Introduce realm and persist temperatures

db.js

@@ -0,0 +1,57 @@
+import realm from 'realm'
+import { v4 as uuid } from 'uuid'
+
+let db
+let cycleDaysSortedbyTempValueView = []
+
+const TemperatureSchema = {
+  name: 'Temperature',
+  properties: {
+    value: 'int',
+    exclude: 'bool'
+  }
+}
+
+const CycleDaySchema = {
+  name: 'CycleDay',
+  primaryKey: 'key',
+  properties: {
+    key: 'string',
+    date: 'date',
+    temperature: {
+      type: 'Temperature',
+      optional: true
+    }
+  }
+}
+
+async function openDatabase() {
+  db = await realm.open({
+    schema: [
+      CycleDaySchema,
+      TemperatureSchema
+    ],
+    // we only want this in dev mode
+    deleteRealmIfMigrationNeeded: true
+  })
+  // just for testing purposes, the highest temperature will be topmost
+  // because I was too layz to make a scroll view
+  cycleDaysSortedbyTempValueView = db.objects('CycleDay').sorted('temperature.value', true)
+}
+
+async function saveTemperature(date, temperature) {
+  db.write(() => {
+    const doc = {
+      key: uuid(),
+      date,
+      temperature
+    }
+    db.create('CycleDay', doc)
+  })
+}
+
+export {
+  cycleDaysSortedbyTempValueView,
+  openDatabase,
+  saveTemperature
+}