"""Conservative adjacency candidates for narrow surveyed outlines; no polygon union."""
import math


def signed_area(ring):
    ox, oy = ring[0]
    return sum((a[0]-ox)*(b[1]-oy)-(b[0]-ox)*(a[1]-oy)
               for a,b in zip(ring,ring[1:]+ring[:1])) / 2


def shared_boundary_length(first, second, tolerance=.06):
    """Measure overlapping opposite-facing edges, merging duplicate overlap intervals."""
    a = first if signed_area(first)>0 else list(reversed(first))
    b = second if signed_area(second)>0 else list(reversed(second))
    total = 0
    for p,q in zip(a,a[1:]+a[:1]):
        dx,dy = q[0]-p[0],q[1]-p[1]
        length = math.hypot(dx,dy)
        if length <= tolerance:
            continue
        ux,uy = dx/length,dy/length
        intervals = []
        for r,s in zip(b,b[1:]+b[:1]):
            if (s[0]-r[0])*ux+(s[1]-r[1])*uy >= 0:
                continue  # CCW neighbors run opposite ways along a shared boundary
            distances = [abs((v[0]-p[0])*uy-(v[1]-p[1])*ux) for v in (r,s)]
            if max(distances)>tolerance:
                continue
            t = [(v[0]-p[0])*ux+(v[1]-p[1])*uy for v in (r,s)]
            low,high = max(0,min(t)),min(length,max(t))
            if high>low:
                intervals.append((low,high))
        end = -math.inf
        for low,high in sorted(intervals):
            total += max(0,high-max(end,low))
            end = max(end,high)
    return total


def attachment_candidates(strip, buildings):
    """Geometry evidence only; ambiguity must be resolved before assigning an export role."""
    short,long = sorted((strip['width'],strip['depth']))
    if strip['kind']!='massing' or short>2 or short<=0 or long<4 or long/short<4:
        return []
    area = abs(signed_area(strip['footprintENU']))
    candidates = []
    for host in buildings:
        if host['id']==strip['id'] or min(host['width'],host['depth'])<4:
            continue
        if abs(signed_area(host['footprintENU']))<area*4:
            continue
        shared = shared_boundary_length(strip['footprintENU'],host['footprintENU'])
        if shared>=long*.7:
            candidates.append({'primaryId':host['id'],'sharedBoundaryM':round(shared,4),
                               'sharedToLongSideRatio':round(shared/long,4)})
    return sorted(candidates,key=lambda row:(-row['sharedBoundaryM'],row['primaryId']))


def validate_composition_scopes(buildings, profile):
    pairs = {}
    for building in buildings:
        scope = building.get('massingFacadeScope', 'building')
        if scope not in ('building', 'shell-only'):
            raise ValueError('unsupported facade scope')
        if scope == 'shell-only':
            composition = building.get('composition', {})
            if profile != 'compact' or composition.get('role') != 'attached-narrow-outline':
                raise ValueError('shell-only requires an explicit compact attachment role')
            pairs[building['id']] = composition.get('primaryId')
    if pairs:
        annotate_reviewed_attachments(buildings, pairs)


def annotate_reviewed_attachments(buildings, reviewed_pairs):
    """Annotate an isolated plan; reject missing hosts, ambiguity or incorrect pairs."""
    by_id = {b['id']:b for b in buildings}
    if len(by_id)!=len(buildings):
        raise ValueError('duplicate building IDs')
    for strip_id,primary_id in reviewed_pairs.items():
        if strip_id not in by_id or primary_id not in by_id or primary_id in reviewed_pairs:
            raise ValueError('missing or invalid attachment primary')
        candidates = attachment_candidates(by_id[strip_id],buildings)
        if len(candidates)!=1 or candidates[0]['primaryId']!=primary_id:
            raise ValueError('ambiguous or unsupported attachment: '+strip_id)
    return [{**building, 'massingFacadeScope':'shell-only',
             'composition':{'role':'attached-narrow-outline', 'primaryId':reviewed_pairs[building['id']],
                            'geometryUnchanged':True}}
            if building['id'] in reviewed_pairs else dict(building) for building in buildings]