"""Stage and compile the bridge, retaining a hash-checked rollback artifact."""
import hashlib
import json
import shutil
import time
from pathlib import Path
from . import native


def stage():
    root = native.STATE_ROOT
    receipt_path = root/'deployment.json'
    old = json.loads(receipt_path.read_text())
    target = Path(old['mod_path'])
    if native.legacy.manage.digest(target) != old['mod_sha256']:
        raise RuntimeError('Installed bridge changed outside the devkit')
    folder = root/'artifacts'/('build-'+str(time.time_ns()))
    folder.mkdir(parents=True)
    shutil.copy2(target,folder/'previous.ws')
    native.legacy.atomic_json(folder/'previous-receipt.json',old)
    source = native.legacy.bridge_source(native.ROOT)
    build = hashlib.sha256(source.encode()).hexdigest()[:16]
    target.write_text(source.replace('@@BUILD@@',build))
    updated = dict(old,build=build,mod_sha256=native.legacy.manage.digest(target))
    try:
        result = native.recompile()
    except (OSError,RuntimeError,ValueError) as error:
        result = {'ok':False,'phase':'compile_outcome_unknown','error':str(error)}
    if not result['ok']:
        shutil.copy2(target,folder/'failed.ws')
        shutil.copy2(folder/'previous.ws',target)
        try:rollback = native.recompile()
        except (OSError,RuntimeError,ValueError) as error:
            rollback = {'ok':False,'error':str(error),'runtime_build_unknown':True}
        result.update(rollback_compiled=rollback['ok'],rollback=rollback)
        if not rollback['ok']:
            try:
                session = native.state()
                session['uncertain'] = {'command':'stage','reason':'rollback compilation unverified','artifacts':str(folder)}
                native.legacy.atomic_json(native.STATE,session)
            except (OSError,RuntimeError):pass
    else:
        native.legacy.atomic_json(receipt_path,updated)
        try:
            session = native.state()
        except (OSError,RuntimeError):
            session = None
        if session:
            session['build'] = build
            native.legacy.atomic_json(native.STATE,session)
        result.update(build=build,restart_required_for_layout_changes=True)
    result['staging_artifacts']=str(folder)
    native.legacy.atomic_json(folder/'result.json',result)
    return result

if __name__ == '__main__':
    import fcntl
    with (native.STATE_ROOT/'.lock').open('a') as lock:
        fcntl.flock(lock,fcntl.LOCK_EX|fcntl.LOCK_NB)
        print(json.dumps(stage()))