycopg.Pipeline._not_supported_reason())


def pytest_configure(config):
    # register pg marker
    markers = [
        "pg(version_expr): run the test only with matching server version"
        " (e.g. '>= 10', '< 9.6')",
        "pipeline: the test runs with connection in pipeline mode",
    ]
    for marker in markers:
        config.addinivalue_line("markers", marker)


@pytest.fixture(scope="session")
def session_dsn(request):
    """
    Return the dsn used to connect to the `--test-dsn` database (session-wide).
    """
    dsn = request.config.getoption("--test-dsn")
    if dsn is None:
        pytest.skip("skipping test as no --test-dsn")

    warm_up_database(dsn)
    return dsn


@pytest.fixture
def dsn(session_dsn, request):
    """Return the dsn used to connect to the `--test-dsn` database."""
    check_connection_version(request.node)
    return session_dsn


@pytest.fixture(scope="session")
def tracefile(request):
    """Open and yield a file for libpq client/server communication traces if
    --pq-tracefile option is set.
    """
    tracefile = request.config.getoption("--pq-trace")
    if not tracefile:
        yield None
        return

    if tracefile.lower() == "stderr":
        try:
            sys.stderr.fileno()
        except io.UnsupportedOperation:
            raise pytest.UsageError(
                "cannot use stderr for --pq-trace (in-memory file?)"
            ) from None

        yield sys.stderr
        return

    with open(tracefile, "w") as f:
        yield f


@contextmanager
def maybe_trace(pgconn, tracefile, function):
    """Handle libpq client/server communication traces for a single test
    function.
    """
    if tracefile is None:
        yield None
        return

    if tracefile != sys.stderr:
        title = f" {function.__module__}::{function.__qualname__} ".center(80, "=")
        tracefile.write(title + "\n")
        tracefile.flush()

    pgconn.trace(tracefile.fileno())
    try:
        pgconn.set_trace_flags(pq.Trace.SUPPRESS_TIMESTAMPS | pq.Trace.REGRESS_MODE)
    except psycopg.NotSupportedError:
        pass
    try:
        yield None
    finally:
        pgconn.untrace()


@pytest.fixture(autouse=True)
def pgconn_debug(request):
    if not request.config.getoption("--pq-debug"):
        return
    if pq.__impl__ != "python":
        raise pytest.UsageError("set PSYCOPG_IMPL=python to use --pq-debug")
    logging.basicConfig(level=logging.INFO, format="%(message)s")
    logger = logging.getLogger("psycopg.debug")
    logger.setLevel(logging.INFO)
    pq.PGconn = PGconnDebug


@pytest.fixture
def pgconn(dsn, request, tracefile):
    """Return a PGconn connection open to `--test-dsn`."""
    check_connection_version(request.node)

    conn = pq.PGconn.connect(dsn.encode())
    if conn.status != pq.ConnStatus.OK:
        pytest.fail(f"bad connection: {conn.error_message.decode('utf8', 'replace')}")

    with maybe_trace(conn, tracefile, request.function):
        yield conn

    conn.finish()


@pytest.fixture
def conn(conn_cls, dsn, request, tracefile):
    """Return a `Connection` connected to the ``--test-dsn`` database."""
    check_connection_version(request.node)

    conn = conn_cls.connect(dsn)
    with maybe_trace(conn.pgconn, tracefile, request.function):
        yield conn
    conn.close()


@pytest.fixture(params=[True, False], ids=["pipeline=on", "pipeline=off"])
def pipeline(request, conn):
    if request.param:
        if not psycopg.Pipeline.is_supported():
            pytest.skip(psycopg.Pipeline._not_supported_reason())
        with conn.pipeline() as p:
            yield p
        return
    else:
        yield None


@pytest.fixture
async def aconn(dsn, aconn_cls, request, tracefile):
    """Return an `AsyncConnection` connected to the ``--test-dsn`` database."""
    check_connection_version(request.node)

    conn = await aconn_cls.connect(dsn)
    with maybe_trace(conn.pgconn, tracefile, request.function):
        yield conn
    await conn.close()


