/*
 * Copyright 2018 Allan Wang
 *
 * 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 ca.allanwang.kau.kpref

import android.content.SharedPreferences
import ca.allanwang.kau.kotlin.ILazyResettable

/**
 * Created by Allan Wang on 2017-06-07.
 *
 * Singular KPref Delegate for booleans
 * When the shared pref is not initialized, it will return [true] then set the pref to [false]
 * All subsequent retrievals will be [false]
 * This is useful for one time toggles such as showcasing items
 */
interface KPrefSingleDelegate : ILazyResettable<Boolean>

class KPrefSingleDelegateAndroid internal constructor(
    private val key: String,
    private val pref: KPref,
    private val prefBuilder: KPrefBuilderAndroid
) : KPrefSingleDelegate {

    @Volatile
    private var _value: Boolean? = null
    private val lock = this

    private val sp: SharedPreferences get() = prefBuilder.sp

    init {
        if (pref.prefMap.containsKey(key))
            throw KPrefException("$key is already used elsewhere in preference ${pref.preferenceName}")
        pref.prefMap[key] = this
    }

    override fun invalidate() {
        _value = null
    }

    override val value: Boolean
        get() {
            val _v1 = _value
            if (_v1 != null) {
                return _v1
            }
            return synchronized(lock) {
                val _v2 = _value
                if (_v2 != null) {
                    _v2
                } else {
                    _value = sp.getBoolean(key, true)
                    if (_value!!) {
                        sp.edit().putBoolean(key, false).apply()
                        _value = false
                        true
                    } else false
                }
            }
        }

    override fun isInitialized(): Boolean = _value != null

    override fun toString(): String = if (isInitialized()) value.toString() else "Lazy kPref $key not initialized yet."
}

class KPrefSingleDelegateInMemory internal constructor(
    private val key: String,
    private val pref: KPref
) : KPrefSingleDelegate {
    @Volatile
    private var _value: Boolean? = null
    private val lock = this

    init {
        if (pref.prefMap.containsKey(key))
            throw KPrefException("$key is already used elsewhere in preference ${pref.preferenceName}")
        pref.prefMap[key] = this
    }

    override fun invalidate() {
        // No op
    }

    override val value: Boolean
        get() {
            val _v1 = _value
            if (_v1 != null) {
                return _v1
            }
            return synchronized(lock) {
                val _v2 = _value
                if (_v2 != null) {
                    _v2
                } else {
                    _value = false
                    true
                }
            }
        }

    override fun isInitialized(): Boolean = _value != null

    override fun toString(): String = if (isInitialized()) value.toString() else "Lazy kPref $key not initialized yet."
}