# node -v
v10.24.1

struct Book {
       string name;
       string description;
       bool valid; // false if been borrowed
       uint256 price; // TRX per day
       address owner; // owner of the book
   }

uint256 public bookId;

mapping (uint256 => Book) public books;

struct Tracking {
       uint256 bookId;
       uint256 startTime;  // start time, in timestamp
       uint256 endTime;    // end time, in timestamp
       address borrower;   // borrower's address
}

uint256 public trackingId;

mapping(uint256 => Tracking) public trackings;

/**
* @dev Add a Book with predefined `name`, `description` and `price`
* to the library.
* * Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {NewBook} event.
*/
function addBook(string memory name, string memory description, uint256 price) public returns (bool) {
       Book memory book = Book(name, description, true, price, _msgSender());

       books[bookId] = book;

       emit NewBook(bookId++);

       return true;
}

/**
* @dev Emitted when a new book is added to the library.
* Note bookId starts from 0.
*/
event NewBook(uint256 bookId);

/**
* @dev Borrow a book has `_bookId`. The rental period starts from
* `startTime` ends with `endTime`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a `NewRental` event.
*/
function borrowBook(uint256 _bookId, uint256 startTime, uint256 endTime) public payable returns(bool) {
       Book storage book = books[_bookId];

       require(book.valid == true, "The book is currently on loan");

       require(_msgValue() == book.price * _days(startTime, endTime), "Incorrect fund sent.");

       _sendTRX(book.owner, _msgValue());

       _createTracking(_bookId, startTime, endTime);

       emit NewRental(_bookId, trackingId++);
 }

/**
* @dev Delete a book from the library. Only the book's owner or the
* library's owner is authorised for this operation.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a `DeleteBook` event.
*/
function deleteBook(uint256 _bookId) public returns(bool) {
       require(_msgSender() == books[_bookId].owner || isOwner(),
               "You are not authorised to delete this book.");
      
       delete books[_bookId];

       emit DeleteBook(_bookId);
    return true;
}

/**
* @dev Send TRX to the book's owner.
*/
function _sendTRX(address receiver, uint256 value) internal {
    payable(address(uint160(receiver))).transfer(value);
}

/**
* @dev Create a new rental tracking.
*/
function _createTracking(uint256 _bookId, uint256 startTime, uint256 endTime) internal {
     trackings[trackingId] = Tracking(_bookId, startTime, endTime, _msgSender());

     Book storage book = books[_bookId];

     book.valid = false;
}

export async function setLibraryContract() {
     bookRentContract = await  window.tronWeb.contract().at('TMH1jAzAjCp2GdWm7hXSmhYyD3iKdpExoZ');
}

async mounted() {
   // init contract object
   await setLibraryContract();
   // fetch all books
   const books = await fetchAllBooks();
   this.posts = books;
 },

postAd() {
     // convert price from TRX to SUN
     postBookInfo(this.title,this.description,tronWeb.toSun(this.price));
}

const result = await bookRentContract.addBook(name,description,price).send({
   feeLimit:100_000_000,
   callValue:0,
   shouldPollResponse:true
 });

const books = [];
 
 const bookId  = await bookRentContract.bookId().call();
 //iterate from 0 till bookId
 for (let i = 0; i < bookId; i++){
   const book = await bookRentContract.books(i).call()
   if(book.name!="") // filter the deleted books
   {
     books.push(
       {id: i,name: book.name,description: book.description,price: tronWeb.fromSun(book.price)}
     )
   } 
 }
return books

// get Start date
     const startDay = this.getDayOfYear(this.startDate)
     // get End date
     const endDay = this.getDayOfYear(this.endDate)
     // price calculation
     const totalPrice =tronWeb.toSun(this.propData.price) * (endDay - startDay)
     // call metamask.bookProperty
     borrowBook(this.propData.id, startDay, endDay, totalPrice)

const result = await bookRentContract.borrowBook(spaceId,checkInDate,checkOutDate).send({
   feeLimit:100_000_000,
   callValue:totalPrice,
   shouldPollResponse:true
 });

npm run dev