"""Portable release identity adapter; original loading and rollout math are unchanged."""
import hashlib
import json
import os
from pathlib import Path

MODEL_NAMES = ('e5',)


def file_sha256(path):
    digest = hashlib.sha256()
    with Path(path).open('rb') as stream:
        for block in iter(lambda: stream.read(8*1024*1024), b''):
            digest.update(block)
    return digest.hexdigest()


def profile(root):
    epoch = os.environ.get('E5_EPOCH', '')
    if epoch not in ('ep2', 'ep6'):
        raise ValueError('Set E5_EPOCH to ep2 or ep6')
    value = json.loads((Path(root)/'configs/evaluation'/(epoch+'.json')).read_text())
    if value['epoch'] != int(epoch[2:]) or value['step'] != {'ep2':17180,'ep6':17178}[epoch]:
        raise ValueError('Release identity mismatch')
    return value


def expected_metadata(root):
    value = profile(root)
    return {'checkpoint_source_kind':'original_public_e5_c3', 'repo_id':value['repo_id'],
            'training_epoch':value['epoch'], 'training_step':value['step'],
            'checkpoint_index_sha256':value['files']['model.safetensors.index.json']['sha256'],
            'checkpoint_config_sha256':value['files']['config.json']['sha256'],
            'checkpoint_files_verified':True, 'action_history_mode':'summary',
            'action_history_length':8, 'action_history_mlp_hidden_size':1024,
            'visual_history_mode':'none', 'state_history_mode':'tokens',
            'state_history_length':2, 'state_history_stride':50}


def verify_checkpoint(root):
    root = Path(root)
    value = profile(root)
    checkpoint = root/'checkpoints'/('ep'+str(value['epoch']))
    for name, expected in value['files'].items():
        if Path(name).name != name:
            raise ValueError('Invalid checkpoint filename')
        path = checkpoint/name
        if path.stat().st_size != expected['bytes'] or file_sha256(path) != expected['sha256']:
            raise ValueError('Checkpoint file hash mismatch: '+name)
    index = json.loads((checkpoint/'model.safetensors.index.json').read_text())
    if len(index['weight_map']) != 1716 or set(index['weight_map'].values()) != {
            f'model-{i:05d}-of-00006.safetensors' for i in range(1,7)}:
        raise ValueError('Checkpoint tensor/shard membership mismatch')
    norm = root/'manifests/norm_stats/robotwin_clean_train_s7.json'
    if file_sha256(norm) != value['normalization_sha256']:
        raise ValueError('Normalization identity mismatch')
    return checkpoint,norm,expected_metadata(root)


def validate_server_identity(metadata,root):
    if any(metadata.get(k) != v for k,v in expected_metadata(root).items()):
        raise ValueError('Server did not load the selected original release')


def validate_lora_identity(metadata,root):
    raise ValueError('This release supports original E5+C3 checkpoints only')