API called in the wrong state.

[kshirsagardeepika]

export const main = Reach.App(() => {
  const A = Participant('Creator', {
    deployed: Fun([], Null),
    setAmount: UInt,
    setToken: Token,
  });
  const B = API('Buyer', {
    payMe:  Fun([], Null),
    myAddr: Fun([Address], Null),
  });
  init();

  A.publish();
  commit();
  A.only(() => {
    const [amt, tok]= declassify([interact.setAmount, interact.setToken]);
  });
  A.publish(amt, tok);
  A.interact.deployed();
  
  var amount = amt;
  invariant( balance() == 0 && balance(tok) >= 0 );
  
  while(true) {
    commit();
    A.pay([[1, tok]]);
    commit();
    // paySpec([tok]);
    const [[me], k1] = 
      call(B.myAddr).assume((a)=> {
        assume(a == this, 'No address'); })
        k1(null);
    commit();
    const [[], k2] =
      call(B.payMe)
          .pay(() => amount);
    k2(null);
    transfer(amount).to(A);
    transfer(1, tok).to(me);
    continue;
  }
  commit();
});

Getting error as
Error: Buyer.myAddr errored with Error: Assertion failed: API called in the wrong state. Currently in state: 6, expected: [5]
while calling api from frontend.
reach version - 0.1.10
reach hashes - 84dc282
reach-sh/stdlib - 0.1.10-rc.4

[jeapostrophe]

You are trying to call an API function when it is not allowed. My guess is that you are trying to call payMe when the program is waiting for a call to myAddr

[jeapostrophe]

You are not waiting for the log. next returns a promise

[kshirsagardeepika]

I am not able to figure out the issue so far. My requirement is, Creator sets token/nft and its price. Idea is multiple buyer should able to buy the NFTmicro . For this initially Creator is setting NFT details and in while loop Buyer is calling API to set his address and amount of nft and then Creator is paying for the token once address is set. Then finally when buyer clicks buy button in the front-end I am calling PayMe API.

export const main = Reach.App(() => {
const A = Participant('Creator', {
deployed: Fun([], Null),
setAmount: UInt,
setToken: Token,
});
const B = API('Buyer', {
payMe: Fun([], Bool),
myAddr: Fun([Address, UInt], Bool)
});
const E = Events('Announcer', {
announce: [Bytes(5)]
});
init();
A.publish();
commit();
A.interact.deployed();
A.only(() => {
const [amt, tok]= declassify([interact.setAmount, interact.setToken]);
});
A.publish(amt, tok);
var amount = amt;
invariant( balance() == 0 && balance(tok) >= 0 );
while(true) {
commit();
const [[me, count], k1] =
call(B.myAddr).assume((a, c)=> {
assume(a == this, 'No address');
check(c > 0, 'Count must be greater than 0');
})
k1(true);
commit();
A.pay([[count, tok]]);
E.announce('code1');
commit();
const [[], k2] =
call(B.payMe)
.pay(() => amount);
transfer(muldiv(balance(), 80, 100)).to(A);
transfer(balance()).to(A);
transfer(count, tok).to(me);
k2(true);
continue;
}
commit();
});

As suggested by @jay I have added Event which is triggered after Creator pays for the token and then only Buyer can execute buy operation. It works fine. But what strange things I noticed in the Event monitor in the front-end

this.attachctc.e.Announcer.announce.monitor((eve: any) => {
console.log('monitor',eve);
});

Now, if there are 5 buyers it triggers 5 times but problem is if any user clicks buy(calls PayMe API) before finishing all the 5 events it breaks and gives error something like
“currently in state 5 expected in state 4”.

How can we solve this issue. In reality there could be 100 buyers and it is not logical to wait for all the 100 events before enabling buy.

[jeapostrophe]

I think you've written your program in a very strange way. You have B call myAddr, then A pays, then B comes back and calls payMe. Thus, every time through the while loop you have three steps that must be done in sequence. I think you really want just one call where a buyer buys with no interaction from A and no second interaction.

[kshirsagardeepika]

Thanks Jay.

I have modified contract as

export const main = Reach.App(() => {
  const A = Participant('Creator', {
    deployed: Fun([], Null),
    setAmount: UInt,
    setToken: Token
  });
  const B = API('Buyer', {
    payMe:  Fun([], Bool),
    myAddr: Fun([Address, UInt], Bool)
  })
  init();
  A.publish();
  commit();
  A.interact.deployed();
  A.only(() => {
    const [amt, tok]= declassify([interact.setAmount, interact.setToken]);
  });
  A.publish(amt, tok);
  commit();
  A.pay([[10, tok]]);
  
  var [amount, nftcounter] = [amt, 10];
  invariant( balance() == 0 && balance(tok) == nftcounter );
  while(nftcounter > 0) {
    commit();
    // paySpec([tok]);
    const [[me, count], k1] =   
      call(B.myAddr)
        .assume((a, c)=> {
          assume(a == this, 'No address');
          check(c > 0, 'Count must be greater than 0');
        })
      k1(true);
        
    commit();
    const total = amount * count;
    const [[], k2] =  
      call(B.payMe)
        .pay(() => total);
        transfer(total).to(A);
        transfer(count, tok).to(me);
      k2(true);
    nftcounter = nftcounter - count;
    continue;
  }
  commit();
});

Now A will pay 10 tokens initially and multiple buyers can buy by specifying the count how much they want in B.myAdd. And when all tokens has been taken by different users while loop should terminate.
But getting theorem failed error when compiled.
Can you please suggest what's wrong with this code?

[kshirsagardeepika]

This issue has been resolved by adding condition before transfer as below.

const [[], k2] = 
      call(B.payMe)
        .pay(() => total)
      
        if(num <= nftcounter) {
          transfer(total).to(A);
          transfer(num, tok).to(me);
        }
      k2(num);

Thanks.