ProjectLaogai/app/src/main/java/org/mosad/seil0/projectlaogai/controller/CacheController.kt

/**
 * ProjectLaogai
 *
 * Copyright 2019-2020  <seil0@mosad.xyz>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 *
 */

package org.mosad.seil0.projectlaogai.controller

import android.content.Context
import android.util.Log
import com.google.gson.Gson
import com.google.gson.GsonBuilder
import com.google.gson.JsonParser
import com.google.gson.reflect.TypeToken
import kotlinx.coroutines.*
import org.mosad.seil0.projectlaogai.controller.PreferencesController.Companion.cCourse
import org.mosad.seil0.projectlaogai.hsoparser.Course
import org.mosad.seil0.projectlaogai.hsoparser.MensaMenu
import org.mosad.seil0.projectlaogai.hsoparser.TimetableCourseWeek
import java.io.BufferedReader
import java.io.File
import java.io.FileReader
import java.util.*
import kotlin.collections.ArrayList

class CacheController(cont: Context) {

    private val className = "CacheController"
    private val context = cont

    init {
        val cal = Calendar.getInstance()
        val currentDay = Calendar.getInstance().get(Calendar.DAY_OF_WEEK)
        val currentTime = System.currentTimeMillis() / 1000

        // check if we need to update the mensa data before displaying it
        readMensa(context)
        cal.time = Date(mensaMenu.meta.updateTime * 1000)

        // if a) it's monday and the last cache update was on sunday or b) the cache is older than 24hr, update blocking
        if ((currentDay == Calendar.MONDAY && cal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) || (currentTime - mensaMenu.meta.updateTime) > 86400) {
           Log.i(className, "update mensa blocking")
            GlobalScope.launch(Dispatchers.Default) { TCoRAPIController.getMensa(context).join() }
        }

        // check if we need to update the timetables before displaying them
        readTimetable(cCourse.courseName, 0, context)
        cal.time = Date(timetables[0].meta.updateTime * 1000)

        // if a) it`s monday and the last cache update was not on a sunday or b) the cache is older than 24hr, update blocking
        if ((currentDay == Calendar.MONDAY && cal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY) || (currentTime - timetables[0].meta.updateTime) > 86400) {
            Log.i(className, "updating timetable after sunday!")

            GlobalScope.launch(Dispatchers.Default) {
                val threads = listOf(
                    TCoRAPIController.getTimetable(cCourse.courseName, 0, context),
                    TCoRAPIController.getTimetable(cCourse.courseName, 1, context)
                )
                threads.joinAll()
            }

            TCoRAPIController.getTimetable(cCourse.courseName, 0, context)
            TCoRAPIController.getTimetable(cCourse.courseName, 1, context)
        }

        // check if an update is necessary, not blocking
        if (currentTime - PreferencesController.coursesCacheTime > 86400)
            TCoRAPIController.getCoursesList(context)

        if (currentTime - PreferencesController.mensaCacheTime > 10800)
            TCoRAPIController.getMensa(context)

        if (currentTime - PreferencesController.timetableCacheTime > 10800) {
            TCoRAPIController.getTimetable(cCourse.courseName, 0, context)
            TCoRAPIController.getTimetable(cCourse.courseName, 1, context)
        }

        readStartCache(cCourse.courseName)
    }

    companion object {
        var coursesList = ArrayList<Course>()
        var timetables = ArrayList<TimetableCourseWeek>()
        var mensaMenu = MensaMenu()

        /**
         * read the courses list from the cached file
         * add them to the coursesList object
         */
        private fun readCoursesList(context: Context) {
            val file = File(context.filesDir, "courses.json")

            // make sure the file exists
            if (!file.exists())
                runBlocking { TCoRAPIController.getCoursesList(context).join() }

            val fileReader = FileReader(file)
            val bufferedReader = BufferedReader(fileReader)
            val coursesObject = JsonParser.parseString(bufferedReader.readLine()).asJsonObject

            coursesList = Gson().fromJson(
                coursesObject.getAsJsonArray("courses"),
                object : TypeToken<List<Course>>() {}.type
            )
        }

        /**
         * get the MensaMenu object from the cached json,
         * if cache is empty create the cache file
         */
        fun readMensa(context: Context) {
            val file = File(context.filesDir, "mensa.json")

            // make sure the file exists
            if (!file.exists())
                runBlocking { TCoRAPIController.getMensa(context).join() }

            val fileReader = FileReader(file)
            val bufferedReader = BufferedReader(fileReader)
            val mensaObject = JsonParser.parseString(bufferedReader.readLine()).asJsonObject

            mensaMenu = GsonBuilder().create().fromJson(mensaObject, MensaMenu().javaClass)
        }

        /**
         * read the weeks timetable from the cached file
         * @param courseName the course name (e.g AI1)
         * @param week the week to read (0 for the current and so on)
         */
        fun readTimetable(courseName: String, week: Int, context: Context) {
            val file = File(context.filesDir, "timetable-$courseName-$week.json")

            // make sure the file exists
            if (!file.exists())
                runBlocking { TCoRAPIController.getTimetable(courseName, week, context).join() }

            val fileReader = FileReader(file)
            val bufferedReader = BufferedReader(fileReader)
            val timetableObject = JsonParser.parseString(bufferedReader.readLine()).asJsonObject

            // make sure you add the single weeks in the exact order!
            if (timetables.size > week) {
                timetables[week] = (Gson().fromJson(timetableObject, TimetableCourseWeek().javaClass))
            } else {
                timetables.add(Gson().fromJson(timetableObject, TimetableCourseWeek().javaClass))
            }
        }
    }

    /**
     * read coursesList, mensa (current and next week), timetable (current and next week)
     * @param courseName the course name (e.g AI1)
     */
    private fun readStartCache(courseName: String) {
        readCoursesList(context)
        readMensa(context)
        readTimetable(courseName, 0, context)
        readTimetable(courseName, 1, context)
    }

}