"""Tests for ChatManager (backend/managers/chat_manager.py)."""

import sys
from pathlib import Path
import pytest
import requests
from unittest.mock import patch, MagicMock

sys.path.insert(0, str(Path(__file__).parent.parent))

from backend.managers.chat_manager import ChatManager


# ── Helpers ──────────────────────────────────────────────────────────────────

def _mock_ok(content="AI reply"):
    """Return a mocked 200 response with a single assistant choice."""
    mock = MagicMock()
    mock.status_code = 200
    mock.json.return_value = {
        "choices": [{"message": {"role": "assistant", "content": content}}]
    }
    mock.text = ""
    return mock


# ── History management ────────────────────────────────────────────────────────

class TestHistory:
    """Tests for add_message and clear_history."""

    @pytest.fixture
    def cm(self):
        return ChatManager()

    def test_add_message_appends_correct_entry(self, cm):
        cm.add_message("user", "Hello")
        assert cm.chat_history == [{"role": "user", "content": "Hello"}]

    def test_add_multiple_messages_preserves_order(self, cm):
        cm.add_message("user", "Hi")
        cm.add_message("assistant", "Hello!")
        assert cm.chat_history[0]["role"] == "user"
        assert cm.chat_history[1]["role"] == "assistant"

    def test_clear_history_empties_list(self, cm):
        cm.add_message("user", "Hi")
        cm.clear_history()
        assert cm.chat_history == []


# ── send_message (mocked HTTP) ────────────────────────────────────────────────

class TestSendMessage:
    """Tests for send_message: history updates, HTTP payload, error handling, and auth headers."""

    @pytest.fixture
    def cm(self):
        return ChatManager()

    def test_user_message_added_to_history(self, cm):
        with patch("requests.post", return_value=_mock_ok()):
            cm.send_message("Hello")
        assert cm.chat_history[0] == {"role": "user", "content": "Hello"}

    def test_assistant_reply_added_to_history(self, cm):
        with patch("requests.post", return_value=_mock_ok("Hi there")):
            cm.send_message("Hello")
        assert cm.chat_history[1] == {"role": "assistant", "content": "Hi there"}

    def test_returns_assistant_content_string(self, cm):
        with patch("requests.post", return_value=_mock_ok("Answer")):
            result = cm.send_message("Question")
        assert result == "Answer"

    def test_full_history_sent_in_request_payload(self, cm):
        """All prior messages must be forwarded so the model has conversation context."""
        cm.add_message("system", "You are helpful.")
        with patch("requests.post", return_value=_mock_ok()) as mock_post:
            cm.send_message("Hello")
        payload = mock_post.call_args.kwargs["json"]
        assert payload["messages"][0]["role"] == "system"
        assert payload["messages"][1]["role"] == "user"

    def test_connection_error_raises_and_adds_error_to_history(self, cm):
        with patch("requests.post", side_effect=requests.exceptions.ConnectionError("refused")):
            with pytest.raises(Exception, match="Connection Error"):
                cm.send_message("Hello")
        assert any("Error" in msg["content"] for msg in cm.chat_history)

    def test_api_error_status_raises(self, cm):
        mock = MagicMock()
        mock.status_code = 500
        mock.text = "Internal Server Error"
        with patch("requests.post", return_value=mock):
            with pytest.raises(Exception, match="API Error 500"):
                cm.send_message("Hello")

    def test_timeout_raises(self, cm):
        with patch("requests.post", side_effect=requests.exceptions.Timeout()):
            with pytest.raises(Exception):
                cm.send_message("Hello")

    def test_empty_choices_raises(self, cm):
        mock = MagicMock()
        mock.status_code = 200
        mock.json.return_value = {"choices": []}
        with patch("requests.post", return_value=mock):
            with pytest.raises(Exception, match="Invalid API response format"):
                cm.send_message("Hello")

    def test_api_key_included_in_header_when_set(self, cm):
        cm.api_key = "test-key-123"
        with patch("requests.post", return_value=_mock_ok()) as mock_post:
            cm.send_message("Hello")
        headers = mock_post.call_args.kwargs["headers"]
        assert headers.get("Authorization") == "Bearer test-key-123"

    def test_api_key_excluded_from_header_when_empty_sentinel(self, cm):
        # "EMPTY" is the sentinel string the UI writes when the user leaves the key field blank.
        cm.api_key = "EMPTY"
        with patch("requests.post", return_value=_mock_ok()) as mock_post:
            cm.send_message("Hello")
        headers = mock_post.call_args.kwargs["headers"]
        assert "Authorization" not in headers

    def test_json_decode_error_raises(self, cm):
        import json
        mock = MagicMock()
        mock.status_code = 200
        mock.json.side_effect = json.JSONDecodeError("bad json", "", 0)
        with patch("requests.post", return_value=mock):
            with pytest.raises(Exception, match="JSON Decode Error"):
                cm.send_message("Hello")


# ── get_chat_display ──────────────────────────────────────────────────────────

class TestGetChatDisplay:
    """Tests for get_chat_display: correct shape and ordering."""

    @pytest.fixture
    def cm(self):
        return ChatManager()

    def test_display_has_role_and_content_keys(self, cm):
        cm.add_message("user", "Hello")
        entry = cm.get_chat_display()[0]
        assert "role" in entry
        assert "content" in entry

    def test_display_preserves_message_order(self, cm):
        cm.add_message("user", "First")
        cm.add_message("assistant", "Second")
        display = cm.get_chat_display()
        assert display[0]["role"] == "user"
        assert display[1]["role"] == "assistant"