TwitterSmartContract.sol

// SPDX-License-Identifier: MIT

pragma solidity >=0.5.0 <0.9.0;



contract TweetContract {



struct Tweet{

uint id;

address author;

string content;

uint createdAt;

}

struct Message{

uint id;

string content;

address from;

address to;

uint createdAt;

}



mapping(uint=>Tweet) public tweets;

mapping(address=>uint[]) public tweetsOf;//0xabc - 2,10,15,19,20,22

mapping(address=>Message[]) public conversations;

mapping(address=>mapping(address=>bool)) public operators;

mapping(address=>address[]) public following;



uint nextId;//0

uint nextMessageId;



function _tweet(address _from,string memory _content) internal{//tweet access check - owner,authority

require(_from==msg.sender || operators[_from][msg.sender],"You don't have access");

tweets[nextId]=Tweet(nextId,_from,_content,block.timestamp);

tweetsOf[_from].push(nextId);

nextId=nextId+1;

}



function _sendMessage(address _from,address _to,string memory _content) internal{ //tweet access check - owner,authority

require(_from==msg.sender || operators[_from][msg.sender],"You don't have access");

conversations[_from].push(Message(nextMessageId,_content,_from,_to,block.timestamp));

nextMessageId++;

}



function tweet(string memory _content) public { //owner

_tweet(msg.sender,_content);

}

function tweet(address _from,string memory _content) public{//owner->address access

_tweet(_from,_content);

}



function sendMessage(string memory _content,address _to) public {//owner

_sendMessage(msg.sender,_to,_content);

}

function sendMessage(address _from,address _to,string memory _content) public { //owner - address access

_sendMessage(_from,_to,_content);

}



function follow(address _followed) public{//abc - def,ghi,opr

following[msg.sender].push(_followed);

}



function allow(address _operator) public{

operators[msg.sender][_operator]=true;

}

function disallow(address _operator) public{

operators[msg.sender][_operator]=false;

}



function getLatestTweets(uint count) public view returns(Tweet[] memory){

require(count>0 && count<=nextId,"Count is not proper");

Tweet[] memory _tweets = new Tweet[](count); //array length - count



uint j;



for(uint i=nextId-count;i<nextId;i++){//count = 5 nextId=7; 7-5=2,3,4,5,6

Tweet storage _structure = tweets[i];

_tweets[j]=Tweet(_structure.id,

_structure.author,

_structure.content,

_structure.createdAt);

j=j+1;

}

return _tweets;

}



function getLatestofUser(address _user,uint count) public view returns(Tweet[] memory) { //7

Tweet[] memory _tweets= new Tweet[](count);//new memory array whoose length is count

//tweetsOf[_user] is having all the id's of the user

uint[] memory ids = tweetsOf[_user]; ///ids is an array



require(count>0 && count<=ids.length,"Count is not defined");

uint j;

for (uint i= ids.length-count;i<ids.length;i++){//5-3 = 2 to 5

Tweet storage _structure = tweets[ids[i]];//i=2 id[2]=15 tweets[15]

_tweets[j]=Tweet(_structure.id,

_structure.author,

_structure.content,

_structure.createdAt);

j=j+1;

}

return _tweets;

}



}