"""Offline cache-view measurement. Never instantiates or contacts an LLM provider."""
import argparse
import hashlib
import json
from pathlib import Path

from viano_bug_analysis.package import PackageReader
from viano_bug_analysis.lifecycle.storage import json_bytes
from .gemini import GeminiProvider
from .stable_context import restore_document


def _size(value):
    return len(json_bytes(value).decode('utf-8'))


def measure_package(path):
    from viano_bug_analysis.analysis.investigation_prompt import build_prompt
    contexts, requests = {}, []
    with PackageReader(path) as reader:
        identity = {k: reader.manifest[k] for k in ('case_id','package_id','analysis_revision','package_generation')}
        for name in reader.files:
            if name.startswith('analysis/investigation/') and '/contexts/' in name and name.endswith('.json'):
                context = json.loads(reader.read_bytes(name))
                if context.get('format') != 'viano-investigation-context':
                    continue
                original = build_prompt(context)
                contexts[hashlib.sha256(json_bytes(original['messages'])).hexdigest()] = context
            elif name.startswith('llm/operations/') and name.endswith('/request.json'):
                req = json.loads(reader.read_bytes(name))
                if req.get('prompt_version','').startswith('investigation_project_'):
                    requests.append(req)
    samples, unmatched = [], 0
    for req in requests:
        context = contexts.get(hashlib.sha256(json_bytes(req['messages'])).hexdigest())
        if context is None:
            unmatched += 1
            continue
        # Historical contexts are immutable. Rebuild a detached v11 model view
        # to measure stable aliases; the original request remains the baseline.
        target = context['prompt_version'] if context.get('prompt_version') in {'investigation_project_v12','investigation_project_v13'} else 'investigation_project_v11'
        context = dict(context, prompt_version=target)
        upgraded = build_prompt(context)
        old_system, old_prefix, old_live = GeminiProvider._messages(req)
        system, prefix, live = GeminiProvider._messages(upgraded, stable_case_context=True)
        prefix_doc = json.loads(prefix[0]['parts'][0]['text'])
        current = json.loads(live[0]['parts'][0]['text'])
        current['output_schema'] = prefix_doc['output_schema']
        canonical = json.loads(upgraded['messages'][1]['content'])
        assert restore_document(prefix_doc['stable_case_context'], current) == canonical
        samples.append({'prefix_id':hashlib.sha256(json_bytes([system,prefix])).hexdigest(),
            'historical_prompt':req['prompt_version'],
            'rebuilt_prompt':target,
            'old_prefix_characters':_size([old_system,old_prefix]),
            'new_prefix_characters':_size([system,prefix]),
            'old_live_characters':_size(old_live), 'new_live_characters':_size(live),
            'full_v11_characters':_size(upgraded['messages']), 'exact_reconstruction':True})
    old_live = sum(s['old_live_characters'] for s in samples)
    new_live = sum(s['new_live_characters'] for s in samples)
    return {'measurement':'stable_case_cache_offline_v1', **identity,
            'requests':len(samples),'unmatched_requests':unmatched,
            'unique_prefixes':len({s['prefix_id'] for s in samples}),
            'old_live_characters':old_live, 'new_live_characters':new_live,
            'live_character_reduction_percent':round(100*(old_live-new_live)/old_live,2) if old_live else None,
            'all_exactly_reconstructed':all(s['exact_reconstruction'] for s in samples) and bool(samples),
            'limitations':['Characters are not provider token counts or a paid quality benchmark.',
                'Historical requests are compared to reconstructed v11 views; earlier view policies may differ.',
                'Prefix counts ignore remote TTL expiry, credentials, latency and storage billing.'],
            'samples':samples}


def main(argv=None):
    parser=argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--package',type=Path,required=True)
    parser.add_argument('--output',type=Path)
    args=parser.parse_args(argv)
    report=measure_package(args.package)
    data=json.dumps(report,ensure_ascii=False,indent=2)+'\n'
    if args.output:
        args.output.parent.mkdir(parents=True,exist_ok=True)
        args.output.write_text(data,encoding='utf-8',newline='\n')
    else:
        print(data,end='')
    return 0


if __name__=='__main__':
    raise SystemExit(main())