

- Capabilities to be supported in future  
	- Non supported - flexi SKUs - quote doesn't need it
	- Bring KDDs for pitching UB 
	- So if there are so many changes, why not move to simpler model with UB
- Adarsh, Mohan, you, me, Hari - 
### UB Architecture
![[UB System Design.png]]
### UB schema - Aug 2024
```json
// ! Below is domain model. User request models should be different from domain models
// Basket Conainer - Db model
{
    // Basket Container Id
    "id": "string",
    // Basket container resource
    "resource": {
        /**
        * Basket container schema url
        * ! is this really required?
        * ? how to maintain the versioning?
        * ? Open Api should give out latest schema?
        * todo: Get the consensus
        */
        "schemaUrl": "https://example.com/schemas/v1/basket-conainer-schema.json",
        // Unique identifier for versioning, useful for caching
        "eTag": "string",
        // Type of relationship (e.g., 'self')
        "relType": "string",
        // Hyperlink reference
        "url": "string",
        // Timestamp when the resource was created
        "createdOn": "DataTimeOffset",
        // Timestamp when the resource was last modified, Useful when combined with eTag
        "lastModifiedOn": "DataTimeOffset"
    },
    // Basket domain model
    "basket": {
        // Basket id
        // * should be equal to container id
        "id": "string",
        // Basket domain resource
        "resource": {
            /**
            *  ? is it required
            */
            "schemaUrl": "https://example.com/schemas/basket-schema.json",
            // Unique identifier for versioning, useful for caching
            "eTag": "string",
            // Type of relationship (e.g., 'self')
            "relType": "string",
            // Hyperlink reference
            "url": "string",
            // Timestamp when the resource was created
            "createdOn": "DataTimeOffset",
            // Timestamp when the resource was last modified
            "lastModifiedOn": "DataTimeOffset",
        },
        /** 
        * Basket number
        * ? should we given new series, Ex. 4XXX
        */
        "number": 0,
        // Basket version, Default 1
        "version": 0,
        // Basket name 
        "name": "string?",
        // Basket description
        "description": "string?",
        /**
        * Basket status
        */
        "status": "enum", //Edit, Quoted, Cancelled, Checkout, Ordered
        /**
        * Basket type
        * ? Maverick business use case for type
        * 
        */
        "type": "string?",
        /**
        * Purchase order model - extensible
        * ? should this be captured under contact?
        * ? primary purchase order is SoldTo PO?
        * ? user journey for purchase order
        * todo: Identify the transact level in maverick
        * number
        */
        "purchaseOrder": {
            "number": "string?",
        },
        // "poNumber": "string?", //determine on where will be approapriate level to capture this in Maverick? Transaction or Item level
        /**
        * Basket status transitions collection
        * * one node per status with latest timestamp
        * ? Should order details be at basket level
        * ? Populating hold reasons - How do they work in maverick?
        * ? DpId vs Order Number in maverick
        */
        "statusTransitions": [
            {
                "status": "status.enum.Quoted",
                "lastModifiedOn": "DateTimeOffset?",
                "reason": "string?"
            },
            {
                "status": "status.enum.Cancelled",
                "lastModifiedOn": "DateTimeOffset?",
                "reason": "string?"
            },
            {
                "status": "status.enum.Ordered",
                "lastModifiedOn": "DateTimeOffset?",
                "reason": "string?",
                "orderDetails": {
                    "dpId": "string?",
                    "holdReasons": [
                        {
                            "key": "string",
                            "code": "string"
                        }
                    ]
                }
            }
        ],
        // Basket created by - user input/ System default
        "createdBy": "string?",
        // Basket last modified by - user input/ System default
        "lastModifiedBy": "string?",
        // Basket expires on - User Input/ System default 
        "expiresOn": "DateTimeOffset",
        // Basket retention days - User Input/ System default
        "retentionDays": "int",
        /**
        * Basket commerce context
        * ? should it be simply context
        * todo: Review each property, keep it to only required
        */
        "commerceContext": {
            // source application
            // ? should this be enum for better control?
            "sourceApplicationName": "string",
            /**
            * * Sales flow - User persona
            * Default, Consumer, RepeatCommercial, Commercial Etc..
            */
            "persona": "enum",
            /**
            * ? is it needed in future state?
            */
            "originalSourceApplicationName": "string?",
            // ? is it needed in future state?
            "companyNumber": "string?",
            // Country
            "country": "string",
            // Currency
            "currency": "string",
            // Display Currency
            "displayCurrency": "string",
            // ? Customer Set
            "customerSet": "string",
            // Language
            "language": "string",
