Merge pull request #841 from toastkidjp/feature/#818_loan

Feature/#818 loan

app/build.gradle

@@ -76,6 +76,7 @@ dependencies {
     implementation project(":api")
     implementation project(":rss")
     implementation project(":image")
+    implementation project(":loan")
 
     implementation "androidx.appcompat:appcompat:$libVersions.appcompat"
     implementation "androidx.cardview:cardview:$libVersions.cardview"

app/src/main/java/jp/toastkid/yobidashi/menu/Menu.kt

@@ -47,6 +47,8 @@ enum class Menu(
 
     WHAT_HAPPENED_TODAY(R.string.menu_what_happened_today, R.drawable.ic_what_happened_today),
 
+    LOAN_CALCULATOR(R.string.title_loan_calculator, R.drawable.ic_loan_calculator),
+
     PLANNING_POKER(R.string.title_planning_poker, R.drawable.ic_card),
 
     GESTURE_MEMO(R.string.title_gesture_memo, R.drawable.ic_gesture_memo),

app/src/main/java/jp/toastkid/yobidashi/menu/MenuUseCase.kt

@@ -19,6 +19,7 @@ import jp.toastkid.lib.BrowserViewModel
 import jp.toastkid.lib.ContentViewModel
 import jp.toastkid.lib.Urls
 import jp.toastkid.lib.preference.PreferenceApplier
+import jp.toastkid.loan.view.LoanCalculatorFragment
 import jp.toastkid.media.music.popup.MediaPlayerPopup
 import jp.toastkid.planning.CardListFragment
 import jp.toastkid.rss.RssReaderFragment
@@ -89,6 +90,9 @@ class MenuUseCase(
                 }
                 return
             }
+            Menu.LOAN_CALCULATOR-> {
+                nextFragment(LoanCalculatorFragment::class.java)
+            }
             Menu.PLANNING_POKER-> {
                 nextFragment(CardListFragment::class.java)
             }

app/src/main/res/values/strings.xml

@@ -435,6 +435,5 @@
     <string name="hourly_trends">Hourly trends</string>
     <string name="sample_text_color_filter">A</string>
     <string name="message_backup_is_empty">Backup is empty.</string>
-    <string name="title_loan">Loan calculator</string>
 
 </resources>

loan/.gitignore

@@ -0,0 +1 @@
+/build

loan/build.gradle

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2021 toastkidjp.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompany this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html.
+ */
+
+plugins {
+    id 'com.android.library'
+    id 'kotlin-android'
+    id 'kotlin-kapt'
+}
+android {
+    compileSdkVersion rootProject.ext.compileSdk
+
+    defaultConfig {
+        minSdkVersion rootProject.ext.minSdk
+        targetSdkVersion 31
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    buildFeatures.dataBinding = true
+}
+
+dependencies {
+    implementation project(":lib")
+
+    implementation "androidx.appcompat:appcompat:$libVersions.appcompat"
+    implementation "androidx.cardview:cardview:$libVersions.cardview"
+    implementation "androidx.constraintlayout:constraintlayout:$libVersions.constraintlayout"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$libVersions.coroutines"
+    implementation "com.google.android.material:material:$libVersions.material"
+
+    testImplementation "junit:junit:$libVersions.junit"
+    testImplementation "io.mockk:mockk:$libVersions.mockk"
+}

loan/src/main/AndroidManifest.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="jp.toastkid.loan">
+
+</manifest>

loan/src/main/java/jp/toastkid/loan/Calculator.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2021 toastkidjp.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompany this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html.
+ */
+
+package jp.toastkid.loan
+
+import jp.toastkid.loan.model.Factor
+import kotlin.math.max
+import kotlin.math.pow
+
+class Calculator {
+
+    operator fun invoke(factor: Factor) = invoke(
+        factor.amount,
+        factor.term,
+        factor.interestRate,
+        factor.downPayment,
+        factor.managementFee,
+        factor.renovationReserves
+    )
+
+    operator fun invoke(
+        amount: Int,
+        term: Int,
+        interestRate: Double,
+        downPayment: Int,
+        managementFee: Int,
+        renovationReserves: Int
+    ): Int {
+        val paymentCount = (term * 12).toDouble()
+        val convertedRate = interestRate / 100.0
+        val poweredMonthlyInterestRate = (1 + convertedRate / 12).pow(paymentCount)
+
+        val numerator = ((amount - downPayment) * convertedRate) / 12 * poweredMonthlyInterestRate
+        val denominator = poweredMonthlyInterestRate - 1
+
+        return (max(numerator / denominator, 0.0)).toInt() + managementFee + renovationReserves
+    }
+
+}

loan/src/main/java/jp/toastkid/loan/model/Factor.kt

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2021 toastkidjp.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompany this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html.
+ */
+
+package jp.toastkid.loan.model
+
+class Factor(
+    val amount: Int,
+    val term: Int,
+    val interestRate: Double,
+    val downPayment: Int,
+    val managementFee: Int,
+    val renovationReserves: Int
+)

