-
Notifications
You must be signed in to change notification settings - Fork 0
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
feat: Improve types in Mortgage and FairholdLandPurchase
- Loading branch information
1 parent
bb3cbaf
commit 4798881
Showing
4 changed files
with
131 additions
and
133 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,95 +1,115 @@ | ||
| import { MONTHS_PER_YEAR } from "./constants"; | ||
|
|
||
| const DEFAULT_INTEREST_RATE = 0.06; | ||
| const DEFAULT_MORTGAGE_TERM = 30; | ||
| const DEFAULT_INITIAL_DEPOSIT = 0.15; | ||
|
|
||
| type MortgageBreakdown = { | ||
| yearlyPayment: number; | ||
| cumulativePaid: number; | ||
| remainingBalance: number; | ||
| }[]; | ||
|
|
||
| export class Mortgage { | ||
| propertyValue: number; //value of the property for the mortgage | ||
| interestRate: number; // interest rate of the mortgage in percentage e.r, 0.05=5% | ||
| termYears: number; // number of years of the mortgage | ||
| initialDeposit: number; // initial deposit of the value of the mortgage in percentage e.g. 0.15 =15% deposit | ||
| principal?: number; // amount of the morgage requested | ||
| monthlyPayment?: number; // monthly rate of the mortgage | ||
| totalMortgageCost?: number; // total cost of the mortgage | ||
| yearlyPaymentBreakdown?: { | ||
| yearlyPayment: number; | ||
| cumulativePaid: number; | ||
| remainingBalance: number; | ||
| }[]; // yearly breakdown of the mortgage | ||
| propertyValue: number; | ||
| /** | ||
| * This value is given as a percentage. For example, 0.05 represents a 5% rate | ||
| */ | ||
| interestRate: number; | ||
| termYears: number; | ||
| /** | ||
| * This value is given as a percentage. For example, 0.15 represents a 15% deposit | ||
| */ | ||
| initialDeposit: number; | ||
| /** | ||
| * The principle is the value of the property, minus the deposit | ||
| */ | ||
| principal: number; | ||
| monthlyPayment: number; | ||
| totalMortgageCost: number; | ||
| yearlyPaymentBreakdown: MortgageBreakdown; | ||
|
|
||
| constructor({ | ||
| propertyValue, | ||
| interestRate = 0.06, | ||
| termOfTheMortgage = 30, | ||
| initialDeposit = 0.15, | ||
| interestRate = DEFAULT_INTEREST_RATE, | ||
| mortgageTerm = DEFAULT_MORTGAGE_TERM, | ||
| initialDeposit = DEFAULT_INITIAL_DEPOSIT, | ||
| }: { | ||
| propertyValue: number; | ||
| interestRate?: number; | ||
| termOfTheMortgage?: number; | ||
| mortgageTerm?: number; | ||
| initialDeposit?: number; | ||
| }) { | ||
| this.propertyValue = propertyValue; | ||
| this.initialDeposit = initialDeposit; | ||
| this.interestRate = interestRate; | ||
| this.termYears = termOfTheMortgage; | ||
| this.calculateAmountOfTheMortgage(); // calculate the amount of the mortgage | ||
| this.calculateMonthlyMortgagePayment(); // calculate the montly payment | ||
| this.calculateYearlyPaymentBreakdown(); // calculate the yearly breakdown; | ||
| } | ||
| this.termYears = mortgageTerm; | ||
| this.principal = this.calculateMortgagePrinciple(); | ||
|
|
||
| const { monthlyPayment, totalMortgageCost } = | ||
| this.calculateMonthlyMortgagePayment(); | ||
| this.monthlyPayment = monthlyPayment; | ||
| this.totalMortgageCost = totalMortgageCost; | ||
|
|
||
| calculateAmountOfTheMortgage() { | ||
| this.principal = this.propertyValue * (1 - this.initialDeposit); // calculate the amount of the mortgage by removing the deposit | ||
| return this.principal; | ||
| this.yearlyPaymentBreakdown = this.calculateYearlyPaymentBreakdown(); | ||
| } | ||
|
|
||
| calculateMonthlyMortgagePayment() { | ||
| const monthlyInterestRate = this.interestRate / 12; // Convert annual interest rate to monthly rate | ||
| const numberOfPayments = this.termYears * 12; // Convert term in years to total number of payments | ||
| if (this.principal !== undefined) { | ||
| const monthlyPayment = | ||
| (this.principal * | ||
| monthlyInterestRate * | ||
