"""Compare calculable CNY costs on the same destination and billing basis."""

from decimal import Decimal,ROUND_HALF_UP

from .quote_fees import charge_details


def speed_differences(intent, book, rates, fees):
    from .quote_engine import quantity, select_timed_rates,select_cheapest_rates,reference_days

    groups = {}
    for rate in rates:
        key = (rate['origin'], rate['zone'], rate['kind'], rate['unit'], rate['tax'])
        groups.setdefault(key, []).append(rate)
    result = []
    for (origin, zone, kind, unit, tax), candidates in groups.items():
        costs = []
        cheapest=intent.get('selection')=='fastest_cheapest'
        comparison=(select_cheapest_rates(intent,book,candidates,fees) if cheapest
                    else select_timed_rates(candidates,slowest=True))
        selections=(select_timed_rates(candidates),comparison)
        for selected in selections:
            values = []
            for rate in selected:
                amount = quantity(intent, rate)
                if amount is not None:
                    total=amount * Decimal(rate['price']) + charge_details(intent, rate, fees, book)['cny']
                    values.append(total.quantize(Decimal('.01'),rounding=ROUND_HALF_UP))
            costs.append(values)
        fast, slow = costs
        if not fast or not slow:
            continue
        low, high = min(fast) - max(slow), max(fast) - min(slow)
        timing=[]
        for selected in selections:
            bounds=[reference_days(rate) for rate in selected if reference_days(rate)]
            timing.append((min(value[0] for value in bounds),max(value[1] for value in bounds)) if bounds else None)
        result.append({'origin':origin,'zone':zone,'kind':kind,'unit':unit,'tax':tax,
                       'low':low,'high':high,'timing':timing,'cheapest':cheapest})
    return result


def speed_difference_lines(intent, book, rates, fees):
    from .quote_engine import number

    lines=[]
    for row in speed_differences(intent,book,rates,fees):
        label=' · '.join(value for value in (row['origin'],row['zone'],'包税' if row['tax']=='included' else '不包税',
                                             '海派' if row['kind']=='parcel' else '海卡/海铁') if value)
        difference=number(row['low']) if row['low']==row['high'] else number(row['low'])+'至'+number(row['high'])
        pair='最快与最便宜方案' if row['cheapest'] else '快慢方案'
        lines.append(f'- {label}，{pair}可计算运费差额为{difference}元。')
    return lines


def render_difference(intent,book,destinations,remote_fees):
    from .quote_engine import match_rates,number,exact_number
    from .quote_language import translate_quote

    groups={}
    for destination,fees in zip(destinations,remote_fees):
        part=destination.get('allocation')
        billing=({**intent,'weight':part['weight'],'packages':part.get('packages'),'dims':None,'cbm':None,'boxes':part.get('boxes')}
                 if part else intent)
        if part and intent.get('metal_chargeable_weight') is not None:
            billing.update(metal_chargeable_weight=None,metal_scope='partial')
        for row in speed_differences(billing,book,match_rates(billing,book,destination),fees):
            key=(row['origin'],row['kind'],row['unit'],row['tax'],row['low'],row['high'],tuple(row['timing']),
                 row['cheapest'],destination['warehouse'] or destination['postal'],billing.get('weight'))
            groups.setdefault(key,[]).append(row['zone'])
    if not groups:
        return ('Please provide weight, carton dimensions and routes with numeric reference transit times to compare costs.'
                if intent.get('english') else '请提供重量、箱规及有明确数值时效的渠道，继续核算方案差额。')
    lines=['按当前条件，同一交仓地、区域、计费单位和税费口径比较。']
    for (origin,kind,unit,tax,low,high,timing,cheapest,destination,weight),zones in groups.items():
        labels=[origin,destination or '/'.join(dict.fromkeys(zone for zone in zones if zone)),
                '包税' if tax=='included' else '不包税','海派' if kind=='parcel' else '海卡/海铁']
        difference=number(low) if low==high else number(low)+'至'+number(high)
        pair='最快与最便宜方案' if cheapest else '快慢方案'
        line='- '+' · '.join(label for label in labels if label)+f'，{pair}可计算运费差额为{difference}元。'
        if weight:line+=f'按{exact_number(weight)}KG核算。'
        if all(timing):
            days=[number(bounds[0]) if bounds[0]==bounds[1] else number(bounds[0])+'–'+number(bounds[1]) for bounds in timing]
            line+='参考时效分别约'+days[0]+'天、'+days[1]+'天。'
        lines.append(line)
    lines.append('回复“展开报价明细”可查看单价和各方案总价。')
    text='\n'.join(lines)
    return translate_quote(text) if intent.get('english') else text