jsonref: JSON Reference Dereferencing

import jsonref
import json

# Example 1: Loading from a JSON string with internal references
json_str = '''
{
    "data": [1, 2, 3, 4],
    "ref_to_data": {"$ref": "#/data"},
    "ref_to_item": {"$ref": "#/data/1"}
}
'''
data_from_str = jsonref.loads(json_str)

print("--- From jsonref.loads ---")
print(f"Original data: {data_from_str['data']}")
print(f"Reference to data: {data_from_str['ref_to_data']}") # Lazy loaded when accessed
print(f"Reference to item: {data_from_str['ref_to_item']}") # Lazy loaded when accessed
print(f"Is ref_to_data a JsonRef instance? {isinstance(data_from_str['ref_to_data'], jsonref.JsonRef)}")
print(f"Direct access to referent: {data_from_str['ref_to_data'].__subject__}")
print(f"Original reference object: {data_from_str['ref_to_data'].__reference__}")

# Example 2: Replacing references in an existing Python object
from jsonref import replace_refs

python_obj = {
    "items": ["apple", "banana", "cherry"],
    "first_item_ref": {"$ref": "#/items/0"}
}

dereferenced_obj = replace_refs(python_obj)

print("\n--- From jsonref.replace_refs ---")
print(f"Original Python object: {json.dumps(python_obj)}")
print(f"Dereferenced object: {json.dumps(dereferenced_obj)}")
print(f"Accessing dereferenced value: {dereferenced_obj['first_item_ref']}")

# Example 3: Handling external references (requires 'requests' or will use urllib)
# For external references, a loader can be specified. jsonloader is the default.
# This example is conceptual as 'example.com/schema.json' is not guaranteed to exist.
# If you have a local 'schema.json' with {"version": "1.0"}, use 'file:///path/to/schema.json'
external_ref_schema = {
    "my_schema": {"$ref": "http://example.com/schema.json#/version"}
}
# Assuming http://example.com/schema.json contains {"version": "1.0"}
# This would attempt to fetch the external URI:
try:
    # Use a mock loader for demonstration, as live external URIs might be flaky
    def mock_loader(uri):
        if uri == "http://example.com/schema.json":
            return {"version": "1.0", "description": "A simple schema"}
        raise JsonRefError(f"Unknown URI: {uri}", reference={'$ref': uri})

    external_data = replace_refs(external_ref_schema, loader=mock_loader)
    print("\n--- External Reference Example (Conceptual) ---")
    print(f"External data reference: {external_data['my_schema']}")
except JsonRefError as e:
    print(f"\nCould not resolve external reference (expected if example.com is not valid): {e.message}")