// Strict color sanitization for any value that reaches a CSS context — a React
// `style` prop or a raw `<style>` block — in the HTML -> PDF render paths.
//
// Standalone and import-free so it is safe to pull into client bundles (the
// invoice/report templates render in both apps) without dragging in drizzle /
// sqlite / the PDF pipeline. Relative-import it; it is intentionally NOT part of
// the `./utils` barrel.

/**
 * A CSS hex color (`#rgb` / `#rgba` / `#rrggbb` / `#rrggbbaa`) — nothing else.
 * Because it is strict hex, a matching value cannot contain CSS/HTML breakout
 * characters (`;`, `}`, `<`, `>`, whitespace), so it is safe to serialize into
 * a `style` prop or a raw `<style>` declaration.
 */
export const HEX_COLOR = /^#[0-9a-f]{3,8}$/i;

/**
 * A numeric `oklch()` color — `oklch(L C H)` / `oklch(L C H / A)` where the
 * argument list is restricted to digits, dots, whitespace, `%` and an optional
 * `/` alpha separator. This is the format produced by the project palette
 * (`getColorForName` / `getNextColor`, e.g. `oklch(0.6 0.15 137)`). Because the
 * arguments cannot contain CSS/HTML breakout characters (`;`, `}`, `<`, `>`),
 * a matching value is safe to serialize into a `style` prop. Note this
 * intentionally rejects `oklch(... var(--x) ...)` — stored project colors are
 * always concrete numeric values, never CSS custom properties.
 */
export const OKLCH_COLOR = /^oklch\([0-9.%/\s]+\)$/i;

/**
 * True when `value` is a project color we allow to be persisted: a strict hex
 * color or a numeric `oklch()` color. Used at the mutation boundary so a
 * malformed / poisoned color string can never be stored (and later injected raw
 * into a `style` prop by a render site). Rejects everything else — including
 * `null`/`undefined` and non-strings — so callers must handle "clear the color"
 * separately.
 */
export function isValidProjectColor(value: unknown): value is string {
  if (typeof value !== "string") return false;
  const trimmed = value.trim();
  return HEX_COLOR.test(trimmed) || OKLCH_COLOR.test(trimmed);
}

/**
 * Validate an untrusted color string for safe use in a CSS context. Returns the
 * trimmed value only when it is a strict hex color; otherwise FAILS CLOSED to
 * `fallback` (default `undefined`, i.e. "drop the color").
 *
 * React serializes a `style` value faithfully, so an unsanitized value like
 * `red; color: evil` (or `red;}</style><script>…` in a string style) would
 * inject extra declarations / break out of the markup. Running every
 * user-controlled color (e.g. `projects.color`) through this at the render
 * boundary closes that hole.
 */
export function sanitizeHexColor(
  value: string | null | undefined,
  fallback?: string,
): string | undefined {
  if (typeof value !== "string") return fallback;
  const trimmed = value.trim();
  return HEX_COLOR.test(trimmed) ? trimmed : fallback;
}