            // ? Region
            "region": "string",
            // ? is it needed in future state?
            "segment": "string",
            // ? is it needed in future state?
            "businessUnitId": "string",
            // ? is it needed in future statte? Dell spcific Ex Dell, EMC
            "sellingEntity": "string"
        },
        // ? is it neeed in future state ?
        "orderPath": "string",
        "items": [
            {
                // item id
                "id": "string",
                // Resource collection
                "resources": [
                    {
                        // ? Is this required?
                        "schemaUrl": "https://example.com/schemas/item-schema.json",
                        // Unique identifier for versioning, useful for caching
                        "eTag": "string",
                        // Type of relationship (e.g., "Self")
                        "relType": "string",
                        // Hyperlink reference
                        "url": "string",
                        // Timestamp when the resource was created
                        "createdOn": "DataTimeOffset",
                        // Timestamp when the resource was last modified
                        "lastModifiedOn": "DataTimeOffset"
                    },
                    {
                        // ? is it required
                        "schemaUrl": "https://example.com/schemas/item-schema.json",
                        // Unique identifier for versioning, useful for caching
                        "eTag": "string",
                        // Type of relationship (e.g., "TxProduct")
                        "relType": "string",
                        // Hyperlink reference
                        "url": "string",
                        // Timestamp when the resource was created
                        "createdOn": "DataTimeOffset",
                        // Timestamp when the resource was last modified
                        "lastModifiedOn": "DataTimeOffset"
                    }
                ]
            }
        ],
        "shipments": [
            {
                // Shipment id
                "id": "string",
                // Shipment Name
                "shipmentName": "string?",
                // Shipment Method
                "shippingMethod": "string",
                // ? Is it needed in future state
                "instructions": "string",
                // Shipment contacts
                "contacts": [
                    {
                        "id": "string",
                        "resource": {
                            // ? Is it required
                            "schemaUrl": "https://example.com/schemas/item-schema.json",
                            // Unique identifier for versioning, useful for caching
                            "eTag": "string",
                            // Type of relationship (e.g., "Self", "ShipTo","InstallAt" etc)
                            "relType": "string",
                            // Hyperlink reference
                            "url": "string",
                            // Timestamp when the resource was created
                            "createdOn": "DataTimeOffset",
                            // Timestamp when the resource was last modified
                            "lastModifiedOn": "DataTimeOffset"
                        }
                    }
                ],
                "items": [
                    {
                        // Basket item reference
                        "id": "string"
                    }
                ]
            }
        ],
        // system populated - read only for clients
        "auditReferences": [
            {
                // Audit reference id
                "id": "string",
                // Audit source
                "source": "string",
                // Audit resource
                "resource": {
                    // Unique identifier for versioning, useful for caching
                    "eTag": "string",
                    // Type of relationship (e.g., "CopiedFrom", "MergedFrom", etc)
                    "relType": "string",
                    // Hyperlink reference
                    "url": "string",
                    // Timestamp when the resource was created
                    "createdOn": "DataTimeOffset",
                    // Timestamp when the resource was last modified
                    "lastModifiedOn": "DataTimeOffset"
                }
            }
        ],
        // Clients added references - R/W for clients
        "clientReferences": [
            {
                // Basket client reference id
                "id": "string",
                // Client
                "source": "string",
                "resource": {
                    // Unique identifier for versioning, useful for caching
                    "eTag": "string",
                    // Type of relationship (e.g., "NFMirror", "QuoteShare","SmartPrice" etc)
                    "relType": "string",
                    // Hyperlink reference
                    "url": "string",
                    // Timestamp when the resource was created
                    "createdOn": "DataTimeOffset",
                    // Timestamp when the resource was last modified 
                    "lastModifiedOn": "DataTimeOffset"
                }
            }
        ],
        // Client managed state - Third class properties - No of char limited
        "clientState": {
            "properties": {
                "key": "value"
            }
        },
        /**
