/*
 * Copyright (C) 2023 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.settings.datausage

import android.app.settings.SettingsEnums
import android.content.Context
import android.os.Bundle
import android.telephony.SubscriptionManager
import android.view.View
import com.android.settings.R
import com.android.settings.SettingsActivity
import com.android.settings.dashboard.DashboardFragment
import com.android.settings.search.BaseSearchIndexProvider
import com.android.settings.widget.SettingsMainSwitchBar
import com.android.settingslib.search.SearchIndexable

@SearchIndexable
class DataSaverSummary : DashboardFragment() {
    private lateinit var switchBar: SettingsMainSwitchBar
    private lateinit var dataSaverBackend: DataSaverBackend

    // Flag used to avoid infinite loop due if user switch it on/off too quick.
    private var switching = false

    override fun onCreate(bundle: Bundle?) {
        super.onCreate(bundle)

        if (!requireContext().isDataSaverVisible()) {
            finishFragment()
            return
        }

        dataSaverBackend = DataSaverBackend(requireContext())
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        switchBar = (activity as SettingsActivity).switchBar.apply {
            setTitle(getString(R.string.data_saver_switch_title))
            show()
            addOnSwitchChangeListener { _, isChecked -> onSwitchChanged(isChecked) }
        }
    }

    override fun onResume() {
        super.onResume()
        dataSaverBackend.addListener(dataSaverBackendListener)
    }

    override fun onPause() {
        super.onPause()
        dataSaverBackend.remListener(dataSaverBackendListener)
    }

    private fun onSwitchChanged(isChecked: Boolean) {
        synchronized(this) {
            if (!switching) {
                switching = true
                dataSaverBackend.isDataSaverEnabled = isChecked
            }
        }
    }

    override fun getPreferenceScreenResId() = R.xml.data_saver
    override fun getMetricsCategory() = SettingsEnums.DATA_SAVER_SUMMARY
    override fun getHelpResource() = R.string.help_url_data_saver
    override fun getLogTag() = TAG

    private val dataSaverBackendListener = object : DataSaverBackend.Listener {
        override fun onDataSaverChanged(isDataSaving: Boolean) {
            synchronized(this) {
                switchBar.isChecked = isDataSaving
                switching = false
            }
        }
    }

    companion object {
        private const val TAG = "DataSaverSummary"

        private fun Context.isDataSaverVisible(): Boolean =
            resources.getBoolean(R.bool.config_show_data_saver)

        @JvmField
        val SEARCH_INDEX_DATA_PROVIDER = object : BaseSearchIndexProvider(R.xml.data_saver) {
            override fun isPageSearchEnabled(context: Context): Boolean =
                context.isDataSaverVisible() &&
                    DataUsageUtils.hasMobileData(context) &&
                    (DataUsageUtils.getDefaultSubscriptionId(context) !=
                        SubscriptionManager.INVALID_SUBSCRIPTION_ID)
        }
    }
}