ViewPagerChapterFragment.kt

@ExperimentalCoroutinesApi
@AndroidEntryPoint
class ViewPagerChapterFragment :
    BaseFragment<FragmentViewPagerChapterBinding, ViewPagerChapterViewModel>(R.layout.fragment_view_pager_chapter),
    OnRequestAction {

    // var region
    override val viewModel: ViewPagerChapterViewModel by viewModels()

    @Inject
    lateinit var authService: HwAuthService
    private var chapterId = 0
    private var chapterContentList: List<ChapterContentModel>? = null
    private val tabTitles = arrayListOf<String>()
    private val fragmentList = arrayListOf<Fragment>()
    private var contentQuestionIndexList = ArrayList<Int>()
    private var designList: List<String>? = null
    private val args: ViewPagerChapterFragmentArgs by navArgs()
    // end region

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        chapterId = args.chapterId
        CommonConstants.CHAPTER_ID = chapterId
        val userId = authService.getUserId()
        showProgressDialog()
        viewModel.getChapter(userId, chapterId)
        initObserver()
    }

    /**
     * initialize the fragmentList, adapter,viewPager2 and tabTitles
     */
    private fun initObserver() {
        viewModel.chapter.observe(viewLifecycleOwner, Observer {
            when (it.status) {
                Resource.Status.SUCCESS -> {
                    it.data.let { res ->
                        hideProgressDialog()
                        if (res?.contents != null) {
                            chapterContentList = res.contents!!
                            designList = res.design
                            val designSequence = 0 until designList!!.size
                            for (i in designSequence) {
                                contentQuestionIndexList =
                                    getContentAndQuestionIndex(chapterContentList!!, i)
                                val contentIndex = contentQuestionIndexList[0]
                                val questionIndex = contentQuestionIndexList[1]
                                if (designList!![i].equals("info")) {
                                    fragmentList.add(
                                        i,
                                        ChapterDescriptionFragment(chapterContentList!![contentIndex])
                                    )
                                    tabTitles.add(i, "I")
                                } else {
                                    fragmentList.add(
                                        i,
                                        ChapterQuestionFragment(chapterContentList!![contentIndex].questions!![questionIndex])
                                    )
                                    tabTitles.add(i, "Q")
                                }
                            }
                            fragmentList.add(ChapterCompletedFragment())
                            tabTitles.add("C")
                            initialize()
                        }
                    }
                }
                Resource.Status.LOADING -> {
                    Toast.makeText(context, "Loading", Toast.LENGTH_SHORT).show()
                    hideProgressDialog()
                }
                Resource.Status.ERROR -> {
                    LogUtils.d("$this prepareView")
                    Toast.makeText(context, it.message, Toast.LENGTH_SHORT).show()
                    hideProgressDialog()
                }
            }
        })
    }

    // algorithm for get chapter content sequence with description and questions
    private fun getContentAndQuestionIndex(
        contents: List<ChapterContentModel>,
        designPosition: Int
    ): ArrayList<Int> {
        val myList = ArrayList<Int>()
        var sum = 0
        var questionIndex = -1
        val contentIndices = contents.indices
        var contentIndex = 0

        for (i in contentIndices) {
            sum += (contents[i].questions!!.size + 1)
            if (designPosition >= sum) {
                contentIndex += 1
            }
        }
        myList.add(contentIndex)

        if (designList!![designPosition].equals("question")) {

            val contentNumber = 0 until contentIndex
            var untilSumSize = 0
            if (contentIndex == 0) {
                questionIndex =
                    abs(designPosition - (contents[contentIndex].questions!!.size + 1)) - 1
            } else {
                for (i in contentNumber) {
                    untilSumSize += (contents[i].questions!!.size + 1)
                }
                questionIndex = abs(designPosition - untilSumSize) - 1
            }
        }
        myList.add(questionIndex)


        return myList
    }


    private fun initialize() {
        val adapter = ViewPagerChapterAdapter(
            fragmentList,
            childFragmentManager,
            lifecycle
        )

        binding.viewPager2.adapter = adapter
        binding.viewPager2.isUserInputEnabled = false
        TabLayoutMediator(binding.tabLayout, binding.viewPager2) { tab, position ->
            tab.text = tabTitles[position]
            binding.viewPager2.setCurrentItem(tab.position, true)
        }.attach()
        binding.tabLayout.touchables.forEach { it.isClickable = false }

    }

    override fun nextPage() {
        var page = binding.viewPager2.currentItem
        if (designList!![page].equals("question")) {
            showSnackBar(binding.root, "Correct Answer")
        }
        binding.viewPager2.currentItem = ++page
    }

}