StorageRent

1
2import FungibleToken from 0xf233dcee88fe0abe
3import FlowStorageFees from 0xe467b9dd11fa00df
4import FlowToken from 0x1654653399040a61
5
6access(all)
7contract StorageRent{ 
8	access(all)
9	let StorageRentAdminStoragePath: StoragePath
10	
11	access(contract)
12	var StorageRentRefillThreshold: UInt64
13
14  
15
16  access(contract)
17	var isOpen: Bool
18	
19  access(all) event Refilled(address: Address, amount: UFix64)
20
21
22	access(all)
23	view fun getStorageRentRefillThreshold(): UInt64{ 
24		return self.StorageRentRefillThreshold
25	}
26	
27	access(all)
28	view fun getIsOpen(): Bool{ 
29		return self.isOpen
30	}
31	
32	access(all)
33	fun tryRefill(_ address: Address){ 
34    if self.isOpen == false {
35      return
36    }
37
38		let recipient = getAccount(address)
39		let receiverRef = recipient.capabilities.get<&{FungibleToken.Receiver}>(/public/flowTokenReceiver)!.borrow()
40		if receiverRef == nil || (receiverRef!).owner == nil{ 
41			return
42		}
43
44		var low: UInt64 = recipient.storage.used
45		var high: UInt64 = recipient.storage.capacity
46		if high < low{ 
47			high <-> low
48		}
49		if high - low < self.StorageRentRefillThreshold {
50			let vaultRef = self.account.storage.borrow<auth(FungibleToken.Withdraw) &FlowToken.Vault>(from: /storage/flowTokenVault)
51				?? panic("Could not borrow reference to the owner's Vault!")
52			
53			let requiredAmount = FlowStorageFees.storageCapacityToFlow(FlowStorageFees.convertUInt64StorageBytesToUFix64Megabytes(self.StorageRentRefillThreshold * 2))
54			(receiverRef!).deposit(from: <-(vaultRef!).withdraw(amount: requiredAmount))
55      
56      emit Refilled(address: address, amount: requiredAmount)
57		}
58	}
59
60	
61	access(all)
62	resource Admin{ 
63		access(all)
64		fun setStorageRentRefillThreshold(_ threshold: UInt64){ 
65			StorageRent.StorageRentRefillThreshold = threshold
66		}
67		
68		access(all)
69		fun setIsOpen(_ flag: Bool){ 
70			StorageRent.isOpen = flag
71		}
72	}
73
74	init(){ 
75		self.StorageRentAdminStoragePath = /storage/StorageRentAdmin
76		self.StorageRentRefillThreshold = 5000
77    self.isOpen = true
78		let admin <- create Admin()
79		self.account.storage.save(<-admin, to:  /storage/StorageRentAdmin)
80	}
81}