1 files changed, 227 insertions, 0 deletions
diff --git a/packages/aml-backoffice-ui/src/hooks/form.ts b/packages/aml-backoffice-ui/src/hooks/form.ts
new file mode 100644
index 000000000..70b2db571
--- /dev/null
+++ b/packages/aml-backoffice-ui/src/hooks/form.ts
@@ -0,0 +1,227 @@
+/*
+ This file is part of GNU Taler
+ (C) 2022-2024 Taler Systems S.A.
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+import {
+  AbsoluteTime,
+  AmountJson,
+  TalerExchangeApi,
+  TranslatedString,
+} from "@gnu-taler/taler-util";
+import {
+  UIFieldHandler,
+  UIFormElementConfig,
+  UIHandlerId,
+} from "@gnu-taler/web-util/browser";
+import { useState } from "preact/hooks";
+import { undefinedIfEmpty } from "../pages/CreateAccount.js";
+
+// export type UIField = {
+//   value: string | undefined;
+//   onUpdate: (s: string) => void;
+//   error: TranslatedString | undefined;
+// };
+
+export type FormHandler<T> = {
+  [k in keyof T]?: T[k] extends string
+    ? UIFieldHandler
+    : T[k] extends AmountJson
+      ? UIFieldHandler
+      : T[k] extends TalerExchangeApi.AmlState
+        ? UIFieldHandler
+        : FormHandler<T[k]>;
+};
+
+export type FormValues<T> = {
+  [k in keyof T]: T[k] extends string ? string | undefined : FormValues<T[k]>;
+};
+
+export type RecursivePartial<T> = {
+  [k in keyof T]?: T[k] extends string
+    ? string
+    : T[k] extends AmountJson
+      ? AmountJson
+      : T[k] extends TalerExchangeApi.AmlState
+        ? TalerExchangeApi.AmlState
+        : RecursivePartial<T[k]>;
+};
+
+export type FormErrors<T> = {
+  [k in keyof T]?: T[k] extends string
+    ? TranslatedString
+    : T[k] extends AmountJson
+      ? TranslatedString
+      : T[k] extends AbsoluteTime
+        ? TranslatedString
+        : T[k] extends TalerExchangeApi.AmlState
+          ? TranslatedString
+          : FormErrors<T[k]>;
+};
+
+export type FormStatus<T> =
+  | {
+      status: "ok";
+      result: T;
+      errors: undefined;
+    }
+  | {
+      status: "fail";
+      result: RecursivePartial<T>;
+      errors: FormErrors<T>;
+    };
+
+function constructFormHandler<T>(
+  shape: Array<UIHandlerId>,
+  form: RecursivePartial<FormValues<T>>,
+  updateForm: (d: RecursivePartial<FormValues<T>>) => void,
+  errors: FormErrors<T> | undefined,
+): FormHandler<T> {
+  const handler = shape.reduce((handleForm, fieldId) => {
+    const path = fieldId.split(".");
+
+    function updater(newValue: unknown) {
+      updateForm(setValueDeeper(form, path, newValue));
+    }
+
+    const currentValue = getValueDeeper<string>(form as any, path, undefined);
+    const currentError = getValueDeeper<TranslatedString>(
+      errors as any,
+      path,
+      undefined,
+    );
+    const field: UIFieldHandler = {
+      error: currentError,
+      value: currentValue,
+      onChange: updater,
+      state: {}, //FIXME: add the state of the field (hidden, )
+    };
+
+    return setValueDeeper(handleForm, path, field);
+  }, {} as FormHandler<T>);
+
+  return handler;
+}
+
+/**
+ * FIXME: Consider sending this to web-utils
+ *
+ *
+ * @param defaultValue
+ * @param check
+ * @returns
+ */
+export function useFormState<T>(
+  shape: Array<UIHandlerId>,
+  defaultValue: RecursivePartial<FormValues<T>>,
+  check: (f: RecursivePartial<FormValues<T>>) => FormStatus<T>,
+): [FormHandler<T>, FormStatus<T>] {
+  const [form, updateForm] =
+    useState<RecursivePartial<FormValues<T>>>(defaultValue);
+
+  const status = check(form);
+  const handler = constructFormHandler(shape, form, updateForm, status.errors);
+
+  return [handler, status];
+}
+
+interface Tree<T> extends Record<string, Tree<T> | T> {}
+
+export function getValueDeeper<T>(
+  object: Tree<T> | undefined,
+  names: string[],
+  notFoundValue?: T,
+): T | undefined {
+  if (names.length === 0) return object as T;
+  const [head, ...rest] = names;
+  if (!head) {
+    return getValueDeeper(object, rest, notFoundValue);
+  }
+  if (object === undefined) {
+    return notFoundValue;
+  }
+  return getValueDeeper(object[head] as Tree<T>, rest, notFoundValue);
+}
+
+export function setValueDeeper(object: any, names: string[], value: any): any {
+  if (names.length === 0) return value;
+  const [head, ...rest] = names;
+  if (!head) {
+    return setValueDeeper(object, rest, value);
+  }
+  if (object === undefined) {
+    return undefinedIfEmpty({ [head]: setValueDeeper({}, rest, value) });
+  }
+  return undefinedIfEmpty({ ...object, [head]: setValueDeeper(object[head] ?? {}, rest, value) });
+}
+
+export function getShapeFromFields(
+  fields: UIFormElementConfig[],
+): Array<UIHandlerId> {
+  const shape: Array<UIHandlerId> = [];
+  fields.forEach((field) => {
+    if ("id" in field) {
+      // FIXME: this should be a validation when loading the form
+      // consistency check
+      if (shape.indexOf(field.id) !== -1) {
+        throw Error(`already present: ${field.id}`);
+      }
+      shape.push(field.id);
+    } else if (field.type === "group") {
+      Array.prototype.push.apply(
+        shape,
+        getShapeFromFields(field.fields),
+      );
+    }
+  });
+  return shape;
+}
+
+export function getRequiredFields(
+  fields: UIFormElementConfig[],
+): Array<UIHandlerId> {
+  const shape: Array<UIHandlerId> = [];
+  fields.forEach((field) => {
+    if ("id" in field) {
+      // FIXME: this should be a validation when loading the form
+      // consistency check
+      if (shape.indexOf(field.id) !== -1) {
+        throw Error(`already present: ${field.id}`);
+      }
+      if (!field.required) {
+        return;
+      }
+      shape.push(field.id);
+    } else if (field.type === "group") {
+      Array.prototype.push.apply(
+        shape,
+        getRequiredFields(field.fields),
+      );
+    }
+  });
+  return shape;
+}
+export function validateRequiredFields<FormType>(
+  errors: FormErrors<FormType> | undefined,
+  form: object,
+  fields: Array<UIHandlerId>,
+): FormErrors<FormType> | undefined {
+  let result: FormErrors<FormType> | undefined = errors;
+  fields.forEach((f) => {
+    const path = f.split(".");
+    const v = getValueDeeper(form as any, path);
+    result = setValueDeeper(result, path, !v ? "required" : undefined);
+  });
+  return result;
+}