"""Fixed 350-task default, stratified by language/difficulty/task family."""
from collections import defaultdict
import hashlib
ALLOCATION_1000={'python':(75,38,12),'javascript':(75,37,13),'html':(60,30,10),'css':(60,30,10),
            'cpp':(68,34,11),'c':(68,34,11),'lua':(60,30,10),'csharp':(67,34,11),'rust':(67,33,12)}
ALLOCATION={'python':(26,13,5),'javascript':(27,13,4),'html':(21,11,3),'css':(21,10,4),
            'cpp':(24,12,4),'c':(23,12,4),'lua':(21,11,3),'csharp':(24,11,4),'rust':(23,12,4)}
VERSION='smolscript-0.3.0'

def select(rows,allocation=None,version=None):
    allocation=ALLOCATION if allocation is None else allocation
    version=VERSION if version is None else version
    chosen=set()
    for lang,counts in allocation.items():
        for diff,count in zip(('easy','medium','moderate'),counts):
            groups=defaultdict(list)
            for r in rows:
                if r['language']==lang and r['difficulty']==diff:groups[(r['metadata']['family'],r['category'])].append(r)
            total=sum(map(len,groups.values()))
            quotas={k:count*len(v)//total for k,v in groups.items()}
            for k in sorted(groups,key=lambda k:(-(count*len(groups[k])%total),k))[:count-sum(quotas.values())]:quotas[k]+=1
            for k,group in groups.items():
                ranked=sorted(group,key=lambda r:hashlib.sha256((version+':'+r['id']).encode()).digest())
                chosen.update(r['id'] for r in ranked[:quotas[k]])
    result=[{**r,'metadata':{**r['metadata'],'protocol':version}} for r in rows if r['id'] in chosen]
    assert len(result)==sum(sum(v) for v in allocation.values())
    return result