"""Explicit weight-to-warehouse assignments; unassigned comparisons stay separate."""

from decimal import Decimal
import re


def allocations(text,codes,weight_pattern,to_kg):
    if len(codes)<2:return None
    code='('+'|'.join(re.escape(code) for code in sorted(codes,key=len,reverse=True))+r')(?![A-Za-z0-9])'
    forward=weight_pattern.pattern+r'\s*(?:货物)?\s*(?:发到|发往|送到|发|到|去)?\s*'+code
    reverse=code+r'\s*(?:[：:]|分配|发|重)?\s*'+weight_pattern.pattern
    entries=[];used=[]
    for pattern,backwards in ((forward,False),(reverse,True)):
        for match in re.finditer(pattern,text,re.I):
            if any(match.start()<end and match.end()>start for start,end in used):continue
            values=match.groups()
            destination,value,unit=values if backwards else (values[2],values[0],values[1])
            piece_weight=to_kg(value,unit)
            weight_start=match.start(2 if backwards else 1)
            carton=re.search(r'(第)?(\d+)\s*(?:箱|件)\s*(每(?:箱|件))?\s*$',text[:weight_start])
            boxes=(1 if carton.group(1) else int(carton.group(2))) if carton else None
            pieces=([{'count':boxes,'weight':str(piece_weight),'dims':None,'dim_unit':'cm','position':weight_start}]
                    if carton and (boxes==1 or carton.group(3)) else None)
            weight=piece_weight*boxes if pieces else piece_weight
            entries.append({'warehouse':destination.upper(),'weight':weight,'boxes':boxes,'packages':pieces})
            used.append(match.span())
    if len(entries)<2:return None
    totals={}
    for entry in entries:
        code=entry['warehouse']
        if code not in totals:
            totals[code]=entry
            continue
        total=totals[code]
        total['weight']+=entry['weight']
        total['boxes']=total['boxes']+entry['boxes'] if total['boxes'] is not None and entry['boxes'] is not None else None
        total['packages']=(total['packages']+entry['packages']) if total['packages'] and entry['packages'] else None
    return [{**entry,'weight':str(entry['weight'])} for entry in totals.values()]