import { View, Text, StyleSheet } from 'react-native'
import React, { useEffect, useState } from 'react'
import { Link } from 'expo-router'
import databaseHelper from '../service/databasehelper.js'
import AppContext from '../service/AppContext.js'

const styles = StyleSheet.create({
  container: {
    flex: 1,
    display: 'flex',
    alignItems: 'center',
    justifyContent: 'center'
  },
  linkContainer: {
    display: 'flex',
    flexDirection: 'column',
    justifyContent: 'space-around',
    width: '50%',
    margin: 100,
  },
  linkText: {
    fontSize: 20,
    textAlign: 'center',
    fontWeight: 'bold'
  }
})



export default function Index() {

  //Github copilot gave me the knowledge to fix my error regarding using async functions in useEffect
  //The previous error was that await functions returned a promise, and useEffect does not support promises/returning anything (except clean up)
  //Now the initiliasing of the db is wrapped in an async function, this async function does not return anything.
  //asyncInitDb is also local to the scope of UseEffect.
  //The [] at the end of useEffect is an empty dependency array, this means that the useEffect will only run once, when the component mounts.
  useEffect(() => {
    async function asyncInitDb() {

      const dbInitVal = await databaseHelper.readOperatingValues("SELECT value FROM operatingValues WHERE name = 'dbInit'");

      try {
        if (dbInitVal === 0) {
          await databaseHelper.initDatabase()
          databaseHelper.readDb()
        }
      } catch (TypeError) {
        console.log("DB not initialised")
        await databaseHelper.initDatabase()
        databaseHelper.readDb()
      }
    }

      asyncInitDb();
  }, []);

  const [template1, setTemplate1] = useState([]);
  const [template2, setTemplate2] = useState([]);
  const [isLoading, setIsLoading] = useState(true);  //Prevents data from rendering before data is fetched from the database

  useEffect(() => {
      /**
       * Inserts workout templates into the database and reads all templates.
       * @returns {Promise<void>}
       */
      async function testTemplatesAndRead() {
          const templatesInit = await databaseHelper.readOperatingValues("SELECT value FROM operatingValues WHERE name = 'templatesInit'");

          if (templatesInit[0].value === 0) {

              //Create template the "pull" template.
              await databaseHelper.insertWorkoutTemplate(1, "Push", 1, 0, 20, 1, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 1, 0, 15, 2, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 1, 0, 10, 3, 1);

              await databaseHelper.insertWorkoutTemplate(1, "Push", 7, 55, 8, 1, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 7, 55, 6, 2, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 7, 55, 4, 3, 1);

              await databaseHelper.insertWorkoutTemplate(1, "Push", 9, 25, 8, 1, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 9, 25, 6, 2, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 9, 25, 4, 3, 1);

              await databaseHelper.insertWorkoutTemplate(1, "Push", 14, 25, 10, 1, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 14, 25, 8, 2, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 14, 25, 6, 3, 1);

              await databaseHelper.insertWorkoutTemplate(1, "Push", 12, 30, 8, 1, 1);
              await databaseHelper.insertWorkoutTemplate(1, "Push", 12, 30, 6, 2, 1);

              //The "push" template.
              await databaseHelper.insertWorkoutTemplate(2, "Pull", 4, 12, 8, 1, 1);
              await databaseHelper.insertWorkoutTemplate(2, "Pull", 4, 12, 6, 2, 1);

              await databaseHelper.insertWorkoutTemplate(2, "Pull", 6, 120, 8, 1, 1);
              await databaseHelper.insertWorkoutTemplate(2, "Pull", 6, 120, 6, 2, 1);

              await databaseHelper.insertWorkoutTemplate(2, "Pull", 11, 0, 8, 1, 1);
              await databaseHelper.insertWorkoutTemplate(2, "Pull", 11, 0, 6, 2, 1);

              await databaseHelper.readOperatingValues("UPDATE operatingValues SET value = 1 WHERE name = 'templatesInit'");
          }

          const tempTemplate1 = await databaseHelper.readTemplates("SELECT * FROM Templates INNER JOIN Workouts ON Templates.workoutId = Workouts.workoutId WHERE Templates.templateId = 1");
          console.log("This is template1" + tempTemplate1);
          setTemplate1(tempTemplate1);

          const tempTemplate2 = await databaseHelper.readTemplates("SELECT * FROM Templates INNER JOIN Workouts ON Templates.workoutId = Workouts.workoutId WHERE Templates.templateId = 2");
          console.log("This is template2" + tempTemplate2);
          setTemplate2(tempTemplate2);

          setIsLoading(false); //Indicates that the data has been fetched from the database

  }

  testTemplatesAndRead();
}, []);

  return (
    <AppContext.Provider value={{ template1, template2, isLoading }}>
      <View style={styles.container}>

        <View style={styles.linkContainer}>
          <Link push href="/home">
            <Text style={styles.linkText}>Home</Text>
          </Link>
        </View>

        <View style={styles.linkContainer}>
          <Link push href="/trainer">
            <Text style={styles.linkText}>Trainer</Text>
          </Link>
        </View>

      </View>
    </AppContext.Provider>
  )
}