"""
backend/tests/test_api.py
Comprehensive tests for all FastAPI endpoints.

Tests cover:
  - Successful requests with valid data
  - Input validation errors (422)
  - HuggingFace API failures (502 fallback)
  - Timeout handling
  - Malformed response data
  - Error status-code mapping

Run with:  pytest backend/tests/test_api.py -v
"""

import asyncio
import json
import os
import sys
from typing import Any, Dict, List
from unittest.mock import AsyncMock, MagicMock, patch

import pytest  # type: ignore[import-not-found]
from fastapi.testclient import TestClient

# Add backend directory to path
sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))

# automation_engine has Firebase dependencies - mock its heavy parts
# but keep the Pydantic model classes
mock_ae = MagicMock()

# Define minimal Pydantic-like classes for payloads automation_engine exports
from pydantic import BaseModel as _BM

class _DiagnosticCompletionPayload(_BM):
    studentId: str
    results: list
    gradeLevel: str | None = None
    questionBreakdown: dict | None = None

class _QuizSubmissionPayload(_BM):
    studentId: str
    quizId: str
    subject: str
    score: float
    totalQuestions: int
    correctAnswers: int
    timeSpentSeconds: int

class _StudentEnrollmentPayload(_BM):
    studentId: str
    name: str
    email: str
    gradeLevel: str | None = None
    teacherId: str | None = None

class _DataImportPayload(_BM):
    teacherId: str
    students: list
    columnMapping: dict

class _ContentUpdatePayload(_BM):
    adminId: str
    action: str
    contentType: str
    contentId: str
    subjectId: str | None = None
    details: str | None = None

class _AutomationResult(_BM):
    success: bool = True
    message: str = ""
    actions: list = []

mock_ae.automation_engine = MagicMock()
mock_ae.DiagnosticCompletionPayload = _DiagnosticCompletionPayload
mock_ae.QuizSubmissionPayload = _QuizSubmissionPayload
mock_ae.StudentEnrollmentPayload = _StudentEnrollmentPayload
mock_ae.DataImportPayload = _DataImportPayload
mock_ae.ContentUpdatePayload = _ContentUpdatePayload
mock_ae.AutomationResult = _AutomationResult
sys.modules["automation_engine"] = mock_ae

# Override HF_TOKEN so client init doesn't fail
os.environ["HF_TOKEN"] = "test-token-for-testing"

# analytics.py is importable directly (its heavy deps are guarded)
from main import app  # noqa: E402

client = TestClient(app)


# ─── Fixtures ──────────────────────────────────────────────────


class FakeClassificationElement:
    """Mimics huggingface_hub ZeroShotClassificationOutputElement."""

    def __init__(self, label: str, score: float):
        self.label = label
        self.score = score


def make_zsc_client(
    classification: list | None = None,
):
    """Create a mock InferenceClient with predictable zero-shot outputs.

    Used only for risk-prediction tests (the only endpoint still using
    ``get_client()`` / ``InferenceClient``).
    """
    mock_client = MagicMock()

    if classification is None:
        classification = [
            FakeClassificationElement("low risk academically stable", 0.85),
            FakeClassificationElement("medium academic risk", 0.10),
            FakeClassificationElement("high risk of failing", 0.05),
        ]
    mock_client.zero_shot_classification.return_value = classification

    return mock_client


# ─── Health & Root ─────────────────────────────────────────────


class TestHealthEndpoints:
    def test_health_returns_200(self):
        response = client.get("/health")
        assert response.status_code == 200
        data = response.json()
        assert data["status"] == "healthy"
        assert "models" in data

    def test_root_returns_api_info(self):
        response = client.get("/")
        assert response.status_code == 200
        data = response.json()
        assert data["name"] == "MathPulse AI API"
        assert "version" in data

    def test_health_includes_request_id_header(self):
        response = client.get("/health")
        assert "x-request-id" in response.headers


