fix: fallback to default params on index (#15)

internal/handlers/calc.go

@@ -3,6 +3,8 @@ package handlers
 import (
 	"fmt"
 	"net/http"
+	"net/url"
+	"strconv"
 
 	"debtrecyclingcalc.com/internal/calc"
 	"debtrecyclingcalc.com/internal/charts"
@@ -21,13 +23,12 @@ func CalcHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	params, err := getFormParams(r)
+	params, err := getParamsFromForm(r.Form)
 	if err != nil {
-		http.Error(w, err.Error(), http.StatusBadRequest)
+		http.Error(w, "error parsing form params", http.StatusBadRequest)
 		return
 	}
 
-	// if params is empty respond with error
 	data, err := calc.DebtRecycling(*params)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
@@ -84,3 +85,71 @@ func CalcHandler(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 	}
 }
+
+func getParamsFromForm(form url.Values) (*calc.Parameters, error) {
+	parseFloat := func(key string) (float64, error) {
+		return strconv.ParseFloat(form.Get(key), 64)
+	}
+
+	parseInt := func(key string) (int, error) {
+		return strconv.Atoi(form.Get(key))
+	}
+
+	salary, err := parseFloat("salary")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing salary: %w", err)
+	}
+
+	initialInvestmentAmount, err := parseFloat("initial_investment")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing initial investment amount: %w", err)
+	}
+
+	annualInvestmentAmount, err := parseFloat("annual_investment")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing annual investment amount: %w", err)
+	}
+
+	mortgageSize, err := parseFloat("mortgage_size")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing mortgage size: %w", err)
+	}
+
+	mortgageInterestRate, err := parseFloat("mortgage_interest_rate")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing mortgage interest rate: %w", err)
+	}
+
+	dividendReturnRate, err := parseFloat("dividend_return_rate")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing dividend return rate: %w", err)
+	}
+
+	capitalGrowthRate, err := parseFloat("capital_growth_rate")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing capital growth rate: %w", err)
+	}
+
+	years, err := parseInt("years")
+	if err != nil {
+		return nil, fmt.Errorf("error parsing years: %w", err)
+	}
+
+	country := form.Get("country")
+	reinvestDividends := form.Get("reinvest_dividends") == "true"
+	reinvestTaxRefunds := form.Get("reinvest_tax_refunds") == "true"
+
+	return &calc.Parameters{
+		Salary:               salary,
+		InitialInvestment:    initialInvestmentAmount,
+		AnnualInvestment:     annualInvestmentAmount,
+		MortgageSize:         mortgageSize,
+		MortgageInterestRate: mortgageInterestRate / 100,
+		DividendReturnRate:   dividendReturnRate / 100,
+		CapitalGrowthRate:    capitalGrowthRate / 100,
+		NumYears:             years,
+		Country:              country,
+		ReinvestDividends:    reinvestDividends,
+		ReinvestTaxRefunds:   reinvestTaxRefunds,
+	}, nil
+}

internal/handlers/index.go

@@ -2,6 +2,8 @@ package handlers
 
 import (
 	"net/http"
+	"net/url"
+	"strconv"
 
 	"debtrecyclingcalc.com/internal/buildinfo"
 	"debtrecyclingcalc.com/internal/calc"
@@ -43,13 +45,8 @@ func IndexHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	query := r.URL.Query()
-	var err error
 	if len(query) != 0 {
-		params, err = getQueryParams(query)
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
+		setParamsFromQuery(params, query)
 	}
 
 	data, err := calc.DebtRecycling(*params)
@@ -88,3 +85,70 @@ func IndexHandler(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 	}
 }
+
+func setParamsFromQuery(params *calc.Parameters, query url.Values) {
+	parseFloat := func(key string) (float64, error) {
+		if val := query.Get(key); val != "" {
+			return strconv.ParseFloat(val, 64)
+		}
+		return 0, nil // Return zero but no error if key is absent
+	}
+
+	parseInt := func(key string) (int, error) {
+		if val := query.Get(key); val != "" {
+			return strconv.Atoi(val)
+		}
+		return 0, nil // Return zero but no error if key is absent
+	}
+
+	// Update fields if the corresponding query parameter is present
+	if salary, err := parseFloat("salary"); err == nil && salary != 0 {
+		params.Salary = salary
+	}
+
+	if initialInvestmentAmount, err := parseFloat("initial_investment"); err == nil &&
+		initialInvestmentAmount != 0 {
+		params.InitialInvestment = initialInvestmentAmount
+	}
+
+	if annualInvestmentAmount, err := parseFloat("annual_investment"); err == nil &&
+		annualInvestmentAmount != 0 {
+		params.AnnualInvestment = annualInvestmentAmount
+	}
+
+	if mortgageSize, err := parseFloat("mortgage_size"); err == nil && mortgageSize != 0 {
+		params.MortgageSize = mortgageSize
+	}
+
+	if mortgageInterestRate, err := parseFloat("mortgage_interest_rate"); err == nil &&
+		mortgageInterestRate != 0 {
+		params.MortgageInterestRate = mortgageInterestRate / 100
+	}
+
+	if dividendReturnRate, err := parseFloat("dividend_return_rate"); err == nil &&
+		dividendReturnRate != 0 {
+		params.DividendReturnRate = dividendReturnRate / 100
+	}
+
+	if capitalGrowthRate, err := parseFloat("capital_growth_rate"); err == nil &&
+		capitalGrowthRate != 0 {
+		params.CapitalGrowthRate = capitalGrowthRate / 100
+	}
+
+	if years, err := parseInt("years"); err == nil && years != 0 {
+		params.NumYears = years
+	}
+
+	// Simple string params
+	if country := query.Get("country"); country != "" {
+		params.Country = country
+	}
+
+	// Checkboxes for reinvestment toggles: maintain defaults if not present
+	if query["reinvest_dividends"] != nil {
+		params.ReinvestDividends = query.Get("reinvest_dividends") == "true"
+	}
+	if query["reinvest_tax_refunds"] != nil {
+		params.ReinvestTaxRefunds = query.Get("reinvest_tax_refunds") == "true"
+	}
+}

internal/templates/form.templ

@@ -129,7 +129,7 @@ templ Form(params *calc.Parameters) {
             <label for="country_selection" class="block text-sm font-medium text-gray-700">
                 Country
             </label>
-            <select id="country_selection" name="country" autocomplete="on" class="mt-1 block w-full border border-gray-300 rounded-md shadow-sm focus:ring-indigo-500 focus:border-indigo-500 sm:text-sm">
+            <select id="country_selection" name="country" class="mt-1 block w-full border border-gray-300 rounded-md shadow-sm focus:ring-indigo-500 focus:border-indigo-500 sm:text-sm">
               <option value="AU">🇦🇺 Australia</option>
               <option value="NZ">🇳🇿 New Zealand</option>
             </select>
@@ -138,7 +138,7 @@ templ Form(params *calc.Parameters) {
             <input 
                 type="checkbox"
                 name="reinvest_dividends"
-                autocomplete="on"
+                value="true"
                 id="reinvest_dividends"
                 class="h-4 w-4 text-blue-600 border-gray-300 rounded"
             if params.ReinvestDividends {
@@ -151,6 +151,7 @@ templ Form(params *calc.Parameters) {
             <input
                 type="checkbox"
                 name="reinvest_tax_refunds"
+                value="true"
                 id="reinvest_tax_refunds"
                 class="h-4 w-4 text-blue-600 border-gray-300 rounded"
             if params.ReinvestTaxRefunds {