"""Smoke tests for POST /v1/messages with stream=true (SSE). Verified live 2026-09-18, < $0.0002 total."""
from __future__ import annotations

import json

MSG = "/v1/messages"


def _events(lines):
    name = None
    for line in lines:
        if line.startswith("event:"):
            name = line[6:].strip()
        elif line.startswith("data:"):
            yield name, json.loads(line[5:].strip())


def test_sse_event_order_and_shapes(anthropic, models):
    st, gen, hdrs = anthropic("POST", MSG, {"model": models["anthropic"], "max_tokens": 16, "stream": True,
                                            "messages": [{"role": "user", "content": "Reply with OK."}]}, stream=True, note="test_streaming basic")
    assert st == 200
    assert "text/event-stream" in {k.lower(): v for k, v in hdrs.items()}["content-type"]
    evs = list(_events(gen))
    names = [n for n, _ in evs]
    for n, d in evs:
        assert d["type"] == n  # SSE event name == data.type
    assert names[0] == "message_start" and names[-1] == "message_stop"
    assert names.count("message_start") == 1 and names.count("message_stop") == 1
    assert names.index("content_block_start") < names.index("content_block_delta") < names.index("content_block_stop") < names.index("message_delta")
    start = evs[0][1]["message"]
    assert start["content"] == [] and start["stop_reason"] is None and "usage" in start
    delta = next(d for n, d in evs if n == "message_delta")
    assert delta["delta"]["stop_reason"] == "end_turn"
    assert set(delta["usage"]) >= {"input_tokens", "output_tokens", "cache_creation_input_tokens", "cache_read_input_tokens"}
    text = "".join(d["delta"]["text"] for n, d in evs if n == "content_block_delta" and d["delta"]["type"] == "text_delta")
    assert "OK" in text
    assert all(n in {"message_start", "content_block_start", "content_block_delta", "content_block_stop", "message_delta", "message_stop", "ping"} for n in names)


def test_sse_tool_use_input_json_delta(anthropic, models):
    tool = {"name": "get_weather", "description": "Weather for a city", "input_schema": {"type": "object", "properties": {"city": {"type": "string"}}, "required": ["city"]}}
    st, gen, _ = anthropic("POST", MSG, {"model": models["anthropic"], "max_tokens": 48, "stream": True, "tools": [tool],
                                         "tool_choice": {"type": "tool", "name": "get_weather"},
                                         "messages": [{"role": "user", "content": "Weather in Paris?"}]}, stream=True, note="test_streaming tool_use")
    assert st == 200
    evs = list(_events(gen))
    start = next(d for n, d in evs if n == "content_block_start")
    assert start["content_block"]["type"] == "tool_use" and start["content_block"]["input"] == {}
    partial = "".join(d["delta"]["partial_json"] for n, d in evs if n == "content_block_delta" and d["delta"]["type"] == "input_json_delta")
    assert json.loads(partial).get("city")
    assert next(d for n, d in evs if n == "message_delta")["delta"]["stop_reason"] == "tool_use"