1 files changed, 213 insertions, 0 deletions
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt
new file mode 100644
index 0000000..1b70016
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt
@@ -0,0 +1,213 @@
+/*
+ * This file is part of GNU Taler
+ * (C) 2020 Taler Systems S.A.
+ *
+ * GNU Taler is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3, or (at your option) any later version.
+ *
+ * GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+package net.taler.merchantpos.order
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.MotionEvent
+import android.view.View
+import android.view.ViewGroup
+import android.widget.TextView
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.recyclerview.selection.ItemDetailsLookup
+import androidx.recyclerview.selection.ItemKeyProvider
+import androidx.recyclerview.selection.SelectionPredicates
+import androidx.recyclerview.selection.SelectionTracker
+import androidx.recyclerview.selection.StorageStrategy
+import androidx.recyclerview.widget.AsyncListDiffer
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.recyclerview.widget.RecyclerView.Adapter
+import androidx.recyclerview.widget.RecyclerView.ViewHolder
+import kotlinx.android.synthetic.main.fragment_order_state.*
+import net.taler.merchantpos.MainViewModel
+import net.taler.merchantpos.R
+import net.taler.merchantpos.fadeIn
+import net.taler.merchantpos.fadeOut
+import net.taler.merchantpos.order.OrderAdapter.OrderLineLookup
+import net.taler.merchantpos.order.OrderAdapter.OrderViewHolder
+
+class OrderStateFragment : Fragment() {
+
+    private val viewModel: MainViewModel by activityViewModels()
+    private val orderManager by lazy { viewModel.orderManager }
+    private val liveOrder by lazy { orderManager.getOrder(orderManager.currentOrderId.value!!) }
+    private val adapter = OrderAdapter()
+    private var tracker: SelectionTracker<String>? = null
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        return inflater.inflate(R.layout.fragment_order_state, container, false)
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        orderList.apply {
+            adapter = this@OrderStateFragment.adapter
+            layoutManager = LinearLayoutManager(requireContext())
+        }
+        val detailsLookup = OrderLineLookup(orderList)
+        val tracker = SelectionTracker.Builder(
+            "order-selection-id",
+            orderList,
+            adapter.keyProvider,
+            detailsLookup,
+            StorageStrategy.createStringStorage()
+        ).withSelectionPredicate(
+            SelectionPredicates.createSelectSingleAnything()
+        ).build()
+        savedInstanceState?.let { tracker.onRestoreInstanceState(it) }
+        adapter.tracker = tracker
+        this.tracker = tracker
+        if (savedInstanceState == null) {
+            // select last selected order line when re-creating this fragment
+            // do it before attaching the tracker observer
+            liveOrder.selectedProductKey?.let { tracker.select(it) }
+        }
+        tracker.addObserver(object : SelectionTracker.SelectionObserver<String>() {
+            override fun onItemStateChanged(key: String, selected: Boolean) {
+                super.onItemStateChanged(key, selected)
+                val item = if (selected) adapter.getItemByKey(key) else null
+                liveOrder.selectOrderLine(item)
+            }
+        })
+        liveOrder.order.observe(viewLifecycleOwner, Observer { order ->
+            onOrderChanged(order, tracker)
+        })
+        liveOrder.orderTotal.observe(viewLifecycleOwner, Observer { orderTotal ->
+            if (orderTotal == 0.0) {
+                totalView.fadeOut()
+                totalView.text = null
+            } else {
+                val currency = viewModel.configManager.merchantConfig?.currency
+                totalView.text = getString(R.string.order_total, orderTotal, currency)
+                totalView.fadeIn()
+            }
+        })
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        tracker?.onSaveInstanceState(outState)
+    }
+
+    private fun onOrderChanged(order: Order, tracker: SelectionTracker<String>) {
+        adapter.setItems(order.products) {
+            liveOrder.lastAddedProduct?.let {
+                val position = adapter.findPosition(it)
+                if (position >= 0) {
+                    // orderList can be null m(
+                    orderList?.scrollToPosition(position)
+                    orderList?.post { this.tracker?.select(it.id) }
+                }
+            }
+            // workaround for bug: SelectionObserver doesn't update when removing selected item
+            if (tracker.hasSelection()) {
+                val key = tracker.selection.first()
+                val product = order.products.find { it.id == key }
+                if (product == null) tracker.clearSelection()
+            }
+        }
+    }
+
+}
+
+private class OrderAdapter : Adapter<OrderViewHolder>() {
+
+    lateinit var tracker: SelectionTracker<String>
+    val keyProvider = OrderKeyProvider()
+    private val itemCallback = object : DiffUtil.ItemCallback<ConfigProduct>() {
+        override fun areItemsTheSame(oldItem: ConfigProduct, newItem: ConfigProduct): Boolean {
+            return oldItem == newItem
+        }
+
+        override fun areContentsTheSame(oldItem: ConfigProduct, newItem: ConfigProduct): Boolean {
+            return oldItem.quantity == newItem.quantity
+        }
+    }
+    private val differ = AsyncListDiffer(this, itemCallback)
+
+    override fun getItemCount() = differ.currentList.size
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): OrderViewHolder {
+        val view =
+            LayoutInflater.from(parent.context).inflate(R.layout.list_item_order, parent, false)
+        return OrderViewHolder(view)
+    }
+
+    override fun onBindViewHolder(holder: OrderViewHolder, position: Int) {
+        val item = getItem(position)!!
+        holder.bind(item, tracker.isSelected(item.id))
+    }
+
+    fun setItems(items: List<ConfigProduct>, commitCallback: () -> Unit) {
+        // toMutableList() is needed for some reason, otherwise doesn't update adapter
+        differ.submitList(items.toMutableList(), commitCallback)
+    }
+
+    fun getItem(position: Int): ConfigProduct? = differ.currentList[position]
+
+    fun getItemByKey(key: String): ConfigProduct? {
+        return differ.currentList.find { it.id == key }
+    }
+
+    fun findPosition(product: ConfigProduct): Int {
+        return differ.currentList.indexOf(product)
+    }
+
+    private inner class OrderViewHolder(private val v: View) : ViewHolder(v) {
+        private val quantity: TextView = v.findViewById(R.id.quantity)
+        private val name: TextView = v.findViewById(R.id.name)
+        private val price: TextView = v.findViewById(R.id.price)
+
+        fun bind(product: ConfigProduct, selected: Boolean) {
+            v.isActivated = selected
+            quantity.text = product.quantity.toString()
+            name.text = product.localizedDescription
+            price.text = String.format("%.2f", product.priceAsDouble * product.quantity)
+        }
+    }
+
+    private inner class OrderKeyProvider : ItemKeyProvider<String>(SCOPE_MAPPED) {
+        override fun getKey(position: Int) = getItem(position)!!.id
+        override fun getPosition(key: String): Int {
+            return differ.currentList.indexOfFirst { it.id == key }
+        }
+    }
+
+    internal class OrderLineLookup(private val list: RecyclerView) : ItemDetailsLookup<String>() {
+        override fun getItemDetails(e: MotionEvent): ItemDetails<String>? {
+            list.findChildViewUnder(e.x, e.y)?.let { view ->
+                val holder = list.getChildViewHolder(view)
+                val adapter = list.adapter as OrderAdapter
+                val position = holder.adapterPosition
+                return object : ItemDetails<String>() {
+                    override fun getPosition(): Int = position
+                    override fun getSelectionKey(): String = adapter.keyProvider.getKey(position)
+                    override fun inSelectionHotspot(e: MotionEvent) = true
+                }
+            }
+            return null
+        }
+    }
+
+}