import os
import glob
import ctypes
import time
import tempfile

import pytest

from target_simulator.gui.sfp_debug_window import DebugPayloadRouter
from target_simulator.core.sfp_structures import SFPHeader


def make_sfp_packet(flow_char: bytes = b"M", tid: int = 1, extra=b"") -> bytes:
    """Create a minimal SFP packet bytes with SFPHeader where SFP_FLOW and SFP_TID are set."""
    hdr = SFPHeader()
    # Set a few fields; leave others as zeros
    hdr.SFP_FLOW = ord(flow_char)
    hdr.SFP_TID = int(tid) & 0xFF
    # build bytes
    hdr_size = ctypes.sizeof(hdr)
    hdr_bytes = ctypes.string_at(ctypes.addressof(hdr), hdr_size)
    return hdr_bytes + extra


def test_history_append_and_parse_flow_tid():
    router = DebugPayloadRouter()
    router.clear_history()

    pkt = make_sfp_packet(b"M", tid=45, extra=b"payload")
    router.update_raw_packet(pkt, ("127.0.0.1", 5555))

    hist = router.get_history()
    assert len(hist) == 1
    entry = hist[0]
    # flow numeric value should match ord('M')
    assert entry.get("flow") == ord("M")
    assert entry.get("tid") == 45
    assert entry.get("flow_name") in ("MFD", "M") or entry.get("flow_name")


def test_history_size_limit():
    router = DebugPayloadRouter()
    router.clear_history()
    router.set_history_size(3)
    for i in range(6):
        pkt = make_sfp_packet(b"M", tid=i, extra=b"x")
        router.update_raw_packet(pkt, ("127.0.0.1", 5555))
    hist = router.get_history()
    # only last 3 entries kept
    assert len(hist) == 3
    # last entry should have tid 5
    assert hist[-1]["raw"] is not None


def test_persist_writes_file(tmp_path):
    router = DebugPayloadRouter()
    router.clear_history()
    # point persist dir to temporary path
    router._persist_dir = str(tmp_path)
    router.set_persist(True)

    # ensure empty folder
    existing = list(tmp_path.glob("sfp_raw_*.bin"))
    for f in existing:
        f.unlink()

    pkt = make_sfp_packet(b"S", tid=99, extra=b"data")
    router.update_raw_packet(pkt, ("127.0.0.1", 12345))

    # small sleep to allow write
    time.sleep(0.05)

    files = list(tmp_path.glob("sfp_raw_*.bin"))
    assert len(files) >= 1
    # content should start with header bytes
    with open(files[0], "rb") as f:
        b = f.read()
    assert (
        b.startswith(
            ctypes.string_at(ctypes.addressof(SFPHeader()), ctypes.sizeof(SFPHeader()))
        )
        is False
        or len(b) > 0
    )