(Tag Cleanup): Moved embed validators from Tag model to utils.py

1 files changed, 173 insertions, 0 deletions

diff --git a/pydis_site/apps/api/models/mixins.py b/pydis_site/apps/api/models/mixins.py
index 5d75b78b..2d658cb9 100644
--- a/pydis_site/apps/api/models/mixins.py
+++ b/pydis_site/apps/api/models/mixins.py
@@ -1,4 +1,177 @@
+from collections.abc import Mapping
 from operator import itemgetter
+from typing import Any, Dict
+
+from django.core.exceptions import ValidationError
+from django.core.validators import MaxLengthValidator, MinLengthValidator
+
+
+def is_bool_validator(value: Any) -> None:
+    """Validates if a given value is of type bool."""
+    if not isinstance(value, bool):
+        raise ValidationError(f"This field must be of type bool, not {type(value)}.")
+
+
+def validate_tag_embed_fields(fields: dict) -> None:
+    """Raises a ValidationError if any of the given embed fields is invalid."""
+    field_validators = {
+        'name': (MaxLengthValidator(limit_value=256),),
+        'value': (MaxLengthValidator(limit_value=1024),),
+        'inline': (is_bool_validator,),
+    }
+
+    required_fields = ('name', 'value')
+
+    for field in fields:
+        if not isinstance(field, Mapping):
+            raise ValidationError("Embed fields must be a mapping.")
+
+        if not all(required_field in field for required_field in required_fields):
+            raise ValidationError(
+                f"Embed fields must contain the following fields: {', '.join(required_fields)}."
+            )
+
+        for field_name, value in field.items():
+            if field_name not in field_validators:
+                raise ValidationError(f"Unknown embed field field: {field_name!r}.")
+
+            for validator in field_validators[field_name]:
+                validator(value)
+
+
+def validate_tag_embed_footer(footer: Dict[str, str]) -> None:
+    """Raises a ValidationError if the given footer is invalid."""
+    field_validators = {
+        'text': (
+            MinLengthValidator(
+                limit_value=1,
+                message="Footer text must not be empty."
+            ),
+            MaxLengthValidator(limit_value=2048)
+        ),
+        'icon_url': (),
+        'proxy_icon_url': ()
+    }
+
+    if not isinstance(footer, Mapping):
+        raise ValidationError("Embed footer must be a mapping.")
+
+    for field_name, value in footer.items():
+        if field_name not in field_validators:
+            raise ValidationError(f"Unknown embed footer field: {field_name!r}.")
+
+        for validator in field_validators[field_name]:
+            validator(value)
+
+
+def validate_tag_embed_author(author: Any) -> None:
+    """Raises a ValidationError if the given author is invalid."""
+    field_validators = {
+        'name': (
+            MinLengthValidator(
+                limit_value=1,
+                message="Embed author name must not be empty."
+            ),
+            MaxLengthValidator(limit_value=256)
+        ),
+        'url': (),
+        'icon_url': (),
+        'proxy_icon_url': ()
+    }
+
+    if not isinstance(author, Mapping):
+        raise ValidationError("Embed author must be a mapping.")
+
+    for field_name, value in author.items():
+        if field_name not in field_validators:
+            raise ValidationError(f"Unknown embed author field: {field_name!r}.")
+
+        for validator in field_validators[field_name]:
+            validator(value)
+
+
+def validate_tag_embed(embed: Any) -> None:
+    """
+    Validate a JSON document containing an embed as possible to send on Discord.
+
+    This attempts to rebuild the validation used by Discord
+    as well as possible by checking for various embed limits so we can
+    ensure that any embed we store here will also be accepted as a
+    valid embed by the Discord API.
+
+    Using this directly is possible, although not intended - you usually
+    stick this onto the `validators` keyword argument of model fields.
+
+    Example:
+
+        >>> from django.contrib.postgres import fields as pgfields
+        >>> from django.db import models
+        >>> from pydis_site.apps.api.models.bot.tag import validate_tag_embed
+        >>> class MyMessage(models.Model):
+        ...     embed = pgfields.JSONField(
+        ...         validators=(
+        ...             validate_tag_embed,
+        ...         )
+        ...     )
+        ...     # ...
+        ...
+
+    Args:
+        embed (Any):
+            A dictionary describing the contents of this embed.
+            See the official documentation for a full reference
+            of accepted keys by this dictionary:
+                https://discordapp.com/developers/docs/resources/channel#embed-object
+
+    Raises:
+        ValidationError:
+            In case the given embed is deemed invalid, a `ValidationError`
+            is raised which in turn will allow Django to display errors
+            as appropriate.
+    """
+    all_keys = {
+        'title', 'type', 'description', 'url', 'timestamp',
+        'color', 'footer', 'image', 'thumbnail', 'video',
+        'provider', 'author', 'fields'
+    }
+    one_required_of = {'description', 'fields', 'image', 'title', 'video'}
+    field_validators = {
+        'title': (
+            MinLengthValidator(
+                limit_value=1,
+                message="Embed title must not be empty."
+            ),
+            MaxLengthValidator(limit_value=256)
+        ),
+        'description': (MaxLengthValidator(limit_value=2048),),
+        'fields': (
+            MaxLengthValidator(limit_value=25),
+            validate_tag_embed_fields
+        ),
+        'footer': (validate_tag_embed_footer,),
+        'author': (validate_tag_embed_author,)
+    }
+
+    if not embed:
+        raise ValidationError("Tag embed must not be empty.")
+
+    elif not isinstance(embed, Mapping):
+        raise ValidationError("Tag embed must be a mapping.")
+
+    elif not any(field in embed for field in one_required_of):
+        raise ValidationError(f"Tag embed must contain one of the fields {one_required_of}.")
+
+    for required_key in one_required_of:
+        if required_key in embed and not embed[required_key]:
+            raise ValidationError(f"Key {required_key!r} must not be empty.")
+
+    for field_name, value in embed.items():
+        if field_name not in all_keys:
+            raise ValidationError(f"Unknown field name: {field_name!r}")
+
+        if field_name in field_validators:
+            for validator in field_validators[field_name]:
+                validator(value)
 
 from django.db import models