        * ! Deprecate
        * Replace by more explicit node
        */
        "properties": {
            "key": "value"
        },
        /**
        * ? is it required in future state
        * ? How to govern?
        */
        "extendedProperties": {
            "key": "value"
        },
        /**
        * Basket contacts
        */
        "contacts": [
            {
                // Basket contact id
                "id": "string",
                // Basket contact resource collection
                "resource": {
                    // Unique identifier for versioning, useful for caching
                    "eTag": "string",
                    // Type of relationship (e.g., "BillTo", "SoldTo","Partner","Reseller","EndUser" etc)
                    "relType": "string",
                    // Hyperlink reference
                    "url": "string",
                    // Timestamp when the resource was created
                    "createdOn": "DataTimeOffset",
                    // Timestamp when the resource was last modified  
                    "lastModifiedOn": "DataTimeOffset"
                }
            }
        ],
        /**
        * Basket price node - Consolidated
        */
        "price": {
            // ? requests, commands - which one better for domain terminology
            "comamnds": {
                // price adjustment commands
                // ? What all needed in future state for adjustments
                "adjustments": [
                    {
                        "id": "string"
                    }
                ],
                // ? How does tax over-rides applied in future state?
                "taxOverrides": [
                    {
                        "id": "string"
                    }
                ],
                // ? How does sku/part price adjustmnets work in future state?
                "skuAdjustments": [
                    {
                        "id": "string"
                    }
                ]
            },
            "results": {
                "resources": [
                    {
                        // Unique identifier for versioning, useful for caching
                        "eTag": "string",
                        // Type of relationship (e.g., "PriceSummaryUrl", "PriceDetailViewUrl","PriceRequestUrl" etc)
                        "relType": "string",
                        // Hyperlink reference
                        "url": "string",
                        // Timestamp when the resource was created
                        "createdOn": "DataTimeOffset",
                        // Timestamp when the resource was last modified
                        "lastModifiedOn": "DataTimeOffset"
                    }
                ]
            }
        },
        /**
        * Basket level contracts
        * ? what level needed in future state ? basket level or item level?
        * ? should we move this under price node and accespt target level ? 
        */
        "contracts": [
            {
                //extensible object
                "code": "string",
                // primary ,seconday
                "type": "string?"
            }
        ],
        // Basket payment
        "payment": {
            // Payment method collections
            "methods": [
                {
                    // Collection id
                    "id": "string",
                    // Global payment id
                    "globalPaymentId": "string",
                    // Payment method description
                    "description": "string"
                }
            ],
            // Payment impacts
            // ? is it needed
            "impacts": [
                {}
            ]
        },
        /**
        * Basket validations
        * Validations collection resource populated every time on post validations
        * ? 
        */
        "validations": {
            // internal domain valdiations as per tx-profile configurations
            // * group fields by severity to avoid collection prolifiration. Follow the ".(dot)" notation to chain
            "internal": [
                {
                    "code": "string",
                    "fields": [
                        "basket.items",
                        "basket.price"
                    ],
                    "rule": "required",
                    "ruleId": "string",
                    "description": "Required fields",
                    "severity": "error"
                },
                {
                    "id": "string",
                    "code": "string",
                    "field": [
                        "basket.contacts",
                        "basket.shipments"
                    ],
                    "rule": "optional",
                    "ruleId": "string",
                    "description": "items are optional",
                    "severity": "warning"
                }
            ],
            // Extensible contract for external validations
            "external": [
                {
                    "service": "TransactPrice",
                    "code": "string",
                    "rule": "string",
                    "description": "string",
                    "severity": "error"
                },
                // basket => item => Validations
                {
                    "service": "ItemService.ValidationService",
                    "code": "string",
                    "rule": "activeCode",
                    "description": "string",
                    "severity": "error"
                }
            ]
        }
    }
}
```


