hooks/stepper: add generic stepper hook

pkgs/clan-app/ui/src/hooks/stepper.tsx

@@ -0,0 +1,120 @@
+import {
+  Accessor,
+  createContext,
+  createSignal,
+  JSX,
+  Setter,
+  useContext,
+} from "solid-js";
+
+export interface StepBase {
+  id: string;
+}
+
+export type Step<ExtraFields = unknown> = StepBase & ExtraFields;
+
+export interface StepOptions<Id> {
+  initialStep: Id;
+}
+
+export function createStepper<
+  T extends readonly Step<Extra>[],
+  StepId extends T[number]["id"],
+  Extra = unknown,
+>(s: { steps: T }, stepOpts: StepOptions<StepId>): StepperReturn<T> {
+  const [activeStep, setActiveStep] = createSignal<T[number]["id"]>(
+    stepOpts.initialStep,
+  );
+
+  /**
+   * Hooks to manage the current step in the workflow.
+   * It provides the active step and a function to set the active step.
+   */
+  return {
+    activeStep,
+    setActiveStep,
+    currentStep: () => {
+      const curr = s.steps.find((step) => step.id === activeStep());
+      if (!curr) {
+        throw new Error(`Step with id ${activeStep()} not found`);
+      }
+      return curr;
+    },
+    next: () => {
+      const currentIndex = s.steps.findIndex(
+        (step) => step.id === activeStep(),
+      );
+      if (currentIndex === -1 || currentIndex === s.steps.length - 1) {
+        throw new Error("No next step available");
+      }
+      setActiveStep(s.steps[currentIndex + 1].id);
+    },
+    previous: () => {
+      const currentIndex = s.steps.findIndex(
+        (step) => step.id === activeStep(),
+      );
+      if (currentIndex <= 0) {
+        throw new Error("No previous step available");
+      }
+      setActiveStep(s.steps[currentIndex - 1].id);
+    },
+    hasPrevious: () => {
+      const currentIndex = s.steps.findIndex(
+        (step) => step.id === activeStep(),
+      );
+      return currentIndex > 0;
+    },
+    hasNext: () => {
+      const currentIndex = s.steps.findIndex(
+        (step) => step.id === activeStep(),
+      );
+      return currentIndex >= 0 && currentIndex < s.steps.length - 1;
+    },
+  };
+}
+
+export interface StepperReturn<
+  T extends readonly Step[],
+  StepId = T[number]["id"],
+> {
+  activeStep: Accessor<StepId>;
+  setActiveStep: Setter<StepId>;
+  currentStep: () => T[number];
+  next: () => void;
+  previous: () => void;
+  hasPrevious: () => boolean;
+  hasNext: () => boolean;
+}
+
+const StepperContext = createContext<unknown>(); // Concrete type will be provided by the provider
+
+// Default assignment to "never" forces users to specify the type when using the hook, otherwise the return type will be `never`.
+export function useStepper<T extends readonly Step[] = never>() {
+  const ctx = useContext(StepperContext);
+  if (!ctx) throw new Error("useStepper must be used inside StepperProvider");
+  return ctx as T extends never ? never : StepperReturn<T, T[number]["id"]>; // type casting required due to context limitations
+}
+
+interface ProviderProps<T extends readonly Step[], StepId> {
+  stepper: StepperReturn<T, StepId>;
+  children: JSX.Element;
+}
+
+interface ProviderProps<
+  T extends readonly Step[],
+  StepId extends T[number]["id"],
+> {
+  stepper: StepperReturn<T, StepId>;
+  children: JSX.Element;
+}
+
+export function StepperProvider<
+  T extends readonly Step[],
+  StepId extends T[number]["id"],
+>(props: ProviderProps<T, StepId>) {
+  return (
+    <StepperContext.Provider value={props.stepper}>
+      {props.children}
+    </StepperContext.Provider>
+  );
+}