"""Check registered sense copper against native physical connectivity."""
import pcbnew as pcb


def check_measurement_branches(board, branches):
    if not branches:
        return {'branches': [], 'errors': []}
    board.BuildConnectivity()
    connection = board.GetConnectivity()
    tracks = {t.m_Uuid.AsString(): t for t in board.GetTracks()}
    pads = {(f.GetReference(), p.GetNumber()): p for f in board.GetFootprints() for p in f.Pads()}
    results, errors = [], []
    for branch in branches:
        name = branch['connection']
        ids = set(branch['track_uuids'])
        source_key, target_key = tuple(branch['from']), tuple(branch['to'])
        source, target = pads.get(source_key), pads.get(target_key)
        issues = []
        if source is None or target is None or not ids <= tracks.keys():
            errors.append({'kind': 'kelvin_missing_items', 'connection': name})
            continue
        if source.GetNetname() != target.GetNetname() or source.GetNetname() != branch['net']:
            issues.append('net_changed')
        if source_key[1] not in ('9', '10') or not target_key[0].startswith('Rs'):
            issues.append('unexpected_measurement_endpoints')
        seen = set()
        pending = {t.m_Uuid.AsString() for t in connection.GetConnectedTracks(source)} & ids
        while pending:
            uid = pending.pop()
            if uid in seen:
                continue
            seen.add(uid)
            pending.update({t.m_Uuid.AsString() for t in connection.GetConnectedTracks(tracks[uid])} & ids - seen)
        if seen != ids:
            issues.append('disconnected_registered_segments')
        touched = set()
        external = set()
        for uid in ids:
            track = tracks[uid]
            if isinstance(track, pcb.PCB_VIA) or track.GetLayer() != pcb.F_Cu:
                issues.append('measurement_changed_layer')
            if track.GetWidth() != pcb.FromMM(branch['width_mm']) or track.GetNetname() != branch['net']:
                issues.append('measurement_geometry_or_net_changed')
            touched.update((p.GetParentFootprint().GetReference(), p.GetNumber()) for p in connection.GetConnectedPads(track))
            for other in connection.GetConnectedTracks(track):
                other_id = other.m_Uuid.AsString()
                if other_id in ids:
                    continue
                # Future load copper may join at the shunt land, never on the sense run.
                shared = [q for q in (track.GetStart(), track.GetEnd())
                          if q == other.GetStart() or q == other.GetEnd()]
                if not shared or not all(target.HitTest(q) for q in shared):
                    external.add(other_id)
        if touched != {source_key, target_key}:
            issues.append('unexpected_or_missing_pad_contact')
        if external:
            issues.append('branch_join_outside_shunt_land')
        length = sum(pcb.ToMM(tracks[uid].GetLength()) for uid in ids)
        if abs(length - branch['length_mm']) > .001:
            issues.append('measurement_length_changed_requires_review')
        result = {'connection': name, 'from': source_key, 'to': target_key,
                  'physically_touched_pads': sorted(touched), 'length_mm': round(length, 5),
                  'external_track_joins': sorted(external), 'passed': not issues}
        results.append(result)
        if issues:
            errors.append({'kind': 'kelvin_branch', 'connection': name, 'issues': sorted(set(issues))})
    return {'branches': results, 'errors': errors,
            'limits': 'Zones and final shunt load-current entry geometry require review after power copper is added'}