import importlib.util
import json
from pathlib import Path
import unittest

spec = importlib.util.spec_from_file_location('timing', Path(__file__).parents[1] / 'platform_timing_summary.py')
timing = importlib.util.module_from_spec(spec)
spec.loader.exec_module(timing)


class EvidenceTests(unittest.TestCase):
    def evidence(self, suspend=0):
        records = []
        for phase in ('start', 'end'):
            for path, value in [('/proc/sys/kernel/osrelease', 'candidate'),
                                ('/proc/sys/kernel/random/boot_id', 'same-boot'),
                                ('/sys/devices/system/clocksource/clocksource0/current_clocksource', 'tsc')]:
                records.append(dict(kind='metadata', phase=phase, path=path, value=value, errno=0))
        records.extend([
            dict(kind='sample', index=0, before_ns=100, after_ns=102, end_ns=106, mono_ns=103),
            dict(kind='sample', index=1, before_ns=200+suspend, after_ns=202+suspend,
                 end_ns=206+suspend, mono_ns=203),
            dict(kind='complete', qualified=False)])
        return records

    def run_summary(self, records):
        return timing.summarize('\n'.join('TIMING ' + json.dumps(r) for r in records))

    def test_suspend_interval_not_point_or_accuracy_claim(self):
        result = self.run_summary(self.evidence(5000))
        self.assertEqual(result['suspend_offset_change_interval_ns'], [4996, 5004])
        self.assertFalse(result['qualified'])
        self.assertIsNone(result['max_elapsed_error_ppb'])

    def test_reject_truncated_evidence(self):
        with self.assertRaises(ValueError):
            self.run_summary(self.evidence()[:-1])

    def test_reject_changed_boot(self):
        records = self.evidence()
        records[4]['value'] = 'new-boot'
        with self.assertRaises(ValueError):
            self.run_summary(records)

    def test_reject_regression_and_missing_sample(self):
        records = self.evidence()
        records[-2]['before_ns'] = 50
        with self.assertRaises(ValueError):
            self.run_summary(records)
        records = self.evidence()
        records[-2]['index'] = 2
        with self.assertRaises(ValueError):
            self.run_summary(records)


if __name__ == '__main__':
    unittest.main()