Improve validation in trivia (#5947)

Co-authored-by: Jakub Kuczys <me@jacken.men>

redbot/cogs/trivia/schema.py

@@ -0,0 +1,121 @@
+import itertools
+import re
+from typing import Any, NoReturn
+
+from schema import And, Const, Optional, Schema, SchemaError, SchemaMissingKeyError, Use
+
+from redbot.core.i18n import Translator
+
+__all__ = ("TRIVIA_LIST_SCHEMA", "format_schema_error")
+
+T_ = Translator("Trivia", __file__)
+KEY_ERROR_MSG_RE = re.compile(r"Key '(.+)' error:")
+
+
+class SchemaErrorMessage(str):
+    def format(self, *args: Any, **kwargs: Any) -> str:
+        return T_(str(self))
+
+
+def int_or_float(value: Any) -> float:
+    if not isinstance(value, (float, int)):
+        raise TypeError("Value needs to be an integer or a float.")
+    return float(value)
+
+
+def not_str(value: Any) -> float:
+    if isinstance(value, str):
+        raise TypeError("Value needs to not be a string.")
+    return value
+
+
+_ = SchemaErrorMessage
+NO_QUESTIONS_ERROR_MSG = _("The trivia list does not contain any questions.")
+ALWAYS_MATCH = Optional(Use(lambda x: x))
+MATCH_ALL_BUT_STR = Optional(Use(not_str))
+TRIVIA_LIST_SCHEMA = Schema(
+    {
+        Optional("AUTHOR"): And(str, error=_("{key} key must be a text value.")),
+        Optional("CONFIG"): And(
+            {
+                Optional("max_score"): And(
+                    int,
+                    lambda n: n >= 1,
+                    error=_("{key} key in {parent_key} must be a positive integer."),
+                ),
+                Optional("timeout"): And(
+                    Use(int_or_float),
+                    lambda n: n > 0.0,
+                    error=_("{key} key in {parent_key} must be a positive number."),
+                ),
+                Optional("delay"): And(
+                    Use(int_or_float),
+                    lambda n: n >= 4.0,
+                    error=_(
+                        "{key} key in {parent_key} must be a positive number"
+                        " greater than or equal to 4."
+                    ),
+                ),
+                Optional("bot_plays"): Const(
+                    bool, error=_("{key} key in {parent_key} must be either true or false.")
+                ),
+                Optional("reveal_answer"): Const(
+                    bool, error=_("{key} key in {parent_key} must be either true or false.")
+                ),
+                Optional("payout_multiplier"): And(
+                    Use(int_or_float),
+                    lambda n: n >= 0.0,
+                    error=_("{key} key in {parent_key} must be a non-negative number."),
+                ),
+                Optional("use_spoilers"): Const(
+                    bool, error=_("{key} key in {parent_key} must be either true or false.")
+                ),
+                # This matches any extra key and always fails validation
+                # for the purpose of better error messages.
+                ALWAYS_MATCH: And(
+                    lambda __: False,
+                    error=_("{key} is not a key that can be specified in {parent_key}."),
+                ),
+            },
+            error=_("{key} should be a 'key: value' mapping."),
+        ),
+        str: And(
+            [str, int, bool, float],
+            error=_("Value of question {key} is not a list of text values (answers)."),
+        ),
+        # This matches any extra key and always fails validation
+        # for the purpose of better error messages.
+        MATCH_ALL_BUT_STR: And(
+            lambda __: False,
+            error=_("A key of question {key} is not a text value."),
+        ),
+    },
+    error=_("A trivia list should be a 'key: value' mapping."),
+)
+
+
+def format_schema_error(exc: SchemaError) -> str:
+    if isinstance(exc, SchemaMissingKeyError):
+        return NO_QUESTIONS_ERROR_MSG.format()
+
+    # dict.fromkeys is used for de-duplication with order preservation
+    errors = {idx: msg for idx, msg in enumerate(exc.errors) if msg is not None}
+    if not errors:
+        return str(exc)
+    error_idx, error_msg_fmt = errors.popitem()
+
+    autos = dict.fromkeys(msg for msg in itertools.islice(exc.autos, error_idx) if msg is not None)
+    keys = [match[1] for msg in autos if (match := KEY_ERROR_MSG_RE.fullmatch(msg)) is not None]
+    key_count = len(keys)
+    if key_count == 2:
+        key = keys[-1]
+        parent_key = keys[-2]
+    elif key_count == 1:
+        key = keys[-1]
+        # should only happen for messages where this field isn't used
+        parent_key = "UNKNOWN"
+    else:
+        # should only happen for messages where neither of the fields are used
+        key = parent_key = "UNKNOWN"
+
+    return error_msg_fmt.format(key=repr(key), parent_key=repr(parent_key))

