"""Tests for the documented significance/confidence/severity formula in
app/change_detection/scoring.py (see ARCHITECTURE.md)."""

from __future__ import annotations

from app.change_detection.scoring import classify_severity, compute_confidence, compute_significance
from app.models.enums import ChangeType, SeverityLevel


def test_significance_scales_with_source_trust():
    high_trust = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT, source_trust_score=1.0, independent_source_count=2
    )
    low_trust = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT, source_trust_score=0.3, independent_source_count=2
    )
    assert high_trust > low_trust


def test_significance_uncorroborated_signal_is_halved():
    corroborated = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT, source_trust_score=1.0, independent_source_count=2
    )
    single_source = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT, source_trust_score=1.0, independent_source_count=1
    )
    assert single_source == round(corroborated / 2, 4)


def test_significance_focus_match_boosts_score():
    matched = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT,
        source_trust_score=1.0,
        independent_source_count=2,
        focus_match=True,
    )
    unmatched = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT,
        source_trust_score=1.0,
        independent_source_count=2,
        focus_match=False,
    )
    assert matched > unmatched


def test_significance_repeat_change_is_dampened():
    fresh = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT, source_trust_score=1.0, is_repeat=False
    )
    repeat = compute_significance(
        change_type=ChangeType.NEW_DOCUMENT, source_trust_score=1.0, is_repeat=True
    )
    assert repeat == round(fresh / 2, 4)


def test_significance_content_modified_scales_with_diff_ratio():
    small_edit = compute_significance(
        change_type=ChangeType.CONTENT_MODIFIED,
        source_trust_score=1.0,
        independent_source_count=2,
        diff_ratio=0.05,
    )
    big_rewrite = compute_significance(
        change_type=ChangeType.CONTENT_MODIFIED,
        source_trust_score=1.0,
        independent_source_count=2,
        diff_ratio=0.9,
    )
    assert big_rewrite > small_edit


def test_significance_never_exceeds_one():
    value = compute_significance(
        change_type=ChangeType.LEADERSHIP_CHANGE,
        source_trust_score=1.0,
        independent_source_count=10,
        focus_match=True,
    )
    assert value <= 1.0


def test_confidence_increases_with_corroboration():
    single = compute_confidence(
        extraction_confidence=0.8, source_trust_score=0.8, independent_source_count=1
    )
    corroborated = compute_confidence(
        extraction_confidence=0.8, source_trust_score=0.8, independent_source_count=2
    )
    assert corroborated > single


def test_confidence_bounded_between_zero_and_one():
    assert (
        0.0
        <= compute_confidence(
            extraction_confidence=0.0, source_trust_score=0.0, independent_source_count=1
        )
        <= 1.0
    )
    assert (
        0.0
        <= compute_confidence(
            extraction_confidence=1.0, source_trust_score=1.0, independent_source_count=5
        )
        <= 1.0
    )


def test_classify_severity_buckets_by_score():
    assert classify_severity(significance=0.9, confidence=0.9) == SeverityLevel.CRITICAL
    assert classify_severity(significance=0.6, confidence=0.9) == SeverityLevel.HIGH
    assert classify_severity(significance=0.3, confidence=0.9) == SeverityLevel.MEDIUM
    assert classify_severity(significance=0.1, confidence=0.9) == SeverityLevel.LOW


def test_classify_severity_critical_requires_high_confidence():
    """A score that would otherwise land in the Critical bucket (>= 0.6)
    must be downgraded to High when confidence is below the floor - an
    uncorroborated single-source signal can't carry the Critical label."""
    score = 1.0 * 0.65
    assert score >= 0.6  # would be CRITICAL by score alone
    severity = classify_severity(significance=1.0, confidence=0.65)
    assert severity == SeverityLevel.HIGH


def test_classify_severity_high_confidence_allows_critical():
    score = 1.0 * 0.8
    assert score >= 0.6
    severity = classify_severity(significance=1.0, confidence=0.8)
    assert severity == SeverityLevel.CRITICAL