loan/src/main/java/jp/toastkid/loan/usecase/DebouncedCalculatorUseCase.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2021 toastkidjp.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompany this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html.
+ */
+
+package jp.toastkid.loan.usecase
+
+import jp.toastkid.loan.Calculator
+import jp.toastkid.loan.model.Factor
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.debounce
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.receiveAsFlow
+import kotlinx.coroutines.launch
+
+class DebouncedCalculatorUseCase(
+    private val inputChannel: Channel<String>,
+    private val currentFactorProvider: () -> Factor,
+    private val onResult: (Int) -> Unit,
+    private val calculator: Calculator = Calculator(),
+    private val debounceMillis: Long = 1000,
+    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO,
+    private val mainDispatcher: CoroutineDispatcher = Dispatchers.Main
+) {
+
+    @FlowPreview
+    operator fun invoke() {
+        CoroutineScope(ioDispatcher).launch {
+            inputChannel
+                .receiveAsFlow()
+                .distinctUntilChanged()
+                .debounce(debounceMillis)
+                .flowOn(mainDispatcher)
+                .collect {
+                    val factor = currentFactorProvider()
+                    val payment = calculator(
+                        factor.amount,
+                        factor.term,
+                        factor.interestRate,
+                        factor.downPayment,
+                        factor.managementFee,
+                        factor.renovationReserves
+                    )
+
+                    onResult(payment)
+                }
+        }
+    }
+
+}

loan/src/main/java/jp/toastkid/loan/view/LoanCalculatorFragment.kt

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2021 toastkidjp.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompany this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html.
+ */
+
+package jp.toastkid.loan.view
+
+import android.os.Bundle
+import android.text.Editable
+import android.text.TextWatcher
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.EditText
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import jp.toastkid.loan.R
+import jp.toastkid.loan.databinding.FragmentLoanCalculatorBinding
+import jp.toastkid.loan.model.Factor
+import jp.toastkid.loan.usecase.DebouncedCalculatorUseCase
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.launch
+
+class LoanCalculatorFragment : Fragment() {
+
+    private var binding: FragmentLoanCalculatorBinding? = null
+
+    private val inputChannel: Channel<String> = Channel()
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        binding = DataBindingUtil.inflate(inflater, R.layout.fragment_loan_calculator, container, false)
+        return binding?.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        val textWatcher = object : TextWatcher {
+
+            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) = Unit
+
+            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
+                CoroutineScope(Dispatchers.IO).launch {
+                    inputChannel.send(s?.toString() ?: "")
+                }
+            }
+
+            override fun afterTextChanged(s: Editable?) = Unit
+
+        }
+
+        binding?.loanAmount?.addTextChangedListener(textWatcher)
+        binding?.term?.addTextChangedListener(textWatcher)
+        binding?.interestRate?.addTextChangedListener(textWatcher)
+        binding?.downPayment?.addTextChangedListener(textWatcher)
+        binding?.monthlyManagementFee?.addTextChangedListener(textWatcher)
+        binding?.monthlyRenovationReserves?.addTextChangedListener(textWatcher)
+
+
+        DebouncedCalculatorUseCase(
+            inputChannel,
+            {
+                Factor(
+                    extractInt(binding?.loanAmount),
+                    extractInt(binding?.term),
+                    extractDouble(binding?.interestRate),
+                    extractInt(binding?.downPayment),
+                    extractInt(binding?.monthlyManagementFee),
+                    extractInt(binding?.monthlyRenovationReserves)
+                )
+            },
+            { binding?.result?.text = getString(R.string.message_result_montly_payment, it) }
+        ).invoke()
+    }
+
+    private fun extractInt(editText: EditText?) =
+        editText?.text?.toString()?.toIntOrNull() ?: 0
+
+    private fun extractDouble(editText: EditText?) =
+        editText?.text?.toString()?.toDoubleOrNull() ?: 0.0
+
+    override fun onDetach() {
+        binding = null
+        super.onDetach()
+    }
+
+}

loan/src/main/res/drawable/ic_loan_calculator.xml

@@ -0,0 +1,5 @@
+<vector android:height="24dp" android:tint="#FFFFFF"
+    android:viewportHeight="24" android:viewportWidth="24"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="@android:color/white" android:pathData="M19,14L19,6c0,-1.1 -0.9,-2 -2,-2L3,4c-1.1,0 -2,0.9 -2,2v8c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2zM10,13c-1.66,0 -3,-1.34 -3,-3s1.34,-3 3,-3 3,1.34 3,3 -1.34,3 -3,3zM23,7v11c0,1.1 -0.9,2 -2,2L4,20v-2h17L21,7h2z"/>
+</vector>