TransparencyLedger.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

/// @title Transparency Ledger for Public or Corporate Projects
/// @notice A decentralized registry that records project details on-chain
/// @dev Designed for transparency, not efficiency (data is public and immutable)
contract TransparencyLedger {
    struct Project {
        uint256 id;
        string projectName;
        uint256 projectValue; // in smallest currency unit, e.g. wei or cents
        string workerCompany;
        string location;
        address addedBy;
        uint256 timestamp;
    }

    Project[] private projects;
    uint256 private nextId = 1;
    address public owner;

    event ProjectAdded(
        uint256 indexed id,
        string projectName,
        uint256 projectValue,
        string workerCompany,
        string location,
        address indexed addedBy
    );

    modifier onlyOwner() {
        require(msg.sender == owner, "Only owner can add projects");
        _;
    }

    constructor() {
        owner = msg.sender;
    }

    /// @notice Add a new project to the public ledger
    /// @param _projectName The project name
    /// @param _projectValue The project value (in smallest unit)
    /// @param _workerCompany The contractor or executing company
    /// @param _location The location where the project is executed
    function addProject(
        string calldata _projectName,
        uint256 _projectValue,
        string calldata _workerCompany,
        string calldata _location
    ) external onlyOwner {
        projects.push(
            Project({
                id: nextId,
                projectName: _projectName,
                projectValue: _projectValue,
                workerCompany: _workerCompany,
                location: _location,
                addedBy: msg.sender,
                timestamp: block.timestamp
            })
        );

        emit ProjectAdded(nextId, _projectName, _projectValue, _workerCompany, _location, msg.sender);
        nextId++;
    }

    /// @notice Returns all recorded projects
    function getAllProjects() external view returns (Project[] memory) {
        return projects;
    }

    /// @notice Get a specific project by ID
    function getProjectById(uint256 _id) external view returns (Project memory) {
        require(_id > 0 && _id < nextId, "Invalid project ID");
        return projects[_id - 1];
    }

    /// @notice Get the total number of recorded projects
    function totalProjects() external view returns (uint256) {
        return projects.length;
    }
}