#!/usr/bin/env python3
"""Run explicit row276 changes only under Sage's grant. --static runs no tests."""
import argparse
import hashlib
import json
import os
from pathlib import Path
import signal
import subprocess
import time

HERE = Path(__file__).resolve().parent
REPO = HERE.parents[3]

def digest(data):
    return hashlib.sha256(data).hexdigest()

def busy():
    p = subprocess.run(['bash', '/mnt/storage/scratch/sage-busy-now.sh'], text=True, capture_output=True)
    if p.returncode or p.stdout.splitlines()[-1:] != ['CLEAR']:
        raise RuntimeError('busy refusal: ' + p.stdout + p.stderr)

def run(command, path, seconds=60):
    if command[:2] == ['node', '--test']:
        limits = json.loads((HERE/'WHOLE-GATE-LIMITS.json').read_text())['files']
        limit = limits.get(command[-1], 900)
        command = ['timeout','-k','10',str(limit),*command]
        seconds = limit + 30
    busy()
    started = time.monotonic()
    command_file = path.with_suffix('.command.json')
    command_file.write_text(json.dumps(command))
    # Keep command text out of wrapper argv: the busy guard scans every argv.
    # launch.py execs the structured command. bash owns a pipefail/tee pipeline.
    p = subprocess.Popen(['bash','-o','pipefail','-c',
        'python3 "$1" "$2" 2>&1 | tee "$3"', '--',str(HERE/'launch.py'),str(command_file),str(path)],
        cwd=REPO,start_new_session=True)
    expired = False
    try:
        code = p.wait(timeout=seconds)
        expired = code in (124, 137)
    except subprocess.TimeoutExpired:
        expired = True
        os.killpg(p.pid, signal.SIGKILL)
        code = p.wait()
    finally:
        try:
            os.killpg(p.pid, signal.SIGKILL)
        except ProcessLookupError:
            pass
    return dict(code=code, timeout=expired, seconds=round(time.monotonic()-started, 3), log=str(path))

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument('--static', action='store_true')
    ap.add_argument('--grant')
    ap.add_argument('--out', type=Path)
    args = ap.parse_args()
    definitions = json.loads((HERE/'changes.json').read_text())
    checked = []
    for d in definitions:
        for file in [d['file'], *d.get('also_files', [])]:
            original = (REPO/file).read_bytes()
            count = original.count(d['old'].encode())
            if count != 1:
                raise RuntimeError(f"{d['id']}: {file}: target occurs {count} times")
            changed = original.replace(d['old'].encode(), d['new'].encode(), 1)
            checked.append(dict(id=d['id'], file=file, occurrences=count,
                                before=digest(original), after=digest(changed)))
    if args.static:
        print(json.dumps(checked, indent=2))
        return
    if not args.grant or not args.out:
        ap.error('execution needs --grant and --out')
    if not os.environ.get('TMPDIR', '').startswith('/mnt/storage/scratch/tmp/g'):
        raise RuntimeError('TMPDIR must be the granted scratch directory')
    status = subprocess.check_output(['git','status','--porcelain','--untracked-files=no'],cwd=REPO)
    args.out.mkdir(parents=True, exist_ok=True)
    results = dict(grant=args.grant, static=checked, bases={}, changes=[])
    failures = 0
    for d in definitions:
        key = d['killer']+'|'+d['pattern']
        command = ['node','--test','--test-reporter=tap','--test-name-pattern',d['pattern'],d['killer']]
        if key not in results['bases']:
            base = run(command, args.out/(d['id']+'-base.log'))
            results['bases'][key] = base
            (args.out/'results.json').write_text(json.dumps(results,indent=2)+'\n')
            if base['code'] != 0 or base['seconds'] > 30:
                raise RuntimeError('base failed or exceeded 30 seconds: '+d['id'])
        originals = {REPO/file: (REPO/file).read_bytes() for file in [d['file'], *d.get('also_files', [])]}
        try:
            for target, original in originals.items():
                target.write_bytes(original.replace(d['old'].encode(),d['new'].encode(),1))
                pre = subprocess.run(['bash','-n',str(target)],capture_output=True)
                if pre.returncode:
                    raise RuntimeError('invalid syntax: '+d['id'])
            result = run(command,args.out/(d['id']+'.log'))
            result.update(id=d['id'], base_seconds=results['bases'][key]['seconds'],
                          outcome='timeout' if result['timeout'] else 'killed' if result['code'] != 0 else 'survived')
            results['changes'].append(result)
            if result['timeout']:
                raise RuntimeError('timeout requires Sage/Mos classification: '+d['id'])
            if result['outcome'] != 'killed':
                failures += 1
        finally:
            for target, original in originals.items():
                target.write_bytes(original)
                assert target.read_bytes() == original
            assert subprocess.check_output(['git','status','--porcelain','--untracked-files=no'],cwd=REPO) == status
            (args.out/'results.json').write_text(json.dumps(results,indent=2)+'\n')
        if failures >= 1:
            raise RuntimeError('first unexpected failure: end the row276 window')
    print(json.dumps(results,indent=2))

if __name__ == '__main__':
    main()