import type { Theme } from "./theme";

export type ResolvedTheme = "light" | "dark";
export type ThemeQueryMode = "light" | "dark" | "system";

export function parseThemeQuery(value: string | null | undefined): ThemeQueryMode | null {
  if (!value) {
    return null;
  }

  const normalized = value.toLowerCase();

  if (normalized === "light" || normalized === "dark") {
    return normalized;
  }

  if (normalized === "auto" || normalized === "system") {
    return "system";
  }

  return null;
}

export function resolveStoredTheme(
  theme: Theme,
  prefersDark: boolean,
): ResolvedTheme {
  if (theme === "system") {
    return prefersDark ? "dark" : "light";
  }

  return theme;
}

export function resolveIncomingThemeMode(
  mode: unknown,
  prefersDark: boolean,
): ResolvedTheme | null {
  if (mode === "light" || mode === "dark") {
    return mode;
  }

  if (mode === "auto" || mode === "system") {
    return prefersDark ? "dark" : "light";
  }

  return null;
}