"""T21-1 embedding 服务单测：embed_texts / embed_text（全部 mock HTTP，不依赖 Ollama）。

覆盖四类：
1. 成功语义：批量顺序一一对应、维度校验通过、空列表短路不发请求；
2. 失败语义：连接拒绝 / 非 200（模型未拉取 404）/ 响应结构异常 → EmbeddingError；
3. 维度防线：维度不符（8 维假数据）必须报错——防静默污染检索（拍板口径）；
4. 便捷方法：embed_text 等价 embed_texts([text])[0]。

httpx.MockTransport 注入：_client() 是 monkeypatch 点（settings 超时透传）。
"""

from __future__ import annotations

import httpx
import pytest

from app.config.settings import settings
from app.service import embedding as emb


def _mock_client(handler) -> httpx.Client:
    """构造 mock 传输层的 httpx.Client（替换真实网络）。"""
    return httpx.Client(transport=httpx.MockTransport(handler), timeout=5)


@pytest.fixture(autouse=True)
def _patch_client(monkeypatch):
    """默认给一个「合法 1024 维响应」的 mock 客户端，各用例按需覆盖。"""

    def handler(request: httpx.Request) -> httpx.Response:
        body = request.read()
        import json

        payload = json.loads(body)
        vectors = [[0.1] * settings.embed_dim for _ in payload["input"]]
        return httpx.Response(200, json={"model": payload["model"], "embeddings": vectors})

    monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))


class TestSuccess:
    """成功语义。"""

    def test_batch_order_preserved(self, monkeypatch):
        def handler(request: httpx.Request) -> httpx.Response:
            import json

            payload = json.loads(request.read())
            # 每条向量以首字符标记，断言顺序一一对应
            vectors = [[float(ord(t[0]))] + [0.0] * (settings.embed_dim - 1) for t in payload["input"]]
            return httpx.Response(200, json={"embeddings": vectors})

        monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))
        out = emb.embed_texts(["甲文本", "乙文本", "丙文本"])
        assert len(out) == 3
        assert out[0][0] == float(ord("甲"))
        assert out[2][0] == float(ord("丙"))

    def test_empty_input_short_circuits(self, monkeypatch):
        # 空列表不发请求：handler 一旦被调用就 fail（返回 500 触发错误）
        def handler(request: httpx.Request) -> httpx.Response:
            raise AssertionError("空输入不应发起 HTTP 请求")

        monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))
        assert emb.embed_texts([]) == []

    def test_request_payload_uses_settings_model(self, monkeypatch):
        captured: dict = {}

        def handler(request: httpx.Request) -> httpx.Response:
            import json

            captured.update(json.loads(request.read()))
            payload = json.loads(request.read())
            vectors = [[0.0] * settings.embed_dim for _ in payload["input"]]
            return httpx.Response(200, json={"embeddings": vectors})

        monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))
        emb.embed_texts(["测试"])
        assert captured["model"] == settings.embed_model
        assert captured["input"] == ["测试"]


class TestFailure:
    """失败语义：一律 EmbeddingError，不静默降级。"""

    def test_connection_refused(self, monkeypatch):
        def handler(request: httpx.Request) -> httpx.Response:
            raise httpx.ConnectError("connection refused")

        monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))
        with pytest.raises(emb.EmbeddingError, match="连接失败"):
            emb.embed_texts(["任意"])

    def test_model_not_found_404(self, monkeypatch):
        def handler(request: httpx.Request) -> httpx.Response:
            return httpx.Response(404, json={"error": "model 'bge-m3' not found"})

        monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))
        with pytest.raises(emb.EmbeddingError, match="HTTP 404"):
            emb.embed_texts(["任意"])

    def test_malformed_response(self, monkeypatch):
        def handler(request: httpx.Request) -> httpx.Response:
            # embeddings 缺失 / 数量不匹配均属结构异常
            return httpx.Response(200, json={"embeddings": [[0.0] * settings.embed_dim]})

        monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))
        with pytest.raises(emb.EmbeddingError, match="数量与输入不匹配"):
            emb.embed_texts(["一", "二"])


class TestDimensionGuard:
    """维度防线（拍板：维度不符必须报错）。"""

    def test_wrong_dimension_rejected(self, monkeypatch):
        def handler(request: httpx.Request) -> httpx.Response:
            import json

            payload = json.loads(request.read())
            vectors = [[0.1] * 8 for _ in payload["input"]]  # 假 8 维
            return httpx.Response(200, json={"embeddings": vectors})

        monkeypatch.setattr(emb, "_client", lambda: _mock_client(handler))
        with pytest.raises(emb.EmbeddingError, match="维度不符"):
            emb.embed_texts(["任意"])


class TestConvenience:
    def test_embed_text_single(self):
        out = emb.embed_text("单条")
        assert len(out) == settings.embed_dim