Improve form and template usage (#66)

* Improve form and template usage.

pkg/form/form.go

@@ -1,13 +1,40 @@
 package form
 
 import (
-	"fmt"
-	"net/http"
-
 	"github.com/labstack/echo/v4"
 	"github.com/mikestefanello/pagoda/pkg/context"
 )
 
+// Form represents a form that can be submitted and validated
+type Form interface {
+	// Submit marks the form as submitted, stores a pointer to it in the context, binds the request
+	// values to the struct fields, and validates the input based on the struct tags.
+	// Returns a validator.ValidationErrors if the form values were not valid.
+	// Returns an echo.HTTPError if the request failed to process.
+	Submit(c echo.Context, form any) error
+
+	// IsSubmitted returns true if the form was submitted
+	IsSubmitted() bool
+
+	// IsValid returns true if the form has no validation errors
+	IsValid() bool
+
+	// IsDone returns true if the form was submitted and has no validation errors
+	IsDone() bool
+
+	// FieldHasErrors returns true if a given struct field has validation errors
+	FieldHasErrors(fieldName string) bool
+
+	// SetFieldError sets a validation error message for a given struct field
+	SetFieldError(fieldName string, message string)
+
+	// GetFieldErrors returns the validation errors for a given struct field
+	GetFieldErrors(fieldName string) []string
+
+	// GetFieldStatusClass returns a CSS class to be used for a given struct field
+	GetFieldStatusClass(fieldName string) string
+}
+
 // Get gets a form from the context or initializes a new copy if one is not set
 func Get[T any](ctx echo.Context) *T {
 	if v := ctx.Get(context.FormKey); v != nil {
@@ -17,18 +44,13 @@ func Get[T any](ctx echo.Context) *T {
 	return &v
 }
 
-// Set sets a form in the context and binds the request values to it
-func Set(ctx echo.Context, form any) error {
-	ctx.Set(context.FormKey, form)
-
-	if err := ctx.Bind(form); err != nil {
-		return echo.NewHTTPError(http.StatusInternalServerError, fmt.Sprintf("unable to bind form: %v", err))
-	}
-
-	return nil
-}
-
 // Clear removes the form set in the context
 func Clear(ctx echo.Context) {
 	ctx.Set(context.FormKey, nil)
 }
+
+// Submit submits a form
+// See Form.Submit()
+func Submit(ctx echo.Context, form Form) error {
+	return form.Submit(ctx, form)
+}