# ─── Chat Endpoint ─────────────────────────────────────────────


class TestChatEndpoint:
    @patch("main.call_hf_chat")
    def test_chat_success(self, mock_chat):
        mock_chat.return_value = "Hello! 2+2=4."
        response = client.post("/api/chat", json={
            "message": "What is 2+2?",
            "history": [],
        })
        assert response.status_code == 200
        assert "4" in response.json()["response"]

    @patch("main.call_hf_chat")
    def test_chat_with_history(self, mock_chat):
        mock_chat.return_value = "Yes, that's right."
        response = client.post("/api/chat", json={
            "message": "Is that correct?",
            "history": [
                {"role": "user", "content": "What is 2+2?"},
                {"role": "assistant", "content": "4"},
            ],
        })
        assert response.status_code == 200
        # Verify history was included in messages
        call_args = mock_chat.call_args
        messages = call_args.args[0] if call_args.args else call_args.kwargs.get("messages", [])
        assert len(messages) >= 3  # system + 2 history + 1 current

    def test_chat_missing_message_returns_422(self):
        response = client.post("/api/chat", json={"history": []})
        assert response.status_code == 422

    @patch("main.call_hf_chat")
    def test_chat_hf_failure_returns_502(self, mock_chat):
        mock_chat.side_effect = Exception("HF API down")
        response = client.post("/api/chat", json={
            "message": "Hello",
            "history": [],
        })
        assert response.status_code == 502


# ─── Risk Prediction ──────────────────────────────────────────


class TestRiskPrediction:
    @patch("main.get_client")
    def test_predict_risk_success(self, mock_get):
        mock_get.return_value = make_zsc_client()
        response = client.post("/api/predict-risk", json={
            "engagementScore": 80,
            "avgQuizScore": 75,
            "attendance": 90,
            "assignmentCompletion": 85,
        })
        assert response.status_code == 200
        data = response.json()
        assert data["riskLevel"] in ("High", "Medium", "Low")
        assert 0 <= data["confidence"] <= 1

    def test_predict_risk_invalid_score_range(self):
        response = client.post("/api/predict-risk", json={
            "engagementScore": 150,  # > 100
            "avgQuizScore": 75,
            "attendance": 90,
            "assignmentCompletion": 85,
        })
        assert response.status_code == 422

    def test_predict_risk_negative_score(self):
        response = client.post("/api/predict-risk", json={
            "engagementScore": -5,
            "avgQuizScore": 75,
            "attendance": 90,
            "assignmentCompletion": 85,
        })
        assert response.status_code == 422

    def test_predict_risk_missing_fields(self):
        response = client.post("/api/predict-risk", json={
            "engagementScore": 80,
        })
        assert response.status_code == 422

    @patch("main.get_client")
    def test_predict_risk_hf_failure(self, mock_get):
        hf = make_zsc_client()
        hf.zero_shot_classification.side_effect = Exception("HF down")
        mock_get.return_value = hf
        response = client.post("/api/predict-risk", json={
            "engagementScore": 80,
            "avgQuizScore": 75,
            "attendance": 90,
            "assignmentCompletion": 85,
        })
        assert response.status_code == 502

    @patch("main.get_client")
    def test_batch_risk_prediction(self, mock_get):
        mock_get.return_value = make_zsc_client()
        response = client.post("/api/predict-risk/batch", json={
            "students": [
                {"engagementScore": 80, "avgQuizScore": 75, "attendance": 90, "assignmentCompletion": 85},
                {"engagementScore": 30, "avgQuizScore": 40, "attendance": 50, "assignmentCompletion": 35},
            ],
        })
        assert response.status_code == 200
        assert len(response.json()) == 2


