#!/usr/bin/env python3
"""Summarize raw collector evidence without inventing qualification bounds."""
import argparse
import hashlib
import json
from pathlib import Path


def summarize(data):
    records = [json.loads(line[7:]) for line in data.splitlines() if line.startswith('TIMING ')]
    if not records or records[-1] != {'kind': 'complete', 'qualified': False}:
        raise ValueError('missing completed collection')
    samples = [r for r in records if r['kind'] == 'sample']
    if len(samples) < 2 or [r['index'] for r in samples] != list(range(len(samples))):
        raise ValueError('missing or reordered samples')
    metadata = {phase: {r['path']: r for r in records
                       if r['kind'] == 'metadata' and r['phase'] == phase}
                for phase in ('start', 'end')}
    for path in ('/proc/sys/kernel/osrelease', '/proc/sys/kernel/random/boot_id',
                 '/sys/devices/system/clocksource/clocksource0/current_clocksource'):
        a, b = (metadata[p].get(path) for p in ('start', 'end'))
        if not a or not b or a['errno'] or b['errno'] or not a['value'].strip() or a['value'] != b['value']:
            raise ValueError('missing/changed platform identity: ' + path)
    previous = 0
    for s in samples:
        if not previous <= s['before_ns'] <= s['after_ns'] <= s['end_ns']:
            raise ValueError('BOOTTIME regression')
        previous = s['end_ns']
    first, last = samples[0], samples[-1]
    # mono is read between after and end. Thus BOOTTIME-minus-MONOTONIC
    # offset lies in [after-mono, end-mono]; subtract intervals, not midpoints.
    suspend_low = (last['after_ns'] - last['mono_ns']) - (first['end_ns'] - first['mono_ns'])
    suspend_high = (last['end_ns'] - last['mono_ns']) - (first['after_ns'] - first['mono_ns'])
    return dict(qualified=False, samples=len(samples), metadata=metadata,
                measured_max_bracket_ns=max(s['after_ns'] - s['before_ns'] for s in samples),
                measured_boottime_elapsed_ns=last['before_ns'] - first['before_ns'],
                suspend_offset_change_interval_ns=[suspend_low, suspend_high],
                independent_reference=False, max_elapsed_error_ppb=None,
                max_observation_error_ns=None,
                note='Observed extrema only; correlated clocks cannot establish UTC accuracy or future bounds.')


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('evidence', type=Path)
    parser.add_argument('--output', type=Path, help='create a new JSON evidence summary')
    args = parser.parse_args()
    raw = args.evidence.read_bytes()
    result = summarize(raw.decode())
    result['evidence_sha256'] = hashlib.sha256(raw).hexdigest()
    encoded = json.dumps(result, indent=2) + '\n'
    if args.output:
        with args.output.open('x') as stream:
            stream.write(encoded)
        print(json.dumps({k: v for k, v in result.items() if k != 'metadata'}))
    else:
        print(encoded, end='')


if __name__ == '__main__':
    main()