/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.fenix.settings.deletebrowsingdata

import android.content.DialogInterface
import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AlertDialog
import androidx.fragment.app.Fragment
import androidx.lifecycle.lifecycleScope
import androidx.navigation.fragment.findNavController
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers.IO
import kotlinx.coroutines.Dispatchers.Main
import kotlinx.coroutines.cancel
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import mozilla.components.lib.state.ext.flowScoped
import mozilla.components.support.ktx.kotlinx.coroutines.flow.ifChanged
import org.mozilla.fenix.R
import org.mozilla.fenix.components.FenixSnackbar
import org.mozilla.fenix.components.metrics.Event
import org.mozilla.fenix.databinding.FragmentDeleteBrowsingDataBinding
import org.mozilla.fenix.ext.requireComponents
import org.mozilla.fenix.ext.settings
import org.mozilla.fenix.ext.showToolbar
import org.mozilla.fenix.utils.Settings

@SuppressWarnings("TooManyFunctions", "LargeClass")
class DeleteBrowsingDataFragment : Fragment(R.layout.fragment_delete_browsing_data) {

    private lateinit var controller: DeleteBrowsingDataController
    private var scope: CoroutineScope? = null
    private lateinit var settings: Settings

    private var _binding: FragmentDeleteBrowsingDataBinding? = null
    private val binding get() = _binding!!

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        val tabsUseCases = requireComponents.useCases.tabsUseCases
        val downloadUseCases = requireComponents.useCases.downloadUseCases

        _binding = FragmentDeleteBrowsingDataBinding.bind(view)
        controller = DefaultDeleteBrowsingDataController(
            tabsUseCases.removeAllTabs,
            downloadUseCases.removeAllDownloads,
            requireComponents.core.historyStorage,
            requireComponents.core.permissionStorage,
            requireComponents.core.store,
            requireComponents.core.icons,
            requireComponents.core.engine
        )
        settings = requireContext().settings()

        getCheckboxes().iterator().forEach {
            it.onCheckListener = { _ ->
                updateDeleteButton()
                updatePreference(it)
            }
        }

        getCheckboxes().iterator().forEach {
            it.isChecked = when (it.id) {
                R.id.open_tabs_item -> settings.deleteOpenTabs
                R.id.browsing_data_item -> settings.deleteBrowsingHistory
                R.id.cookies_item -> settings.deleteCookies
                R.id.cached_files_item -> settings.deleteCache
                R.id.site_permissions_item -> settings.deleteSitePermissions
                R.id.downloads_item -> settings.deleteDownloads
                else -> true
            }
        }

        binding.deleteData.setOnClickListener {
            askToDelete()
        }
        updateDeleteButton()
    }

    private fun updatePreference(it: DeleteBrowsingDataItem) {
        when (it.id) {
            R.id.open_tabs_item -> settings.deleteOpenTabs = it.isChecked
            R.id.browsing_data_item -> settings.deleteBrowsingHistory = it.isChecked
            R.id.cookies_item -> settings.deleteCookies = it.isChecked
            R.id.cached_files_item -> settings.deleteCache = it.isChecked
            R.id.site_permissions_item -> settings.deleteSitePermissions = it.isChecked
            R.id.downloads_item -> settings.deleteDownloads = it.isChecked
            else -> return
        }
    }

    override fun onStart() {
        super.onStart()

        scope = requireComponents.core.store.flowScoped(viewLifecycleOwner) { flow ->
            flow.map { state -> state.tabs.size }
                .ifChanged()
                .collect { openTabs -> updateTabCount(openTabs) }
        }
    }

    override fun onResume() {
        super.onResume()
        showToolbar(getString(R.string.preferences_delete_browsing_data))

        getCheckboxes().forEach {
            it.visibility = View.VISIBLE
        }

        updateItemCounts()
    }

    private fun updateDeleteButton() {
        val enabled = getCheckboxes().any { it.isChecked }

        binding.deleteData.isEnabled = enabled
        binding.deleteData.alpha = if (enabled) ENABLED_ALPHA else DISABLED_ALPHA
    }

    private fun askToDelete() {
        context?.let {
            AlertDialog.Builder(it).apply {
                setMessage(
                    it.getString(
                        R.string.delete_browsing_data_prompt_message_3,
                        it.getString(R.string.app_name)
                    )
                )

                setNegativeButton(R.string.delete_browsing_data_prompt_cancel) { it: DialogInterface, _ ->
                    it.cancel()
                }

