> For the complete documentation index, see [llms.txt](https://docs.degenlab.io/gamefistacks/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.degenlab.io/gamefistacks/lootbox-on-chain-m3/smart-contracts/lootbox-manager.md).

# Lootbox Manager

This smart contract manages who can mint lootboxes, and how many, by using a map `remaining-mints` with the key as a `principal` and the value being the number of mints available. 

```lisp
(define-map remaining-mints principal uint)
```

It checks if the address selected can mint NFTs through the read-only `can-mint-lootbox` returning true if minting is possible, false otherwise. 

{% code lineNumbers="true" %}

```lisp
(define-read-only (can-mint-lootbox (address principal))
  (let ((remains (map-get? remaining-mints address)) )
  ;; map-get address not is-none
  (if (is-none remains) (ok false) 
    ;; map-get > u1
    (if (< u0 (unwrap! remains err-invalid-remains)) (ok true)
      (ok false)))))
```

{% endcode %}

If the address can-mint, it can call the `claim-lootbox` and get a lootbox, while decreasing by 1 the number of mints available, directly in the map where we store them.

{% code lineNumbers="true" %}

```lisp
(define-public (claim-lootbox ) 
  (if (is-eq (ok true) (can-mint-lootbox tx-sender))
    (let ((address tx-sender)) 
      (is-ok (set-remaining-mints address (- (unwrap! (map-get? remaining-mints address) err-invalid-remains) u1)))
      (as-contract (contract-call? .lootbox-background create-lootbox address)))
    (ok false)))

(define-public (set-remaining-mints (address principal) (number uint))
  (begin 
    (asserts! (is-eq tx-sender (var-get contract-admin)) err-admin-only) 
    (ok (map-set remaining-mints address number))))
```

{% endcode %}

If a user knows he can mint multiple but doesn't know how many he has left, he can call the read-only `get-remaining-mints`.

{% code lineNumbers="true" %}

```lisp
(define-read-only (get-remaining-mints (address principal)) 
  (map-get? remaining-mints address))
```

{% endcode %}

Admin can always update the number of the available mints for a given address based on any off-chain event.&#x20;

{% code lineNumbers="true" %}

```lisp
(define-constant err-admin-only (err u100))
(define-public (set-remaining-mints (address principal) (number uint))
  (begin 
    (asserts! (is-eq tx-sender (var-get contract-admin)) err-admin-only) 
    (ok (map-set remaining-mints address number))))
```

{% endcode %}


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