import {randId} from "./random";
import {fetchDelete, fetchGet, fetchPatch, fetchPost} from "./fetcher";
import {nullish} from "./null";

const localData = {};
const callbacks = [];

export function subscribeToGroup(groupId, callback) {
  const callbackId = randId();

  callbacks.push({callbackId, groupId, callback});

  if (groupId >= 0) {
    fetchOne(groupId);
  } else {
    fetchAll();
  }

  return callbackId;
}

export function unsubscribeFromGroup(callbackId) {
  const callback = callbacks.find(c => c !== null && c.callbackId === callbackId);
  const index = callbacks.indexOf(callback);
  callbacks[index] = null;
}

export function addGroup(name) {
  fetchPost("/group/", {name}).then(({data, error}) => {
    if (error === null) {
      handleGroup(data);
      fetchAll();
    }
  })
}

export function deleteGroup(groupId) {
  fetchDelete(`/group/${groupId}`).then(({data, error}) => {
    if (error === null) {
      fetchAll();
    }
  });
}

export function saveGroupMetadata(groupId, name) {
  fetchPatch(`/group/${groupId}`, {name}).then(({data, error}) => {
    if (error === null) {
      fetchAll();
    }
  });
}

export function savePermissions(groupId, userId, permissions) {
  fetchPatch(`/group/${groupId}/permission/${userId}`, permissions).then(({data, error}) => {
    if (error === null) {
      fetchAll();
    }
  });
}

function fetchAll() {
  fetchGet("/group/").then(({data, error}) => {
    if (error === null) {
      handleGroups(data);
    }
  });
}

function fetchOne(id) {
  fetchGet(`/group/${id}`).then(({data, error}) => {
    if (error === null) {
      handleGroup(data);
    }
  });
}

function handleGroups(groups) {
  groups.forEach(g => handleGroup(g));

  for (let key in localData) {
    if (localData.hasOwnProperty(key) && nullish(groups.find(g => g.id === key))) {
      delete localData[key];
    }
  }

  dispatch(groups);
}

function handleGroup(group) {
  localData[group.id] = group;

  dispatch(group);
}

function dispatch(data) {
  if (Array.isArray(data)) {
    callbacks
      .filter(c => c !== null)
      .filter(c => c.groupId === -1)
      .forEach(c => c.callback(data));
  } else {
    callbacks
      .filter(c => c !== null)
      .filter(c => c.groupId === data.id)
      .forEach(c => c.callback(data));
  }
}