import { validateDesignSystem, type DesignSystem, type DesignToken } from "@wrnexus/design-system";

export const MANUAL_COLORS = {
  primary: "Brand / primary",
  secondary: "Secondary",
  bg: "Page background",
  surface: "Surface",
  "surface-2": "Subtle surface",
  text: "Text",
  "text-muted": "Muted text",
  border: "Borders",
  success: "Success",
  warning: "Warning",
  danger: "Error",
  info: "Information",
} as const;
export const MANUAL_FONTS = {
  sans: '"Helvetica Neue", Arial, sans-serif',
  humanist: '"Trebuchet MS", Arial, sans-serif',
  serif: 'Georgia, "Times New Roman", serif',
  mono: '"Courier New", monospace',
};
export type ManualEdit =
  | { kind: "color"; mode: string; name: string; value: string }
  | { kind: "token"; name: string; value: string }
  | { kind: "mode"; value: string }
  | { kind: "buttonStyle"; value: "solid" | "outline" }
  | { kind: "tilt"; value: "none" | "subtle" | "expressive" };
function ink(hex: string) {
  const channels = hex
    .slice(1)
    .match(/../g)!
    .map((s) => parseInt(s, 16) / 255)
    .map((c) => (c <= 0.04045 ? c / 12.92 : ((c + 0.055) / 1.055) ** 2.4));
  const luminance = channels.reduce((sum, c, i) => sum + c * [0.2126, 0.7152, 0.0722][i]!, 0);
  return (luminance + 0.05) / 0.05 >= 1.05 / (luminance + 0.05) ? "#000000" : "#FFFFFF";
}
export function manualDesign(source: DesignSystem, edit: ManualEdit): DesignSystem {
  const system = structuredClone(source);
  const set = (
    tokens: Record<string, DesignToken>,
    name: string,
    value: string,
    type: DesignToken["type"] = "color",
    legacy?: string,
  ) => {
    tokens[name] = {
      ...tokens[name],
      type,
      value,
      ...(legacy ? { legacy: tokens[name]?.legacy ?? legacy } : {}),
    };
  };
  if (edit.kind === "buttonStyle") {
    const recipe = ((system.recipes ??= {}).Button ??= { contractVersion: 1, base: {} });
    const variant = {
      when: { variant: "default" },
      parts: {
        control: {
          backgroundImage: "none",
          backgroundColor: edit.value === "outline" ? "transparent" : { ref: "color.primary" },
          color: { ref: edit.value === "outline" ? "color.primary" : "color.primary-contrast" },
          borderColor: { ref: "color.primary" },
        },
      },
    };
    recipe.variants = [
      ...(recipe.variants ?? []).filter(
        (rule) => !(Object.keys(rule.when).length === 1 && rule.when.variant === "default"),
      ),
      variant,
    ];
  } else if (edit.kind === "tilt") {
    for (const [name, part, angle] of [
      [
        "Button",
        "control",
        edit.value === "none" ? "0deg" : edit.value === "subtle" ? "-0.5deg" : "-2deg",
      ],
      [
        "Card",
        "panel",
        edit.value === "none" ? "0deg" : edit.value === "subtle" ? "0.25deg" : "1deg",
      ],
    ]) {
      const recipe = ((system.recipes ??= {})[name!] ??= { contractVersion: 1, base: {} });
      ((recipe.base ??= {})[part!] ??= {}).rotate = angle!;
    }
  } else if (edit.kind === "mode") {
    if (!Object.hasOwn(system.modes ?? {}, edit.value))
      throw Error("Choose an existing light or dark mode.");
    system.defaultMode = edit.value;
  } else if (edit.kind === "color") {
    if (
      (!Object.hasOwn(MANUAL_COLORS, edit.name) &&
        system.tokens["color." + edit.name]?.type !== "color" &&
        system.modes?.[edit.mode]?.["color." + edit.name]?.type !== "color") ||
      !/^#[a-f0-9]{6}$/i.test(edit.value)
    )
      throw Error("Choose a color or enter a six-digit hex value, such as #00677B.");
    const layer = edit.mode === "base" ? system.tokens : system.modes?.[edit.mode];
    if (!layer) throw Error("Choose an existing light or dark mode.");
    const color = (name: string, value = edit.value) =>
      set(
        layer,
        "color." + name,
        value,
        "color",
        layer["color." + name]?.legacy ?? system.tokens["color." + name]?.legacy ?? "color-" + name,
      );
    color(edit.name);
    for (const alias of (
      {
        bg: ["background"],
        surface: ["surface-raised", "input-background"],
        "surface-2": [
          "surface-soft",
          "surface-muted",
          "primary-soft",
          "primary-muted",
          "code-background",
        ],
        text: ["foreground", "code-text"],
        "text-muted": ["text-subtle", "muted"],
        border: ["border-strong", "input-border", "code-border"],
      } as Record<string, string[]>
    )[edit.name] ?? [])
      color(alias);
    if (["primary", "secondary", "success", "warning", "danger", "info"].includes(edit.name)) {
      color(edit.name + "-contrast", ink(edit.value));
      color(edit.name + "-soft", edit.value + "1A");
      if (edit.name === "primary") color("primary-muted", edit.value + "1A");
      color(edit.name + "-text");
      for (const [suffix, factor] of [
        ["-hover", 0.88],
        ["-active", 0.75],
      ] as const)
        color(
          edit.name + suffix,
          "#" +
            edit.value
              .slice(1)
              .match(/../g)!
              .map((c) =>
                Math.round(parseInt(c, 16) * factor)
                  .toString(16)
                  .padStart(2, "0"),
              )
              .join(""),
        );
      if (edit.name === "primary") color("focus");
    }
  } else {
    const allowed: Record<string, [DesignToken["type"], string | undefined]> = {
      "shape.control": ["dimension", "radius-sm"],
      "shape.panel": ["dimension", "radius-md"],
      "shape.dialog": ["dimension", "radius-lg"],
      "type.body": ["fontFamily", "font-sans"],
      "type.heading": ["fontFamily", undefined],
      "elevation.panel": ["shadow", "shadow-1"],
      "space.control": ["dimension", undefined],
      "space.panel": ["dimension", "space-panel"],
    };
    if (!allowed[edit.name]) throw Error("Unsupported manual design setting.");
    const [type, legacy] = allowed[edit.name]!;
    if (
      type === "dimension" &&
      (!/^\d+(?:\.\d+)?px$/.test(edit.value) ||
        parseFloat(edit.value) > (edit.name.startsWith("shape.") ? 999 : 64))
    )
      throw Error("Enter corners between 0 and 999 pixels, or padding between 0 and 64 pixels.");
    set(system.tokens, edit.name, edit.value, type, legacy);
    // Existing mode overrides must not silently win over a shared foundation edit.
    for (const layer of Object.values(system.modes ?? {}))
      if (layer[edit.name]) set(layer, edit.name, edit.value, type, legacy);
    if (edit.name === "shape.panel")
      set(system.tokens, "shape.base", edit.value, "dimension", "radius");
  }
  const errors = validateDesignSystem(system);
  if (errors.length) throw Error(errors.map((e) => e.message).join("\n"));
  return system;
}