@pytest.fixture(params=[True, False], ids=["pipeline=on", "pipeline=off"])
async def apipeline(request, aconn):
    if request.param:
        if not psycopg.Pipeline.is_supported():
            pytest.skip(psycopg.Pipeline._not_supported_reason())
        async with aconn.pipeline() as p:
            yield p
        return
    else:
        yield None


@pytest.fixture(scope="session")
def conn_cls(session_dsn):
    cls = psycopg.Connection
    if crdb_version:
        from psycopg.crdb import CrdbConnection

        cls = CrdbConnection

    return cls


@pytest.fixture(scope="session")
def aconn_cls(session_dsn):
    cls = psycopg.AsyncConnection
    if crdb_version:
        from psycopg.crdb import AsyncCrdbConnection

        cls = AsyncCrdbConnection

    return cls


@pytest.fixture(scope="session")
def svcconn(conn_cls, session_dsn):
    """
    Return a session `Connection` connected to the ``--test-dsn`` database.
    """
    conn = conn_cls.connect(session_dsn, autocommit=True)
    yield conn
    conn.close()


@pytest.fixture
def commands(conn, monkeypatch):
    """The list of commands issued internally by the test connection."""
    yield patch_exec(conn, monkeypatch)


@pytest.fixture
def acommands(aconn, monkeypatch):
    """The list of commands issued internally by the test async connection."""
    yield patch_exec(aconn, monkeypatch)


def patch_exec(conn, monkeypatch):
    """Helper to implement the commands fixture both sync and async."""
    _orig_exec_command = conn._exec_command
    L = ListPopAll()

    def _exec_command(command, *args, **kwargs):
        cmdcopy = command
        if isinstance(cmdcopy, bytes):
            cmdcopy = cmdcopy.decode(conn.info.encoding)
        elif isinstance(cmdcopy, sql.Composable):
            cmdcopy = cmdcopy.as_string(conn)

        L.append(cmdcopy)
        return _orig_exec_command(command, *args, **kwargs)

    monkeypatch.setattr(conn, "_exec_command", _exec_command)
    return L


class ListPopAll(list):  # type: ignore[type-arg]
    """A list, with a popall() method."""

    def popall(self):
        out = self[:]
        del self[:]
        return out


def check_connection_version(node):
    try:
        pg_version
    except NameError:
        # First connection creation failed. Let the tests fail.
        pytest.fail("server version not available")

    for mark in node.iter_markers():
        if mark.name == "pg":
            assert len(mark.args) == 1
            msg = check_postgres_version(pg_version, mark.args[0])
            if msg:
                pytest.skip(msg)

        elif mark.name in ("crdb", "crdb_skip"):
            from .fix_crdb import check_crdb_version

            msg = check_crdb_version(crdb_version, mark)
            if msg:
                pytest.skip(msg)


@pytest.fixture
def hstore(svcconn):
    try:
        with svcconn.transaction():
            svcconn.execute("create extension if not exists hstore")
    except psycopg.Error as e:
        pytest.skip(str(e))


@cache
def warm_up_database(dsn: str) -> None:
    """Connect to the database before returning a connection.

    In the CI sometimes, the first test fails with a timeout, probably because
    the server hasn't started yet. Absorb the delay before the test.

    In case of error, abort the test run entirely, to avoid failing downstream
    hundreds of times.
    """
    global pg_version, crdb_version

    try:
        with psycopg.connect(dsn, connect_timeout=10) as conn:
            conn.execute("select 1")

            pg_version = conn.info.server_version

            crdb_version = None
            param = conn.info.parameter_status("crdb_version")
            if param:
                from psycopg.crdb import CrdbConnectionInfo

                crdb_version = CrdbConnectionInfo.parse_crdb_version(param)
    except Exception as exc:
        pytest.exit(f"failed to connect to the test database: {exc}")