nips/15.md

NIP-15
======

Nostr Marketplace (for resilient marketplaces)
-----------------------------------

`draft` `optional` `author:fiatjaf` `author:benarc`  `author:motorina0` `author:talvasconcelos`

> Based on https://github.com/lnbits/Diagon-Alley

> Implemented in [NostrMarket](https://github.com/lnbits/nostrmarket) and [Plebeian Market](https://github.com/PlebeianTech/plebeian-market) 

## Terms

- `merchant` - seller of products with NOSTR key-pair
- `customer` - buyer of products with NOSTR key-pair
- `product` - item for sale by the `merchant`
- `stall` - list of products controlled by `merchant` (a `merchant` can have multiple stalls)
- `marketplace` - clientside software for searching `stalls` and purchasing `products`

## Nostr Marketplace Clients

### Merchant admin

Where the `merchant` creates, updates and deletes `stalls` and `products`, as well as where they manage sales, payments and communication with `customers`.

The `merchant` admin software can be purely clientside, but for `convenience` and uptime, implementations will likely have a server client listening for NOSTR events.

### Marketplace

`Marketplace` software should be entirely clientside, either as a stand-alone app, or as a purely frontend webpage. A `customer` subscribes to different merchant NOSTR public keys, and those `merchants` `stalls` and `products` become listed and searchable. The marketplace client is like any other ecommerce site, with basket and checkout. `Marketplaces` may also wish to include a `customer` support area for direct message communication with `merchants`.

## `Merchant` publishing/updating products (event)

A merchant can publish these events:
| Kind      |                    | Description                                                                                                     |
| --------- | ------------------ | --------------------------------------------------------------------------------------------------------------- |
| `0    `   | `set_meta`         | The merchant description (similar with any `nostr` public key).                                                 |
| `30017`   | `set_stall`        | Create or update a stall.                                                                                       |
| `30018`   | `set_product`      | Create or update a product.                                                                                     |
| `4    `   | `direct_message`   | Communicate with the customer. The messages can be plain-text or JSON.                                          |
| `5    `   | `delete`           | Delete a product or a stall.                                                                                    |

### Event `30017`: Create or update a stall.

**Event Content**:
```json
{
    "id": <String, UUID generated by the merchant. Sequential IDs (`0`, `1`, `2`...) are discouraged>,
    "name": <String, stall name>,
    "description": <String (optional), stall description>,
    "currency": <String, currency used>,
    "shipping": [
        {
            "id": <String, UUID of the shipping zone, generated by the merchant>,
            "name": <String (optional), zone name>,
            "cost": <float, base cost for shipping. The currency is defined at the stall level>,
            "countries": [<String, countries included in this zone>],
        }
    ]
}
```

Fields that are not self-explanatory:
 - `shipping`:
   - an array with possible shipping zones for this stall.
   - the customer MUST choose exactly one of those shipping zones.
   - shipping to different zones can have different costs. For some goods (digital for example) the cost can be zero.
   - the `id` is an internal value used by the merchant. This value must be sent back as the customer selection.
   - each shipping zone contains the base cost for orders made to that shipping zone, but a specific shipping cost per
   product can also be specified if the shipping cost for that product is higher than what's specified by the base cost.

**Event Tags**:
```json
  "tags": [["d", <String, id of stall]]
```
 - the `d` tag is required, its value MUST be the same as the stall `id`.

### Event `30018`: Create or update a product

**Event Content**:
```json
{
    "id": <String, UUID generated by the merchant.Sequential IDs (`0`, `1`, `2`...) are discouraged>,
    "stall_id": <String, UUID of the stall to which this product belong to>,
    "name": <String, product name>,
    "description": <String (optional), product description>,
    "images": <[String], array of image URLs, optional>,
    "currency": <String, currency used>,
    "price": <float, cost of product>,
    "quantity": <int, available items>,
    "specs": [
        [<String, spec key>, <String, spec value>]
    ],
    "shipping": [
        {
            "id": <String, UUID of the shipping zone. Must match one of the zones defined for the stall>,
            "cost": <float, extra cost for shipping. The currency is defined at the stall level>,
        }
    ]
}
```

Fields that are not self-explanatory:
 - `specs`:
   - an optional array of key pair values. It allows for the Customer UI to present product specifications in a structure mode. It also allows comparison between products
   - eg: `[["operating_system", "Android 12.0"], ["screen_size", "6.4 inches"], ["connector_type", "USB Type C"]]`

    _Open_: better to move `spec` in the `tags` section of the event?

