TheCitadelofRicks/src/main/kotlin/org/mosad/thecitadelofricks/APIController.kt

/**
 * TheCitadelofRicks
 *
 * Copyright 2019  <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.thecitadelofricks

import kotlinx.coroutines.*
import org.mosad.thecitadelofricks.hsoparser.CourseListParser
import org.mosad.thecitadelofricks.hsoparser.MensaParser
import org.mosad.thecitadelofricks.hsoparser.TimetableParser
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RequestParam
import org.springframework.web.bind.annotation.RestController
import java.util.ArrayList


@RestController
class APIController {

    private val mensaLink = "https://www.swfr.de/de/essen-trinken/speiseplaene/mensa-offenburg/"
    private val mensaName = "Offenburg"

    private var coursesLinkList = ArrayList<Course>()
    private var coursesLastUpdate: Long = 0

    private var timetableList = ArrayList<TimetableCourse>() // this list contains all timetables

    private var mensaCurrentWeek = MensaWeek()
    private var mensaNextWeek = MensaWeek()
    private var mensaLastUpdate: Long = 0

    init {
        initUpdates()
    }

    @RequestMapping("/courses")
    fun courses(): CoursesList {
        println("courses request at " + System.currentTimeMillis() / 1000 + "!")
        updateCoursesAsync() // check if we need to update and perform the update if so
        return  CoursesList(CoursesMeta(coursesLinkList.size, coursesLastUpdate), coursesLinkList)
    }

    @RequestMapping("/mensamenu")
    fun mensamenu(): Mensa {
        println("mensamenu request at " + System.currentTimeMillis() / 1000 + "!")
        updateMensa() // check if we need to update and perform the update if so
        return  Mensa(MensaMeta(mensaName, mensaLastUpdate), mensaCurrentWeek, mensaNextWeek)
    }

    @RequestMapping("/timetable")
    fun timetable(@RequestParam(value = "courseName", defaultValue = "AI4") courseName: String): TimetableCourse {
        println("timetable request at " + System.currentTimeMillis() / 1000 + "!")
        updateTimetableCourse(courseName) // check if we need to update and perform the update if so
        return timetableList.stream().filter { x -> x.meta.courseName == courseName }.findAny().orElse(null)
    }

    /**
     * checks if we need to update the courses list and if so does it async
     * during the update process the old data will be returned for a API request
     * update if the last update was 24 hours ago
     */
    private fun updateCoursesAsync() = GlobalScope.launch {
        val currentTime = System.currentTimeMillis() / 1000
        if ((currentTime - coursesLastUpdate) > 86400) {
            coursesLinkList = CourseListParser().getCourseLinks()
            coursesLastUpdate = currentTime
            println("updated courses successful at "  + System.currentTimeMillis() / 1000)
        } else {
            println("courses are up to date!")
        }
    }

    /**
     * this function checks if we need to update the mensa menu list and if so does it
     * during the update process the old data will be returned for a API request
     * update if the last update was 6 hours ago
     */
    private fun updateMensa() = GlobalScope.launch {
        val currentTime = System.currentTimeMillis() / 1000
        if ((currentTime - coursesLastUpdate) > 21600) {
            mensaCurrentWeek = MensaParser().getMensaMenu(mensaLink)
            mensaNextWeek = MensaParser().getMensaMenu(MensaParser().getMenuLinkNextWeek(mensaLink))
            mensaLastUpdate = currentTime
            println("updated mensamenu successful at "  + System.currentTimeMillis() / 1000)
        } else {
            println("mensamenu is up to date!")
        }
    }

    /**
     * this function checks if we need to update the timetable for a given course and if so does it
     * during the update process the old data will be returned for a API request
     * update if the last update was 6 hours ago
     */
    private fun updateTimetableCourse(courseName: String) = runBlocking {
        val currentTime = System.currentTimeMillis() / 1000
        var currentWeek = TimetableWeek()
        var nextWeek = TimetableWeek()
        // check if the timetable already exists and is up to date
        val result = timetableList.stream().filter { x -> x.meta.courseName == courseName }.findAny().orElse(null)

        when {
            // there is no such course yet, create one
            result == null -> {
                val courseLink = coursesLinkList.stream().filter { x -> x.courseName == courseName }.findFirst().orElse(null).courseLink
                val timetableMeta = TimetableMeta(courseName, courseLink, currentTime)

                val jobCurrent = GlobalScope.async {
                    currentWeek = TimetableParser().getTimeTable(courseLink)
                }

                val jobNext = GlobalScope.async {
                    nextWeek = TimetableParser().getTimeTable(courseLink.replace("week=0","week=1"))
                }

                jobCurrent.await()
                jobNext.await()

                timetableList.add(TimetableCourse(timetableMeta, currentWeek, nextWeek))
            }
            // update
            (currentTime - result.meta.time) > 21600 -> {
                val index = timetableList.indexOf(result)
                println("update $courseName wit index: $index")

                GlobalScope.async {
                    val courseLink = coursesLinkList.stream().filter { x -> x.courseName == courseName }.findFirst().orElse(null).courseLink

                    timetableList[index].currentWeek = TimetableParser().getTimeTable(courseLink)
                    timetableList[index].nextWeek = TimetableParser().getTimeTable(courseLink.replace("week=0","week=1"))
                    timetableList[index].meta.time = currentTime
                }
            }
            else -> println("timetable for $courseName is up to date")
        }
    }

    private fun initUpdates() = runBlocking {
        // get all courses on startup
        val jobCourseUpdate = GlobalScope.async{
            coursesLinkList = CourseListParser().getCourseLinks()
            coursesLastUpdate = System.currentTimeMillis() / 1000
        }

        // get the current and next weeks mensa menus
        val jobCurrentMensa = GlobalScope.async{
            mensaCurrentWeek = MensaParser().getMensaMenu(mensaLink)
        }

        val jobNextMensa = GlobalScope.async{
            mensaCurrentWeek = MensaParser().getMensaMenu(mensaLink)
            mensaLastUpdate = System.currentTimeMillis() / 1000
        }

        jobCourseUpdate.await()
        jobCurrentMensa.await()
        jobNextMensa.await()
    }

}