### Copilot chats - Aug 2024

#### Prompt: 
I am building basket application that will have APIs to manage lifecycle of a basket. The basket is designed to manage lifecycle of eCommerce transactions which start all the way from "add item to cart" user operation to "submit order" user operation. There can be several UX clients using the basket APIs. Throughout the lifecycle of the basket, several operations can happen in between such as "view cart", "update quantity in cart's item", "checkout cart", "add payment details in the cart". Consider that Basket object will have status with enum values - Edit, Quoted, Cancelled, Checkout, Ordered. Since basket can go through a lifecycle where basket status can change (for example, from "edit" to "checkout" to "ordered"), I want to customize validation behavior in each status based on what UX client wants. I want to make basket behavior configurable using unique configurations for each UX client so that configuration controls what elements are mandatory (true/false) in the basket and what is the validation behavior on each element (error/warning) in the basket. Take an example of basket ID: 11 and give me 1 way how I should build configuration for UX client. Keep the configuration simple. This basket object is built in json using following key elements. Answer for use case where status is "edit". Number, version, name, description, metadata (createdBy, lastModifiedBy, expiresOn, retentionDays) Status: enum //Edit, Quoted, Cancelled, Checkout, Ordered StatusTransitions[] CommerceContext{} Items[] Shipments[] auditReferences[] ClientReferences[] ClientState[], Properties[], ExtendedProperties[] Contacts[] Price[] Contracts[] Payments[]

Copilot

#### Sent by Copilot:

To build a configuration for a UX client that customizes the validation behavior of a basket in the “edit” status, you can define a JSON configuration object. This configuration will specify which elements are mandatory and the type of validation (error or warning) for each element. Here’s a simple example:

##### Configuration for UX Client

JSON

```json
{
  "clientId": "UXClient1",
  "basketId": 11,
  "status": "edit",
  "validationRules": {
    "Number": {
      "mandatory": true,
      "validationType": "error"
    },
    "version": {
      "mandatory": true,
      "validationType": "error"
    },
    "name": {
      "mandatory": true,
      "validationType": "error"
    },
    "description": {
      "mandatory": false,
      "validationType": "warning"
    },
    "metadata": {
      "createdBy": {
        "mandatory": true,
        "validationType": "error"
      },
      "lastModifiedBy": {
        "mandatory": false,
        "validationType": "warning"
      },
      "expiresOn": {
        "mandatory": false,
        "validationType": "warning"
      },
      "retentionDays": {
        "mandatory": false,
        "validationType": "warning"
      }
    },
    "Items": {
      "mandatory": true,
      "validationType": "error"
    },
    "Contacts": {
      "mandatory": false,
      "validationType": "warning"
    },
    "Price": {
      "mandatory": true,
      "validationType": "error"
    },
    "Payments": {
      "mandatory": false,
      "validationType": "warning"
    }
  }
}
```

AI-generated code. Review and use carefully. .

##### Explanation

- **clientId**: Identifies the UX client.
- **basketId**: The ID of the basket.
- **status**: The current status of the basket, which is “edit” in this case.
- **validationRules**: Contains the validation rules for each element in the basket.
    - **mandatory**: Indicates whether the element is required (`true` or `false`).
    - **validationType**: Specifies the type of validation (`error` or `warning`).

This configuration allows you to control the behavior of the basket based on the client’s requirements. You can extend this configuration to include more elements or different statuses as needed.

Would you like to see an example for a different status or any other specific feature?

You

#### Sent by you:

Thank you. I don't want to run into challenges where the configuration object becomes too large. Also, I want to pre-load all configurations that UX clients will be defining in my app server, so that whenever a UX client uses basket API for an operation, I already know what configuration to pick and apply validation behavior on the basket accordingly. Let's continue with basket ID:11 for the example and show me how following scenario will play out. UXClient1 wants to increase item qty for itemA from 1 to 5 via PATCH API call on /basket/{basketId}/items endpoint. Explain what I should load in my app's server memory and how I should code to apply the configuration on basket ID:11.

Copilot

#### Sent by Copilot:

To handle the scenario where UXClient1 wants to increase the item quantity for itemA from 1 to 5 via a PATCH API call on `/basket/{basketId}/items`, you need to pre-load the configuration for UXClient1 into your app server’s memory. Here’s how you can approach this:

##### Step 1: Pre-load Configuration

Load the configuration for UXClient1 into your app server’s memory. This can be done during the server startup or when the configuration is updated. The configuration can be stored in a dictionary or a similar data structure for quick access.

