let onLoad = new Promise(function (resolve, reject) {
  window.onload = resolve;
});

function dropdownDateToDaysDiff(val) {
  if (val === "one day") {
    return 1;
  } else if (val === "two days") {
    return 2;
  } else if (val === "three days") {
    return 3;
  } else if (val === "a week") {
    return 7;
  }

  throw new Exception("Unknown value " + val);
}

function dropdownBuildToVal(val) {
  if (val === "one build") {
    return 1;
  } else if (val === "two builds") {
    return 2;
  } else if (val === "three builds") {
    return 3;
  }

  throw new Exception("Unknown value " + val);
}

function betaBuildToTag(val) {
  return "FIREFOX_" + val.replace(".", "_") + "_RELEASE";
}

function subtractFromBetaBuild(version, val) {
  let major = version.substring(0, version.indexOf("b"));
  let betaBuild = version.substring(version.indexOf("b") + 1);
  return major + "b" + (Number(betaBuild) - val);
}

function checkIsBuildID(val) {
  let isBuildID = true;

  try {
    let res = parseBuildID(val);
    if (
      isNaN(res.year) ||
      isNaN(res.month) ||
      isNaN(res.day) ||
      isNaN(res.hour) ||
      isNaN(res.minute) ||
      isNaN(res.second) ||
      res.year < 2000 ||
      res.month < 0 ||
      res.month > 12 ||
      res.day < 0 ||
      res.day > 31 ||
      res.hour < 0 ||
      res.hour > 24
    ) {
      isBuildID = false;
    }
  } catch (ex) {
    isBuildID = false;
  }

  return isBuildID;
}

function getPushlogLink(channel) {
  let base;
  if (channel === "nightly") {
    base = "https://hg.mozilla.org/mozilla-central";
  }

  let firstAffected = document.getElementById(channel + "_first_affected")
    .value;
  if (firstAffected) {
    let isBuildID = checkIsBuildID(firstAffected);

    let startDateElem = document.getElementById(channel + "_days");
    let startDate = dropdownDateToDaysDiff(
      startDateElem.options[startDateElem.selectedIndex].value
    );
    let pushlogLinkElem = document.getElementById(channel + "_pushloglink");

    return new Promise(function (resolve, reject) {
      if (!isBuildID) {
        resolve(firstAffected);
      } else {
        fromBuildIDtoChangeset(firstAffected, channel).then((changesetURL) =>
          resolve(getRevFromChangeset(changesetURL, channel))
        );
      }
    }).then((changeset) =>
      getChangesetDate(changeset, channel).then((date) => {
        date.setDate(date.getDate() - startDate);
        let year = date.getFullYear();
        let month = toTwoDigits(date.getMonth() + 1);
        let day = toTwoDigits(date.getDate());
        let pushlogLink =
          base +
          "/pushloghtml?startdate=" +
          year +
          "-" +
          month +
          "-" +
          day +
          "&tochange=" +
          changeset;
        pushlogLinkElem.textContent = pushlogLinkElem.href = pushlogLink;
        return pushlogLink;
      })
    );
  }

  return null;
}

function getCommonLandings() {
  let pushlog_link_promises = [];

  // Nightly
  let nightlyPushlogLink = getPushlogLink("nightly");
  if (nightlyPushlogLink) {
    pushlog_link_promises.push(nightlyPushlogLink);
  }

  // Beta
  let betaFirstAffected = document.getElementById("beta_first_affected").value;
  if (betaFirstAffected) {
    let betaStartBuildElem = document.getElementById("beta_builds");
    let betaStartBuild = subtractFromBetaBuild(
      betaFirstAffected,
      dropdownBuildToVal(
        betaStartBuildElem.options[betaStartBuildElem.selectedIndex].value
      )
    );
    let betaPushlogLink =
      "https://hg.mozilla.org/releases/mozilla-beta/pushloghtml?fromchange=" +
      betaBuildToTag(betaStartBuild) +
      "&tochange=" +
      betaBuildToTag(betaFirstAffected);

    let betaPushlogLinkElem = document.getElementById("beta_pushloglink");
    betaPushlogLinkElem.textContent = betaPushlogLinkElem.href = betaPushlogLink;
    pushlog_link_promises.push(Promise.resolve(betaPushlogLink));
  }

  return Promise.all(
    pushlog_link_promises.map((link_promise) =>
      link_promise.then((link) =>
        fetch(link)
          .then((response) => response.text())
          .then((html) => {
            let bugs = [];

            let result;
            let re = /Bug ([0-9]+)/gi;
            while ((result = re.exec(html)) !== null) {
              bugs.push(result[1]);
            }

            return bugs;
          })
      )
    )
  )
    .then((arrays) => {
      if (arrays.length === 0) {
        return [];
      }

      return arrays[0].filter((elem) => {
        let is_everywhere = true;

        for (let array of arrays.slice(1)) {
          is_everywhere &= array.includes(elem);
        }

        return is_everywhere;
      });
    })
    .then((bugs) => new Set(bugs));
}

onLoad.then(function () {
  document.getElementById("getCommonLandings").onclick = function () {
    // Clean old results.
    let results = document.getElementById("results");

    while (results.firstChild) {
      results.removeChild(results.firstChild);
    }

    results.textContent = "";

    getCommonLandings().then((bugs) => {
      if (bugs.size === 0) {
        results.textContent = "None";
        return;
      }

      let a = document.createElement("a");
      a.textContent = "List of common landings on Bugzilla";
      a.href = "https://bugzilla.mozilla.org/buglist.cgi?bug_id=";
      a.id = "buglist";
      results.appendChild(a);

      for (let bug of bugs) {
        let a = document.getElementById("buglist");
        a.href += bug + ",";
      }
    });
  };
});