data.py

"""@namespace IMP.mmcif.data
   @brief Classes to represent data structures used in mmCIF.
"""

import IMP.atom
import ihm.location
import ihm.metadata
import ihm.startmodel
import ihm.analysis
import ihm.protocol
import ihm.model
import ihm.citations
import ihm.reference
import operator
import inspect


# Map from IMP ResidueType to ihm ChemComp
_imp_to_ihm = {}


def _fill_imp_to_ihm():
    d = dict(x for x in inspect.getmembers(IMP.atom)
             if isinstance(x[1], IMP.atom.ResidueType))
    # Handle standard amino acids plus some extras like MSE, UNK
    for comp in ihm.LPeptideAlphabet._comps.values():
        if comp.id in d:
            _imp_to_ihm[d[comp.id]] = comp
    # Handle RNA and DNA
    alpha = ihm.RNAAlphabet()
    for code in ['ADE', 'CYT', 'GUA', 'URA']:
        _imp_to_ihm[d[code]] = alpha[d[code].get_string()]
    alpha = ihm.DNAAlphabet()
    for code in ['DADE', 'DCYT', 'DGUA', 'DTHY']:
        _imp_to_ihm[d[code]] = alpha[d[code].get_string()]
    # Pass through missing IMP residue
    _imp_to_ihm[None] = None


_fill_imp_to_ihm()


def get_molecule(h):
    """Given a Hierarchy, walk up and find the parent Molecule"""
    while h:
        if IMP.atom.Molecule.get_is_setup(h):
            return IMP.atom.Molecule(h)
        h = h.get_parent()
    return None


def _check_sequential(fragment, resinds):
    for i in range(1, len(resinds)):
        if resinds[i - 1] + 1 != resinds[i]:
            raise ValueError(
                "%s: non-sequential residue indices are not supported"
                % str(fragment))


def _get_all_state_provenance(state_h, top_h, types):
    """Yield all provenance information for the given state.
       If the given State Hierarchy node contains no provenance information,
       fall back to any provenance information for the top-level node
       (if provided)."""
    count = 0
    for p in IMP.core.get_all_provenance(state_h, types=types):
        count += 1
        yield p
    if count == 0 and top_h is not None:
        for p in IMP.core.get_all_provenance(top_h, types=types):
            yield p


class _CustomDNAAlphabet(ihm.Alphabet):
    """Custom DNA alphabet that maps A,C,G,T (rather than DA,DC,DG,DT
       as in python-ihm)"""
    _comps = dict([cc.code_canonical, cc]
                  for cc in ihm.DNAAlphabet._comps.values())


class _EntityMapper(dict):
    """Handle mapping from IMP chains to CIF entities.
       Multiple components may map to the same entity if they
       share sequence."""
    def __init__(self, system):
        self.system = system
        super().__init__()
        self._sequence_dict = {}
        self._entities = []
        self._alphabet_map = {
            IMP.atom.UnknownChainType: ihm.LPeptideAlphabet,
            IMP.atom.Protein: ihm.LPeptideAlphabet,
            IMP.atom.RNA: ihm.RNAAlphabet,
            IMP.atom.DNA: _CustomDNAAlphabet}

    def _get_sequence_from_residues(self, chain, seq_from_res):
        seq_id_begin, seq = seq_from_res
        if not seq:
            raise ValueError("Chain %s has no sequence and no residues"
                             % chain)
        missing_seq = [ind + seq_id_begin
                       for (ind, res) in enumerate(seq) if res is None]
        if missing_seq:
            raise ValueError(
                "Chain %s has no declared sequence; tried to determine the "
                "sequence from Residues, but the following residue indices "
                "have no residue type (perhaps covered only by Fragments): %s"
                % (chain, str(missing_seq)))
        return seq_id_begin - 1, tuple(seq)

    def add(self, chain, seq_from_res=None):
        sequence = chain.get_sequence()
        offset = chain.get_sequence_offset()
        if sequence == '':
            if seq_from_res is not None:
                offset, sequence = self._get_sequence_from_residues(
                    chain, seq_from_res)
            else:
                raise ValueError("Chain %s has no sequence" % chain)
        else:
            # Map one-letter codes to ihm.ChemComp
            alphabet = self._alphabet_map[chain.get_chain_type()]()
            sequence = tuple(alphabet[x] for x in sequence)
        if sequence not in self._sequence_dict:
            entity = ihm.Entity(sequence)
            self.system.entities.append(entity)
            self._entities.append(entity)
            self._sequence_dict[sequence] = entity
            uniprot = chain.get_uniprot_accession()
            if uniprot:
                up = ihm.reference.UniProtSequence.from_accession(uniprot)
                entity.references.append(up)
        self[chain] = self._sequence_dict[sequence]
        return self[chain], offset

    def get_all(self):
        """Yield all entities"""
        return self._entities


def _assign_id(obj, seen_objs, obj_by_id):
    """Assign a unique ID to obj, and track all ids in obj_by_id."""
    if obj not in seen_objs:
        if not hasattr(obj, 'id'):
            obj_by_id.append(obj)
            obj.id = len(obj_by_id)
        seen_objs[obj] = obj.id
    else:
        obj.id = seen_objs[obj]


class _Component:
    """An mmCIF component. This is an instance of an _Entity. Multiple
       _Components may map to the same _Entity but must have unique
       asym_ids. A _Component is similar to an IMP Chain but multiple
       Chains may map to the same _Component (the Chains represent the
       same structure, just in different states, and potentially in
       different IMP Models). A _Component may also represent something
       that is described by an experiment but was not modeled by IMP, and
       so no Chains map to it but a string name does."""
    def __init__(self, entity, asym_id, name):
        self.entity, self.asym_id, self.name = entity, asym_id, name


class _ComponentMapper:
    """Handle mapping from IMP Chains to CIF AsymUnits."""
    def __init__(self, system):
        super().__init__()
        self.system = system
        self._used_entities = set()
        self._all_components = []
        self._map = {}

    def __getitem__(self, chain):
        asym_id, map_key, name = self._handle_chain(chain)
        return self._map[map_key]

    def _handle_chain(self, chain):
        mol = get_molecule(chain)
        asym_id = chain.get_id()
        name = mol.get_name() if mol else None
        # Avoid conflict between name="A" and asym_id="A"
        if name:
            map_key = "name", name
        else:
            map_key = "asym_id", asym_id
        return asym_id, map_key, name

    def add(self, chain, entity, offset):
        """Add a chain (an IMP Chain object)"""
        asym_id, map_key, name = self._handle_chain(chain)
        if map_key not in self._map:
            component = _Component(entity, asym_id, name)
            if entity not in self._used_entities:
                self._used_entities.add(entity)
                # Assign entity name from the component; strip out anything
                # after a @ or .
                if component.name:
                    entity.description = \
                        component.name.split("@")[0].split(".")[0]
            self._all_components.append(component)
            asym = ihm.AsymUnit(entity, name, id=asym_id,
                                auth_seq_id_map=offset)
            self.system.asym_units.append(asym)
            component.asym_unit = asym
            self._map[map_key] = component
        else:
            component = self._map[map_key]
            if component.entity != entity:
                raise ValueError("Two chains have the same ID (%s) but "
                                 "different sequences - rename one of the "
                                 "chains" % component.asym_unit.id)
            if component.asym_unit.auth_seq_id_map != offset:
                raise ValueError(
                    "Two chains have the same ID (%s) but different offsets "
                    "(%d, %d) - this is not supported"
                    % (component.asym_unit.id,
                       component.asym_unit.auth_seq_id_map, offset))
        return component

    def get_all(self):
        """Get all components"""
        return self._all_components


class _RepSegmentFactory:
    """Make ihm.representation.Segment objects for each set of contiguous
       particles with the same representation"""
    def __init__(self, asym):
        self.asym = asym
        # Offset from IHM to IMP numbering
        self.offset = asym.auth_seq_id_map
        self.particles = []
        self.imp_residue_range = ()  # inclusive range, using IMP numbering

    def add(self, particle, starting_model):
        """Add a new particle to the last segment (and return None).
           Iff the particle could not be added, return the segment and start
           a new one."""
        (resrange, rigid_body,
         is_res, is_atom) = self._get_particle_info(particle)

        def start_new_segment():
            self.particles = [particle]
            self.imp_residue_range = resrange
            self.rigid_body = rigid_body
            self.is_res = is_res
            self.is_atom = is_atom
            self.starting_model = starting_model
        if not self.particles:
            # First particle in a segment
            start_new_segment()
        elif (type(particle) == type(self.particles[0])  # noqa: E721
              and is_res == self.is_res
              and is_atom == self.is_atom
              and resrange[0] <= self.imp_residue_range[1] + 1
              and starting_model == self.starting_model
              and self._same_rigid_body(rigid_body)):
            # Continue an existing segment
            self.particles.append(particle)
            self.imp_residue_range = (self.imp_residue_range[0], resrange[1])
        else:
            # Make a new segment
            seg = self.get_last()
            start_new_segment()
            return seg

    def get_last(self):
        """Return the last segment, or None"""
        if self.particles:
            # Convert residue_range from IMP to IHM
            asym = self.asym(self.imp_residue_range[0] - self.offset,
                             self.imp_residue_range[1] - self.offset)
            if self.is_atom:
                return ihm.representation.AtomicSegment(
                        asym_unit=asym, rigid=self.rigid_body is not None,
                        starting_model=self.starting_model)
            elif self.is_res:
                return ihm.representation.ResidueSegment(
                        asym_unit=asym,
                        rigid=self.rigid_body is not None, primitive='sphere',
                        starting_model=self.starting_model)
            else:
                return ihm.representation.FeatureSegment(
                        asym_unit=asym,
                        rigid=self.rigid_body is not None, primitive='sphere',
                        count=len(self.particles),
                        starting_model=self.starting_model)

    def _same_rigid_body(self, rigid_body):
        # Note: can't just use self.rigid_body == rigid_body as IMP may
        # crash when comparing a RigidBody object against None
        if self.rigid_body is None and rigid_body is None:
            return True
        elif self.rigid_body is None or rigid_body is None:
            return False
        else:
            return self.rigid_body == rigid_body

    def _get_particle_info(self, p):
        # Note that we consider nonrigid members to not be rigid here
        if IMP.core.RigidMember.get_is_setup(p):
            rigid_body = IMP.core.RigidMember(p).get_rigid_body()
        else:
            rigid_body = None
        if isinstance(p, IMP.atom.Residue):
            return (p.get_index(), p.get_index()), rigid_body, True, False
        elif isinstance(p, IMP.atom.Atom):
            res = IMP.atom.get_residue(p)
            return (res.get_index(), res.get_index()), rigid_body, False, True
        elif isinstance(p, IMP.atom.Fragment):
            resinds = p.get_residue_indexes()
            return (resinds[0], resinds[-1]), rigid_body, False, False
        raise TypeError("Unknown particle ", p)


def _get_all_structure_provenance(p):
    """Yield all StructureProvenance decorators for the given particle."""
    return IMP.core.get_all_provenance(p, types=[IMP.core.StructureProvenance])


class _StartingModelAtomHandler:
    def __init__(self, templates, asym):
        self._seq_dif = []
        self._last_res_index = None
        self.templates = templates
        self.asym = asym

    def _residue_first_atom(self, res):
        """Return True iff we're looking at the first atom in this residue"""
        # Only add one seq_dif record per residue
        ind = res.get_index()
        if ind != self._last_res_index:
            self._last_res_index = ind
            return True

    def handle_residue(self, res, comp_id, seq_id, offset):
        res_name = res.get_residue_type().get_string()
        # MSE in the original PDB is automatically mutated
        # by IMP to MET, so reflect that in the output,
        # and pass back to populate the seq_dif category.
        if res_name == 'MSE' and comp_id == 'MET':
            if self._residue_first_atom(res):
                # This should only happen when we're using
                # a crystal structure as the source (a
                # comparative model would use MET in
                # the sequence)
                assert len(self.templates) == 0
                self._seq_dif.append(ihm.startmodel.MSESeqDif(
                            res.get_index(), seq_id))
        elif res_name != comp_id:
            if self._residue_first_atom(res):
                print("WARNING: Starting model residue %s does not match "
                      "that in the output model (%s) for chain %s residue %d. "
                      "Check offset (currently %d)."
                      % (res_name, comp_id, self.asym._id, seq_id, offset))
                self._seq_dif.append(ihm.startmodel.SeqDif(
                         db_seq_id=res.get_index(), seq_id=seq_id,
                         db_comp_id=res_name,
                         details="Mutation of %s to %s" % (res_name, comp_id)))

    def get_ihm_atoms(self, particles, offset):
        for a in particles:
            coord = IMP.core.XYZ(a).get_coordinates()
            atom = IMP.atom.Atom(a)
            element = atom.get_element()
            element = IMP.atom.get_element_table().get_name(element)
            atom_name = atom.get_atom_type().get_string()
            het = atom_name.startswith('HET:')
            if het:
                atom_name = atom_name[4:]
            res = IMP.atom.get_residue(atom)

            seq_id = res.get_index() + offset
            comp_id = self.asym.entity.sequence[seq_id-1].id
            self.handle_residue(res, comp_id, seq_id, offset)
            yield ihm.model.Atom(asym_unit=self.asym, seq_id=seq_id,
                                 atom_id=atom_name, type_symbol=element,
                                 x=coord[0], y=coord[1], z=coord[2],
                                 het=het, biso=atom.get_temperature_factor())


class _StartingModel(ihm.startmodel.StartingModel):
    _eq_keys = ['filename', 'asym_id', 'offset']

    def __init__(self, asym_unit, struc_prov):
        self.filename = struc_prov[0].get_filename()
        super().__init__(
            asym_unit=asym_unit(0, 0),  # will update in _add_residue()
            # will fill in later with _set_sources_datasets()
            dataset=None,
            asym_id=struc_prov[0].get_chain_id(),
            offset=struc_prov[0].get_residue_offset())

    def _add_residue(self, resind):
        # Update seq_id_range to accommodate this residue
        seq_id_end = resind
        seq_id_begin = self.asym_unit.seq_id_range[0]
        if seq_id_begin == 0:
            seq_id_begin = seq_id_end
        self.asym_unit = self.asym_unit.asym(seq_id_begin, seq_id_end)

    # Two starting models with same filename, chain ID, and offset
    # compare identical
    # note: this results in separate starting models if only the
    # offset differs; maybe consolidate into one?
    def _eq_vals(self):
        return tuple([self.__class__]
                     + [getattr(self, x) for x in self._eq_keys])

    def __eq__(self, other):
        return other is not None and self._eq_vals() == other._eq_vals()

    def __hash__(self):
        return hash(self._eq_vals())

    def _set_sources_datasets(self, system, datasets):
        # Attempt to identify PDB file vs. comparative model
        if (hasattr(ihm.metadata, 'CIFParser')
                and self.filename.endswith('.cif')):
            p = ihm.metadata.CIFParser()
        else:
            p = ihm.metadata.PDBParser()
        r = p.parse_file(self.filename)
        system.software.extend(r.get('software', []))
        dataset = datasets.add(r['dataset'])
        # We only want the templates that model the starting model chain
        templates = r.get('templates', {}).get(self.asym_id, [])
        for t in templates:
            if t.alignment_file:
                system.locations.append(t.alignment_file)
            if t.dataset:
                datasets.add(t.dataset)
        self.dataset = dataset
        self.templates = templates
        self.metadata = r.get('metadata', [])

    def _read_coords(self):
        """Read the coordinates for this starting model"""
        m = IMP.Model()
        # todo: support reading other subsets of the atoms (e.g. CA/CB)
        slt = IMP.atom.ChainPDBSelector([self.asym_id]) \
            & IMP.atom.NonWaterNonHydrogenPDBSelector()
        hier = IMP.atom.read_pdb_or_mmcif(self.filename, m, slt)
        rng = self.asym_unit.seq_id_range
        sel = IMP.atom.Selection(
            hier, residue_indexes=list(range(rng[0] - self.offset,
                                             rng[1] + 1 - self.offset)))
        return m, sel

    def get_seq_dif(self):
        return self._seq_dif  # filled in by get_atoms()

    def get_atoms(self):
        mh = _StartingModelAtomHandler(self.templates, self.asym_unit)
        m, sel = self._read_coords()
        for a in mh.get_ihm_atoms(sel.get_selected_particles(), self.offset):
            yield a
        self._seq_dif = mh._seq_dif


class _StartingModelFinder:
    """Map IMP particles to starting model objects"""
    def __init__(self, asym, existing_starting_models, system, datasets):
        self._seen_particles = {}
        self._asym = asym
        self._seen_starting_models = {}
        for sm in existing_starting_models:
            self._seen_starting_models[sm] = sm
        self._system = system
        self._datasets = datasets

    def find(self, particle):
        """Return a StartingModel object, or None, for this particle"""
        def _get_starting_model(sp, resind):
            s = _StartingModel(self._asym, sp)
            if s not in self._seen_starting_models:
                self._seen_starting_models[s] = s
                s._set_sources_datasets(self._system, self._datasets)
                self._system.orphan_starting_models.append(s)
            s = self._seen_starting_models[s]
            if s:
                s._add_residue(resind)
            return s
        resind = None
        if IMP.atom.Residue.get_is_setup(particle):
            resind = IMP.atom.Residue(particle).get_index()
        sp = list(_get_all_structure_provenance(particle))
        if sp:
            return _get_starting_model(sp, resind)
        elif IMP.atom.Hierarchy.get_is_setup(particle):
            h = IMP.atom.Hierarchy(particle).get_parent()
            # Remember all nodes we inspect
            seen_parents = []
            while h:
                if IMP.atom.Residue.get_is_setup(h):
                    resind = IMP.atom.Residue(h).get_index()
                pi = h.get_particle_index()
                seen_parents.append(pi)
                # If we inspected this node before, return the cached result
                if pi in self._seen_particles:
                    sp = self._seen_particles[pi]
                    if sp and sp[0] and resind is not None:
                        sp[0]._add_residue(resind)
                    return sp[0] if sp else None
                else:
                    sp = list(_get_all_structure_provenance(h))
                    self._seen_particles[pi] = []
                    if sp:
                        s = _get_starting_model(sp, resind)
                        # Set cache for this node and all the children we
                        # inspected on the way up
                        for spi in seen_parents:
                            self._seen_particles[spi].append(s)
                        return s
                h = h.get_parent()


class _Datasets:
    """Store all datasets used."""
    def __init__(self, system):
        super().__init__()
        self._datasets = {}
        self._groups = {}
        self.system = system

    def add(self, d):
        """Add and return a new dataset."""
        if d not in self._datasets:
            self._datasets[d] = d
            self.system.orphan_datasets.append(d)
        return self._datasets[d]

    def add_group(self, datasets, name):
        """Add and return a new group of datasets"""
        seen = set()
        # Remove duplicates
        d = []
        for dataset in datasets:
            if dataset not in seen:
                d.append(dataset)
                seen.add(dataset)
        d = tuple(d)
        if d not in self._groups:
            g = ihm.dataset.DatasetGroup(d, name=name)
            self._groups[d] = g
            self.system.orphan_dataset_groups.append(g)
        return self._groups[d]

    def get_all(self):
        """Yield all datasets"""
        return self._datasets.keys()


class _AllSoftware:
    """Keep track of all Software objects."""

    # IMP/RMF doesn't store citation info for software, so provide it
    # for known software packages
    cites = {'Integrative Modeling Platform (IMP)': ihm.citations.imp,
             'IMP PMI module': ihm.citations.pmi}

    def __init__(self, system):
        self.system = system
        self._by_namever = {}
        super().__init__()

    def add_hierarchy(self, h, top_h=None):
        # todo: if no SoftwareProvenance available, use RMF producer field
        for p in _get_all_state_provenance(
                h, top_h, types=[IMP.core.SoftwareProvenance]):
            self._add_provenance(p)

    def _add_provenance(self, p):
        """Add Software from SoftwareProvenance"""
        # Only reference the same version of a given software package once
        name = p.get_software_name()
        version = p.get_version()
        if (name, version) not in self._by_namever:
            s = ihm.Software(name=name,
                             classification='integrative model building',
                             description=None, version=version,
                             location=p.get_location(),
                             citation=self.cites.get(name))
            self.system.software.append(s)
            self._by_namever[name, version] = s
        return self._by_namever[name, version]

    def _add_previous_provenance(self, prov):
        """Add Software from a previous SoftwareProvenance, if any"""
        while prov:
            if IMP.core.SoftwareProvenance.get_is_setup(prov):
                return self._add_provenance(IMP.core.SoftwareProvenance(prov))
            prov = prov.get_previous()


class _ExternalFiles:
    """Track all externally-referenced files
       (i.e. anything that refers to a Location that isn't
       a DatabaseLocation)."""
    def __init__(self, system):
        self.system = system
        self._by_path = {}

    def add_hierarchy(self, h, top_h=None):
        # Add all Python scripts that were used in the modeling
        for p in _get_all_state_provenance(
                h, top_h, types=[IMP.core.ScriptProvenance]):
            self._add_provenance(p)

    def _add_provenance(self, p):
        """Add external file from ScriptProvenance"""
        # Only reference the same path once
        path = p.get_filename()
        if path not in self._by_path:
            loc = ihm.location.WorkflowFileLocation(
                path=p.get_filename(),
                details='Integrative modeling Python script')
            self.system.locations.append(loc)
            self._by_path[path] = loc
        return self._by_path[path]


class _ProtocolStep(ihm.protocol.Step):
    """A single step (e.g. sampling, refinement) in a protocol."""
    def __init__(self, prov, num_models_begin, assembly, all_software):
        method = prov.get_method()
        if prov.get_number_of_replicas() > 1:
            method = "Replica exchange " + method
        super().__init__(
            assembly=assembly,
            # todo: fill in useful value for dataset_group
            dataset_group=None,
            method=method, name='Sampling',
            num_models_begin=num_models_begin,
            num_models_end=prov.get_number_of_frames(),
            # todo: support multiple states, time ordered
            multi_state=False, ordered=False,
            # todo: revisit assumption all models are multiscale
            multi_scale=True,
            software=all_software._add_previous_provenance(prov))

    def add_combine(self, prov):
        self.num_models_end = prov.get_number_of_frames()
        return self.num_models_end


class _Protocol(ihm.protocol.Protocol):
    """A modeling protocol.
       Each protocol consists of a number of protocol steps (e.g. sampling,
       refinement) followed by a number of postprocessing steps (e.g.
       filtering, rescoring, clustering)"""

    def add_step(self, prov, num_models, assembly, all_software):
        if isinstance(prov, IMP.core.CombineProvenance):
            # Fold CombineProvenance into a previous sampling step
            if len(self.steps) == 0:
                raise ValueError("CombineProvenance with no previous sampling")
            return self.steps[-1].add_combine(prov)
        else:
            ps = _ProtocolStep(prov, num_models, assembly, all_software)
            self.steps.append(ps)
            return ps.num_models_end

    def add_postproc(self, prov, num_models, assembly):
        if not self.analyses:
            self.analyses.append(ihm.analysis.Analysis())
        if isinstance(prov, IMP.core.FilterProvenance):
            pp = ihm.analysis.FilterStep(
                feature='energy/score', assembly=assembly,
                num_models_begin=num_models,
                num_models_end=prov.get_number_of_frames())
        elif isinstance(prov, IMP.core.ClusterProvenance):
            # Assume clustering uses all models
            pp = ihm.analysis.ClusterStep(
                feature='RMSD', assembly=assembly, num_models_begin=num_models,
                num_models_end=num_models)
        else:
            raise ValueError("Unhandled provenance", prov)
        self.analyses[-1].steps.append(pp)
        return pp.num_models_end


class _Protocols:
    """Track all modeling protocols used."""
    def __init__(self, system):
        self.system = system

    def _add_protocol(self, prot):
        # Protocol isn't hashable or sortable, so just compare dicts
        # with existing protocols. This should still be performant as
        # we generally don't have more than one or two protocols.
        # We exclude dataset_group from the comparison as this is typically
        # filled in later.
        def step_equal(x, y):
            def get_dict(d):
                return {x: y for x, y in d.__dict__.items()
                        if x != 'dataset_group'}

            return (type(x) == type(y)  # noqa: E721
                    and get_dict(x) == get_dict(y))

        def analysis_equal(x, y):
            return (len(x.steps) == len(y.steps)
                    and all(step_equal(a, b)
                            for (a, b) in zip(x.steps, y.steps)))

        for existing in self.system.orphan_protocols:
            if (len(existing.steps) == len(prot.steps)
                and len(existing.analyses) == len(prot.analyses)
                and all(step_equal(x, y)
                        for (x, y) in zip(existing.steps, prot.steps))
                and all(analysis_equal(x, y)
                        for (x, y) in zip(existing.analyses, prot.analyses))):
                return existing
        self.system.orphan_protocols.append(prot)
        return prot

    def _add_hierarchy(self, h, top_h, modeled_assembly, all_software):
        num_models = 0  # assume we always start with no models
        prot_types = (IMP.core.SampleProvenance, IMP.core.CombineProvenance)
        pp_types = (IMP.core.FilterProvenance, IMP.core.ClusterProvenance)
        in_postproc = False
        prot = _Protocol()
        for p in reversed(list(_get_all_state_provenance(
                h, top_h, types=prot_types + pp_types))):
            if isinstance(p, pp_types):
                num_models = prot.add_postproc(p, num_models, modeled_assembly)
                in_postproc = True
            else:
                if in_postproc:
                    # Start a new protocol
                    self._add_protocol(prot)
                    prot = _Protocol()
                num_models = prot.add_step(p, num_models, modeled_assembly,
                                           all_software)
                in_postproc = False
        if len(prot.steps) > 0:
            return self._add_protocol(prot)


class _CoordinateHandler:
    def __init__(self, system, datasets):
        self._system = system
        self._datasets = datasets
        self._representation = ihm.representation.Representation()
        # IHM atoms/spheres corresponding to IMP beads/residues/atoms
        # We build them up front (rather than on the fly) as the original
        # IMP objects may have been destroyed or changed (e.g. if we read
        # multiple frames from an RMF file) by the time we write the mmCIF.
        self._atoms = []
        self._spheres = []

    def get_residue_sequence(self, ps):
        """Determine the primary sequence based on Residue particles.
           Return the index of the first residue and the sequence, as a list
           of ihm.ChemComp objects (or None)"""
        restyp = {}
        for p in ps:
            if isinstance(p, IMP.atom.Atom):
                residue = IMP.atom.get_residue(p)
                restyp[residue.get_index()] = residue.get_residue_type()
            elif isinstance(p, IMP.atom.Residue):
                restyp[p.get_index()] = p.get_residue_type()
            else:  # fragment
                resinds = p.get_residue_indexes()
                for ri in resinds:
                    if ri not in restyp:   # don't overwrite residue/atom info
                        restyp[ri] = None
        if not restyp:
            return 1, []
        seq_id_begin = min(restyp.keys())
        seq_id_end = max(restyp.keys())
        return (seq_id_begin,
                [_imp_to_ihm[restyp.get(x)]
                 for x in range(seq_id_begin, seq_id_end + 1)])

    def add_chain(self, ps, asym):
        def matches_asym(s):
            # Match AsymUnit or AsymUnitRange
            return s == asym or hasattr(s, 'asym') and s.asym == asym

