"""Unit tests for the role-suggestion service + endpoint.

suggest_roles ranks every active role by the user's skill fit (reusing
compute_gap_report) so the UI can show "Recommended for you" above the rest
of the catalog, while every role stays reachable (search / switch-track case).
"""
import pytest
from django.contrib.auth import get_user_model
from rest_framework.test import APIClient

from apps.analysis.services import suggest_roles
from apps.roles.models import Role, RoleSkill
from apps.skills.models import Skill, UserSkill

User = get_user_model()
pytestmark = pytest.mark.django_db

URL = '/api/role-suggestions/'


@pytest.fixture
def user():
    return User.objects.create_user(
        username='sugg@example.com', email='sugg@example.com',
        password='password123', name='Sugg Tester',
    )


@pytest.fixture
def auth_client(user):
    client = APIClient()
    client.force_authenticate(user=user)
    return client


def _skill(name, category='Programming'):
    return Skill.objects.create(
        skill_name=name, category=category, difficulty_level='BEGINNER',
    )


def _role(name, skill_specs, industry='Tech', is_active=True):
    """skill_specs: list of (Skill, level, weight, mandatory)."""
    role = Role.objects.create(
        role_name=name, industry=industry, is_active=is_active,
    )
    for skill, level, weight, mandatory in skill_specs:
        RoleSkill.objects.create(
            role=role, skill=skill,
            required_level=level, weight=weight, is_mandatory=mandatory,
        )
    return role


def _set_prof(user, skill, proficiency, level='INTERMEDIATE'):
    UserSkill.objects.update_or_create(
        user=user, skill=skill,
        defaults={'proficiency': proficiency, 'user_level': level},
    )


def test_better_fit_role_ranks_higher(user):
    python = _skill('Python')
    rust = _skill('Rust')
    _role('Backend (Python)', [(python, 'INTERMEDIATE', 1.0, True)])
    _role('Systems (Rust)', [(rust, 'INTERMEDIATE', 1.0, True)])
    _set_prof(user, python, 100)  # fully meets the Python role; Rust unset → 0

    result = suggest_roles(user)
    names = [r['role_name'] for r in result['roles']]
    assert names.index('Backend (Python)') < names.index('Systems (Rust)')

    good = next(r for r in result['roles'] if r['role_name'] == 'Backend (Python)')
    assert good['readiness'] == 100.0
    assert good['matched_skills'] == 1
    assert good['total_skills'] == 1
    assert good['top_missing_skills'] == []


def test_top_missing_skills_lists_unmet(user):
    python = _skill('Python')
    sql = _skill('SQL')
    _role('Data Role', [
        (python, 'INTERMEDIATE', 1.0, True),
        (sql, 'INTERMEDIATE', 1.0, True),
    ])
    _set_prof(user, python, 100)  # MET; SQL missing

    result = suggest_roles(user)
    row = next(r for r in result['roles'] if r['role_name'] == 'Data Role')
    assert row['matched_skills'] == 1
    assert row['total_skills'] == 2
    assert 'SQL' in row['top_missing_skills']
    assert 'Python' not in row['top_missing_skills']


def test_no_requirements_role_sinks_to_bottom(user):
    python = _skill('Python')
    _role('Empty Role', [])  # no RoleSkill → no_requirements, readiness=100 (spurious)
    _role('Backend (Python)', [(python, 'INTERMEDIATE', 1.0, True)])
    _set_prof(user, python, 50)  # partial fit on the real role

    result = suggest_roles(user)
    names = [r['role_name'] for r in result['roles']]
    assert names[-1] == 'Empty Role'

    empty = next(r for r in result['roles'] if r['role_name'] == 'Empty Role')
    assert empty['no_requirements'] is True


def test_has_skills_false_when_user_has_no_skills(user):
    python = _skill('Python')
    _role('Backend (Python)', [(python, 'INTERMEDIATE', 1.0, True)])

    result = suggest_roles(user)
    assert result['has_skills'] is False
    # Roles are still returned (all low fit) so the catalog stays browsable.
    assert len(result['roles']) == 1


def test_has_skills_true_after_setting_a_skill(user):
    python = _skill('Python')
    _role('Backend (Python)', [(python, 'INTERMEDIATE', 1.0, True)])
    _set_prof(user, python, 70)

    assert suggest_roles(user)['has_skills'] is True


def test_low_fit_role_still_listed_and_reachable(user):
    """The switch-track case: a strong analyst can still see (and pick) a
    poorly-fitting role — it's just ranked below the good matches."""
    python = _skill('Python')
    k8s = _skill('Kubernetes')
    _role('Data Analyst', [(python, 'INTERMEDIATE', 1.0, True)])
    _role('DevOps Engineer', [(k8s, 'ADVANCED', 1.0, True)])
    _set_prof(user, python, 80)  # strong analyst, zero DevOps

    result = suggest_roles(user)
    names = [r['role_name'] for r in result['roles']]
    assert 'DevOps Engineer' in names  # reachable despite poor fit
    assert names.index('Data Analyst') < names.index('DevOps Engineer')


def test_inactive_roles_excluded(user):
    python = _skill('Python')
    _role('Active Role', [(python, 'INTERMEDIATE', 1.0, True)], is_active=True)
    _role('Inactive Role', [(python, 'INTERMEDIATE', 1.0, True)], is_active=False)

    names = [r['role_name'] for r in suggest_roles(user)['roles']]
    assert 'Active Role' in names
    assert 'Inactive Role' not in names


def test_endpoint_returns_ranked_roles(user, auth_client):
    python = _skill('Python')
    _role('Backend (Python)', [(python, 'INTERMEDIATE', 1.0, True)])
    _set_prof(user, python, 100)

    r = auth_client.get(URL)
    assert r.status_code == 200, r.data
    assert r.data['has_skills'] is True
    assert r.data['roles'][0]['role_name'] == 'Backend (Python)'


def test_endpoint_requires_authentication():
    r = APIClient().get(URL)
    assert r.status_code == 401