- `shipping`:
   - an _optional_ array of extra costs to be used per shipping zone, only for products that require special shipping costs to be added to the base shipping cost defined in the stall
   - the `id` should match the id of the shipping zone, as defined in the `shipping` field of the stall
   - to calculate the total cost of shipping for an order, the user will choose a shipping option during checkout, and then the client must consider this costs:
     - the `base cost from the stall` for the chosen shipping option
     - the result of multiplying the product units by the `shipping costs specified in the product`, if any. 

**Event Tags**:
```json
  "tags": [
       ["d", <String, id of product],
       ["t", <String (optional), product category],
       ["t", <String (optional), product category],
       ...
    ]
```

 - the `d` tag is required, its value MUST be the same as the product `id`.
 - the `t` tag is as searchable tag, it represents different categories that the product can be part of (`food`, `fruits`). Multiple `t` tags can be present.

## Checkout events

All checkout events are sent as JSON strings using ([NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md)).

The `merchant` and the `customer` can exchange JSON messages that represent different actions. Each `JSON` message `MUST` have a `type` field indicating the what the JSON represents. Possible types:

| Message Type | Sent By  | Description         |
|--------------|----------|---------------------|
| 0            | Customer | New Order           |
| 1            | Merchant | Payment Request     |
| 2            | Merchant | Order Status Update |


### Step 1: `customer` order (event)
The below json goes in content of [NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md).

```json
{
    "id": <String, UUID generated by the customer>,
    "type": 0,
    "name": <String (optional), ???>,
    "address": <String (optional), for physical goods an address should be provided>
    "message": "<String (optional), message for merchant>,
    "contact": {
        "nostr": <32-bytes hex of a pubkey>,
        "phone": <String (optional), if the customer wants to be contacted by phone>,
        "email": <String (optional), if the customer wants to be contacted by email>,
    },
    "items": [
        {
            "product_id": <String, UUID of the product>,
            "quantity": <int, how many products the customer is ordering>
        }
    ],
    "shipping_id": <String, UUID of the shipping zone>
}

```

_Open_: is `contact.nostr` required?


### Step 2: `merchant` request payment (event)

Sent back from the merchant for payment. Any payment option is valid that the merchant can check.

The below json goes in `content` of [NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md).

`payment_options`/`type` include:

- `url` URL to a payment page, stripe, paypal, btcpayserver, etc
- `btc` onchain bitcoin address
- `ln` bitcoin lightning invoice
- `lnurl` bitcoin lnurl-pay

```json
{
    "id": <String, UUID of the order>,
    "type": 1,
    "message": <String, message to customer, optional>,
    "payment_options": [
        {
            "type": <String, option type>,
            "link": <String, url, btc address, ln invoice, etc>
        },
        {
            "type": <String, option type>,
            "link": <String, url, btc address, ln invoice, etc>
        },
                {
            "type": <String, option type>,
            "link": <String, url, btc address, ln invoice, etc>
        }
    ]
}
```

### Step 3: `merchant` verify payment/shipped (event)

Once payment has been received and processed.

The below json goes in `content` of [NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md).

```json
{
    "id": <String, UUID of the order>,
    "type": 2,
    "message": <String, message to customer>,
    "paid": <Bool, true/false has received payment>,
    "shipped": <Bool, true/false has been shipped>,
}
```

## Customer support events

Customer support is handled over whatever communication method was specified. If communicating via nostr, NIP-04 is used https://github.com/nostr-protocol/nips/blob/master/04.md.

## Additional

Standard data models can be found <a href="https://raw.githubusercontent.com/lnbits/nostrmarket/main/models.py">here</a>