GraphQL Schema Designer

**Context**: 
Designing a robust and efficient GraphQL schema is crucial for building scalable and maintainable APIs. A well-structured schema serves as the foundation for querying and manipulating data, ensuring that the API is both intuitive and performant. The goal is to create a comprehensive GraphQL schema that meets the requirements of a complex application, considering factors such as data relationships, query optimization, and security.

**Detailed Instructions**: 
Design a GraphQL schema for an e-commerce platform that includes the following entities: products, orders, customers, and reviews. The schema should support queries for retrieving product information, customer details, order history, and review listings. Additionally, it should allow for mutations to create new orders, update customer profiles, and submit new product reviews.

1. Define the types for each entity, including their respective fields and relationships (e.g., a product can have multiple reviews, and a customer can have multiple orders).
2. Implement resolvers for each query and mutation, ensuring they are properly linked to the defined types.
3. Incorporate input types for mutations to handle variable data (e.g., creating a new order requires input fields like product IDs, quantities, and customer ID).
4. Consider implementing interfaces or unions if necessary, to handle variations in data types or to create reusable fields across multiple types.
5. Ensure the schema is documented with descriptions for types, fields, and resolvers to enhance readability and usability.
6. Optimize the schema for performance by considering factors like query complexity, data fetching strategies (e.g., batching, caching), and potential bottlenecks.
7. Implement authorization and authentication mechanisms to restrict access to certain queries and mutations based on user roles (e.g., customers can only view their own orders, while admins can view all orders).

**Output Format**: 
The output should be a GraphQL schema definition language (SDL) file that includes all the specified types, queries, mutations, and resolvers. The schema should be well-documented and formatted for readability.

**Examples**: 
- Query to retrieve a product by ID: `product(id: "123") { name, price, reviews { rating, text } }`
- Mutation to create a new order: `createOrder(input: { customerId: "456", products: [{ id: "123", quantity: 2 }] }) { id, total }`
- Query to fetch a customer's order history: `customer(id: "456") { orders { id, date, products { name, quantity } } }`