/* ------------------------------ Chrome Stuff ------------------------------ */

const openAndSend = ({url, message, timeout, callback=() => {}}) => 
  chrome.tabs.create({url: url})
  .then(tab => 
    setTimeout(() => 
      chrome.tabs.sendMessage(tab.id, message, callback),
      timeout
    ));

/* ----------------------------- Boolean Algebra ---------------------------- */

const openBoolean = msg =>
  openAndSend({
    url: "https://boolean-algebra.com",
    message: {type: "bool_alg", content: msg},
    timeout: 5000,
    callback: (res) => 
      openAndSend({
        url: "pages/answer/answer.html",
        message: {type: "bool_alg_ans", content: res.content},
        timeout: 1000,
      })
  });

/* ----------------------------- Induction Proof ---------------------------- */

openInduction = msg =>
  openAndSend({
    url: "https://www.wolframalpha.com/input/?i=" + encodeURIComponent(msg.expression),
    message: {type: "induction", content: msg},
    timeout: 15000,
    callback: (res) => 
      openAndSend({
        url: "pages/answer/answer.html",
        message: {type: "induction_ans", content: res.content},
        timeout: 1000,
      })
  });

/* ------------------------ Permutation, Combination ------------------------ */

const fac = (n) => {
  let val=1;
  for (let i = 2; i <= n; i++)
    val = val * i;
  return val;
}

const perm = (n, r) => fac(n) / fac(n - r);

const comb = (n, r) => fac(n) / (fac(n - r) * fac(r));

const openPerm = msg =>
  openAndSend({
    url: "pages/answer/answer.html",
    message: {type: "perms_ans", content: `\\[ \\nPr{${msg.n}}{${msg.r}} = ${perm(msg.n, msg.r)} \\]`},
    timeout: 1000,
  });

const openComb = msg =>
  openAndSend({
    url: "pages/answer/answer.html",
    message: {type: "combs_ans", content: `\\[ \\nCr{${msg.n}}{${msg.r}} = ${comb(msg.n, msg.r)} \\]`},
    timeout: 1000,
  })


/* ----------------------------- Message switch ----------------------------- */


chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
  console.log("Message recieved!");
  console.log("Checking message type!");

  switch (message.type) {
    case "bool_alg":
      openBoolean(message.content);
      break;

    case "induction":
      openInduction(message.content);
      break;

    case "perm":
      openPerm(message.content);
      break;

    case "comb":
      openComb(message.content);
      break;
  
    default:
      console.error("Couldn't recognize message!");
      break;
  }
});