redbot/cogs/trivia/trivia.py

@@ -4,7 +4,7 @@ import math
 import pathlib
 from collections import Counter
 from typing import Any, Dict, List, Literal, Union
-from schema import Schema, Optional, Or, SchemaError
+import schema
 
 import io
 import yaml
@@ -23,26 +23,11 @@ from .checks import trivia_stop_check
 from .converters import finite_float
 from .log import LOG
 from .session import TriviaSession
+from .schema import TRIVIA_LIST_SCHEMA, format_schema_error
 
 __all__ = ("Trivia", "UNIQUE_ID", "InvalidListError", "get_core_lists", "get_list")
 
 UNIQUE_ID = 0xB3C0E453
-TRIVIA_LIST_SCHEMA = Schema(
-    {
-        Optional("AUTHOR"): str,
-        Optional("CONFIG"): {
-            Optional("max_score"): int,
-            Optional("timeout"): Or(int, float),
-            Optional("delay"): Or(int, float),
-            Optional("bot_plays"): bool,
-            Optional("reveal_answer"): bool,
-            Optional("payout_multiplier"): Or(int, float),
-            Optional("use_spoilers"): bool,
-        },
-        str: [str, int, bool, float],
-    }
-)
-
 _ = Translator("Trivia", __file__)
 
 
@@ -120,7 +105,7 @@ class Trivia(commands.Cog):
     @triviaset.command(name="maxscore")
     async def triviaset_max_score(self, ctx: commands.Context, score: int):
         """Set the total points required to win."""
-        if score < 0:
+        if score <= 0:
             await ctx.send(_("Score must be greater than 0."))
             return
         settings = self.config.guild(ctx.guild)
@@ -293,18 +278,18 @@ class Trivia(commands.Cog):
         try:
             await self._save_trivia_list(ctx=ctx, attachment=parsedfile)
         except yaml.error.MarkedYAMLError as exc:
-            await ctx.send(_("Invalid syntax: ") + str(exc))
+            await ctx.send(_("Invalid syntax:\n") + box(str(exc)))
         except yaml.error.YAMLError:
             await ctx.send(
                 _("There was an error parsing the trivia list. See logs for more info.")
             )
             LOG.exception("Custom Trivia file %s failed to upload", parsedfile.filename)
-        except SchemaError as e:
+        except schema.SchemaError as exc:
             await ctx.send(
                 _(
                     "The custom trivia list was not saved."
                     " The file does not follow the proper data format.\n{schema_error}"
-                ).format(schema_error=box(e))
+                ).format(schema_error=box(format_schema_error(exc)))
             )
 
     @commands.is_owner()
@@ -740,8 +725,6 @@ def get_list(path: pathlib.Path) -> Dict[str, Any]:
     ------
     InvalidListError
         Parsing of list's YAML file failed.
-    SchemaError
-        The list does not adhere to the schema.
     """
     with path.open(encoding="utf-8") as file:
         try:
@@ -751,6 +734,6 @@ def get_list(path: pathlib.Path) -> Dict[str, Any]:
 
     try:
         TRIVIA_LIST_SCHEMA.validate(trivia_dict)
-    except SchemaError as exc:
+    except schema.SchemaError as exc:
         raise InvalidListError("The list does not adhere to the schema.") from exc
     return trivia_dict