2 files changed, 358 insertions, 0 deletions
diff --git a/Year_3/Blockchain/MafiaToken/MafiaToken.sol b/Year_3/Blockchain/MafiaToken/MafiaToken.sol
new file mode 100644
index 0000000..14723cc
--- /dev/null
+++ b/Year_3/Blockchain/MafiaToken/MafiaToken.sol
@@ -0,0 +1,278 @@
+// Cariotti 1000001948
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import "./exam-2022-06-24-specs.sol";
+
+contract MafiaToken is ERC20, MafiosoTokenSpecs {
+    enum Role { USER, PICCIOTTO, GODFATHER }
+    struct Mafioso {
+        address id;
+        uint tokens;
+        Role role;
+        bool active;
+        uint8 children;
+    }
+    
+    struct Approve {
+        address owner;
+        uint amount;
+    }
+
+    mapping(address => Mafioso) mafiosi;
+    address[] address_users;
+    address public override immutable godfather;
+    mapping(address => Approve[]) approves;
+
+
+    uint public override totalSupply;
+
+    uint8 private pizzo; // Use `pizzoRate()`
+    uint private salary; // Use `picciottiSalary()`
+
+    uint immutable creation_time;
+    uint last_salary;
+
+    error GodfatherCantPay(uint min_tokens);
+
+    constructor(uint initialSupply) {
+        totalSupply = initialSupply;
+        godfather = msg.sender;
+
+        mafiosi[msg.sender] = Mafioso({
+            id: msg.sender,
+            tokens: initialSupply,
+            role: Role.GODFATHER,
+            active: true,
+            children: 0
+        });
+        address_users.push(msg.sender);
+        salary = 100; // Default initial salary
+
+        creation_time = block.timestamp;
+        last_salary = block.timestamp;
+    }
+
+    modifier MustBeAMafioso(address account) {
+        require(mafiosi[account].id != address(0), "This address is not a 'mafioso'");
+
+        _;
+    }
+
+    modifier MustBeTheGodfather() {
+        require(msg.sender == godfather, "This action is available only for the godfather.");
+
+        _;
+    }
+
+    modifier MustBeAtLeastAPicciotto(address account) {
+        require(
+            account == godfather || mafiosi[account].role == Role.PICCIOTTO,
+            "This action is available only for the godfather and picciottis."
+        );
+
+        _;
+    }
+
+    function balanceOf(address account) public view override MustBeAMafioso(account) returns (uint256) {
+        return mafiosi[account].tokens;
+    }
+
+    function _transfer_money(address sender, address recipient, uint amount) internal {
+        uint to_godfather = (
+            (sender == godfather) ?
+            0 : amount - (amount * pizzo / 100)
+        );
+    
+        mafiosi[sender].tokens -= amount;
+        mafiosi[recipient].tokens += (amount - to_godfather);
+        mafiosi[godfather].tokens += to_godfather;
+
+        emit Transfer(sender, recipient, (amount - to_godfather));
+        emit Transfer(recipient, godfather, to_godfather);
+    }
+
+    function transfer(address recipient, uint256 amount) 
+        public 
+        override 
+        MustBeAMafioso(recipient) MustBeAMafioso(msg.sender) 
+        returns (bool) 
+    {
+        require(mafiosi[msg.sender].tokens >= amount, "You don't have enough tokens to make this transfer");
+
+        _transfer_money(msg.sender, recipient, amount);
+
+        // Always returns a true
+        return true;
+    }
+
+
+    function approve(address spender, uint256 amount)
+        public
+        override
+        MustBeAMafioso(msg.sender) MustBeAMafioso(spender)
+        returns (bool)
+    {
+        approves[spender].push(Approve({
+            owner: msg.sender,
+            amount: amount
+        }));
+
+
+        emit Approval(msg.sender, spender, amount);
+
+        // Always return a true
+        return true;
+    }
+
+    function transferFrom(address sender, address recipient, uint256 amount) 
+        public 
+        override
+        MustBeAMafioso(recipient) MustBeAMafioso(sender)
+        returns (bool)
+    {
+        bool sent = false;
+        for (uint8 i = 0; i < approves[msg.sender].length; ++i) {
+            if (approves[msg.sender][i].owner == sender) {
+                if (approves[msg.sender][i].amount >= amount) {  
+                    _transfer_money(sender, recipient, amount);
+                    approves[msg.sender][i].amount -= amount;
+                    sent = true;
+                }
+            }
+            
+            if (sent) return true;
+        }
+
+        return false;
+    }
+
+    function allowance(address owner, address spender) 
+        public view 
+        override
