"""TDD — HttpTransport.push_mpack_presign: client-side Step 1 of the mpack push protocol.

PP-1  Happy path: POST returns {upload_url, mpack_key} — both echoed back correctly.
PP-2  The POST body contains mpack_key == blob_id(mpack_bytes) and correct size_bytes.
PP-3  The POST is sent to /{owner}/{slug}/push/mpack-presign.
PP-4  Non-200 response raises TransportError.
PP-5  Response missing upload_url raises TransportError.
"""
from __future__ import annotations

from unittest.mock import MagicMock, patch

import msgpack
import pytest

from muse.core.transport import HttpTransport, TransportError
from muse.core.types import blob_id

_URL = "https://staging.musehub.ai/gabriel/muse"
_UPLOAD_URL = "https://minio.example.com/mpacks/sha256:abc?sig=fake"


def _presign_response(mpack_key: str, upload_url: str = _UPLOAD_URL) -> bytes:
    return msgpack.packb(
        {"upload_url": upload_url, "mpack_key": mpack_key},
        use_bin_type=True,
    )


class _Resp:
    def __init__(self, body: bytes, status: int = 200) -> None:
        self.status_code = status
        self.content = body


def _mock_client(resp: _Resp) -> MagicMock:
    mock = MagicMock()
    mock.__enter__ = MagicMock(return_value=mock)
    mock.__exit__ = MagicMock(return_value=False)
    mock.post = MagicMock(return_value=resp)
    return mock


# ── PP-1 ──────────────────────────────────────────────────────────────────────

def test_pp1_happy_path_returns_upload_url_and_mpack_key() -> None:
    """Server 200 → dict with upload_url and mpack_key returned to caller."""
    mpack_bytes = b"fake mpack content"
    mpack_key = blob_id(mpack_bytes)
    mock_client = _mock_client(_Resp(_presign_response(mpack_key)))

    transport = HttpTransport()
    with patch("muse.core.transport._httpx_mod.Client", return_value=mock_client):
        result = transport.push_mpack_presign(_URL, None, mpack_bytes)

    assert result["upload_url"] == _UPLOAD_URL
    assert result["mpack_key"] == mpack_key


# ── PP-2 ──────────────────────────────────────────────────────────────────────

def test_pp2_post_body_contains_correct_key_and_size() -> None:
    """The POST body must encode mpack_key = blob_id(bytes) and size_bytes = len(bytes)."""
    mpack_bytes = b"x" * 512
    mpack_key = blob_id(mpack_bytes)
    mock_client = _mock_client(_Resp(_presign_response(mpack_key)))

    transport = HttpTransport()
    with patch("muse.core.transport._httpx_mod.Client", return_value=mock_client):
        transport.push_mpack_presign(_URL, None, mpack_bytes)

    call_kwargs = mock_client.post.call_args
    sent_body: bytes = call_kwargs[1].get("content") or call_kwargs[0][1]
    payload = msgpack.unpackb(sent_body, raw=False)
    assert payload["mpack_key"] == mpack_key
    assert payload["size_bytes"] == 512


# ── PP-3 ──────────────────────────────────────────────────────────────────────

def test_pp3_posts_to_correct_endpoint() -> None:
    """POST must go to /{owner}/{slug}/push/mpack-presign."""
    mpack_bytes = b"data"
    mpack_key = blob_id(mpack_bytes)
    mock_client = _mock_client(_Resp(_presign_response(mpack_key)))

    transport = HttpTransport()
    with patch("muse.core.transport._httpx_mod.Client", return_value=mock_client):
        transport.push_mpack_presign(_URL, None, mpack_bytes)

    posted_url: str = mock_client.post.call_args[0][0]
    assert posted_url.endswith("/push/mpack-presign")


# ── PP-4 ──────────────────────────────────────────────────────────────────────

def test_pp4_non_200_raises_transport_error() -> None:
    """A 4xx/5xx response must raise TransportError."""
    mock_client = _mock_client(_Resp(b"quota exceeded", status=429))

    transport = HttpTransport()
    with patch("muse.core.transport._httpx_mod.Client", return_value=mock_client):
        with pytest.raises(TransportError):
            transport.push_mpack_presign(_URL, None, b"bytes")


# ── PP-5 ──────────────────────────────────────────────────────────────────────

def test_pp5_missing_upload_url_raises_transport_error() -> None:
    """If the server omits upload_url, TransportError must be raised."""
    mpack_bytes = b"data"
    mpack_key = blob_id(mpack_bytes)
    bad_resp = msgpack.packb({"mpack_key": mpack_key}, use_bin_type=True)
    mock_client = _mock_client(_Resp(bad_resp))

    transport = HttpTransport()
    with patch("muse.core.transport._httpx_mod.Client", return_value=mock_client):
        with pytest.raises(TransportError, match="upload_url"):
            transport.push_mpack_presign(_URL, None, mpack_bytes)