Enhancement: Paginate conversation calls in tabs (#560)

* Use conversationPage module for pagination

* Load more conversations

* Reset list if conversation status is changed

* Add specs to conversationPage

* Reset filter when page is re-mounted

* Update text

* Update text

app/javascript/dashboard/store/modules/conversationPage.js

@@ -0,0 +1,70 @@
+import Vue from 'vue';
+import * as types from '../mutation-types';
+
+const state = {
+  currentPage: {
+    me: 0,
+    unassigned: 0,
+    all: 0,
+  },
+  hasEndReached: {
+    me: false,
+    unassigned: false,
+    all: false,
+  },
+};
+
+export const getters = {
+  getHasEndReached: $state => filter => {
+    return $state.hasEndReached[filter];
+  },
+  getCurrentPage: $state => filter => {
+    return $state.currentPage[filter];
+  },
+};
+
+export const actions = {
+  setCurrentPage({ commit }, { filter, page }) {
+    commit(types.default.SET_CURRENT_PAGE, { filter, page });
+  },
+  setEndReached({ commit }, { filter }) {
+    commit(types.default.SET_CONVERSATION_END_REACHED, { filter });
+  },
+  reset({ commit }) {
+    commit(types.default.CLEAR_CONVERSATION_PAGE);
+  },
+};
+
+export const mutations = {
+  [types.default.SET_CURRENT_PAGE]: ($state, { filter, page }) => {
+    Vue.set($state.currentPage, filter, page);
+  },
+  [types.default.SET_CONVERSATION_END_REACHED]: ($state, { filter }) => {
+    if (filter === 'all') {
+      Vue.set($state.hasEndReached, 'unassigned', true);
+      Vue.set($state.hasEndReached, 'me', true);
+    }
+    Vue.set($state.hasEndReached, filter, true);
+  },
+  [types.default.CLEAR_CONVERSATION_PAGE]: $state => {
+    $state.currentPage = {
+      me: 0,
+      unassigned: 0,
+      all: 0,
+    };
+
+    $state.hasEndReached = {
+      me: false,
+      unassigned: false,
+      all: false,
+    };
+  },
+};
+
+export default {
+  namespaced: true,
+  state,
+  getters,
+  actions,
+  mutations,
+};