"""
Unit tests for Token Endpoint.

Tests token exchange endpoint including validation, error handling, and security.
"""
import os
import pytest
from fastapi.testclient import TestClient

from gondulf.database.connection import Database
from gondulf.services.token_service import TokenService
from gondulf.storage import CodeStore


@pytest.fixture(scope="function")
def test_config(monkeypatch):
    """Configure test environment."""
    # Set required environment variables
    monkeypatch.setenv("GONDULF_SECRET_KEY", "test_secret_key_" + "x" * 32)
    monkeypatch.setenv("GONDULF_BASE_URL", "https://auth.example.com")
    monkeypatch.setenv("GONDULF_DATABASE_URL", "sqlite:///:memory:")

    # Import after environment is set
    from gondulf.config import Config
    Config.load()
    Config.validate()
    return Config


@pytest.fixture
def test_database(tmp_path):
    """Create test database."""
    db_path = tmp_path / "test.db"
    db = Database(f"sqlite:///{db_path}")
    db.ensure_database_directory()
    db.run_migrations()
    return db


@pytest.fixture
def test_code_storage():
    """Create test code storage."""
    return CodeStore(ttl_seconds=600)


@pytest.fixture
def test_token_service(test_database):
    """Create test token service."""
    return TokenService(
        database=test_database,
        token_length=32,
        token_ttl=3600
    )


@pytest.fixture
def client(test_config, test_database, test_code_storage, test_token_service):
    """Create test client with dependency overrides."""
    # Import app after config is set
    from gondulf.dependencies import get_code_storage, get_database, get_token_service
    from gondulf.main import app

    app.dependency_overrides[get_database] = lambda: test_database
    app.dependency_overrides[get_code_storage] = lambda: test_code_storage
    app.dependency_overrides[get_token_service] = lambda: test_token_service

    yield TestClient(app)

    app.dependency_overrides.clear()


@pytest.fixture
def valid_auth_code(test_code_storage):
    """Create a valid authorization code (authorization flow)."""
    code = "test_auth_code_12345"
    metadata = {
        "client_id": "https://client.example.com",
        "redirect_uri": "https://client.example.com/callback",
        "response_type": "code",  # Authorization flow - exchange at token endpoint
        "state": "xyz123",
        "me": "https://user.example.com",
        "scope": "",
        "code_challenge": "abc123",
        "code_challenge_method": "S256",
        "created_at": 1234567890,
        "expires_at": 1234568490,
        "used": False
    }
    test_code_storage.store(f"authz:{code}", metadata)
    return code, metadata


class TestTokenExchangeSuccess:
    """Tests for successful token exchange."""

    def test_token_exchange_success(self, client, valid_auth_code):
        """Test successful token exchange returns access token."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert response.status_code == 200
        data = response.json()
        assert "access_token" in data
        assert data["token_type"] == "Bearer"
        assert data["me"] == metadata["me"]
        assert data["scope"] == metadata["scope"]

    def test_token_exchange_response_format(self, client, valid_auth_code):
        """Test token response matches OAuth 2.0 format."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert response.status_code == 200
        data = response.json()

        # Required fields per OAuth 2.0
        assert "access_token" in data
        assert "token_type" in data
        assert "me" in data
        assert isinstance(data["access_token"], str)
        assert len(data["access_token"]) == 43  # base64url encoded

    def test_token_exchange_cache_headers(self, client, valid_auth_code):
        """Test OAuth 2.0 cache headers are set."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert response.headers["Cache-Control"] == "no-store"
        assert response.headers["Pragma"] == "no-cache"

    def test_token_exchange_deletes_code(self, client, valid_auth_code, test_code_storage):
        """Test authorization code is deleted after exchange."""
        code, metadata = valid_auth_code

        client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        # Code should be deleted
        assert test_code_storage.get(f"authz:{code}") is None


class TestTokenExchangeErrors:
    """Tests for error conditions."""

