from Bio import Align
aligner = Align.PairwiseAligner(mode="global", match_score=2, mismatch_score=-1, open_gap_score=-5, extend_gap_score=-0.5)


def project(ref_seq, seqres, labels):
    """Map labels on `seqres` onto positions of `ref_seq` (identity if equal, else via global alignment)."""
    if ref_seq == seqres:
        return labels, "identical"
    aln = aligner.align(ref_seq, seqres)[0]
    out = [None] * len(ref_seq)
    for (a0, a1), (b0, b1) in zip(*aln.aligned):
        for k in range(a1 - a0):
            out[a0 + k] = labels[b0 + k]
    return out, f"aligned ({sum(a1 - a0 for (a0, a1), _ in zip(*aln.aligned))}/{len(ref_seq)} positions)"