| Math.pow(1 + monthlyInterestRate, numberOfPayments)) / | ||
| (Math.pow(1 + monthlyInterestRate, numberOfPayments) - 1); // Calculate the monthly payment | ||
| this.monthlyPayment = parseFloat(monthlyPayment.toFixed(2)); // Store monthly payment rounded to 2 decimal places in class property | ||
| this.totalMortgageCost = this.monthlyPayment * numberOfPayments; // total cost of the mortgage | ||
| return this.monthlyPayment; | ||
| } else { | ||
| throw new Error("amountOfTheMortgage is undefined"); | ||
| } | ||
| private calculateMortgagePrinciple() { | ||
| const principal = this.propertyValue * (1 - this.initialDeposit); | ||
| return principal; | ||
| } | ||
| calculateYearlyPaymentBreakdown() { | ||
| if (this.monthlyPayment == undefined || this.totalMortgageCost == undefined) | ||
| throw new Error("monthlyPayment or totalMortgageCost is undefined"); | ||
|
|
||
| private calculateMonthlyMortgagePayment() { | ||
| const monthlyInterestRate = this.interestRate / MONTHS_PER_YEAR; | ||
| const numberOfPayments = this.termYears * MONTHS_PER_YEAR; | ||
|
|
||
| let monthlyPayment = | ||
| (this.principal * | ||
| monthlyInterestRate * | ||
| Math.pow(1 + monthlyInterestRate, numberOfPayments)) / | ||
| (Math.pow(1 + monthlyInterestRate, numberOfPayments) - 1); | ||
| monthlyPayment = parseFloat(monthlyPayment.toFixed(2)); | ||
|
|
||
| const totalMortgageCost = monthlyPayment * numberOfPayments; | ||
|
|
||
| return { monthlyPayment, totalMortgageCost }; | ||
| } | ||
| private calculateYearlyPaymentBreakdown() { | ||
| let yearlyPayment = | ||
| this.initialDeposit * this.propertyValue + this.monthlyPayment * 12; | ||
| this.initialDeposit * this.propertyValue + | ||
| this.monthlyPayment * MONTHS_PER_YEAR; | ||
| let cumulativePaid = | ||
| this.initialDeposit * this.propertyValue + this.monthlyPayment * 12; | ||
| let remainingBalance = this.totalMortgageCost - this.monthlyPayment * 12; | ||
| this.initialDeposit * this.propertyValue + | ||
| this.monthlyPayment * MONTHS_PER_YEAR; | ||
| let remainingBalance = | ||
| this.totalMortgageCost - this.monthlyPayment * MONTHS_PER_YEAR; | ||
|
|
||
| interface mortgageBreakdownTypes { | ||
| yearlyPayment: number; | ||
| cumulativePaid: number; | ||
| remainingBalance: number; | ||
| } | ||
| let yearlyPaymentBreakdown: mortgageBreakdownTypes[] = [ | ||
| let yearlyPaymentBreakdown: MortgageBreakdown = [ | ||
| { | ||
| yearlyPayment: yearlyPayment, | ||
| cumulativePaid: cumulativePaid, | ||
| remainingBalance: remainingBalance, | ||
| }, | ||
| ]; // initialize the yearlyPaymentBreakdown | ||
| ]; | ||
|
|
||
| for (let i = 0; i < this.termYears - 1; i++) { | ||
| if (i != this.termYears - 1) { | ||
| yearlyPayment = this.monthlyPayment * 12; // calculate the yearly payment | ||
| yearlyPayment = this.monthlyPayment * MONTHS_PER_YEAR; | ||
| } else { | ||
| yearlyPayment = remainingBalance; // last year just pay the remaining balance | ||
| // last year just pay the remaining balance | ||
| yearlyPayment = remainingBalance; | ||
| } | ||
|
|
||
| cumulativePaid = cumulativePaid + yearlyPayment; // calculate the updated cumulative paid | ||
| remainingBalance = remainingBalance - yearlyPayment; // calculate the updated remaining balance | ||
| cumulativePaid = cumulativePaid + yearlyPayment; | ||
| remainingBalance = remainingBalance - yearlyPayment; | ||
|
|
||
| yearlyPaymentBreakdown.push({ | ||
| yearlyPayment: yearlyPayment, | ||
| cumulativePaid: cumulativePaid, | ||
| remainingBalance: remainingBalance, | ||
| }); // add the current yearly payment to the yearlyPaymentBreakdown | ||
| }); | ||
| } | ||
| this.yearlyPaymentBreakdown = yearlyPaymentBreakdown; // set the yearlyPaymentBreakdown | ||
|
|
||
| return yearlyPaymentBreakdown; | ||
| } | ||
| } | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1 @@ | ||
| export const MONTHS_PER_YEAR = 12; |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters