Overcome backwards xl-id form by handling both

This adds the "normal" form (used in XL) as a sameAs to generated
records if they are to have the backwards form mistakenly minted by this
repository.

An upper timestamp per dataset is used to check for if its member
records are to have the backwards form.

(Eventually we want to "garbage collect" this backwards form from XL, to
ensure they don't "squat" on XL id:s in the future.)

common.py

@@ -11,6 +11,7 @@
     context="sys/context/base.jsonld",
     system_base_iri="",
     union="common.jsonld.lines",
+    last_backwards_id_time="2022-10-14T16:26:16Z"
 )
 
 if __name__ == "__main__":

lxltools/datacompiler.py

@@ -33,7 +33,8 @@ def __init__(self, *,
                  context=None,
                  record_thing_link='mainEntity',
                  system_base_iri=None,
-                 union='all.jsonld.lines'):
+                 union='all.jsonld.lines',
+                 last_backwards_id_time=None):
         self.datasets_description = datasets_description
         self.datasets = {}
         self.current_ds_resources = set()
@@ -49,6 +50,11 @@ def __init__(self, *,
         self.current_ds_file = None
         self.no_records = False
 
+        self.last_backwards_id_time = (
+            timeutil.w3c_dtz_to_ms(last_backwards_id_time)
+            if isinstance(last_backwards_id_time, str)
+            else None)
+
         if datasets_description:
             self._handlers_from_datasets_description(datasets_description)
 
@@ -155,7 +161,8 @@ def _compile_dataset(self, name, result):
             data = self.to_jsonld(data)
 
         ds_url = urljoin(self.dataset_id, name)
-        self._create_dataset_description(ds_url, ds_created_ms, ds_modified_ms)
+        self._create_dataset_description(
+            ds_url, ds_created_ms, ds_created_ms=ds_created_ms)
 
         base_id = urljoin(self.dataset_id, base)
 
@@ -172,10 +179,6 @@ def _compile_dataset(self, name, result):
             modified_ms = None
             fpath = urlparse(nodeid).path[1:]
 
-            if self.no_records:
-                self.write(node, fpath)
-                continue
-
             meta = node.pop('meta', None)
             if meta:
                 if 'created' in meta:
@@ -189,10 +192,25 @@ def _compile_dataset(self, name, result):
                     node,
                     created_ms,
                     modified_ms,
-                    datasets=[self.dataset_id, ds_url])
-            self.write(desc, fpath)
+                    datasets=[self.dataset_id, ds_url],
+                    ds_created_ms=ds_created_ms)
+
+            # Keep sameAs "fowards" form in meta even if no_records is used
+            if self.no_records:
+                meta = meta or {}
+                sameas = meta.setdefault('sameAs', [])
+                rec = desc['@graph'][0]
+                if 'sameAs' in rec:
+                    sameas.append({"@id": rec['@id']})
+                for same in rec.get('sameAs', []):
+                    sameas.append(same)
+                node['meta'] = meta
+                self.write(node, fpath)
+            else:
+                self.write(desc, fpath)
 
-    def _create_dataset_description(self, ds_url, created_ms, modified_ms=None, label=None):
+    def _create_dataset_description(self, ds_url, created_ms, modified_ms=None,
+            label=None, ds_created_ms=None):
         if not label:
             label = ds_url.rsplit('/', 1)[-1]
         ds = {
@@ -211,7 +229,7 @@ def _create_dataset_description(self, ds_url, created_ms, modified_ms=None, labe
             return
 
         desc = self._to_node_description(ds, created_ms, modified_ms,
-                datasets={self.dataset_id, ds_url})
+                datasets={self.dataset_id, ds_url}, ds_created_ms=ds_created_ms)
 
         record = desc['@graph'][0]
         if self.tool_id:
@@ -220,14 +238,16 @@ def _create_dataset_description(self, ds_url, created_ms, modified_ms=None, labe
         self.write(desc, ds_path)
 
     def _to_node_description(self, node, created_ms,
-            modified_ms=None, datasets=None):
+            modified_ms=None, datasets=None, ds_created_ms=None):
         assert self.record_thing_link not in node
 
         node_id = node['@id']
 
         record = OrderedDict()
         record['@type'] = 'Record'
-        record['@id'] = self.generate_record_id(created_ms, node_id)
+
+        self.set_record_id(record, created_ms, node_id, ds_created_ms)
+
         record[self.record_thing_link] = {'@id': node_id}
 
         # Add provenance
@@ -241,9 +261,19 @@ def _to_node_description(self, node, created_ms,
 
         return {'@graph': items}
 
-    def generate_record_id(self, created_ms, node_id):
-        # FIXME: backwards_form=created_ms < 2015
-        slug = lxlslug.librisencode(created_ms, lxlslug.checksum(node_id))
+    def set_record_id(self, record, created_ms, node_id, ds_created_ms=None):
+        if ds_created_ms is None:
+            ds_created_ms = created_ms
+        backwards_form = ds_created_ms < self.last_backwards_id_time
+        # TODO: use normal form and keep backwards_form as sameAs until "GC:able"?
+        record['@id'] = self.generate_record_id(created_ms, node_id, backwards_form)
+        if backwards_form:
+            record['sameAs'] = [{'@id': self.generate_record_id(created_ms, node_id)}]
+
+    def generate_record_id(self, created_ms, node_id, backwards_form=False):
+        slug = lxlslug.librisencode(
+            created_ms, lxlslug.checksum(node_id), backwards_form=backwards_form
+        )
         return urljoin(self.system_base_iri, slug)
 
     def write(self, node, name):

lxltools/lxlslug.py

@@ -32,9 +32,10 @@ def rotate(c):
 def checksum(data):
     return crc32(data.encode('utf-8')) & 0xffffffff
 
-def librisencode(a, b):
+def librisencode(a, b, backwards_form=True):
+    form = reversed if backwards_form else lambda x: x
     alphabet = lower_consonants_numbers
-    timepart = "".join(reversed(caesarize(alphabet, tobase(alphabet, a))))
+    timepart = "".join(form(caesarize(alphabet, tobase(alphabet, a))))
     codepart = tobase(alphabet, b)
     codelen = len(codepart)
     if codelen < 7:

syscore.py

@@ -31,7 +31,8 @@ def _get_repo_version():
                     context='sys/context/base.jsonld',
                     record_thing_link='mainEntity',
                     system_base_iri='',
-                    union='syscore.jsonld.lines')
+                    union='syscore.jsonld.lines',
+                    last_backwards_id_time='2022-11-20T00:00:00Z')
 
 
 @compiler.handler
@@ -145,7 +146,7 @@ def _insert_record(graph, created_ms, dataset_id):
     record = {'@type': 'SystemRecord'}
     record[compiler.record_thing_link] = {'@id': entity['@id']}
     graph.insert(0, record)
-    record['@id'] = compiler.generate_record_id(created_ms, entity['@id'])
+    compiler.set_record_id(record, created_ms, entity['@id'])
     record['inDataset'] = [{'@id': compiler.dataset_id}, {'@id': dataset_id}]