1 files changed, 109 insertions, 0 deletions
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/LiveOrder.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/LiveOrder.kt
new file mode 100644
index 0000000..ff6061a
--- /dev/null
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/LiveOrder.kt
@@ -0,0 +1,109 @@
+/*
+ * 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 androidx.annotation.UiThread
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.Transformations
+import net.taler.merchantpos.CombinedLiveData
+import net.taler.merchantpos.order.RestartState.DISABLED
+import net.taler.merchantpos.order.RestartState.ENABLED
+import net.taler.merchantpos.order.RestartState.UNDO
+
+internal enum class RestartState { ENABLED, DISABLED, UNDO }
+
+internal interface LiveOrder {
+    val order: LiveData<Order>
+    val orderTotal: LiveData<Double>
+    val restartState: LiveData<RestartState>
+    val modifyOrderAllowed: LiveData<Boolean>
+    val lastAddedProduct: ConfigProduct?
+    val selectedProductKey: String?
+    fun restartOrUndo()
+    fun selectOrderLine(product: ConfigProduct?)
+    fun increaseSelectedOrderLine()
+    fun decreaseSelectedOrderLine()
+}
+
+internal class MutableLiveOrder(
+    val id: Int,
+    private val productsByCategory: HashMap<Category, ArrayList<ConfigProduct>>
+) : LiveOrder {
+    private val availableCategories: Map<Int, Category>
+        get() = productsByCategory.keys.map { it.id to it }.toMap()
+    override val order: MutableLiveData<Order> = MutableLiveData(Order(id, availableCategories))
+    override val orderTotal: LiveData<Double> = Transformations.map(order) { it.total }
+    override val restartState = MutableLiveData(DISABLED)
+    private val selectedOrderLine = MutableLiveData<ConfigProduct>()
+    override val selectedProductKey: String?
+        get() = selectedOrderLine.value?.id
+    override val modifyOrderAllowed =
+        CombinedLiveData(restartState, selectedOrderLine) { restartState, selectedOrderLine ->
+            restartState != DISABLED && selectedOrderLine != null
+        }
+    override var lastAddedProduct: ConfigProduct? = null
+    private var undoOrder: Order? = null
+
+    @UiThread
+    internal fun addProduct(product: ConfigProduct) {
+        lastAddedProduct = product
+        order.value = order.value!! + product
+        restartState.value = ENABLED
+    }
+
+    @UiThread
+    internal fun removeProduct(product: ConfigProduct) {
+        val modifiedOrder = order.value!! - product
+        order.value = modifiedOrder
+        restartState.value = if (modifiedOrder.products.isEmpty()) DISABLED else ENABLED
+    }
+
+    @UiThread
+    internal fun isEmpty() = order.value!!.products.isEmpty()
+
+    @UiThread
+    override fun restartOrUndo() {
+        if (restartState.value == UNDO) {
+            order.value = undoOrder
+            restartState.value = ENABLED
+            undoOrder = null
+        } else {
+            undoOrder = order.value
+            order.value = Order(id, availableCategories)
+            restartState.value = UNDO
+        }
+    }
+
+    @UiThread
+    override fun selectOrderLine(product: ConfigProduct?) {
+        selectedOrderLine.value = product
+    }
+
+    @UiThread
+    override fun increaseSelectedOrderLine() {
+        val orderLine = selectedOrderLine.value ?: throw IllegalStateException()
+        addProduct(orderLine)
+    }
+
+    @UiThread
+    override fun decreaseSelectedOrderLine() {
+        val orderLine = selectedOrderLine.value ?: throw IllegalStateException()
+        removeProduct(orderLine)
+    }
+
+}