Validate JSON against a protobuf-like schema

You are given a simplified protobuf-like schema definition and a JSON value. Determine whether the JSON conforms to the schema.

Schema model

• A schema contains named message types .
• Each message type contains fields . Each field has:
  • name (string)
  • type (one of: int , float , bool , string , or another message type name)
  • optional (boolean)

Assume:

• The JSON root is an object corresponding to a specified root message type.
• A required field ( optional = false ) must be present.
• An optional field may be missing.
• If a field is present, its JSON value must match the expected type:
  • int : JSON number with no fractional part
  • float : JSON number (integer values are allowed)
  • bool : JSON boolean
  • string : JSON string
  • message type: JSON object that recursively validates against that message
• Extra JSON keys not in the schema make the JSON invalid.

Task

Implement isValid(schema, rootTypeName, jsonValue) -> bool.

Constraints

• Up to ~10^4 total fields across all message types.
• Message nesting depth is bounded (e.g., ≤ 50).

Example

Schema:

• User { id:int (required), name:string (optional) }

Valid JSON: { "id": 1 } Invalid JSON: { "name": "a" } (missing required id) Invalid JSON: { "id": 1, "age": 10 } (unknown field age)