    def test_invalid_grant_type(self, client, valid_auth_code):
        """Test unsupported grant_type returns error."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "password",  # Wrong grant type
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert response.status_code == 400
        data = response.json()
        assert data["detail"]["error"] == "unsupported_grant_type"

    def test_code_not_found(self, client):
        """Test invalid authorization code returns error."""
        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": "invalid_code_123",
                "client_id": "https://client.example.com",
                "redirect_uri": "https://client.example.com/callback"
            }
        )

        assert response.status_code == 400
        data = response.json()
        assert data["detail"]["error"] == "invalid_grant"

    def test_client_id_mismatch(self, client, valid_auth_code):
        """Test client_id mismatch returns error."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": "https://wrong-client.example.com",  # Wrong client
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert response.status_code == 400
        data = response.json()
        assert data["detail"]["error"] == "invalid_client"

    def test_redirect_uri_mismatch(self, client, valid_auth_code):
        """Test redirect_uri mismatch returns error."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": "https://wrong-uri.example.com/callback"  # Wrong URI
            }
        )

        assert response.status_code == 400
        data = response.json()
        assert data["detail"]["error"] == "invalid_grant"

    def test_code_replay_prevention(self, client, valid_auth_code, test_code_storage):
        """Test authorization code cannot be used twice."""
        code, metadata = valid_auth_code

        # Mark code as used
        metadata["used"] = True
        test_code_storage.store(f"authz:{code}", metadata)

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert response.status_code == 400
        data = response.json()
        assert data["detail"]["error"] == "invalid_grant"


class TestPKCEHandling:
    """Tests for PKCE parameter handling."""

    def test_code_verifier_accepted_but_not_validated(self, client, valid_auth_code):
        """Test code_verifier is accepted but not validated in v1.0.0."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"],
                "code_verifier": "some_verifier_string"
            }
        )

        # Should still succeed (PKCE not validated in v1.0.0)
        assert response.status_code == 200


class TestSecurityValidation:
    """Tests for security validations."""

    def test_token_generated_via_service(self, client, valid_auth_code, test_token_service):
        """Test token is generated through token service."""
        code, metadata = valid_auth_code

        response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert response.status_code == 200
        data = response.json()

        # Validate token was actually stored
        token_metadata = test_token_service.validate_token(data["access_token"])
        assert token_metadata is not None
        assert token_metadata["me"] == metadata["me"]


class TestTokenVerification:
    """Tests for GET /token token verification endpoint."""

    def test_verify_valid_token_success(self, client, test_token_service):
        """Test successful token verification with valid token."""
        # Generate a token
        token = test_token_service.generate_token(
            me="https://user.example.com",
            client_id="https://client.example.com",
            scope=""
        )

        # Verify the token
        response = client.get(
            "/token",
            headers={"Authorization": f"Bearer {token}"}
        )

        assert response.status_code == 200
        data = response.json()
        assert data["me"] == "https://user.example.com"
        assert data["client_id"] == "https://client.example.com"
        assert data["scope"] == ""

    def test_verify_token_with_scope(self, client, test_token_service):
        """Test token verification includes scope."""
        # Generate a token with scope
        token = test_token_service.generate_token(
            me="https://user.example.com",
            client_id="https://client.example.com",
            scope="create update"
        )

        # Verify the token
        response = client.get(
            "/token",
            headers={"Authorization": f"Bearer {token}"}
        )

        assert response.status_code == 200
        data = response.json()
        assert data["scope"] == "create update"

    def test_verify_invalid_token(self, client):
        """Test verification of invalid token returns 401."""
        response = client.get(
            "/token",
            headers={"Authorization": "Bearer invalid_token_xyz123"}
        )

        assert response.status_code == 401
        data = response.json()
        assert data["detail"]["error"] == "invalid_token"
        assert "WWW-Authenticate" in response.headers
        assert response.headers["WWW-Authenticate"] == "Bearer"

    def test_verify_missing_authorization_header(self, client):
        """Test verification without Authorization header returns 401."""
        response = client.get("/token")

        assert response.status_code == 401
        data = response.json()
        assert data["detail"]["error"] == "invalid_token"
        assert "WWW-Authenticate" in response.headers

    def test_verify_invalid_auth_scheme(self, client):
        """Test verification with non-Bearer auth scheme returns 401."""
        response = client.get(
            "/token",
            headers={"Authorization": "Basic dXNlcjpwYXNz"}
        )

        assert response.status_code == 401
        data = response.json()
        assert data["detail"]["error"] == "invalid_token"

    def test_verify_empty_token(self, client):
        """Test verification with empty token returns 401."""
        response = client.get(
            "/token",
            headers={"Authorization": "Bearer "}
        )

        assert response.status_code == 401
        data = response.json()
        assert data["detail"]["error"] == "invalid_token"

    def test_verify_case_insensitive_bearer(self, client, test_token_service):
        """Test Bearer scheme is case-insensitive per RFC 6750."""
        # Generate a token
        token = test_token_service.generate_token(
            me="https://user.example.com",
            client_id="https://client.example.com",
            scope=""
        )

