import { Meta, Story, Source } from "@storybook/addon-docs";

<Meta title="Component Library/Form" />

# Forms

Component Library forms should always be built using [Angular Reactive Forms][reactive]. Please read
[ADR-0001][adr-0001] for a background to this decision. In practice this means that forms should
always use the native `form` element and bind a `formGroup`.

<Story id="component-library-form--full-example" />

<Source id="component-library-form--full-example" />

## Form spacing and sections

Forms consists of 1 or more inputs, and ends with 1 or 2 buttons.

If there are many inputs in a form, they should should be organized into sections as content
relates. **Example:** Item type form

Each input within a section should follow the following spacing guidelines (see
[Tailwind CSS spacing documentation](https://tailwindcss.com/docs/customizing-spacing)):

- 1.5rem of vertical spacing between form elements: `mb-6`
- 1.5rem of horizontal spacing between form elements: `mr-6`
- 3rem of vertical spacing below a form section: `mb-12`
- 1rem of vertical spacing between a form group divider and the group's title; so title tag has:
  `my-4`
- Form section titles should be styled using `text-lg`
- Each form sections may have a single column, double or triple column layout. No form should have
  more than 3 columns. Do NOT use different column layouts within the same form section. Choose the
  best layout based on the number of fields and type of fields included.

## Input Types

### Field

A form field is the most common input in a form. It consists of a label, control and an optional
hint.

The styling of form fields applies to all field types: `text`, `number`, `select`, `text-area`,
`date`, etc.

Be sure to use an appropriate type attribute on fields when defining new field components (e.g.
`email` for email address or `number` for numerical information) to take advantage of newer input
controls like email verification, number selection, and more.

#### Default with required attribute

<Story id="component-library-form-field--default" />

#### Password Toggle

<Story id="component-library-form-password-toggle--default" />

#### Search

<Story id="component-library-form-search--default" />

### Selects

#### Searchable single select (default)

<Story id="component-library-form-select--default" />

#### Multi-select

<Story id="component-library-form-multi-select--members" />

### Radio group

Radio buttons should always be in radio groups.

Radio groups are form fields that consists of a main label and multiple radio buttons. Each radio
button consists of a label and a radio input.

The full form control + label should be selectable to allow the user a larger click target.

Radio groups should always have a default selected value.

Radio groups may optionally include extra helper text below each radio button.

If a radio group has more than 4 options and the options do not need helper text, a
[select menu](?path=/docs/component-library-form-multi-select--docs) should be used instead. Avoid
using a radio group for more than 5 options even if the options require additional explanation text.

`TODO: extend the select component to support a dropdown menu with descriptions below each option`

#### Block

<Story id="component-library-form-radio-button--block" />

#### Inline

<Story id="component-library-form-radio-button--inline" />

[reactive]: https://angular.io/guide/reactive-forms
[adr-0001]: https://contributing.bitwarden.com/architecture/adr/reactive-forms

### Checkbox

The checkbox input is used to toggle an action on/off.

Checkboxes can be displayed on their own or in a group (select multiple form question). When
displayed in a group, include an input Label and any associated required/validation logic for the
field.

Unlike radio groups, checkbox groups are not required to have a default selected value.

Checkbox groups can include extra explanation text below each radio button or just the checkbox
button itself.

If a checkbox group has more than 4 options a
[multi-select components](?path=/docs/component-library-form-multi-select--docs) should be used.

#### Single checkbox

<Story id="component-library-form-checkbox--default" />

## Accessibility

### Required Fields

- Use "(required)" in the label of each required form field styled the same as the field's helper
  text (`.muted-text`).
- If whether or not a form field is required depends on another field, add this to the field's
  helper text.
  - **Example:** "Billing Email is required if owned by a business".

### Form Field Errors

- When a resting field is filled out, validation is triggered when the user de-focuses the field
  (`onblur`). If the control is invalid, assistive technology should announce the error (consider
  using `role="alert"` or an `aria-live="assertive"`).
- Validation should not be triggered if the control is left untouched; this allows a user of
  assistive technology to read the entire form if they wish without triggering validation that could
  interrupt them. - **TODO:** research how we might implement this behavior; as previous research
  has shown Angular may not allow both validation when `dirty` `onblur` AND validation on Submit
  which is a requirement
- A form control with an error should change to the error UI and the error text should be displayed
  below the element and be associated to their respective fields (consider using `aria-describedby`)
- When a field with an error is focused, assistive technology should announce the label and
  elements' invalid state and then the error text.
  - **Example:** "URL required, Error, URL format is not acceptable."
- Once the user has re-focused the field, and starts typing. The error will disappear. Validation
  should not occur when typing in most cases. Once th user unfocuses the field, validation triggers
  again.

### Validation on Submit

- Validation must also occur on submit. A user may select the submit button directly without
  changing focus from a form input. Or a user may disable their browser's javascript which is what
  supports the inline onblur validation. Finally, there may be a server side error that can only be
  checked on submit.
- On submit, a summary error should appear near the submit button or at the top of the form alerting
  the user of what errors need to be addressed. This summary should be read out by assistive
  technology after submit regardless of whether or not it was already on screen.
- Any invalid form control will display an inline error following the field's helper text (or in
  place of)
- If submit is successful, use a success toast to alert the user of the successful action.
- For any server side errors, the Danger toast may still be used. Be sure to adjust the toast's
  timeout to follow the 6 second

* 1 second for each additional 120 words rule.

### Helper Text

Similar to a field error, helper text should be associated to a field using `aria-describedby`. This
allows assistive technology to read out the instructional text and field requirements in addition to
the field’s label.

### Visual style

- All field inputs are interactive elements that must follow the WCAG graphic contrast guidelines.
  Maintain a ratio of 3:1 with the form's background.
- Error styling should not rely only on using the `danger-600`color change. Use
  <i class="bwi bwi-error"></i> as a prefix to highlight the text as error text versus helper
