"""Tests for the separate line/branch coverage policy gate."""

from __future__ import annotations

import importlib.util
from pathlib import Path


SCRIPT = Path(__file__).parents[1] / "scripts" / "check_coverage_thresholds.py"
SPEC = importlib.util.spec_from_file_location("check_coverage_thresholds", SCRIPT)
assert SPEC is not None and SPEC.loader is not None
MODULE = importlib.util.module_from_spec(SPEC)
SPEC.loader.exec_module(MODULE)


def _report(line: float = 55.0, branch: float = 42.0) -> dict[str, object]:
    return {
        "totals": {
            "percent_statements_covered": line,
            "percent_branches_covered": branch,
        },
        "files": {
            "obliteratus/example.py": {
                "summary": {"percent_statements_covered": 70.0},
                "executed_lines": [1, 2, 4],
                "missing_lines": [3],
            },
        },
    }


def test_validate_coverage_accepts_exact_floors():
    assert MODULE.validate_coverage(
        _report(), min_line=55.0, min_branch=42.0,
    ) == []


def test_validate_coverage_reports_each_regression():
    failures = MODULE.validate_coverage(
        _report(line=54.9, branch=41.9), min_line=55.0, min_branch=42.0,
    )

    assert failures == [
        "line coverage 54.90% is below the 55.00% floor",
        "branch coverage 41.90% is below the 42.00% floor",
    ]


def test_validate_coverage_rejects_malformed_totals():
    assert MODULE.validate_coverage(
        {}, min_line=55.0, min_branch=42.0,
    ) == ["coverage report is missing the totals object"]


def test_validate_coverage_rejects_non_numeric_metrics():
    report = _report()
    report["totals"]["percent_statements_covered"] = True
    report["totals"]["percent_branches_covered"] = float("nan")

    assert MODULE.validate_coverage(
        report, min_line=55.0, min_branch=42.0,
    ) == [
        "coverage report is missing numeric percent_statements_covered",
        "coverage report is missing numeric percent_branches_covered",
    ]


def test_validate_coverage_enforces_critical_file_floors():
    assert MODULE.validate_coverage(
        _report(),
        min_line=55.0,
        min_branch=42.0,
        file_floors={"obliteratus/example.py": 70.0},
    ) == []

    report = _report()
    report["files"]["obliteratus/example.py"]["summary"]["percent_statements_covered"] = 69.9
    assert MODULE.validate_coverage(
        report,
        min_line=55.0,
        min_branch=42.0,
        file_floors={"obliteratus/example.py": 70.0, "missing.py": 70.0},
    ) == [
        "critical file obliteratus/example.py coverage 69.90% is below the 70.00% floor",
        "coverage report is missing critical file missing.py",
    ]


def test_parse_changed_lines_and_measurement_ignore_non_executable_lines():
    diff = """diff --git a/obliteratus/example.py b/obliteratus/example.py
+++ b/obliteratus/example.py
@@ -1,2 +1,4 @@
diff --git a/tests/test_example.py b/tests/test_example.py
+++ b/tests/test_example.py
@@ -0,0 +1,2 @@
"""
    changed = MODULE.parse_changed_lines(diff)
    assert changed == {
        "obliteratus/example.py": {1, 2, 3, 4},
        "tests/test_example.py": {1, 2},
    }
    assert MODULE.changed_line_coverage(_report(), changed) == (3, 4, 75.0)
    assert MODULE.validate_changed_coverage(
        _report(), changed, minimum=90.0,
    ) == ["changed-line coverage 75.00% (3/4) is below the 90.00% floor"]


def test_changed_line_gate_passes_when_diff_has_no_measured_source():
    assert MODULE.changed_line_coverage(_report(), {"tests/test_example.py": {1}}) == (
        0,
        0,
        100.0,
    )