// Pins :hover, :active and :focus-visible visuals for state Stories (Storybook only, never loaded by the app).
// Every rule that uses :hover, :active or :focus-visible is cloned right after itself with the pseudo-class swapped for a
// data attribute, so cascade order and specificity stay the same. No declaration or value is authored here.
// 2026-11-13: :focus-visible → data-sb-focus, so a Focus specimen can show its ring without holding the page focus (only one
// element can be focused; e.g. Selection Controls focuses the Checkbox and pins the Radio Group / Switch rings).
const HOVER = "data-sb-hover"
const ACTIVE = "data-sb-active"
const FOCUS = "data-sb-focus"
const PSEUDO = /:hover\b|:active\b|:focus-visible\b/
// A negated :focus-visible (:not(:focus-visible)) would match every element without the attribute, so such a rule keeps its
// :focus-visible and only its :hover / :active (if any) are swapped.
const NEGATED_FOCUS = /:not\([^)]*:focus-visible/
const mirrored = new WeakSet<CSSStyleSheet>()

function mirror(list: CSSStyleSheet | CSSGroupingRule) {
  for (let i = list.cssRules.length - 1; i >= 0; i--) {
    const rule = list.cssRules[i]
    if (rule instanceof CSSStyleRule) {
      if (PSEUDO.test(rule.selectorText)) {
        // `base` keeps :focus-visible (the pre-2026-11-13 clone), so real focus + data-sb-hover / data-sb-active still matches
        // a compound rule such as :focus-visible:active (Slider Focus + Drag). `full` also swaps :focus-visible.
        const base = rule.cssText.replace(/:hover\b/g, `[${HOVER}]`).replace(/:active\b/g, `[${ACTIVE}]`)
        const full = NEGATED_FOCUS.test(rule.selectorText) ? base : base.replace(/:focus-visible\b/g, `[${FOCUS}]`)
        if (full !== base) list.insertRule(full, i + 1)
        if (base !== rule.cssText) list.insertRule(base, i + 1)
      }
    } else if ("cssRules" in rule) {
      mirror(rule as CSSGroupingRule)
    }
  }
}

export function ensurePseudoStates() {
  for (const sheet of document.styleSheets) {
    if (mirrored.has(sheet)) continue
    mirrored.add(sheet)
    try {
      mirror(sheet)
    } catch {
      // Unreadable (cross-origin) sheet: nothing to mirror.
    }
  }
}