        # Test with lowercase "bearer"
        response = client.get(
            "/token",
            headers={"Authorization": f"bearer {token}"}
        )

        assert response.status_code == 200
        data = response.json()
        assert data["me"] == "https://user.example.com"

    def test_verify_expired_token(self, client, test_database):
        """Test verification of expired token returns 401."""
        # Create token service with very short TTL
        short_ttl_service = TokenService(
            database=test_database,
            token_length=32,
            token_ttl=0  # Expires immediately
        )

        # Generate token (will be expired)
        token = short_ttl_service.generate_token(
            me="https://user.example.com",
            client_id="https://client.example.com",
            scope=""
        )

        # Import app to override dependency temporarily
        from gondulf.dependencies import get_token_service
        from gondulf.main import app

        # Override with short TTL service
        app.dependency_overrides[get_token_service] = lambda: short_ttl_service

        try:
            # Verify the token (should be expired)
            response = client.get(
                "/token",
                headers={"Authorization": f"Bearer {token}"}
            )

            assert response.status_code == 401
            data = response.json()
            assert data["detail"]["error"] == "invalid_token"
        finally:
            # Clean up override
            app.dependency_overrides.clear()


class TestTokenVerificationIntegration:
    """Integration tests for full token lifecycle."""

    def test_full_token_lifecycle(self, client, valid_auth_code, test_token_service):
        """Test complete flow: exchange code, verify token."""
        code, metadata = valid_auth_code

        # Step 1: Exchange authorization code for token
        exchange_response = client.post(
            "/token",
            data={
                "grant_type": "authorization_code",
                "code": code,
                "client_id": metadata["client_id"],
                "redirect_uri": metadata["redirect_uri"]
            }
        )

        assert exchange_response.status_code == 200
        token_data = exchange_response.json()
        access_token = token_data["access_token"]

        # Step 2: Verify the token
        verify_response = client.get(
            "/token",
            headers={"Authorization": f"Bearer {access_token}"}
        )

        assert verify_response.status_code == 200
        verify_data = verify_response.json()
        assert verify_data["me"] == metadata["me"]
        assert verify_data["client_id"] == metadata["client_id"]
        assert verify_data["scope"] == metadata["scope"]

    def test_verify_revoked_token(self, client, test_token_service):
        """Test verification of revoked token returns 401."""
        # Generate a token
        token = test_token_service.generate_token(
            me="https://user.example.com",
            client_id="https://client.example.com",
            scope=""
        )

        # Revoke the token
        revoked = test_token_service.revoke_token(token)
        assert revoked is True

        # Try to verify revoked token
        response = client.get(
            "/token",
            headers={"Authorization": f"Bearer {token}"}
        )

        assert response.status_code == 401
        data = response.json()
        assert data["detail"]["error"] == "invalid_token"

    def test_verify_cross_client_token(self, client, test_token_service):
        """Test token verification returns correct client_id."""
        # Generate tokens for two different clients
        token_a = test_token_service.generate_token(
            me="https://user.example.com",
            client_id="https://client-a.example.com",
            scope=""
        )

        token_b = test_token_service.generate_token(
            me="https://user.example.com",
            client_id="https://client-b.example.com",
            scope=""
        )

        # Verify token A returns client A
        response_a = client.get(
            "/token",
            headers={"Authorization": f"Bearer {token_a}"}
        )
        assert response_a.status_code == 200
        assert response_a.json()["client_id"] == "https://client-a.example.com"

        # Verify token B returns client B
        response_b = client.get(
            "/token",
            headers={"Authorization": f"Bearer {token_b}"}
        )
        assert response_b.status_code == 200
        assert response_b.json()["client_id"] == "https://client-b.example.com"