created a DocumentRegistry smart contract using ACL

Author: code-architect

solidity-design-pattern/contracts/DocumentRegistryACL.sol

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.6.12 <0.9.0;
+
+contract ACL {
+
+    // Role definition
+    enum Role { None, User, Admin }
+
+    // Mapping of addresses to roles
+    mapping(address => Role) private roles;
+
+    // Event emitted when a role is granted
+    event RoleGranted(address indexed addr, Role role);
+
+    // Event emitted when a role is revoked
+    event RoleRevoked(address indexed addr, Role role);
+
+    // Modifier to restrict function access to specific roles
+    modifier onlyRole(Role role) {
+        require(hasRole(msg.sender, role), "No permission to perform this action");
+        _;
+    }
+
+    constructor(address _admin) {
+        roles[_admin] = Role.Admin; // Assign admin role to the deployer address
+        emit RoleGranted(_admin, Role.Admin);
+    }
+
+    // Grant a role to an address
+    function grantRole(address _addr, Role _role) public onlyRole(Role.Admin) {
+        roles[_addr] = _role;
+        emit RoleGranted(_addr, _role);
+    }
+
+    // Revoke a role from an address
+    function revokeRole(address _addr, Role _role) public onlyRole(Role.Admin) {
+        roles[_addr] = Role.None;
+        emit RoleRevoked(_addr, _role);
+    }
+
+    // Check if an address has a specific role
+    function hasRole(address _addr, Role _role) public view returns (bool) {
+        return roles[_addr] == _role;
+    }
+}
+
+contract DocumentRegistry is ACL
+{
+    struct Document 
+    {
+        address owner;
+        string content;
+    }
+
+    mapping(uint => Document) private documents;
+    uint private nextDocumentId = 1;
+
+    constructor(address _admin) ACL(_admin) {}
+
+    function createDocument(string memory _IPFSHash) public onlyRole(Role.User) returns (uint)
+    {
+        uint documentId = nextDocumentId++;
+        documents[documentId] = Document(msg.sender, _IPFSHash);
+        return documentId;
+    }
+
+    function updateDocument(uint _documentId, string memory _newIPFSHash) public  onlyRole(Role.User) 
+    {
+        require(msg.sender == documents[_documentId].owner, "Only the document owner can update the document");
+        documents[_documentId].content = _newIPFSHash;
+    }
+
+    function getDocumentContent(uint _documentId) public view returns (string memory) {
+        return documents[_documentId].content;
+    }
+}