        # Consolidate starting models if the same model was used for this
        # asym in a different state or for a different model_id
        smf = _StartingModelFinder(
            asym, [s for s in self._system.orphan_starting_models
                   if matches_asym(s.asym_unit)],
            self._system, self._datasets)
        segfactory = _RepSegmentFactory(asym)
        offset = asym.auth_seq_id_map
        for p in ps:
            starting_model = smf.find(p)
            seg = segfactory.add(p, starting_model)
            if seg:
                self._representation.append(seg)
            self._add_atom_or_sphere(p, asym, offset)
        last = segfactory.get_last()
        if last:
            self._representation.append(last)

    def _add_atom_or_sphere(self, p, asym, offset):
        if isinstance(p, IMP.atom.Atom):
            residue = IMP.atom.get_residue(p)
            xyz = IMP.core.XYZ(p).get_coordinates()
            element = p.get_element()
            element = IMP.atom.get_element_table().get_name(element)
            atom_name = p.get_atom_type().get_string()
            het = atom_name.startswith('HET:')
            if het:
                atom_name = atom_name[4:]
            self._atoms.append(ihm.model.Atom(
                asym_unit=asym, seq_id=residue.get_index() - offset,
                atom_id=atom_name, type_symbol=element,
                x=xyz[0], y=xyz[1], z=xyz[2], het=het,
                biso=p.get_temperature_factor(),
                occupancy=p.get_occupancy()))
        else:
            if isinstance(p, IMP.atom.Fragment):
                resinds = p.get_residue_indexes()
                sbegin = resinds[0]
                send = resinds[-1]
            else:  # residue
                sbegin = send = p.get_index()
            xyzr = IMP.core.XYZR(p)
            xyz = xyzr.get_coordinates()
            self._spheres.append(ihm.model.Sphere(
                asym_unit=asym, seq_id_range=(sbegin - offset, send - offset),
                x=xyz[0], y=xyz[1], z=xyz[2], radius=xyzr.get_radius()))

    def get_structure_particles(self, h):
        """Return particles sorted by residue index"""
        ps = []
        if h.get_number_of_children() == 0:
            return []
        if not h.get_is_valid():
            raise ValueError("Invalid hierarchy as input")
        for p in IMP.atom.Selection(
                hierarchy=h, resolution=0.).get_selected_particles():
            if IMP.atom.Residue.get_is_setup(p):
                residue = IMP.atom.Residue(p)
                ps.append((residue.get_index(), residue))
            elif IMP.atom.Fragment.get_is_setup(p):
                fragment = IMP.atom.Fragment(p)
                resinds = fragment.get_residue_indexes()
                _check_sequential(fragment, resinds)
                resind = resinds[len(resinds) // 2]
                ps.append((resind, fragment))
            elif IMP.atom.Atom.get_is_setup(p):
                atom = IMP.atom.Atom(p)
                residue = IMP.atom.get_residue(atom)
                ps.append((residue.get_index(), atom))
        return [p[1] for p in sorted(ps, key=operator.itemgetter(0))]


class _ModelAssemblies:
    def __init__(self, system):
        self.system = system
        self._seen_assemblies = {}

    def add(self, asyms):
        # list isn't hashable but tuple is
        asyms = tuple(asyms)
        if asyms not in self._seen_assemblies:
            assembly = ihm.Assembly(
                asyms, name="Modeled assembly",
                description="All components modeled by IMP")
            self.system.orphan_assemblies.append(assembly)
            self._seen_assemblies[asyms] = assembly
        return self._seen_assemblies[asyms]


class _Representations:
    def __init__(self, system):
        self.system = system

    def add(self, rep):
        # Representation isn't hashable or sortable, so just compare dicts
        # with existing representations. This should still be performant as
        # we generally don't have more than one or two representations.
        for existing in self.system.orphan_representations:
            if (len(existing) == len(rep)
                and all(type(x) == type(y)  # noqa: E721
                        and x.__dict__ == y.__dict__
                        for (x, y) in zip(existing, rep))):
                return existing
        self.system.orphan_representations.append(rep)
        return rep