export const APPEARANCE_PREFERENCES = ["system", "light", "dark"] as const;

export type AppearancePreference = (typeof APPEARANCE_PREFERENCES)[number];

export type ResolvedAppearance = "light" | "dark";

export const UI_APPEARANCE_STORAGE_KEY = "rakazo.uiAppearance";

/**
 * Semantic palette shared by web, Electron, and Expo. Names follow the shadcn
 * convention so the same slot means the same thing on every surface: a `border`
 * is always a border and never a fill.
 */
export type ColorTokens = {
  background: string;
  foreground: string;
  card: string;
  cardForeground: string;
  popover: string;
  popoverForeground: string;
  primary: string;
  primaryForeground: string;
  secondary: string;
  secondaryForeground: string;
  chatUser: string;
  chatUserForeground: string;
  muted: string;
  mutedForeground: string;
  accent: string;
  accentForeground: string;
  destructive: string;
  destructiveForeground: string;
  border: string;
  input: string;
  ring: string;
  sidebar: string;
  sidebarForeground: string;
  sidebarBorder: string;
  sidebarAccent: string;
  sidebarAccentForeground: string;
  link: string;
  success: string;
  warning: string;
  overlay: string;
  scrollbar: string;
  scrollbarHover: string;
};

export const darkTokens = {
  background: "#07080A",
  foreground: "#F3F4F6",
  card: "#0F1115",
  cardForeground: "#F3F4F6",
  popover: "#12151B",
  popoverForeground: "#F3F4F6",
  primary: "#FFFFFF",
  primaryForeground: "#07080A",
  secondary: "#151820",
  secondaryForeground: "#F3F4F6",
  chatUser: "#161B26",
  chatUserForeground: "#F9FAFB",
  muted: "#12151B",
  mutedForeground: "#A1A8B5",
  accent: "#1A1E29",
  accentForeground: "#FFFFFF",
  destructive: "#FF453A",
  destructiveForeground: "#FFFFFF",
  border: "#1C202B",
  input: "#13161D",
  ring: "#0A84FF",
  sidebar: "#0B0C10",
  sidebarForeground: "#F3F4F6",
  sidebarBorder: "#161820",
  sidebarAccent: "#171A23",
  sidebarAccentForeground: "#FFFFFF",
  link: "#0A84FF",
  success: "#30D158",
  warning: "#FFD60A",
  overlay: "rgba(3, 4, 6, 0.78)",
  scrollbar: "#1C202B",
  scrollbarHover: "#2C3242",
} as const satisfies ColorTokens;

export const lightTokens = {
  background: "#FFFFFF",
  foreground: "#1A1A1A",
  card: "#FFFFFF",
  cardForeground: "#1A1A1A",
  popover: "#FFFFFF",
  popoverForeground: "#1A1A1A",
  primary: "#1A1A1A",
  primaryForeground: "#FFFFFF",
  secondary: "#F4F4F1",
  secondaryForeground: "#1A1A1A",
  chatUser: "#EFEFEB",
  chatUserForeground: "#1A1A1A",
  muted: "#F4F4F1",
  mutedForeground: "#67676C",
  accent: "#ECECE8",
  accentForeground: "#1A1A1A",
  destructive: "#DC2626",
  destructiveForeground: "#FFFFFF",
  border: "#E5E5E0",
  input: "#DADAD4",
  ring: "#9C9C97",
  sidebar: "#F5F5F2",
  sidebarForeground: "#1A1A1A",
  sidebarBorder: "#E8E8E3",
  sidebarAccent: "#FFFFFF",
  sidebarAccentForeground: "#1A1A1A",
  link: "#2563EB",
  success: "#1E7F37",
  warning: "#A16207",
  overlay: "rgba(24, 24, 22, 0.28)",
  scrollbar: "#D3D3CD",
  scrollbarHover: "#B3B3AC",
} as const satisfies ColorTokens;

/** Dark palette. Prefer `tokensForAppearance` when theme-aware. */
export const tokens = darkTokens;

export const RADIUS = "0.75rem";

/**
 * Shared UI scale for typography, icons, controls, and spacing. Values are
 * appearance-neutral; light and dark themes use the same scale.
 */
export type ScaleTokens = {
  fontSizeCaption: string;
  fontSizeLabel: string;
  fontSizeBodySm: string;
  fontSizeBody: string;
  fontSizeReading: string;
  fontSizeTitleSm: string;
  fontSizeTitle: string;
  lineHeightBody: string;
  lineHeightReading: string;
  lineHeightTight: string;
  iconSm: string;
  iconMd: string;
  iconLg: string;
  controlHeightXs: string;
  controlHeightSm: string;
  controlHeightMd: string;
  controlHeightLg: string;
  spacingXs: string;
  spacingSm: string;
  spacingMd: string;
  spacingLg: string;
  spacingXl: string;
  spacingShell: string;
  spacingSidebarRowX: string;
  spacingSidebarRowY: string;
};

