# CombinedLiveData.kt

    /*
     * The MIT License
     *
     * Original work sponsored and donated by The Danish Health Data Authority (http://www.sundhedsdatastyrelsen.dk)
     *
     * Copyright (C) 2021 The Danish Health Data Authority (http://www.sundhedsdatastyrelsen.dk)
     *
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy of
     * this software and associated documentation files (the "Software"), to deal in
     * the Software without restriction, including without limitation the rights to
     * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
     * of the Software, and to permit persons to whom the Software is furnished to do
     * so, subject to the following conditions:
     *
     *
     * The above copyright notice and this permission notice shall be included in all
     * copies or substantial portions of the Software.
     *
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */

    package dk.nsp.mingraviditet.util.livedata

    import androidx.lifecycle.LiveData
    import androidx.lifecycle.MediatorLiveData
    import androidx.lifecycle.Observer

    class CombinedLiveData<T, K, S>(
        source1: LiveData<T>,
        source2: LiveData<K>,
        private val combine: (data1: T?, data2: K?) -> S
    ) : MediatorLiveData<S>() {

        private var data1: T? = null
        private var data2: K? = null

        init {
            super.addSource(source1) {
                data1 = it
                value = combine(data1, data2)
            }
            super.addSource(source2) {
                data2 = it
                value = combine(data1, data2)
            }
        }

        override fun <T : Any?> addSource(source: LiveData<T>, onChanged: Observer<in T>) {
            throw UnsupportedOperationException()
        }

        override fun <T : Any?> removeSource(toRemote: LiveData<T>) {
            throw UnsupportedOperationException()
        }
    }