+        returns (uint256)
+    {
+        uint amount = 0;
+        for (uint8 i = 0; i < approves[spender].length; ++i) {
+            if (approves[spender][i].owner == owner) {
+                amount += approves[spender][i].amount;
+            }
+        }
+
+        return amount;
+    }
+
+    function picciotti() override public view returns (address[] memory) {
+        address[] memory _mafiosi_list = new address[](address_users.length);
+
+        uint8 j = 0;
+
+        for (uint8 i = 0; i < address_users.length; ++i) {
+            if (mafiosi[address_users[i]].role == Role.PICCIOTTO &&
+                mafiosi[address_users[i]].active
+            ) {
+                _mafiosi_list[j++] = address_users[i];
+            }
+        }
+
+        return _mafiosi_list;
+    }
+
+    function addPicciotto(address id, uint8 children) public override MustBeTheGodfather {
+        mafiosi[id] = Mafioso({
+            id: id,
+            tokens: 0,
+            role: Role.PICCIOTTO,
+            active: true,
+            children: children
+        });
+        address_users.push(id);
+    }
+
+    function removePicciotto(address id) public override MustBeTheGodfather MustBeAMafioso(id) {
+        mafiosi[id].active = false;
+    }
+
+    function pizzoRate() public view override returns (uint8) {
+        return pizzo;
+    }
+
+    function setPizzoRate(uint8 rate) public override MustBeTheGodfather {
+        require(rate >= 0 && rate <= 100, "You entered not valid value");
+
+        pizzo = rate;
+    }
+
+    function forgeNewTokens(uint additionalSupply) public override MustBeTheGodfather {
+        require(additionalSupply >= 0, "You entered a negative rate");
+
+        mafiosi[godfather].tokens += additionalSupply;
+        totalSupply += additionalSupply;
+
+        /* This event have to me emitted? */
+        emit Transfer(address(0), godfather, additionalSupply);
+    }
+
+
+    function stealTokens(address robbed, uint amount)
+        public
+        override
+        MustBeAtLeastAPicciotto(robbed) 
+        MustBeAtLeastAPicciotto(msg.sender)
+    {
+        require(robbed != godfather, "You can't steal tokens from the godfather!");
+        require(mafiosi[robbed].tokens >= amount, "Robbed mafioso does not have enough tokens");
+
+
+        mafiosi[msg.sender].tokens += amount;
+        mafiosi[robbed].tokens -= amount;
+
+        emit Transfer(robbed, msg.sender, amount);
+    }
+
+    function picciottiSalary() public view override returns (uint) {
+        return salary;
+    }
+
+    function setPicciottiPerChildSalary(uint amount) public override MustBeTheGodfather {
+        require(amount >= 0, "You entered a negative rate");
+
+        salary = amount;
+    }
+
+    function triggerMonthlyPicciottiSalary() public override {
+        /* Change `30 days` value to test this method. */
+        require(block.timestamp >= (last_salary + 30 days), "Already paid.");
+
+        uint need_tokens = 0;
+
+        for (uint8 i = 0; i < address_users.length; ++i) {
+            if (mafiosi[address_users[i]].role != Role.GODFATHER &&
+                mafiosi[address_users[i]].active
+            ) {
+                need_tokens += (salary * mafiosi[address_users[i]].children);
+            }
+        }
+
+        if (mafiosi[godfather].tokens < need_tokens) {
+            revert GodfatherCantPay(need_tokens);
+        }
+
+        for (uint8 i = 0; i < address_users.length; ++i) {
+            if (
+                mafiosi[address_users[i]].role != Role.GODFATHER &&
+                mafiosi[address_users[i]].active
+            ) {
+                uint amount = (salary * mafiosi[address_users[i]].children);
+                mafiosi[address_users[i]].tokens += amount;
+                _transfer_money(godfather, address_users[i], amount);
+            }
+        }
+
+        mafiosi[godfather].tokens -= need_tokens;
+
+        last_salary = block.timestamp;
+    }
+}
+
diff --git a/Year_3/Blockchain/MafiaToken/exam-2022-06-24-specs.sol b/Year_3/Blockchain/MafiaToken/exam-2022-06-24-specs.sol
new file mode 100644
index 0000000..ac59c10
--- /dev/null
+++ b/Year_3/Blockchain/MafiaToken/exam-2022-06-24-specs.sol
@@ -0,0 +1,80 @@
+/*
+    Corso Blockchain & Cryptocurrencies - Compito di laboratorio del 24/06/2022
+
+    Scrivere un contratto `MafiaToken` che implementi sia l'interfaccia standard `ERC20`, vista a lezione, che 
+    quella addizionale `MafiosoTokenSpecs` che realizzi, usando il linguaggio Solidity, un 
+    "particolare token" sulla piattaforma Ethereum.
