recursive var names

tests/unit/entries/test_entry.py

@@ -8,6 +8,7 @@ from ytdl_subscribe.validators.base.string_formatter_validators import (
 from ytdl_subscribe.validators.config.overrides.overrides_validator import (
     OverridesValidator,
 )
+from ytdl_subscribe.validators.exceptions import ValidationException
 
 
 class TestEntry(object):
@@ -68,6 +69,45 @@ class TestEntry(object):
             == expected_string
         )
 
+    def test_entry_formatter_override_recursive(self, mock_entry):
+        overrides = OverridesValidator(
+            name="test",
+            value={
+                "level_a": "level a",
+                "level_b": "level b and {level_a}",
+                "level_c": "level c and {level_b}",
+            },
+        )
+
+        format_string = StringFormatterValidator(
+            name="test", value="level d and {level_c}"
+        )
+        expected_string = "level d and level c and level b and level a"
+
+        assert (
+            mock_entry.apply_formatter(format_string, overrides=overrides)
+            == expected_string
+        )
+
+    def test_entry_formatter_override_recursive_fail_cycle(self, mock_entry):
+        overrides = OverridesValidator(
+            name="test",
+            value={
+                "level_a": "{level_b}",
+                "level_b": "{level_a}",
+            },
+        )
+
+        expected_error_msg = (
+            f"Attempted to format 'test' but failed after reaching max recursion depth of 3. "
+            f"Try to keep variables dependent on only one other variable."
+        )
+
+        format_string = StringFormatterValidator(name="test", value="{level_a}")
+
+        with pytest.raises(ValidationException, match=expected_error_msg):
+            _ = mock_entry.apply_formatter(format_string, overrides=overrides)
+
     def test_entry_missing_kwarg(self, mock_entry):
         key = "dne"
         expected_error_msg = f"Expected '{key}' in Entry but does not exist."

ytdl_subscribe/entries/entry.py

@@ -1,3 +1,4 @@
+from collections import OrderedDict
 from pathlib import Path
 from typing import Any
 from typing import Dict
@@ -11,6 +12,7 @@ from ytdl_subscribe.validators.base.string_formatter_validators import (
 from ytdl_subscribe.validators.config.overrides.overrides_validator import (
     OverridesValidator,
 )
+from ytdl_subscribe.validators.exceptions import ValidationException
 
 
 class Entry:
@@ -18,6 +20,8 @@ class Entry:
     Entry object to represent a single media object returned from yt-dlp.
     """
 
+    _MAX_FORMATTER_RECURSION = 3
+
     def __init__(self, **kwargs):
         """
         Initialize the entry using ytdl metadata
@@ -129,4 +133,27 @@ class Entry:
                     f"for {self.__class__.__name__}. Available fields: {available_fields}"
                 )
 
-        return formatter.format_string.format(**entry_dict)
+        format_string = formatter.format_string
+        variables_present = True
+        recursion_depth = 0
+        while variables_present and recursion_depth < self._MAX_FORMATTER_RECURSION:
+            format_string = format_string.format(**OrderedDict(entry_dict))
+            variables_present = (
+                len(
+                    StringFormatterValidator(
+                        name="__recursive_formatter_update__",
+                        value=format_string,
+                    ).format_variables
+                )
+                > 0
+            )
+            recursion_depth += 1
+
+        if variables_present:
+            raise ValidationException(
+                f"Attempted to format '{formatter._name}' but failed after reaching max recursion "
+                f"depth of {self._MAX_FORMATTER_RECURSION}. Try to keep variables dependent on "
+                f"only one other variable."
+            )
+
+        return format_string