Textarea draft v0.1.0

/*
 * Textarea — vanilla CSS reference implementation.
 * Spec:   packages/components/specs/components/textarea.spec.json
 * Tokens: packages/tokens/dist/css/components/textarea.css (generated from packages/tokens/src/components/textarea.tokens.json)
 *
 * Rules:
 *  - Only --textarea-* custom properties may appear here. No raw values, no semantic tokens.
 *  - The root is a wrapper (label, control, description, error message, stacked); the native
 *    textarea is the control, drawn by the component.
 *  - Size is a data attribute on the root; states are native pseudo-classes or attributes of the
 *    control, and the root's [data-state="<state>"] forces them for review. Precedence follows the
 *    spec order: default < hover < focus-visible < invalid < readonly < disabled: hover only tints the
 *    background, invalid only recolors the border, so they combine as the token rule combines them.
 *  - Private properties (--_*) are the single place an option or a state writes to.
 */

.ds-textarea {
  /* Defaults = size "medium", state "default". */
  --_control-background: var(--textarea-control-background-default);
  --_control-border-color: var(--textarea-control-border-color-default);
  --_control-color: var(--textarea-control-color-default);
  --_placeholder-color: var(--textarea-control-placeholder-color-default);
  --_label-color: var(--textarea-label-color-default);
  --_description-color: var(--textarea-description-color-default);
  --_min-height: var(--textarea-control-min-height-medium);
  --_padding-inline: var(--textarea-control-padding-inline-medium);
  --_font-family: var(--textarea-control-typography-medium-font-family);
  --_font-size: var(--textarea-control-typography-medium-font-size);
  --_font-weight: var(--textarea-control-typography-medium-font-weight);
  --_line-height: var(--textarea-control-typography-medium-line-height);
  --_letter-spacing: var(--textarea-control-typography-medium-letter-spacing);
  --_padding-block: var(--textarea-control-padding-block-medium);

  box-sizing: border-box;
  display: inline-flex;
  flex-direction: column;
  align-items: stretch;
  gap: var(--textarea-container-gap);
  min-inline-size: 0;
  vertical-align: middle;
}

/* ---- Size ---------------------------------------------------------------- */

.ds-textarea[data-size="small"] {
  --_min-height: var(--textarea-control-min-height-small);
  --_padding-inline: var(--textarea-control-padding-inline-small);
  --_font-family: var(--textarea-control-typography-small-font-family);
  --_font-size: var(--textarea-control-typography-small-font-size);
  --_font-weight: var(--textarea-control-typography-small-font-weight);
  --_line-height: var(--textarea-control-typography-small-line-height);
  --_letter-spacing: var(--textarea-control-typography-small-letter-spacing);
  --_padding-block: var(--textarea-control-padding-block-small);
}

.ds-textarea[data-size="large"] {
  --_min-height: var(--textarea-control-min-height-large);
  --_padding-inline: var(--textarea-control-padding-inline-large);
  --_font-family: var(--textarea-control-typography-large-font-family);
  --_font-size: var(--textarea-control-typography-large-font-size);
  --_font-weight: var(--textarea-control-typography-large-font-weight);
  --_line-height: var(--textarea-control-typography-large-line-height);
  --_letter-spacing: var(--textarea-control-typography-large-letter-spacing);
  --_padding-block: var(--textarea-control-padding-block-large);
}

/* ---- Parts --------------------------------------------------------------- */

.ds-textarea__label {
  color: var(--_label-color);
  font-family: var(--textarea-label-typography-font-family);
  font-size: var(--textarea-label-typography-font-size);
  font-weight: var(--textarea-label-typography-font-weight);
  line-height: var(--textarea-label-typography-line-height);
  letter-spacing: var(--textarea-label-typography-letter-spacing);
}

.ds-textarea__control {
  box-sizing: border-box;
  inline-size: 100%;
  min-height: var(--_min-height);
  margin: 0;
  padding-block: 0;
  padding-inline: var(--_padding-inline);
  border: var(--textarea-control-border-width) solid var(--_control-border-color);
  border-radius: var(--textarea-control-border-radius);
  background-color: var(--_control-background);
  color: var(--_control-color);
  font-family: var(--_font-family);
  font-size: var(--_font-size);
  font-weight: var(--_font-weight);
  line-height: var(--_line-height);
  letter-spacing: var(--_letter-spacing);
  appearance: none;
  -webkit-appearance: none;
  transition:
    background-color var(--textarea-control-transition-duration) var(--textarea-control-transition-easing),
    border-color var(--textarea-control-transition-duration) var(--textarea-control-transition-easing);
}

.ds-textarea__control::placeholder {
  color: var(--_placeholder-color);
  opacity: 1;
}

.ds-textarea__description {
  margin: 0;
  color: var(--_description-color);
  font-family: var(--textarea-description-typography-font-family);
  font-size: var(--textarea-description-typography-font-size);
  font-weight: var(--textarea-description-typography-font-weight);
  line-height: var(--textarea-description-typography-line-height);
  letter-spacing: var(--textarea-description-typography-letter-spacing);
}

.ds-textarea__error-message {
  margin: 0;
  color: var(--textarea-error-message-color);
  font-family: var(--textarea-error-message-typography-font-family);
  font-size: var(--textarea-error-message-typography-font-size);
  font-weight: var(--textarea-error-message-typography-font-weight);
  line-height: var(--textarea-error-message-typography-line-height);
  letter-spacing: var(--textarea-error-message-typography-letter-spacing);
}