+
+    I metodi standard dell'interfaccia `ERC20` hanno i seguenti compiti:
+    - `totalSupply`: fornisce il totale dei token in circolazione;
+    - `balanceOf`: fornisce l'ammontare di token associati ad uno specifico indirizzo;
+    - `transfer`: trasferisce all'indirizzo `recipient` l'ammontare specificato attingendo dal conto del 
+      chiamante;
+    - `approve`: autorizza l'indirizzo `spender` a spendere al piu' l'ammontare specificato attingendo dal
+      conto del chiamante;
+    - `transferFrom`: trasferisce all'indirizzo `recipient` l'ammontare specificato (purche' pre-autorizzato
+      tramite `approve`) attingendo dal conto dell'indirizzo `spender`;
+    - `allowance`: riporta l'ammontare pre-autorizzato per delega (vedi `approve`) da `owner` a favore di 
+      `spender`.
+
+    Passando all'interfaccia `MafiosoTokensSpecs`: questa prevede di identificare come "padrino" (godfather)
+    il proprietario/creatore del contratto e dal riservargli alcune azioni previste tra cui: `addPicciotto`, 
+    `removePicciotto`, `setPizzoRate`, `setMonthlyPicciottiSalary` e `forgeNewTokens`. 
+    Viene anche gestito un gruppo di utenti speciali detti "picciotti" che unicamente il padrino puo' gestire.
+    A tale gruppo sono permesse alcune azioni e ricevono uno "stipendio" mensile dal padrino.
+
+    In particolare:
+    - `forgeNewTokens`, utilizzabile solo dal padrino, creano nuovi token e li accredita allo stesso;
+    - `stealTokens`, utilizzabile dal padrino e dai picciotti, puo' essere usato per "rubare" token 
+      all'indirizzo `robbed` specificato;
+    - tramite `pizzoRate` e `setPizzoRate` e' possibile consultare e impostare, da parte del padrino,
+      la percentuale che lo stesso trattiene ad ogni trasferimento effettuato tramite i metodi standard
+      `transfer` e `transferFrom`; la percentuale e' espressa come un intero tra 0 e 100;
+    - tramite `picciottiSalary` e `setPicciottiPerChildSalary` e' possibile consultare e impostare, 
+      da parte del padrino, l'ammontare in token che lo stesso paghera' mensilmente agli stessi; il metodo 
+      `triggerMonthlyPicciottiSalary`, invocabile da chiunque, effettuera' il pagamento agli stessi, con 
+      periodicita' di 30 giorni, usando come data di riferimento quella di creazione del contratto. Il salario
+      mensile per figlio predefinito alla creazione del contratto e' di 100 token.
+
+    L'evento standard `Approve` dovra' essere emesso in occasione di una pre-autorizzazione al transferimento e
+    quello `Transfer` ogni qualvolta si configuri un trasferimento di proprieta' di token: anche per i metodi
+    dell'interfaccia `MafiosoTokenSpecs`.
+    
+    Il contratto dovrà occuparsi di validare gli input ricevuti secondo criteri ovvi di sensatezza.
+
+    Declaration: we don't like Mafia, we are just making fun of it!
+    
+*/
+
+// SPDX-License-Identifier: None
+
+pragma solidity ^0.8.0;
+
+/* https://eips.ethereum.org/EIPS/eip-20 */
+interface ERC20 {
+    function totalSupply() external view returns (uint256);
+    function balanceOf(address account) external view returns (uint256);
+    function transfer(address recipient, uint256 amount) external returns (bool);
+    function allowance(address owner, address spender) external view returns (uint256);
+    function approve(address spender, uint256 amount) external returns (bool);
+    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
+
+    event Transfer(address indexed from, address indexed to, uint256 value);
+    event Approval(address indexed owner, address indexed spender, uint256 value);
+}
+
+interface MafiosoTokenSpecs {
+  /* constructor(uint initialSupply) */
+
+  function godfather() external view returns (address);
+  function picciotti() external view returns (address[]);
+  function addPicciotto(address id, uint8 children) external;
+  function removePicciotto(address id) external;
+  function forgeNewTokens(uint additionalSupply) external;
+  function stealTokens(address robbed, uint amount) external;
+  function pizzoRate() external view returns (uint8);
+  function setPizzoRate(uint8 rate) external;
+  function picciottiSalary() external view returns (uint);
+  function setPicciottiPerChildSalary(uint amount) external;
+  function triggerMonthlyPicciottiSalary() external;
+}