JSON

```json
{
  "UXClient1": {
    "basketId": 11,
    "status": "edit",
    "validationRules": {
      "Number": {
        "mandatory": true,
        "validationType": "error"
      },
      "version": {
        "mandatory": true,
        "validationType": "error"
      },
      "name": {
        "mandatory": true,
        "validationType": "error"
      },
      "description": {
        "mandatory": false,
        "validationType": "warning"
      },
      "metadata": {
        "createdBy": {
          "mandatory": true,
          "validationType": "error"
        },
        "lastModifiedBy": {
          "mandatory": false,
          "validationType": "warning"
        },
        "expiresOn": {
          "mandatory": false,
          "validationType": "warning"
        },
        "retentionDays": {
          "mandatory": false,
          "validationType": "warning"
        }
      },
      "Items": {
        "mandatory": true,
        "validationType": "error"
      },
      "Contacts": {
        "mandatory": false,
        "validationType": "warning"
      },
      "Price": {
        "mandatory": true,
        "validationType": "error"
      },
      "Payments": {
        "mandatory": false,
        "validationType": "warning"
      }
    }
  }
}
```

AI-generated code. Review and use carefully. .

##### Step 2: Handle PATCH API Call

When a PATCH API call is made to `/basket/{basketId}/items`, you need to:

1. Retrieve the configuration for the UX client.
2. Validate the request based on the configuration.
3. Apply the changes if the validation passes.

##### Example Code

Here’s a simplified example in Python to illustrate how you might handle this:

Python

```python
from flask import Flask, request, jsonify

app = Flask(__name__)

# Pre-loaded configurations
configurations = {
    "UXClient1": {
        "basketId": 11,
        "status": "edit",
        "validationRules": {
            "Number": {"mandatory": True, "validationType": "error"},
            "version": {"mandatory": True, "validationType": "error"},
            "name": {"mandatory": True, "validationType": "error"},
            "description": {"mandatory": False, "validationType": "warning"},
            "metadata": {
                "createdBy": {"mandatory": True, "validationType": "error"},
                "lastModifiedBy": {"mandatory": False, "validationType": "warning"},
                "expiresOn": {"mandatory": False, "validationType": "warning"},
                "retentionDays": {"mandatory": False, "validationType": "warning"}
            },
            "Items": {"mandatory": True, "validationType": "error"},
            "Contacts": {"mandatory": False, "validationType": "warning"},
            "Price": {"mandatory": True, "validationType": "error"},
            "Payments": {"mandatory": False, "validationType": "warning"}
        }
    }
}

# Sample basket data
baskets = {
    11: {
        "Number": "12345",
        "version": "1.0",
        "name": "Sample Basket",
        "description": "A sample basket",
        "metadata": {
            "createdBy": "user1",
            "lastModifiedBy": "user2",
            "expiresOn": "2024-12-31",
            "retentionDays": 30
        },
        "Items": [
            {"itemId": "itemA", "quantity": 1}
        ],
        "Contacts": [],
        "Price": 100.0,
        "Payments": []
    }
}

@app.route('/basket/<int:basket_id>/items', methods=['PATCH'])
def update_item_quantity(basket_id):
    client_id = request.headers.get('Client-ID')
    if client_id not in configurations:
        return jsonify({"error": "Invalid client ID"}), 400

    config = configurations[client_id]
    if basket_id != config["basketId"]:
        return jsonify({"error": "Invalid basket ID"}), 400

    basket = baskets.get(basket_id)
    if not basket:
        return jsonify({"error": "Basket not found"}), 404

    data = request.json
    item_id = data.get("itemId")
    new_quantity = data.get("quantity")

    # Validate based on configuration
    if config["validationRules"]["Items"]["mandatory"] and not basket["Items"]:
        return jsonify({"error": "Items are mandatory"}), 400

    # Update item quantity
    for item in basket["Items"]:
        if item["itemId"] == item_id:
            item["quantity"] = new_quantity
            break
    else:
        return jsonify({"error": "Item not found"}), 404

    return jsonify(basket), 200

if __name__ == '__main__':
    app.run(debug=True)
```

AI-generated code. Review and use carefully. .

##### Explanation

1. **Pre-load Configuration**: The configuration for UXClient1 is loaded into the `configurations` dictionary.
2. **Handle PATCH API Call**:
    - Retrieve the client ID from the request headers.
    - Validate the client ID and basket ID.
    - Retrieve the basket and validate the request based on the configuration.
    - Update the item quantity if validation passes.

This approach ensures that the configuration is pre-loaded and readily available for validation during API calls, keeping the process efficient and scalable.

Would you like to dive deeper into any specific part of this process?

