simplfy contract

contracts/StakeManager.sol

@@ -1,49 +1,77 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity 0.6.12;
+pragma solidity 0.8.19;
 
 import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 
 contract StakeManager is ERC20 {
 
-    address stakedToken;
-    
-    bytes32 vaultCodehash;
-    uint256 mp_supply = 0;
-    uint256 public constant MP_APY = 1; 
+    ERC20 stakedToken;
+
+   uint256 public constant MP_APY = 1; 
     uint256 public constant STAKE_APY = 1; 
     uint256 public constant MAX_BOOST = 1; 
+    uint256 public constant MAX_MP = 1; 
+    mapping (address => Account) accounts;
+
+    struct Account {
+        uint256 lockTime;
+        uint256 balance;
+        uint256 multiplier;
+        uint256 multiplierUpdate;
+    }
 
     mapping (address => Account) account;
 
 
-    modifier onlyVault {
-        require(msg.sender.codehash() == vaultCodehash, "Unauthorized Codehash");
+    function increaseBalance(uint256 _amount, uint256 _time) external {
+        accounts[msg.sender].balance += _amount;
+        uint256 mp = calcInitialMultiplierPoints(_amount, _time);
+        accounts[msg.sender].multiplier += mp;
+        multiplierSupply += mp;
+        accounts[msg.sender].update = now();
+        accounts[msg.sender].lockTime = now() + _time;
+        mint(msg.sender, _amount);
     }
 
-    function join(uint256 amount) external onlyVault {
-
+    function decreaseBalance(uint256 _amount) external {
+        accounts[msg.sender].balance -= _amount;
+        accounts[msg.sender].multiplier -= calcInitialMultiplierPoints(_amount, 1);
+        burn(msg.sender, _amount);
     }
 
-    function lock(uint256 amount, uint256 time) external onlyVault {
-        
+
+    function balanceLock(uint256 _time) external {
+        require(now() + _time > accounts[msg.sender].lockTime, "Cannot decrease lock time");
+        accounts[msg.sender].lockTime =  now() + _time;
     }
 
-    function joinAndLock(uint256 amount, uint256 time) external onlyVault {
-
+    /**
+     * @dev Function called to increase the Multiplier Points of a Vault
+     * @param _vault 
+     */
+    function mintMultiplierPoints(address _vault) external {
+        uint256 dT = now() - accounts[msg.sender].update; 
+        accounts[msg.sender].update = now();
+        uint256 mp = calcAccuredMultiplierPoints(accounts[_vault].balance, accounts[_vault].multiplier, dT);
+        multiplierSupply += mp;
+        accounts[_vault].multiplier += mp;
     }
 
-    function leave(uint256 amount) external {
-
+    function calcInitialMultiplierPoints(uint256 _amount, uint256 _time) pure public returns(uint256) {
+        return _amount * (_time + 1);
     }
 
+    function calcAccuredMultiplierPoints(uint256 _balance, uint256 _currentMp, uint256 _deltaTime) pure public returns(uint256) {
+        uint256 accured = _balance * (MP_APY * _deltaTime);
+        uint256 newMp = accured + _currentMp;
+        return newMp > MAX_MP ? MAX_MP - newMp : accurred;
+    }
+
+
     function getRewardsEmissions() public view returns(uint256){
-
-    }
-    
-
-    function increase_mp(uint256 amount) {
-        
+        uint256 totalStaked = this.totalSupply;
+        uint256 share = this.multiplierSupply +totalSupply;
     }