const admin = require("firebase-admin");

const timeDiff = (ds1, ds2) => {
  const d1 = new Date(ds1);
  const d2 = new Date(ds2);
  var diff = (d2.getTime() - d1.getTime()) / 1000;
  diff /= 60 * 60;
  return Math.abs(Math.round(diff));
};

const roomIdList = async (refs) => {
  const startedTime = new Date();
  return await admin
    .firestore()
    .getAll(...refs)
    .then((roomDataList) =>
      roomDataList.map((roomData) => {
        if (
          !roomData.exists ||
          (timeDiff(roomData.createTime.toDate(), startedTime) >= 24 &&
            timeDiff(roomData.updateTime.toDate(), startedTime) >= 4) ||
          timeDiff(roomData.updateTime.toDate(), startedTime) >= 12
        ) {
          return roomData.id;
        }
      })
    )
    .then((ids) => ids.filter((v) => v !== undefined));
};

const batchDeleteRooms = async (roomList, totalNumber, batch, count = 0) => {
  if (roomList.length > 0 && count < 500) {
    const roomId = roomList.splice(0, 1)[0];
    await admin
      .firestore()
      .collection(`rooms/${roomId}/messages`)
      .listDocuments()
      .then((docs) => {
        docs.map((doc) => {
          if (count < 500) {
            batch.delete(doc);
            count++;
          }
        });
        return;
      });
    await admin
      .firestore()
      .collection(`rooms/${roomId}/users`)
      .listDocuments()
      .then((docs) => {
        docs.map((doc) => {
          if (count < 500) {
            batch.delete(doc);
            count++;
          }
        });
        return;
      });
    if (count < 500) {
      await batch.delete(admin.firestore().collection("rooms").doc(roomId));
      count++;
    }
    await batchDeleteRooms(roomList, totalNumber, batch, count);
    return;
  } else {
    console.info(
      `[DONE]\tWEBHOOKS/Room Clean Up\tDeleted all ${totalNumber} rooms`
    );
    return;
  }
};

module.exports = async (req, res) => {
  const roomList = await admin
    .firestore()
    .collection("rooms")
    .listDocuments()
    .then((rL) => rL)
    .catch((err) => {
      console.error(
        `Failed to run auto clean up (get room list) @ ${new Date().toLocaleTimeString()}`,
        err
      );
    });

  if (roomList.length > 0) {
    var ids = await roomIdList(roomList);
    if (ids.length > 0) {
      const totalNumber = ids.length;
      console.info(
        `[PROGRESS]\tWEBHOOKS/Room Clean Up\tROOMS ${JSON.stringify(ids)}`
      );
      try {
        const batch = admin.firestore().batch();
        await batchDeleteRooms(ids, totalNumber, batch);
        await batch.commit();
        res.status(200).send({
          message: `[${new Date().toLocaleString("en-US", {
            timeZone: "America/New_York",
          })}]    [DONE]    WEBHOOKS    Room Clean Up   ${totalNumber} rooms deleted`,
        });
      } catch (err) {
        res.status(400).send({
          message: `[${new Date().toLocaleString("en-US", {
            timeZone: "America/New_York",
          })}]    [ERROR]   WEBHOOKS    Room Clean Up   Batch delete failed - ${JSON.stringify(
            err
          )}`,
        });
      }
    } else {
      console.info(`[DONE]\tWEBHOOKS/Room Clean Up\tNo rooms to delete`);
      res.status(200).send({
        message: `[${new Date().toLocaleString("en-US", {
          timeZone: "America/New_York",
        })}]    [DONE]    WEBHOOKS    Room Clean Up    No rooms to delete`,
      });
    }
  }

  return;
};