/* Multi-line: the block padding sets the inset of the first and last line; the control can be resized vertically. */
.ds-textarea__control {
  padding-block: var(--_padding-block);
  resize: vertical;
}

/* ---- States -------------------------------------------------------------- */

.ds-textarea:where([data-state="hover"]) .ds-textarea__control:not(:disabled, [readonly]),
.ds-textarea:not([data-state]) .ds-textarea__control:hover:not(:disabled, [readonly]) {
  --_control-background: var(--textarea-control-background-hover);
}

.ds-textarea:where([data-state="invalid"]) .ds-textarea__control,
.ds-textarea__control[aria-invalid="true"] {
  --_control-border-color: var(--textarea-control-border-color-invalid);
}

.ds-textarea:where([data-state="readonly"]) .ds-textarea__control,
.ds-textarea__control[readonly] {
  --_control-background: var(--textarea-control-background-readonly);
}

.ds-textarea:where([data-state="disabled"]),
.ds-textarea:has(.ds-textarea__control:disabled) {
  --_label-color: var(--textarea-label-color-disabled);
  --_description-color: var(--textarea-description-color-disabled);
}
.ds-textarea:where([data-state="disabled"]) .ds-textarea__control,
.ds-textarea__control:disabled {
  --_control-background: var(--textarea-control-background-disabled);
  --_control-border-color: var(--textarea-control-border-color-disabled);
  --_control-color: var(--textarea-control-color-disabled);
  --_placeholder-color: var(--textarea-control-placeholder-color-disabled);
  cursor: not-allowed;
}

.ds-textarea__control:focus {
  outline: none;
}

.ds-textarea:where([data-state="focus-visible"]) .ds-textarea__control,
.ds-textarea__control:focus-visible {
  outline: var(--textarea-control-outline-width-focus-visible) solid var(--textarea-control-outline-color-focus-visible);
  outline-offset: var(--textarea-control-outline-offset-focus-visible);
}

@media (prefers-reduced-motion: reduce) {
  .ds-textarea__control {
    transition: none;
  }
}

/**
 * Textarea — HTML template for the web implementation.
 * Pure function of the spec properties (packages/components/specs/components/textarea.spec.json) -> HTML string.
 * Used by the docs site (server and client side). No DOM, no framework, no script: a native
 * textarea named by its label, described by its description and, when invalid, by its error message.
 *
 * Extra props: `id` names the control (unique in the page; without it instances are numbered in
 * render order); `name` is the form field's; `attrs` adds HTML attributes to the control.
 * Extra sandbox-only prop: `state` forces a visual state through data-state on the root.
 */
import { escapeHtml, escapeAttr } from '../../lib/template-utils.mjs';

export const meta = { id: 'textarea', selector: '.ds-textarea' };

let count = 0;

export function render(props = {}) {
  const {
    label = 'Label',
    value = '',
    placeholder = null,
    description = null,
    errorMessage = null,
    rows = 3,
    size = 'medium',
    required = false,
    disabled = false,
    readonly = false,
    invalid = false,
    state = null,
    id = null,
    name = null,
    attrs: extra = {},
  } = props;

  const controlId = id ?? `ds-textarea-${++count}`;
  const descriptionId = `${controlId}-description`;
  const errorId = `${controlId}-error`;
  const rootAttrs = ['class="ds-textarea"', `data-size="${escapeAttr(size)}"`];
  if (disabled) rootAttrs.push('data-disabled');
  if (readonly) rootAttrs.push('data-readonly');
  if (invalid) rootAttrs.push('data-invalid');
  if (state && state !== 'default') rootAttrs.push(`data-state="${escapeAttr(state)}"`);

  const controlAttrs = ['class="ds-textarea__control"', 'data-part="control"', `id="${escapeAttr(controlId)}"`, `rows="${escapeAttr(Math.max(1, Number(rows) || 3))}"`];
  if (name) controlAttrs.push(`name="${escapeAttr(name)}"`);
  if (placeholder) controlAttrs.push(`placeholder="${escapeAttr(placeholder)}"`);
  if (required) controlAttrs.push('required');
  if (disabled) controlAttrs.push('disabled');
  if (readonly) controlAttrs.push('readonly');
  if (invalid) controlAttrs.push('aria-invalid="true"');
  const describedBy = [description ? descriptionId : null, invalid && errorMessage ? errorId : null].filter(Boolean);
  if (describedBy.length) controlAttrs.push(`aria-describedby="${escapeAttr(describedBy.join(' '))}"`);
  for (const [k, v] of Object.entries(extra)) {
    if (v === false || v == null) continue;
    controlAttrs.push(v === true ? escapeAttr(k) : `${escapeAttr(k)}="${escapeAttr(v)}"`);
  }

  const parts = [
    `<label class="ds-textarea__label" data-part="label" for="${escapeAttr(controlId)}">${escapeHtml(label)}</label>`,
    `<textarea ${controlAttrs.join(' ')}>${escapeHtml(value ?? '')}</textarea>`,
  ];
  if (description) parts.push(`<p class="ds-textarea__description" data-part="description" id="${escapeAttr(descriptionId)}">${escapeHtml(description)}</p>`);
  if (invalid && errorMessage) parts.push(`<p class="ds-textarea__error-message" data-part="error-message" id="${escapeAttr(errorId)}">${escapeHtml(errorMessage)}</p>`);
  return `<div ${rootAttrs.join(' ')}>${parts.join('')}</div>`;
}