"""Codec micro-benchmarks — no server required.

These measure the tight inner loops the driver hits on every row:
``decode()`` per cell, ``parse_tuple_payload()`` per row,
``encode_param()`` per parameter. A 1M-row fetch hits ``decode()``
5-10M times; a 1% slowdown there is *visible*.

The fixtures synthesize realistic byte payloads — no need for the
Docker container. This makes the benchmarks usable in CI's pre-merge
job (which doesn't run integration tests).
"""

from __future__ import annotations

import datetime
import struct
from io import BytesIO

import pytest

from informix_db._protocol import IfxStreamReader
from informix_db._resultset import ColumnInfo, parse_tuple_payload
from informix_db._types import IfxType
from informix_db.converters import decode, encode_param

pytestmark = pytest.mark.benchmark


# ---------------------------------------------------------------------------
# decode() — per-value dispatch
# ---------------------------------------------------------------------------


def test_decode_int(benchmark) -> None:
    """Hot path: per-cell INT decode. ~5M calls/sec is the kind of speed
    a 1M-row fetch with 5 INT columns needs."""
    raw = struct.pack("!i", 42)
    benchmark(decode, int(IfxType.INT), raw)


def test_decode_smallint(benchmark) -> None:
    raw = struct.pack("!h", 100)
    benchmark(decode, int(IfxType.SMALLINT), raw)


def test_decode_bigint(benchmark) -> None:
    raw = struct.pack("!q", 1234567890123)
    benchmark(decode, int(IfxType.BIGINT), raw)


def test_decode_float(benchmark) -> None:
    raw = struct.pack("!d", 3.14159)
    benchmark(decode, int(IfxType.FLOAT), raw)


def test_decode_date(benchmark) -> None:
    raw = struct.pack("!i", 45678)
    benchmark(decode, int(IfxType.DATE), raw)


def test_decode_varchar_short(benchmark) -> None:
    """20-byte ASCII string — typical name column."""
    raw = b"hello world example "
    benchmark(decode, int(IfxType.VARCHAR), raw)


def test_decode_varchar_long(benchmark) -> None:
    """255-byte VARCHAR — max non-LVARCHAR length."""
    raw = b"x" * 255
    benchmark(decode, int(IfxType.VARCHAR), raw)


def test_decode_varchar_utf8(benchmark) -> None:
    """Multi-byte UTF-8 decode — exercise Phase 20 path."""
    raw = "café résumé naïve Zürich".encode()
    benchmark(decode, int(IfxType.VARCHAR), raw, "utf-8")


# ---------------------------------------------------------------------------
# encode_param() — parameter-binding hot path
# ---------------------------------------------------------------------------


def test_encode_int(benchmark) -> None:
    benchmark(encode_param, 42)


def test_encode_str_ascii(benchmark) -> None:
    benchmark(encode_param, "hello world example", "iso-8859-1")


def test_encode_str_utf8(benchmark) -> None:
    benchmark(encode_param, "café résumé naïve", "utf-8")


def test_encode_float(benchmark) -> None:
    benchmark(encode_param, 3.14159)


def test_encode_date(benchmark) -> None:
    benchmark(encode_param, datetime.date(2026, 5, 4))


def test_encode_datetime(benchmark) -> None:
    benchmark(encode_param, datetime.datetime(2026, 5, 4, 12, 30, 45))


# ---------------------------------------------------------------------------
# parse_tuple_payload() — per-row decode
# ---------------------------------------------------------------------------


def _build_systables_row_payload() -> bytes:
    """Synthesize the SQ_TUPLE bytes a typical systables row produces.

    Layout: [short warn=0][int size][payload][optional pad]
    Payload has columns: tabname VARCHAR(128), owner VARCHAR(32),
                          tabid INT, partnum INT, ncols INT.
    """
    payload = bytearray()
    # tabname VARCHAR: [byte len][bytes] — single-byte length prefix per
    # the discovered tuple format
    name = b"systables"
    payload.append(len(name))
    payload.extend(name)
    # owner VARCHAR
    owner = b"informix"
    payload.append(len(owner))
    payload.extend(owner)
    # tabid INT
    payload.extend(struct.pack("!i", 1))
    # partnum INT
    payload.extend(struct.pack("!i", 1048578))
    # ncols INT
    payload.extend(struct.pack("!i", 32))

    out = bytearray()
    out.extend(struct.pack("!h", 0))  # warn
    out.extend(struct.pack("!i", len(payload)))
    out.extend(payload)
    if len(payload) & 1:
        out.append(0)  # even-byte pad
    return bytes(out)


_SYSTABLES_COLUMNS = [
    ColumnInfo(
        name="tabname",
        type_code=int(IfxType.VARCHAR),
        raw_type_code=int(IfxType.VARCHAR),
        encoded_length=128,
    ),
    ColumnInfo(
        name="owner",
        type_code=int(IfxType.VARCHAR),
        raw_type_code=int(IfxType.VARCHAR),
        encoded_length=32,
    ),
    ColumnInfo(
        name="tabid",
        type_code=int(IfxType.INT),
        raw_type_code=int(IfxType.INT),
        encoded_length=4,
    ),
    ColumnInfo(
        name="partnum",
        type_code=int(IfxType.INT),
        raw_type_code=int(IfxType.INT),
        encoded_length=4,
    ),
    ColumnInfo(
        name="ncols",
        type_code=int(IfxType.INT),
        raw_type_code=int(IfxType.INT),
        encoded_length=4,
    ),
]


def test_parse_tuple_5cols_iso8859(benchmark) -> None:
    """Decode a 5-column row (2 VARCHAR + 3 INT) — typical `systables` shape."""
    payload = _build_systables_row_payload()

    def run() -> tuple:
        reader = IfxStreamReader(BytesIO(payload))
        return parse_tuple_payload(reader, _SYSTABLES_COLUMNS)

    benchmark(run)


def test_parse_tuple_5cols_utf8(benchmark) -> None:
    """Same shape, UTF-8 codec path — verify Phase 20 isn't a bottleneck."""
    payload = _build_systables_row_payload()

    def run() -> tuple:
        reader = IfxStreamReader(BytesIO(payload))
        return parse_tuple_payload(reader, _SYSTABLES_COLUMNS, encoding="utf-8")

    benchmark(run)