Vending machine sketch

implementation/contracts/deposit/DepositFunding.sol

@@ -337,9 +337,7 @@ library DepositFunding {
         _d.setActive();
         _d.logFunded();
 
-        returnFunderBond(_d);
-
-        mintTBTC(_d);
+        // mint Dposit Owner NFT
 
         return true;
     }

implementation/contracts/deposit/DepositUtils.sol

@@ -98,7 +98,7 @@ library DepositUtils {
         require(_observedDiff != ValidateSPV.getErrInvalidChain(), "Invalid headers chain");
         require(_observedDiff != ValidateSPV.getErrLowWork(), "Insufficient work in a header");
 
-        /* TODO: make this better than 6 */
+        /* TODO: Redo for single proof */
         require(
             _observedDiff >= _reqDiff.mul(TBTCConstants.getTxProofDifficultyFactor()),
             "Insufficient accumulated difficulty in header chain"

implementation/contracts/system/Vending.sol

@@ -0,0 +1,94 @@
+pragma solidity ^0.5.10;
+
+import Deposit, TBTCToken, DepositOwnerNFT, DepositBEenficiaryNFT;
+
+contract Vending {
+
+	// Check if a Deposit Owner Token (DOT) is qualified
+	function isQualified(tokenId) public view returns (bool);
+
+	// Qualify a DOT
+	function qualifyDepositOwnerToken(tokenID, proofRequirements) public view returns (bool){
+		require(tokenId has not been redeemed);
+		require(within timeout) // expand on timeout in this context
+		//proof checks out
+		//proofRequirements <> getQualificationRequirements() 
+	}
+
+	// get qualification requirements, currently just number of
+	// confirmations required. This is 6 + X. X depends on volume
+	function getQualificationRequirements() public view returns (uint256){
+		// return current number of blocks needed for qualification
+	}
+
+	// Use a DOT to obtain TBTC (ERC20)
+	// If locked bool == true, maintain exclusive redemption rights,
+	// keep control of DOT and receive TBTC. The DOT is marked as redeemed. Ownership of the DOT
+	// now represents the right to redeem the specific custodied UTXO. 
+	// If locked bool == false, Forfeit exclusive redemption rights, Swap DOT
+	// for Deposit Beneficiary NFT, and receive TBTC.
+	// DOTs controlled by Vending machine do not need to be marked as redeemed due to 
+	// the TBTC burning requirement enforced by getDepositOwnerNFT()
+	// this function can be separated into getTBTCLocked() and getTBTCUnlocked()
+	function GetTBTC(bool locked, uint256 tokenID, proofRequirements ) public {
+		require(isQualified(tokenId, proofRequirements))
+		require(within timeout) // expand on timeout in this context
+		if(!locked){
+			// swap Deposit Owner NFT for TBTC
+			// supply Deposit beneficiary NFT
+			// return
+		}
+		// supply TBTC, but no deposit beneficiary NFT
+	}
+
+	// pay required TBTC to retrieve given DOT (in unredeemed state)
+	function getDepositOwnerNFT(uint256 tokenid) public returns (address) {
+		require(sended approved sufficient TBTC to be burned);
+		if(tokenId == 0){
+			// decide which NFT to return. oldest/random
+			// some market potential here? (note async here will break redemption wrapper)
+			// Market can be external system impacting queue order of UTXO redemption.
+			// could offer an alternative to signer self redemption by paying for redemption priority.
+			// Paying for DOT queue priority would have to somehow lock the DOT to prevent getDepositOwnerNFT()
+			// on the specific DOT (since Ownership of the DOT does not guarantee imminent redemption) 
+			// only in redemption Wrapper: getDepositOwnerNFT(RedemptionQueue.Next()) -- not async, cool. 
+		}
+		// check vending machine for given NFT, revert if it doesn't exist.
+		// transfer Deposit owner NFT
+		// return tokenID
+	}
+
+	// pay required TBTC to retrieve non-specific DOT (in unredeemed state)
+	function getDepositOwnerNFT() public returns (address) {
+			getDepositOwnerNFT(0);
+	}
+
+	// redeem a Deposit with TBTC, specific DOT preference.
+	function redemptionWrapper(uint256 _TokenID) public {
+		uint256 TokenId;
+		if(ownerOf(_TokenId) == msg.sender){
+			tokenId = _TokenID;
+		}
+		else{
+			TokenId = getDepositOwnerNFT(_TokenID);
+		}
+		redeemDepositOwnerToken(TokenId)
+	}
+
+	// redeem a Deposit using TBTC. No Specific DOT preference
+	function redemptionWrapper() public{
+		uint256 TokenId = getDepositOwnerNFT(0);
+		redeemDepositOwnerToken(TokenId)
+	}
+
+	// redeem a Dposit using an unredeemed DOT. not TBTC requirement
+	function redeemDepositOwnerToken(uint256 TokenID) public {
+		require(msg.sender == tokenId owner);
+		require(TokenID is valid and unredeemed)
+		Deposit(address(tokenId)).requestRedemption() //temp
+			// msg.sender issues here? 
+			// will need an approval chain for TBTC burn approval requirements
+			// might need restructure on Deposit to send
+			// beneficiary reward to correct msg.sender instead of address(this) pass var?
+	}
+}