import math

import pytest
from fastapi.testclient import TestClient

from app.config import DEFAULT_DIMENSION, get_settings
from app.main import app


class FakeVector:
    def __init__(self, values: list[float]) -> None:
        self.values = values

    def tolist(self) -> list[float]:
        return self.values


class FakeMatrix:
    def __init__(self, vectors: list[list[float]]) -> None:
        self.vectors = vectors

    def tolist(self) -> list[list[float]]:
        return self.vectors


class FakeModel:
    def encode(self, value, normalize_embeddings: bool = True):
        if isinstance(value, list):
            return FakeMatrix([fake_embedding(item) for item in value])

        return FakeVector(fake_embedding(value))


def fake_embedding(text: str) -> list[float]:
    lowered = text.lower()
    value = 0.01

    if any(keyword in lowered for keyword in ["saldo", "pembayaran", "tiket", "e-ticket"]):
        value = 0.08
    elif any(keyword in lowered for keyword in ["kereta", "terlambat", "stasiun"]):
        value = -0.08

    vector = [value] * DEFAULT_DIMENSION
    norm = math.sqrt(sum(item * item for item in vector))
    return [item / norm for item in vector]


@pytest.fixture(autouse=True)
def fake_model(monkeypatch):
    from app import embedding

    monkeypatch.setattr(embedding, "get_model", lambda: FakeModel())


def cosine_similarity(left: list[float], right: list[float]) -> float:
    dot = sum(a * b for a, b in zip(left, right))
    left_norm = math.sqrt(sum(value * value for value in left))
    right_norm = math.sqrt(sum(value * value for value in right))
    return dot / (left_norm * right_norm)


def test_embed_requires_api_key_when_configured(monkeypatch) -> None:
    monkeypatch.setenv("EMBEDDING_API_KEY", "test-secret")
    get_settings.cache_clear()
    client = TestClient(app)

    missing_key_response = client.post("/embed", json={"text": "Saldo terpotong."})
    wrong_key_response = client.post(
        "/embed",
        headers={"X-API-Key": "wrong"},
        json={"text": "Saldo terpotong."},
    )

    assert missing_key_response.status_code == 401
    assert wrong_key_response.status_code == 401

    monkeypatch.delenv("EMBEDDING_API_KEY", raising=False)
    get_settings.cache_clear()


def test_embed_rejects_invalid_input() -> None:
    client = TestClient(app)

    response = client.post("/embed", json={"text": "   "})

    assert response.status_code == 422
    assert response.json()["detail"] == "Text is required"


def test_embed_returns_normalized_vector() -> None:
    client = TestClient(app)

    response = client.post(
        "/embed",
        json={"text": "Saldo saya terpotong tapi tiket tidak muncul."},
    )
    body = response.json()

    assert response.status_code == 200
    assert body["dimension"] == 384
    assert body["model"] == "sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2"
    assert len(body["embedding"]) == 384
    assert all(isinstance(value, float) for value in body["embedding"])


def test_batch_embed_preserves_input_order() -> None:
    client = TestClient(app)

    response = client.post(
        "/embed/batch",
        json={
            "texts": [
                "Saldo terpotong tapi tiket belum muncul.",
                "Refund pembatalan tiket belum diterima.",
                "Kereta terlambat tanpa pemberitahuan.",
            ],
        },
    )
    body = response.json()

    assert response.status_code == 200
    assert body["dimension"] == 384
    assert len(body["embeddings"]) == 3
    assert all(len(vector) == 384 for vector in body["embeddings"])


def test_semantic_similarity_sanity() -> None:
    client = TestClient(app)

    query = client.post(
        "/embed",
        json={"text": "Saldo saya terpotong tapi tiket tidak muncul."},
    ).json()["embedding"]
    similar = client.post(
        "/embed",
        json={"text": "Pembayaran berhasil namun e-ticket belum terbit di aplikasi."},
    ).json()["embedding"]
    unrelated = client.post(
        "/embed",
        json={"text": "Kereta terlambat selama dua jam di stasiun tujuan."},
    ).json()["embedding"]

    assert cosine_similarity(query, similar) > cosine_similarity(query, unrelated)