You

#### Sent by you:

Regenerate example code in C++

Copilot

#### Sent by Copilot:

Sure! Here’s an example of how you might handle the PATCH API call in C++:

##### Example Code in C++

```cpp
#include <iostream>
#include <unordered_map>
#include <vector>
#include <string>
#include <nlohmann/json.hpp> // Include the JSON library

using json = nlohmann::json;

// Pre-loaded configurations
json configurations = {
    {"UXClient1", {
        {"basketId", 11},
        {"status", "edit"},
        {"validationRules", {
            {"Number", {{"mandatory", true}, {"validationType", "error"}}},
            {"version", {{"mandatory", true}, {"validationType", "error"}}},
            {"name", {{"mandatory", true}, {"validationType", "error"}}},
            {"description", {{"mandatory", false}, {"validationType", "warning"}}},
            {"metadata", {
                {"createdBy", {{"mandatory", true}, {"validationType", "error"}}},
                {"lastModifiedBy", {{"mandatory", false}, {"validationType", "warning"}}},
                {"expiresOn", {{"mandatory", false}, {"validationType", "warning"}}},
                {"retentionDays", {{"mandatory", false}, {"validationType", "warning"}}}
            }},
            {"Items", {{"mandatory", true}, {"validationType", "error"}}},
            {"Contacts", {{"mandatory", false}, {"validationType", "warning"}}},
            {"Price", {{"mandatory", true}, {"validationType", "error"}}},
            {"Payments", {{"mandatory", false}, {"validationType", "warning"}}}
        }}
    }}
};

// Sample basket data
json baskets = {
    {11, {
        {"Number", "12345"},
        {"version", "1.0"},
        {"name", "Sample Basket"},
        {"description", "A sample basket"},
        {"metadata", {
            {"createdBy", "user1"},
            {"lastModifiedBy", "user2"},
            {"expiresOn", "2024-12-31"},
            {"retentionDays", 30}
        }},
        {"Items", {
            {{"itemId", "itemA"}, {"quantity", 1}}
        }},
        {"Contacts", json::array()},
        {"Price", 100.0},
        {"Payments", json::array()}
    }}
};

json update_item_quantity(int basket_id, const std::string& client_id, const json& data) {
    if (configurations.find(client_id) == configurations.end()) {
        return {{"error", "Invalid client ID"}};
    }

    json config = configurations[client_id];
    if (basket_id != config["basketId"]) {
        return {{"error", "Invalid basket ID"}};
    }

    if (baskets.find(basket_id) == baskets.end()) {
        return {{"error", "Basket not found"}};
    }

    json& basket = baskets[basket_id];
    std::string item_id = data["itemId"];
    int new_quantity = data["quantity"];

    // Validate based on configuration
    if (config["validationRules"]["Items"]["mandatory"] && basket["Items"].empty()) {
        return {{"error", "Items are mandatory"}};
    }

    // Update item quantity
    for (auto& item : basket["Items"]) {
        if (item["itemId"] == item_id) {
            item["quantity"] = new_quantity;
            return basket;
        }
    }

    return {{"error", "Item not found"}};
}

int main() {
    // Example PATCH request data
    json request_data = {
        {"itemId", "itemA"},
        {"quantity", 5}
    };

    // Simulate a PATCH API call
    json response = update_item_quantity(11, "UXClient1", request_data);
    std::cout << response.dump(4) << std::endl;

    return 0;
}
```

##### Explanation

1. **Pre-load Configuration**: The configuration for UXClient1 is loaded into the `configurations` JSON object.
2. **Handle PATCH API Call**:
    - Retrieve the client ID and validate it.
    - Validate the basket ID.
    - Retrieve the basket and validate the request based on the configuration.
    - Update the item quantity if validation passes.

This example uses the nlohmann/json library for JSON handling in C++. You can install this library via package managers like `vcpkg` or include it directly in your project.

Would you like to explore any other specific part of this implementation?

#### Sent by you:
For the problem statement we have discussed so far, what is your suggestion on managing such vast variety of UX clients and their unique configurations and allow basket API to provide capabilities such as add/update/delete items, update item quantity, update prices and coupons/discounts, update customer contacts, etx. Suggest if configuration based approach is best in this case or if another approach is needed to code such a basket application.

