Update simple tag implementation from Django PR

yamdl_playground/core/simple_tags.py

@@ -1,5 +1,6 @@
 from inspect import getfullargspec, unwrap
 from django.template.library import parse_bits, SimpleNode
+from django.template.exceptions import TemplateSyntaxError
 from functools import wraps
 
 class SimpleBlockNode(SimpleNode):
@@ -9,43 +10,77 @@ class SimpleBlockNode(SimpleNode):
 
     def get_resolved_arguments(self, context):
         resolved_args, resolved_kwargs = super().get_resolved_arguments(context)
-        resolved_args.insert(1 if self.takes_context else 0, self.nodelist.render(context))
+
+        # Restore the "content" argument.
+        # It will move depending on whether takes_context was passed.
+        resolved_args.insert(
+            1 if self.takes_context else 0, self.nodelist.render(context)
+        )
+
         return resolved_args, resolved_kwargs
 
 
 def simple_block_tag(register, takes_context=None, name=None):
     def dec(func):
-        argspec = getfullargspec(unwrap(func))
+        (
+            params,
+            varargs,
+            varkw,
+            defaults,
+            kwonly,
+            kwonly_defaults,
+            _,
+        ) = getfullargspec(unwrap(func))
         function_name = name or func.__name__
 
         @wraps(func)
-        def tag_compiler(parser, token):
+        def compile_func(parser, token):
+            tag_params = params.copy()
+
+            if takes_context:
+                if len(tag_params) >= 2 and tag_params[1] == "content":
+                    del tag_params[1]
+                else:
+                    raise TemplateSyntaxError(
+                        f"'{function_name}' is decorated with takes_context=True so"
+                        " it must have a first argument of 'context' and a second "
+                        "argument of 'content'"
+                    )
+            else:
+                if tag_params and tag_params[0] == "content":
+                    del tag_params[0]
+                else:
+                    raise TemplateSyntaxError(
+                        f"'{function_name}' must have a first argument of 'content'"
+                    )
+
             bits = token.split_contents()[1:]
             target_var = None
             if len(bits) >= 2 and bits[-2] == "as":
                 target_var = bits[-1]
                 bits = bits[:-2]
 
-            params = argspec.args
-            del params[1 if takes_context else 0]
+            nodelist = parser.parse((f"end{function_name}",))
+            parser.delete_first_token()
 
             args, kwargs = parse_bits(
-                parser=parser,
-                bits=bits,
-                params=params,
-                varargs=argspec.varargs,
-                varkw=argspec.varkw,
-                defaults=argspec.defaults,
-                kwonly=argspec.kwonlyargs,
-                kwonly_defaults=argspec.kwonlydefaults,
-                takes_context=takes_context,
-                name=function_name
+                parser,
+                bits,
+                tag_params,
+                varargs,
+                varkw,
+                defaults,
+                kwonly,
+                kwonly_defaults,
+                takes_context,
+                function_name,
             )
 
-            nodelist = parser.parse((f'end{function_name}',))
-            parser.delete_first_token()
-            return SimpleBlockNode(nodelist, func, takes_context, args, kwargs, target_var)
+            return SimpleBlockNode(
+                nodelist, func, takes_context, args, kwargs, target_var
+            )
 
-        register.tag(function_name, tag_compiler)
+        register.tag(function_name, compile_func)
         return func
+
     return dec