# ─── Learning Path ────────────────────────────────────────────


class TestLearningPath:
    @patch("main.call_hf_chat")
    def test_learning_path_success(self, mock_chat):
        mock_chat.return_value = "1. Review fractions\n2. Practice decimals"
        response = client.post("/api/learning-path", json={
            "weaknesses": ["fractions", "decimals"],
            "gradeLevel": "Grade 7",
        })
        assert response.status_code == 200
        assert "fractions" in response.json()["learningPath"].lower()

    def test_learning_path_missing_weaknesses(self):
        response = client.post("/api/learning-path", json={
            "gradeLevel": "Grade 7",
        })
        assert response.status_code == 422

    def test_learning_path_missing_grade(self):
        response = client.post("/api/learning-path", json={
            "weaknesses": ["fractions"],
        })
        assert response.status_code == 422

    @patch("main.call_hf_chat")
    def test_learning_path_hf_failure(self, mock_chat):
        mock_chat.side_effect = Exception("HF down")
        response = client.post("/api/learning-path", json={
            "weaknesses": ["algebra"],
            "gradeLevel": "Grade 8",
        })
        assert response.status_code == 502


# ─── Daily Insight ─────────────────────────────────────────────


class TestDailyInsight:
    @patch("main.call_hf_chat")
    def test_daily_insight_success(self, mock_chat):
        mock_chat.return_value = "Class is doing well."
        response = client.post("/api/analytics/daily-insight", json={
            "students": [
                {"name": "Alice", "engagementScore": 80, "avgQuizScore": 75, "attendance": 90, "riskLevel": "Low"},
            ],
        })
        assert response.status_code == 200
        assert response.json()["insight"]

    def test_daily_insight_empty_students(self):
        response = client.post("/api/analytics/daily-insight", json={
            "students": [],
        })
        assert response.status_code == 200
        assert "No student data" in response.json()["insight"]


# ─── Quiz Topics ───────────────────────────────────────────────


class TestQuizTopics:
    def test_get_all_topics(self):
        response = client.get("/api/quiz/topics")
        assert response.status_code == 200
        assert "allTopics" in response.json()

    def test_get_topics_by_grade(self):
        response = client.get("/api/quiz/topics?gradeLevel=Grade%207")
        assert response.status_code == 200
        data = response.json()
        assert data["gradeLevel"] == "Grade 7"
        assert "topics" in data

    def test_get_topics_invalid_grade(self):
        response = client.get("/api/quiz/topics?gradeLevel=Grade%2099")
        assert response.status_code == 404


# ─── Quiz Generation ──────────────────────────────────────────


class TestQuizGeneration:
    @patch("main.call_hf_chat")
    def test_generate_quiz_success(self, mock_chat):
        quiz_json = json.dumps([{
            "questionType": "multiple_choice",
            "question": "What is 2+2?",
            "correctAnswer": "4",
            "options": ["A) 3", "B) 4", "C) 5", "D) 6"],
            "bloomLevel": "remember",
            "difficulty": "easy",
            "topic": "Arithmetic",
            "points": 1,
            "explanation": "2+2=4",
        }])
        mock_chat.return_value = quiz_json

        response = client.post("/api/quiz/generate", json={
            "topics": ["Arithmetic"],
            "gradeLevel": "Grade 7",
            "numQuestions": 1,
        })
        assert response.status_code == 200
        data = response.json()
        assert len(data["questions"]) >= 1
        assert data["totalPoints"] > 0

    def test_generate_quiz_missing_topics(self):
        response = client.post("/api/quiz/generate", json={
            "gradeLevel": "Grade 7",
        })
        assert response.status_code == 422

    @patch("main.call_hf_chat")
    def test_generate_quiz_bad_llm_output(self, mock_chat):
        mock_chat.return_value = "This is not valid JSON at all."
        response = client.post("/api/quiz/generate", json={
            "topics": ["Algebra"],
            "gradeLevel": "Grade 8",
            "numQuestions": 1,
        })
        assert response.status_code == 500