Copilot

#### Sent by Copilot:

Managing a vast variety of UX clients with unique configurations can be challenging, but a configuration-based approach can be effective if implemented correctly. Here are some suggestions and considerations for managing this complexity:

##### Configuration-Based Approach

###### Advantages:

1. **Flexibility**: Allows each UX client to have tailored behavior without changing the core logic of the application.
2. **Scalability**: New clients can be added with their configurations without modifying the existing codebase.
3. **Maintainability**: Centralized configurations make it easier to manage and update rules.

###### Implementation Tips:

1. **Configuration Storage**: Store configurations in a database or a configuration management service. This allows for dynamic updates and easy retrieval.
2. **Caching**: Use caching mechanisms to load configurations into memory for quick access, reducing the overhead of frequent database calls.
3. **Validation Framework**: Implement a validation framework that reads the configuration and applies the rules dynamically. This can be done using a rules engine or custom validation logic.
4. **Modular Design**: Design the basket API in a modular way, where each operation (add/update/delete items, update prices, etc.) is a separate module that can be configured independently.

##### Example Architecture

1. **Configuration Service**: A microservice or module responsible for managing and providing configurations.
2. **Validation Engine**: A component that reads the configuration and applies validation rules.
3. **Basket Service**: The core service handling basket operations, interacting with the validation engine and configuration service.

##### Example Workflow

1. **Client Request**: UXClient1 makes a PATCH request to update item quantity.
2. **Configuration Retrieval**: The Basket Service retrieves the configuration for UXClient1 from the Configuration Service or cache.
3. **Validation**: The Validation Engine applies the rules from the configuration to the request.
4. **Operation Execution**: If validation passes, the Basket Service updates the item quantity.

##### Alternative Approaches

##### Policy-Based Approach

Instead of configurations, use policies that define the behavior for different clients. Policies can be more abstract and reusable across different clients.

1. **Policy Definitions**: Define policies for different operations (e.g., item management, pricing, contacts).
2. **Policy Engine**: A component that evaluates policies and determines the behavior for each client.

###### Pros:

- **Reusability**: Policies can be reused across multiple clients.
- **Simplicity**: Easier to manage and update compared to individual configurations.

###### Cons:

- **Less Granular Control**: May not provide the same level of customization as configurations.

##### Recommendation

For your use case, a **configuration-based approach** seems more suitable due to the high level of customization required by different UX clients. However, combining it with a **policy-based approach** for common rules and behaviors can provide a balanced solution.

##### Example Code Snippet (Configuration Retrieval)

Here’s a simplified example in C++ to illustrate how you might retrieve and apply configurations:

```cpp
#include <iostream>
#include <unordered_map>
#include <string>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

// Configuration storage (could be a database in a real application)
std::unordered_map<std::string, json> configurations = {
    {"UXClient1", {
        {"basketId", 11},
        {"status", "edit"},
        {"validationRules", {
            {"Number", {{"mandatory", true}, {"validationType", "error"}}},
            {"version", {{"mandatory", true}, {"validationType", "error"}}},
            {"name", {{"mandatory", true}, {"validationType", "error"}}},
            {"description", {{"mandatory", false}, {"validationType", "warning"}}},
            {"metadata", {
                {"createdBy", {{"mandatory", true}, {"validationType", "error"}}},
                {"lastModifiedBy", {{"mandatory", false}, {"validationType", "warning"}}},
                {"expiresOn", {{"mandatory", false}, {"validationType", "warning"}}},
                {"retentionDays", {{"mandatory", false}, {"validationType", "warning"}}}
            }},
            {"Items", {{"mandatory", true}, {"validationType", "error"}}},
            {"Contacts", {{"mandatory", false}, {"validationType", "warning"}}},
            {"Price", {{"mandatory", true}, {"validationType", "error"}}},
            {"Payments", {{"mandatory", false}, {"validationType", "warning"}}}
        }}
    }}
};

// Function to retrieve configuration
json get_configuration(const std::string& client_id) {
    if (configurations.find(client_id) != configurations.end()) {
        return configurations[client_id];
    }
    return json();
}

int main() {
    std::string client_id = "UXClient1";
    json config = get_configuration(client_id);

    if (!config.empty()) {
        std::cout << "Configuration for " << client_id << ":\n" << config.dump(4) << std::endl;
    } else {
        std::cout << "Configuration not found for " << client_id << std::endl;
    }

    return 0;
}
```

This example demonstrates how to retrieve and print the configuration for a specific client. You can extend this to include validation and other operations as needed.

Would you like to explore any specific part of this approach further?