                setPositiveButton(R.string.delete_browsing_data_prompt_allow) { it: DialogInterface, _ ->
                    it.dismiss()
                    deleteSelected()
                }
                create()
            }.show()
        }
    }

    private fun deleteSelected() {
        startDeletion()
        lifecycleScope.launch(IO) {
            getCheckboxes().mapIndexed { i, v ->
                if (v.isChecked) {
                    when (i) {
                        OPEN_TABS_INDEX -> controller.deleteTabs()
                        HISTORY_INDEX -> controller.deleteBrowsingData()
                        COOKIES_INDEX -> controller.deleteCookies()
                        CACHED_INDEX -> controller.deleteCachedFiles()
                        PERMS_INDEX -> controller.deleteSitePermissions()
                        DOWNLOADS_INDEX -> controller.deleteDownloads()
                    }
                }
            }

            withContext(Main) {
                finishDeletion()
                requireComponents.analytics.metrics.track(Event.ClearedPrivateData)
            }
        }
    }

    private fun startDeletion() {
        binding.progressBar.visibility = View.VISIBLE
        binding.deleteBrowsingDataWrapper.isEnabled = false
        binding.deleteBrowsingDataWrapper.isClickable = false
        binding.deleteBrowsingDataWrapper.alpha = DISABLED_ALPHA
    }

    private fun finishDeletion() {
        val popAfter = binding.openTabsItem.isChecked
        binding.progressBar.visibility = View.GONE
        binding.deleteBrowsingDataWrapper.isEnabled = true
        binding.deleteBrowsingDataWrapper.isClickable = true
        binding.deleteBrowsingDataWrapper.alpha = ENABLED_ALPHA

        updateItemCounts()

        FenixSnackbar.make(
            view = requireView(),
            duration = FenixSnackbar.LENGTH_SHORT,
            isDisplayedWithBrowserToolbar = true
        )
            .setText(resources.getString(R.string.preferences_delete_browsing_data_snackbar))
            .show()

        if (popAfter) {
            viewLifecycleOwner.lifecycleScope.launch(Main) {
                findNavController().apply {
                    // If the user deletes all open tabs we need to make sure we remove
                    // the BrowserFragment from the backstack.
                    popBackStack(R.id.homeFragment, false)
                    navigate(DeleteBrowsingDataFragmentDirections.actionGlobalSettingsFragment())
                }
            }
        }
    }

    override fun onPause() {
        super.onPause()
        binding.progressBar.visibility = View.GONE
    }

    override fun onStop() {
        super.onStop()
        scope?.cancel()
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }

    private fun updateItemCounts() {
        updateTabCount()
        updateHistoryCount()
        updateCookies()
        updateCachedImagesAndFiles()
        updateSitePermissions()
    }

    private fun updateTabCount(openTabs: Int = requireComponents.core.store.state.tabs.size) {
        binding.openTabsItem.apply {
            subtitleView.text = resources.getString(
                R.string.preferences_delete_browsing_data_tabs_subtitle,
                openTabs
            )
        }
    }

    private fun updateHistoryCount() {
        binding.browsingDataItem.subtitleView.text = ""

        viewLifecycleOwner.lifecycleScope.launch(IO) {
            val historyCount = requireComponents.core.historyStorage.getVisited().size
            launch(Main) {
                binding.browsingDataItem.apply {
                    subtitleView.text =
                        resources.getString(
                            R.string.preferences_delete_browsing_data_browsing_data_subtitle,
                            historyCount
                        )
                }
            }
        }
    }

    private fun updateCookies() {
        // NO OP until we have GeckoView methods to count cookies
    }

    private fun updateCachedImagesAndFiles() {
        // NO OP until we have GeckoView methods to count cached images and files
    }

    private fun updateSitePermissions() {
        // NO OP until we have GeckoView methods for cookies and cached files, for consistency
    }

    private fun getCheckboxes(): List<DeleteBrowsingDataItem> {
        return listOf(
            binding.openTabsItem,
            binding.browsingDataItem,
            binding.cookiesItem,
            binding.cachedFilesItem,
            binding.sitePermissionsItem,
            binding.downloadsItem
        )
    }

    companion object {
        private const val ENABLED_ALPHA = 1f
        private const val DISABLED_ALPHA = 0.6f

        private const val OPEN_TABS_INDEX = 0
        private const val HISTORY_INDEX = 1
        private const val COOKIES_INDEX = 2
        private const val CACHED_INDEX = 3
        private const val PERMS_INDEX = 4
        private const val DOWNLOADS_INDEX = 5
    }
}