1010# Define Merkle fields to exclude from hashing
1111MERKLE_FIELDS = {"merkle:object_hash" , "merkle:hash_method" , "merkle:root" }
1212
13+ def remove_merkle_fields (data ):
14+ """
15+ Recursively removes Merkle fields from a nested dictionary.
16+ """
17+ if isinstance (data , dict ):
18+ return {
19+ k : remove_merkle_fields (v )
20+ for k , v in data .items ()
21+ if k not in MERKLE_FIELDS
22+ }
23+ elif isinstance (data , list ):
24+ return [remove_merkle_fields (v ) for v in data ]
25+ else :
26+ return data
27+
1328def compute_merkle_object_hash (
1429 stac_object : Dict [str , Any ],
15- hash_method : Dict [str , Any ],
16- is_item : bool = False ,
30+ hash_method : Dict [str , Any ]
1731) -> str :
1832 """
1933 Computes the merkle:object_hash for a STAC object (Catalog, Collection, or Item).
2034
2135 Parameters:
2236 - stac_object (dict): The STAC object JSON content.
2337 - hash_method (dict): The hash method details from merkle:hash_method.
24- - is_item (bool): Indicates if the object is an Item (Feature).
2538
2639 Returns:
2740 - str: The computed Merkle object hash as a hexadecimal string.
2841 """
2942 fields = hash_method .get ('fields' , ['*' ])
3043 if fields == ['*' ] or fields == ['all' ]:
31- # Exclude Merkle fields
32- if is_item :
33- # For Items, Merkle fields are within 'properties'
34- properties = stac_object .get ('properties' , {})
35- data_to_hash = {k : v for k , v in properties .items () if k not in MERKLE_FIELDS }
36- else :
37- # For Collections and Catalogs, Merkle fields are at the top level
38- data_to_hash = {k : v for k , v in stac_object .items () if k not in MERKLE_FIELDS }
44+ # Exclude Merkle fields from all levels
45+ data_to_hash = remove_merkle_fields (stac_object )
3946 else :
40- if is_item :
41- # Include only specified fields, excluding Merkle fields
42- properties = stac_object .get ('properties' , {})
43- data_to_hash = {field : properties .get (field ) for field in fields if field not in MERKLE_FIELDS }
44- else :
45- # For Collections and Catalogs
46- data_to_hash = {field : stac_object .get (field ) for field in fields if field not in MERKLE_FIELDS }
47-
47+ # Include only specified fields, then remove Merkle fields
48+ selected_data = {field : stac_object .get (field ) for field in fields if field in stac_object }
49+ data_to_hash = remove_merkle_fields (selected_data )
4850 # Serialize the data to a canonical JSON string
4951 json_str = json .dumps (data_to_hash , sort_keys = True , separators = (',' , ':' ))
50-
5152 # Get the hash function
5253 hash_function_name = hash_method .get ('function' , 'sha256' ).replace ('-' , '' ).lower ()
5354 hash_func = getattr (hashlib , hash_function_name , None )
5455 if not hash_func :
5556 raise ValueError (f"Unsupported hash function: { hash_function_name } )
56-
5757 # Compute the hash
5858 merkle_object_hash = hash_func (json_str .encode ('utf-8' )).hexdigest ()
5959 return merkle_object_hash
@@ -120,13 +120,11 @@ def process_item(item_path: Path, hash_method: Dict[str, Any]) -> str:
120120 item_json = json .load (f )
121121
122122 # Compute merkle:object_hash
123- own_hash = compute_merkle_object_hash (item_json , hash_method , is_item = True )
123+ own_hash = compute_merkle_object_hash (item_json , hash_method )
124124
125- # Add Merkle fields to 'properties'
125+ # Add merkle:object_hash to 'properties'
126126 properties = item_json .setdefault ('properties' , {})
127127 properties ['merkle:object_hash' ] = own_hash
128- # Remove the following line to avoid adding 'merkle:hash_method' to Items
129- # properties['merkle:hash_method'] = hash_method
130128
131129 # Ensure the Merkle extension is listed
132130 item_json .setdefault ('stac_extensions' , [])
@@ -163,10 +161,7 @@ def process_collection(collection_path: Path, parent_hash_method: Dict[str, Any]
163161 collection_json = json .load (f )
164162
165163 # Determine the hash_method to use
166- if 'merkle:hash_method' in collection_json :
167- hash_method = collection_json ['merkle:hash_method' ]
168- else :
169- hash_method = parent_hash_method
164+ hash_method = collection_json .get ('merkle:hash_method' , parent_hash_method )
170165
171166 if not hash_method :
172167 raise ValueError (f"Hash method not specified for { collection_path } )
@@ -182,7 +177,7 @@ def process_collection(collection_path: Path, parent_hash_method: Dict[str, Any]
182177 item_hashes .append (item_hash )
183178
184179 # Compute merkle:object_hash
185- own_hash = compute_merkle_object_hash (collection_json , hash_method , is_item = False )
180+ own_hash = compute_merkle_object_hash (collection_json , hash_method )
186181 collection_json ['merkle:object_hash' ] = own_hash
187182 item_hashes .append (own_hash )
188183
@@ -231,7 +226,7 @@ def process_catalog(catalog_path: Path) -> str:
231226 'function' : 'sha256' ,
232227 'fields' : ['*' ],
233228 'ordering' : 'ascending' ,
234- 'description' : 'Computed by including merkle:object_hash values in ascending order and building the Merkle tree.'
229+ 'description' : 'Computed by excluding Merkle fields and including merkle:object_hash values in ascending order to build the Merkle tree.'
235230 }
236231
237232 # Process collections in the collections folder
@@ -254,7 +249,7 @@ def process_catalog(catalog_path: Path) -> str:
254249 click .echo (f"collection.json not found in { collection_dir } , err = True )
255250
256251 # Compute merkle:object_hash
257- own_hash = compute_merkle_object_hash (catalog_json , hash_method , is_item = False )
252+ own_hash = compute_merkle_object_hash (catalog_json , hash_method )
258253 catalog_json ['merkle:object_hash' ] = own_hash
259254 collection_hashes .append (own_hash )
260255
@@ -283,25 +278,3 @@ def process_catalog(catalog_path: Path) -> str:
283278 except Exception as e :
284279 click .echo (f"Error processing Catalog { catalog_path } { e } , err = True )
285280 return ''
286-
287- @click .command ()
288- @click .argument ('catalog_path' , type = click .Path (exists = True , file_okay = True , dir_okay = False ))
289- def main (catalog_path ):
290- """
291- Computes and adds Merkle info to each STAC object in the catalog.
292-
293- CATALOG_PATH is the path to your root catalog.json file.
294- """
295- catalog_path = Path (catalog_path ).resolve ()
296-
297- if not catalog_path .exists ():
298- click .echo (f"Catalog file does not exist: { catalog_path } , err = True )
299- return
300-
301- # Process the root catalog
302- process_catalog (catalog_path )
303-
304- click .echo ("Merkle info computation and addition completed." )
305-
306- if __name__ == '__main__' :
307- main ()
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