// SPDX-License-Identifier: MIT
pragma solidity 0.8.29;

/**
 * @title SokoGuestbook
 * @notice Simple guestbook: anyone can write a message stored with their address and timestamp.
 * @dev Minimal and gas-conscious. Uses calldata for input and stores timestamp as uint64.
 */
contract SokoGuestbook {
    /// @dev Single guestbook entry
    struct Entry {
        address author;
        uint64 timestamp;
        string message;
    }

    /// @dev All entries are stored in this dynamic array
    Entry[] private entries;

    /// @notice Emitted when a new message is written
    event NewMessage(address indexed author, uint64 timestamp, string message);

    /// @notice Write a message to the guestbook
    /// @param message The message to store
    function writeMessage(string calldata message) external {
        // Store entry with compact timestamp type
        entries.push(Entry({author: msg.sender, timestamp: uint64(block.timestamp), message: message}));
        emit NewMessage(msg.sender, uint64(block.timestamp), message);
    }

    /// @notice Get number of messages stored
    /// @return count Number of entries
    function count() external view returns (uint256) {
        return entries.length;
    }

    /// @notice Read all messages
    /// @dev Returns three parallel arrays (authors, timestamps, messages)
    /// @return authors Array of message authors
    /// @return timestamps Array of timestamps (uint64)
    /// @return messages Array of messages
    function getAll() external view returns (address[] memory authors, uint64[] memory timestamps, string[] memory messages) {
        uint256 len = entries.length;
        authors = new address[](len);
        timestamps = new uint64[](len);
        messages = new string[](len);

        for (uint256 i = 0; i < len; ++i) {
            Entry storage e = entries[i];
            authors[i] = e.author;
            timestamps[i] = e.timestamp;
            messages[i] = e.message;
        }
    }
}