    @patch("main.call_hf_chat")
    def test_preview_quiz(self, mock_chat):
        quiz_json = json.dumps([{
            "questionType": "identification",
            "question": "Define slope.",
            "correctAnswer": "Rise over run",
            "bloomLevel": "remember",
            "difficulty": "easy",
            "topic": "Algebra",
            "points": 1,
            "explanation": "Slope = rise/run.",
        }])
        mock_chat.return_value = quiz_json
        response = client.post("/api/quiz/preview", json={
            "topics": ["Algebra"],
            "gradeLevel": "Grade 8",
        })
        assert response.status_code == 200


# ─── Calculator ────────────────────────────────────────────────


class TestCalculator:
    def test_evaluate_simple_expression(self):
        response = client.post("/api/calculator/evaluate", json={
            "expression": "2 + 3",
        })
        # sympy may not be installed in test env — accept 200 or 500
        assert response.status_code in (200, 500)
        if response.status_code == 200:
            data = response.json()
            assert data["result"] == "5"

    def test_evaluate_with_variables(self):
        response = client.post("/api/calculator/evaluate", json={
            "expression": "x**2 + 2*x + 1",
        })
        # Accept 200 (sympy available) or 500 (sympy missing)
        assert response.status_code in (200, 500)

    def test_evaluate_dangerous_expression(self):
        response = client.post("/api/calculator/evaluate", json={
            "expression": "__import__('os').system('rm -rf /')",
        })
        # 400 if validation catches it, 500 if sympy missing or general error
        assert response.status_code in (400, 500)

    def test_evaluate_empty_expression(self):
        response = client.post("/api/calculator/evaluate", json={
            "expression": "",
        })
        assert response.status_code == 422

    def test_evaluate_too_long_expression(self):
        response = client.post("/api/calculator/evaluate", json={
            "expression": "x + " * 200,
        })
        # 400 if length validation, 422 if pydantic validation, 500 if sympy missing
        assert response.status_code in (400, 422, 500)


# ─── Error Handling ────────────────────────────────────────────


class TestErrorHandling:
    def test_404_for_unknown_endpoint(self):
        response = client.get("/api/nonexistent")
        assert response.status_code == 404

    def test_method_not_allowed(self):
        response = client.get("/api/chat")
        assert response.status_code == 405

    def test_request_id_in_error_response(self):
        response = client.get("/api/nonexistent")
        assert "x-request-id" in response.headers

    def test_invalid_json_body(self):
        response = client.post(
            "/api/chat",
            content="this is not json",
            headers={"Content-Type": "application/json"},
        )
        assert response.status_code == 422


# ─── Student Competency ───────────────────────────────────────


class TestStudentCompetency:
    @patch("main.call_hf_chat")
    def test_competency_no_history(self, mock_chat):
        mock_chat.return_value = ""
        response = client.post("/api/quiz/student-competency", json={
            "studentId": "student123",
            "quizHistory": [],
        })
        assert response.status_code == 200
        data = response.json()
        assert data["studentId"] == "student123"
        assert data["competencies"] == []

    @patch("main.call_hf_chat")
    def test_competency_with_history(self, mock_chat):
        mock_chat.return_value = "Good progress overall."
        response = client.post("/api/quiz/student-competency", json={
            "studentId": "student123",
            "quizHistory": [
                {"topic": "Algebra", "score": 8, "total": 10, "timeTaken": 300},
                {"topic": "Algebra", "score": 9, "total": 10, "timeTaken": 250},
                {"topic": "Geometry", "score": 4, "total": 10, "timeTaken": 500},
            ],
        })
        assert response.status_code == 200
        data = response.json()
        assert len(data["competencies"]) > 0
        # Algebra should be higher competency than Geometry
        algebra = next((c for c in data["competencies"] if c["topic"] == "Algebra"), None)
        geometry = next((c for c in data["competencies"] if c["topic"] == "Geometry"), None)
        if algebra and geometry:
            assert algebra["efficiencyScore"] > geometry["efficiencyScore"]


# ─── Run ───────────────────────────────────────────────────────

if __name__ == "__main__":
    pytest.main([__file__, "-v"])