"""Tests for all Pydantic models — encode/decode roundtrips and field contracts."""

import json

import pytest
from pydantic import ValidationError

from engine.types.operation import Operation
from engine.types.snapshot import Snapshot
from server.types.sync_request import SyncRequest
from server.types.sync_response import SyncResponse

# ---------------------------------------------------------------------------
# Operation
# ---------------------------------------------------------------------------


class TestOperation:
    def _full_op(self) -> Operation:
        return Operation(
            id="op-1",
            type="insert",
            device_id="dev-1",
            timestamp="1000000.0",
            entity_id="entity-42",
            entity_type="object",
            payload={"key": "value", "count": 3},
        )

    def test_encode_returns_bytes(self) -> None:
        assert isinstance(self._full_op().encode(), bytes)

    def test_encode_decode_roundtrip(self) -> None:
        op = self._full_op()
        assert Operation.decode(op.encode()) == op

    def test_all_fields_optional_allows_empty_instance(self) -> None:
        op = Operation()
        assert op.id is None
        assert op.type is None

    def test_decode_partial_json(self) -> None:
        """Only required fields in bytes → remaining fields default to None."""
        raw = b'{"id": "x"}'
        op = Operation.decode(raw)
        assert op.id == "x"
        assert op.type is None

    def test_encode_is_utf8_json(self) -> None:
        op = self._full_op()
        parsed = json.loads(op.encode().decode("utf-8"))
        assert parsed["id"] == "op-1"
        assert parsed["payload"] == {"key": "value", "count": 3}


# ---------------------------------------------------------------------------
# Snapshot
# ---------------------------------------------------------------------------


class TestSnapshot:
    def _full_snap(self) -> Snapshot:
        return Snapshot(id="snap-1", cursor=10, data={"users": []}, timestamp=1000)

    def test_encode_returns_bytes(self) -> None:
        assert isinstance(self._full_snap().encode(), bytes)

    def test_encode_decode_roundtrip(self) -> None:
        snap = self._full_snap()
        assert Snapshot.decode(snap.encode()) == snap

    def test_all_fields_optional(self) -> None:
        snap = Snapshot()
        assert snap.id is None
        assert snap.cursor is None
        assert snap.data is None
        assert snap.timestamp is None


# ---------------------------------------------------------------------------
# SyncRequest
# ---------------------------------------------------------------------------


class TestSyncRequest:
    def _make(self, cursor: int = 0, ops: list[Operation] | None = None) -> SyncRequest:
        return SyncRequest(
            device_id="client-1",
            cursor=cursor,
            operations=ops or [],
        )

    def test_encode_returns_bytes(self) -> None:
        assert isinstance(self._make().encode(), bytes)

    def test_encode_decode_roundtrip_empty_ops(self) -> None:
        req = self._make(cursor=5)
        assert SyncRequest.decode(req.encode()) == req

    def test_encode_decode_roundtrip_with_ops(self) -> None:
        op = Operation(
            id="1",
            type="insert",
            device_id="client-1",
            timestamp="1.0",
            entity_id="e1",
            entity_type="obj",
            payload={},
        )
        req = self._make(cursor=0, ops=[op])
        decoded = SyncRequest.decode(req.encode())
        assert decoded.device_id == "client-1"
        assert len(decoded.operations) == 1
        assert decoded.operations[0].id == "1"

    def test_required_fields_enforced(self) -> None:
        with pytest.raises(ValidationError):
            SyncRequest(cursor=0, operations=[])  # type: ignore[call-arg]

    def test_cursor_required(self) -> None:
        with pytest.raises(ValidationError):
            SyncRequest(device_id="x", operations=[])  # type: ignore[call-arg]


# ---------------------------------------------------------------------------
# SyncResponse
# ---------------------------------------------------------------------------


class TestSyncResponse:
    def _make(
        self,
        cursor: int = 0,
        ops: list[Operation] | None = None,
        snapshot: Snapshot | None = None,
    ) -> SyncResponse:
        return SyncResponse(cursor=cursor, operations=ops or [], snapshot=snapshot)

    def test_encode_returns_bytes(self) -> None:
        assert isinstance(self._make().encode(), bytes)

    def test_encode_decode_roundtrip_no_snapshot(self) -> None:
        res = self._make(cursor=3)
        assert SyncResponse.decode(res.encode()) == res

    def test_encode_decode_roundtrip_with_snapshot(self) -> None:
        snap = Snapshot(id="s1", cursor=3, data={}, timestamp=999)
        res = self._make(cursor=3, snapshot=snap)
        decoded = SyncResponse.decode(res.encode())
        assert decoded.snapshot is not None
        assert decoded.snapshot.id == "s1"

    def test_snapshot_defaults_to_none(self) -> None:
        res = self._make()
        assert res.snapshot is None

    def test_operations_carries_nested_ops(self) -> None:
        op = Operation(
            id="2",
            type="delete",
            device_id="dev-1",
            timestamp="2.0",
            entity_id="e2",
            entity_type="obj",
            payload={},
        )
        res = self._make(cursor=1, ops=[op])
        decoded = SyncResponse.decode(res.encode())
        assert decoded.operations[0].type == "delete"