/** Comfortable UI scale — body chrome ~15.5px, reading ~17px, touch controls 44px. */
export const scaleTokens = {
  fontSizeCaption: "0.75rem",
  fontSizeLabel: "0.84375rem",
  fontSizeBodySm: "0.875rem",
  fontSizeBody: "0.96875rem",
  fontSizeReading: "1.0625rem",
  fontSizeTitleSm: "1.125rem",
  fontSizeTitle: "1.25rem",
  lineHeightBody: "1.5",
  lineHeightReading: "1.65",
  lineHeightTight: "1.3",
  iconSm: "1rem",
  iconMd: "1.125rem",
  iconLg: "1.25rem",
  controlHeightXs: "1.75rem",
  controlHeightSm: "2.25rem",
  controlHeightMd: "2.5rem",
  controlHeightLg: "2.75rem",
  spacingXs: "0.25rem",
  spacingSm: "0.5rem",
  spacingMd: "0.75rem",
  spacingLg: "1rem",
  spacingXl: "1.25rem",
  spacingShell: "0.625rem",
  spacingSidebarRowX: "0.75rem",
  spacingSidebarRowY: "0.625rem",
} as const satisfies ScaleTokens;

export const botColors = [
  "#3EC5A8",
  "#F5A03C",
  "#6A6BF5",
  "#9B5CF6",
  "#3B82F6",
  "#F2622A",
  "#D9508A",
] as const;

export function isAppearancePreference(
  value: string | null | undefined,
): value is AppearancePreference {
  return value === "system" || value === "light" || value === "dark";
}

export function normalizeAppearancePreference(
  raw: string | null | undefined,
): AppearancePreference {
  return isAppearancePreference(raw) ? raw : "system";
}

export type ResolveAppearancePreferenceOptions = {
  stored?: string | null;
  storage?: Pick<Storage, "getItem"> | null;
};

function getLocalStorage(): Pick<Storage, "getItem" | "setItem"> | null {
  try {
    return typeof localStorage !== "undefined" ? localStorage : null;
  } catch {
    return null;
  }
}

export function resolveAppearancePreference(
  options: ResolveAppearancePreferenceOptions = {},
): AppearancePreference {
  const stored =
    options.stored !== undefined
      ? options.stored
      : readStoredAppearance(options.storage ?? getLocalStorage());
  return normalizeAppearancePreference(stored);
}

export function persistAppearancePreference(
  preference: AppearancePreference,
  storage: Pick<Storage, "setItem"> | null = getLocalStorage(),
): void {
  if (!storage) return;
  try {
    storage.setItem(UI_APPEARANCE_STORAGE_KEY, preference);
  } catch {
    // Ignore quota / private-mode failures; in-memory preference still applies.
  }
}

export function resolveAppearance(
  preference: AppearancePreference,
  system: ResolvedAppearance = "dark",
): ResolvedAppearance {
  if (preference === "system") return system;
  return preference;
}

export function tokensForAppearance(appearance: ResolvedAppearance): ColorTokens {
  return appearance === "light" ? lightTokens : darkTokens;
}

function readStoredAppearance(storage: Pick<Storage, "getItem"> | null | undefined): string | null {
  if (!storage) return null;
  try {
    return storage.getItem(UI_APPEARANCE_STORAGE_KEY);
  } catch {
    return null;
  }
}

/** `cardForeground` -> `--card-foreground` */
export function cssVariableName(token: keyof ColorTokens): string {
  return `--${token.replace(/[A-Z]/g, (letter) => `-${letter.toLowerCase()}`)}`;
}

/** `fontSizeBody` -> `--font-size-body` */
export function scaleCssVariableName(token: keyof ScaleTokens): string {
  return `--${token.replace(/[A-Z]/g, (letter) => `-${letter.toLowerCase()}`)}`;
}

function renderScaleLines() {
  return (Object.keys(scaleTokens) as (keyof ScaleTokens)[]).map(
    (token) => `  ${scaleCssVariableName(token)}: ${scaleTokens[token]};`,
  );
}

function renderBlock(selector: string, colorScheme: ResolvedAppearance, palette: ColorTokens) {
  const colorLines = (Object.keys(palette) as (keyof ColorTokens)[]).map(
    (token) => `  ${cssVariableName(token)}: ${palette[token].toLowerCase()};`,
  );
  const scaleLines = renderScaleLines();
  return `${selector} {\n  color-scheme: ${colorScheme};\n${colorLines.join("\n")}\n  --radius: ${RADIUS};\n${scaleLines.join("\n")}\n}`;
}

/** The CSS in `tokens.css`. Generated from the TS palette so both stay in sync. */
export function renderTokensCss(): string {
  return `${[
    "/* Generated by `pnpm --filter @rakazo/ui-tokens generate`. Edit src/index.ts instead. */",
    renderBlock(':root,\n[data-theme="dark"]', "dark", darkTokens),
    renderBlock('[data-theme="light"]', "light", lightTokens),
  ].join("\n\n")}\n`;
}