140 lines
4.6 KiB
Solidity
140 lines
4.6 KiB
Solidity
pragma solidity ^0.4.24;
|
|
|
|
contract DTwitter {
|
|
/**
|
|
* User
|
|
*
|
|
* Struct holding the profile deatils of the user.
|
|
*/
|
|
struct User {
|
|
uint creationDate; // date user was created
|
|
string username; // username of the user
|
|
string description; // user profile description
|
|
address owner; // address of the account who created the user
|
|
string picture; // IFPS hash of the user's profile picture
|
|
string[] tweets; // array that holds the user's tweets
|
|
}
|
|
|
|
/**
|
|
* users
|
|
*
|
|
* Maps the keccak256 hash of a username to the deatils of the user
|
|
*
|
|
* {bytes32} [KEY] the keccak256 hash of the username
|
|
* {User} the User struct containing the deatils of the user
|
|
*/
|
|
mapping (bytes32 => User) public users;
|
|
|
|
|
|
/**
|
|
* owners
|
|
*
|
|
* Maps the address of the owner account to the username hash of the
|
|
* owned user. This is needed so we can retrieve an account from the
|
|
* current address
|
|
*
|
|
* {address} [KEY] the address of the owner who owns the user
|
|
* {bytes32} the keccak256 hash of the username
|
|
*/
|
|
mapping (address => bytes32) public owners;
|
|
|
|
/**
|
|
* NewTweet
|
|
*
|
|
* Event to be emitted once a tweet is stored in the contract
|
|
* {bytes32} _from - keccak256-hashed username of user who posted the tweet.
|
|
* This field is indexed so it can be filtered.
|
|
* {string} tweet - the tweet contents
|
|
*/
|
|
event NewTweet(
|
|
bytes32 indexed _from,
|
|
string tweet,
|
|
uint time
|
|
);
|
|
|
|
/**
|
|
* createAccount
|
|
*
|
|
* Creates a user account, storing the user (and user details) in the contract.
|
|
* Additionally, a mapping is created between the owner who created the user
|
|
* (msg.sender) and the keccak256-hash of the username
|
|
* {string} username - the username of the user
|
|
* {string} description - the user profile description
|
|
*/
|
|
function createAccount(string username, string description) public {
|
|
// ensure a null or empty string wasn't passed in
|
|
require(bytes(username).length > 0);
|
|
|
|
// generate the username hash using keccak
|
|
bytes32 usernameHash = keccak256(abi.encodePacked(username));
|
|
|
|
// reject if username already registered
|
|
require(users[usernameHash].creationDate == 0);
|
|
|
|
// reject if sending adddress already created a user
|
|
require(owners[msg.sender] == 0);
|
|
|
|
// add a user to the users mapping and populate details
|
|
// (creationDate, owner, username, description)
|
|
|
|
// add entry to our owners mapping so we can retrieve
|
|
// user by their address
|
|
|
|
}
|
|
|
|
/**
|
|
* editAccount
|
|
*
|
|
* Edits the deteails of a user's profile.
|
|
* {bytes32} usernameHash - the keccak256-hashed username of the user to edit
|
|
* {string} description (optional) - the updated user profile description
|
|
* {string} pictureHash (optional) - the IFPS hash of the user's updated profile picture
|
|
*/
|
|
function editAccount(bytes32 usernameHash, string description, string pictureHash) public {
|
|
// ensure the user exists and that the creator of the user is the
|
|
// sender of the transaction
|
|
require(users[usernameHash].owner == msg.sender);
|
|
|
|
// update the description (could be empty)
|
|
|
|
// only update the user's picture if the hash passed in is
|
|
// not empty or null (essentially disallows deletions)
|
|
}
|
|
|
|
/**
|
|
* userExists
|
|
*
|
|
* Validates whether or not a user has an account in the user mapping
|
|
* {bytes32} usernameHash - the keccak256-hashed username of the user to validate
|
|
* {bool} - returns true if the hashed username exists in the user mapping, false otherwise
|
|
*/
|
|
function userExists(bytes32 usernameHash) public view returns (bool) {
|
|
// must check a property... bc solidity!
|
|
|
|
}
|
|
|
|
/**
|
|
* tweet
|
|
*
|
|
* Adds a tweet to the user's tweets and emits an event notifying listeners
|
|
* that a tweet happened. Assumes the user sending the transaction is the tweeter.
|
|
* {string} content - the tweet content
|
|
*/
|
|
function tweet(string content) public {
|
|
// ensure the sender has an account
|
|
require(owners[msg.sender].length > 0);
|
|
|
|
// get the username hash of the sender's account
|
|
bytes32 usernameHash = owners[msg.sender];
|
|
|
|
// get our user
|
|
|
|
// get our new tweet index
|
|
|
|
// update the user's tweets at the tweet index
|
|
|
|
// emit the tweet event and notify the listeners
|
|
}
|
|
|
|
}
|