"""Unit tests for the path engine (SLICE-05, TASK-05-04)."""

from __future__ import annotations

from pathlib import Path as FsPath

import pytest
import yaml
from pydantic import ValidationError

from server.paths.engine import PathEngine, clear_cache
from server.paths.schema import Path, PathWeek, WeekGate

_REPO_PATHS_DIR = FsPath(__file__).resolve().parent.parent / "paths"


@pytest.fixture(autouse=True)
def _clear_path_cache():
    clear_cache()
    yield
    clear_cache()


def _passing_progress(week: int, distinct_passed: int = 3, mastery_score: float = 3.5) -> dict:
    return {
        "current_week": week,
        "distinct_passed": distinct_passed,
        "mastery_score": mastery_score,
    }


def test_load_customer_service_path_has_six_weeks():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    assert path.slug == "customer_service"
    assert path.skill == "customer_service"
    assert len(path.weeks) == 6
    assert [w.week for w in path.weeks] == [1, 2, 3, 4, 5, 6]
    titles = [w.title for w in path.weeks]
    assert "Foundations" in titles[0]
    assert "De-escalation" in titles[1]
    assert "Policy Exceptions" in titles[2]
    assert "Multi-Issue Resolution" in titles[3]
    assert "Recovery" in titles[4]
    assert "Mastery Demonstration" in titles[5]


def test_each_week_gate_defaults_match_d032():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    for w in path.weeks:
        assert w.gate.required_scenarios == 3
        assert w.gate.required_score == 3.5


def test_path_scenario_ids_reference_expected_set():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    expected = [
        "cs_refund_ca_v01",
        "cs_escalation_ca_v02",
        "cs_policy_exception_ca_v03",
        "cs_multi_issue_ca_v04",
        "cs_recovery_ca_v05",
        "cs_mastery_demonstration_ca_v06",
    ]
    assert path.all_scenario_ids() == expected


def test_gate_open_when_three_passed_and_score_3_5():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    progress = _passing_progress(week=1, distinct_passed=3, mastery_score=3.5)
    assert engine.check_gate(progress, 1, path) is True


def test_gate_open_above_threshold():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    progress = _passing_progress(week=2, distinct_passed=4, mastery_score=4.0)
    assert engine.check_gate(progress, 2, path) is True


def test_gate_closed_when_only_two_passed():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    progress = _passing_progress(week=1, distinct_passed=2, mastery_score=4.0)
    assert engine.check_gate(progress, 1, path) is False


def test_gate_closed_when_score_below_threshold():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    progress = _passing_progress(week=1, distinct_passed=3, mastery_score=3.0)
    assert engine.check_gate(progress, 1, path) is False


def test_advance_week_increments_current_week():
    engine = PathEngine()
    progress = _passing_progress(week=1)
    advanced = engine.advance_week(progress)
    assert advanced["current_week"] == 2
    assert progress["current_week"] == 1


def test_advance_week_caps_at_six():
    engine = PathEngine()
    progress = _passing_progress(week=6)
    advanced = engine.advance_week(progress)
    assert advanced["current_week"] == 6


def test_current_week_defaults_to_one():
    engine = PathEngine()
    assert engine.current_week({}) == 1
    assert engine.current_week({"current_week": 99}) == 6
    assert engine.current_week({"current_week": 0}) == 1


def test_is_path_complete_true_when_week6_gate_open():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    progress = _passing_progress(week=6, distinct_passed=3, mastery_score=3.5)
    assert engine.is_path_complete(progress, path) is True


def test_is_path_complete_false_when_week6_gate_closed():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    progress = _passing_progress(week=6, distinct_passed=2, mastery_score=4.0)
    assert engine.is_path_complete(progress, path) is False


def test_check_gate_rejects_unknown_week():
    engine = PathEngine()
    path = engine.load_path("customer_service")
    progress = _passing_progress(week=1)
    with pytest.raises(ValueError):
        engine.check_gate(progress, 7, path)


def test_reject_five_weeks(tmp_path: FsPath):
    slug = "five_week_path"
    data = {
        "slug": slug,
        "name": "Five Week Path",
        "skill": "customer_service",
        "weeks": [
            {"week": i, "title": f"Week {i}", "scenario_ids": [f"s{i}"], "gate": {"required_scenarios": 3, "required_score": 3.5}}
            for i in range(1, 6)
        ],
    }
    p = tmp_path / f"{slug}.yaml"
    p.write_text(yaml.safe_dump(data), encoding="utf-8")
    engine = PathEngine(paths_dir=tmp_path)
    with pytest.raises(ValidationError):
        engine.load_path(slug)


def test_reject_seven_weeks(tmp_path: FsPath):
    slug = "seven_week_path"
    data = {
        "slug": slug,
        "name": "Seven Week Path",
        "skill": "customer_service",
        "weeks": [
            {"week": i, "title": f"Week {i}", "scenario_ids": [f"s{i}"], "gate": {"required_scenarios": 3, "required_score": 3.5}}
            for i in range(1, 8)
        ],
    }
    p = tmp_path / f"{slug}.yaml"
    p.write_text(yaml.safe_dump(data), encoding="utf-8")
    engine = PathEngine(paths_dir=tmp_path)
    with pytest.raises(ValidationError):
        engine.load_path(slug)


def test_reject_non_sequential_week_numbers(tmp_path: FsPath):
    slug = "nonseq_path"
    data = {
        "slug": slug,
        "name": "Non-Sequential Path",
        "skill": "customer_service",
        "weeks": [
            {"week": i, "title": f"W{i}", "scenario_ids": [f"s{i}"], "gate": {"required_scenarios": 3, "required_score": 3.5}}
            for i in [1, 2, 3, 4, 5, 5]
        ],
    }
    p = tmp_path / f"{slug}.yaml"
    p.write_text(yaml.safe_dump(data), encoding="utf-8")
    engine = PathEngine(paths_dir=tmp_path)
    with pytest.raises(ValidationError):
        engine.load_path(slug)


def test_reject_duplicate_scenario_ids_in_week():
    with pytest.raises(ValidationError):
        PathWeek(week=1, title="W", scenario_ids=["s1", "s1"])


def test_week_gate_defaults():
    g = WeekGate()
    assert g.required_scenarios == 3
    assert g.required_score == 3.5


def test_validate_scenarios_exist_passes_with_stub_library():
    engine = PathEngine()
    path = engine.load_path("customer_service")

    class _StubLib:
        def __init__(self) -> None:
            self._ids = set(path.all_scenario_ids())

        def get(self, sid: str):
            if sid not in self._ids:
                raise KeyError(sid)
            return object()

    refs = engine.validate_scenarios_exist(path, _StubLib())
    assert set(refs) == set(path.all_scenario_ids())


def test_validate_scenarios_exist_reports_missing():
    engine = PathEngine()
    path = engine.load_path("customer_service")

    class _EmptyLib:
        def get(self, sid: str):
            raise KeyError(sid)

    with pytest.raises(ValueError):
        engine.validate_scenarios_exist(path, _EmptyLib())


def test_load_path_caches():
    engine = PathEngine()
    p1 = engine.load_path("customer_service")
    p2 = engine.load_path("customer_service")
    assert p1 is p2


def test_load_path_missing_raises():
    engine = PathEngine(paths_dir=FsPath("/nonexistent_paths_dir_xyz"))
    with pytest.raises(FileNotFoundError):
        engine.load_path("no_such_path")