Correção no cálculo de taxa de rendimento (#64)

* feat: add period selection

* fix: interest income calculation ('poupança')

components/InvestmentInput.vue

@@ -4,7 +4,10 @@
     <v-card-text>
       <v-form @submit.prevent="submit">
         <AmountInput />
-        <DurationInput />
+        <div class="duration-container">
+          <DurationInput />
+          <DurationTypeInput />
+        </div>
         <IndexDiInput />
         <IndexSelicInput />
         <IndexCdbInput />
@@ -15,6 +18,7 @@
 </template>
 <script>
 import AmountInput from './investment/AmountInput.vue'
+import DurationTypeInput from './investment/DurationTypeInput.vue'
 import DurationInput from './investment/DurationInput.vue'
 import IndexDiInput from './investment/IndexDiInput.vue'
 import IndexSelicInput from './investment/IndexSelicInput.vue'
@@ -23,6 +27,7 @@ import IndexLcxInput from './investment/IndexLcxInput.vue'
 export default {
   components: {
     AmountInput,
+    DurationTypeInput,
     DurationInput,
     IndexDiInput,
     IndexSelicInput,
@@ -31,3 +36,11 @@ export default {
   }
 }
 </script>
+
+<style scoped>
+.duration-container {
+  display: flex;
+  flex-direction: row;
+  align-items: center;
+}
+</style>

components/InvestmentSimulation.vue

@@ -32,11 +32,17 @@ import InvestmentResult from './InvestmentResult.vue'
 import { getCDBResult } from '~/src/cdb'
 import { getLcxResult } from '~/src/lcx'
 import { getPoupancaResult } from '~/src/poupanca'
+import { DurationType } from '~/store/investment'
 export default {
   components: { InvestmentResult },
   data() {
     return {
-      investment: this.$store.state.investment
+      investment: this.$store.state.investment,
+      periodMultiplier: {
+        [DurationType.Days]: 1,
+        [DurationType.Months]: 365 / 12,
+        [DurationType.Years]: 365
+      }
     }
   },
   computed: {
@@ -45,22 +51,30 @@ export default {
         this.investment.amount,
         this.investment.di,
         this.investment.cdb,
-        this.investment.duration
+        this.getDurationInDays()
       )
     },
     resultLcx() {
       return getLcxResult(
         this.investment.amount,
         this.investment.di,
         this.investment.lcx,
-        this.investment.duration
+        this.getDurationInDays()
       )
     },
     resultPoupanca() {
       return getPoupancaResult(
         this.investment.amount,
         this.investment.poupanca,
-        this.investment.duration
+        this.getDurationInDays()
+      )
+    }
+  },
+  methods: {
+    getDurationInDays() {
+      return Math.floor(
+        this.investment.duration *
+          this.periodMultiplier[this.investment.durationType]
       )
     }
   }

components/investment/DurationInput.vue

@@ -4,7 +4,6 @@
     type="number"
     label="Vencimento"
     prepend-icon="mdi-calendar"
-    suffix="meses"
     min="1"
     :rules="[rules.required, rules.positive]"
   />

components/investment/DurationTypeInput.vue

@@ -0,0 +1,27 @@
+<template>
+  <v-select
+    v-model="durationType"
+    label="Tipo de período"
+    :items="durationTypeOptions"
+    density="compact"
+  ></v-select>
+</template>
+<script>
+export default {
+  computed: {
+    durationTypeOptions: {
+      get() {
+        return this.$store.state.investment.durationTypeOptions
+      }
+    },
+    durationType: {
+      get() {
+        return this.$store.state.investment.durationType
+      },
+      set(value) {
+        this.$store.commit('investment/setDurationType', value)
+      }
+    }
+  }
+}
+</script>

package.json

@@ -58,10 +58,10 @@
     "lint-staged": "^13.0.3",
     "postcss-html": "^1.3.0",
     "prettier": "^2.5.1",
-    "stylelint": "^14.1.0",
-    "stylelint-config-prettier": "^9.0.3",
-    "stylelint-config-recommended-vue": "^1.1.0",
-    "stylelint-config-standard": "^28.0.0",
+    "stylelint": "^14.16.1",
+    "stylelint-config-prettier": "^9.0.5",
+    "stylelint-config-recommended-vue": "^1.4.0",
+    "stylelint-config-standard": "^29.0.0",
     "ts-jest": "^27.1.1",
     "vue-jest": "^3.0.4"
   }

src/cdb.js

@@ -13,5 +13,5 @@ export function getCDBResult(amount, di, yearlyIndex, periods) {
 
 function getIndexCDB(yearlyInterest, di) {
   const index = yearlyInterest / 100
-  return Math.pow((index * di) / 100 + 1, 1 / 12)
+  return Math.pow((index * di) / 100 + 1, 1 / 365)
 }

src/finance.js

@@ -1,13 +1,13 @@
-export function compoundInterest(amount, index, periods) {
-  return amount * Math.pow(index, periods) - amount
+export function compoundInterest(amount, index, days) {
+  return amount * Math.pow(index, days) - amount
 }
 
-export function getIndexIR(periods) {
-  if (periods <= 6) {
+export function getIndexIR(days) {
+  if (days <= 180) {
     return 22.5
-  } else if (periods <= 12) {
+  } else if (days <= 360) {
     return 20
-  } else if (periods <= 24) {
+  } else if (days <= 720) {
     return 17.5
   } else {
     return 15

src/lcx.js

@@ -11,5 +11,5 @@ export function getLcxResult(amount, di, yearlyIndex, periods) {
 
 function getIndexLcx(yearlyInterest, di) {
   const index = yearlyInterest / 100
-  return Math.pow((index * di) / 100 + 1, 1 / 12)
+  return Math.pow((index * di) / 100 + 1, 1 / 365)
 }

src/poupanca.js

@@ -4,13 +4,17 @@ export function getPoupancaResult(amount, index, periods) {
   const interestAmount = finance.compoundInterest(
     amount,
     getIndexPoupanca(index),
-    periods
+    calculateFullMonthsDays(periods)
   )
-  const taxAmount = 0
-  const taxPercentage = 0
-  return { interestAmount, taxAmount, taxPercentage }
+
+  return { interestAmount }
+}
+
+export function calculateFullMonthsDays(days) {
+  const daysInMonth = 30
+  return days < daysInMonth ? 0 : Math.floor(days / daysInMonth) * daysInMonth
 }
 
 function getIndexPoupanca(index) {
-  return index / 100 + 1
+  return Math.pow(index / 100 + 1, 1 / 30)
 }