import { readFile } from "node:fs/promises";
import { join } from "node:path";

const OG_FONT_DIR = join(process.cwd(), "src/fonts/og");

function toArrayBuffer(buf: Buffer): ArrayBuffer {
  return buf.buffer.slice(
    buf.byteOffset,
    buf.byteOffset + buf.byteLength,
  ) as ArrayBuffer;
}

async function loadFont(fileName: string): Promise<ArrayBuffer> {
  return toArrayBuffer(await readFile(join(OG_FONT_DIR, fileName)));
}

type OgFont = {
  name: string;
  data: ArrayBuffer;
  weight: 300 | 400 | 600 | 700 | 800;
  style: "normal" | "italic";
};

/** latin + latin-ext çiftini aynı aile/ağırlıkta kaydeder (Türkçe glifler için). */
async function latinPair(
  name: string,
  weight: OgFont["weight"],
  latinFile: string,
  latinExtFile: string,
  style: OgFont["style"] = "normal",
): Promise<OgFont[]> {
  const [latin, latinExt] = await Promise.all([
    loadFont(latinFile),
    loadFont(latinExtFile),
  ]);
  return [
    { name, data: latin, weight, style },
    { name, data: latinExt, weight, style },
  ];
}

let siteOgFontsPromise: Promise<OgFont[]> | null = null;
let rehberOgFontsPromise: Promise<OgFont[]> | null = null;

/** Ana sayfa OG: Bricolage (marka) + ClarityCity (gövde). */
export function loadSiteOgFonts(): Promise<OgFont[]> {
  if (!siteOgFontsPromise) {
    siteOgFontsPromise = (async () => {
      const [bricolage, clarityLight, claritySemiBold] = await Promise.all([
        Promise.all([
          latinPair(
            "Bricolage Grotesque",
            300,
            "bricolage-grotesque-latin-300-normal.woff",
            "bricolage-grotesque-latin-ext-300-normal.woff",
          ),
          latinPair(
            "Bricolage Grotesque",
            600,
            "bricolage-grotesque-latin-600-normal.woff",
            "bricolage-grotesque-latin-ext-600-normal.woff",
          ),
        ]).then((pairs) => pairs.flat()),
        loadFont("ClarityCity-Light.ttf"),
        loadFont("ClarityCity-SemiBold.ttf"),
      ]);

      return [
        ...bricolage,
        {
          name: "Clarity City",
          data: clarityLight,
          weight: 300,
          style: "normal" as const,
        },
        {
          name: "Clarity City",
          data: claritySemiBold,
          weight: 600,
          style: "normal" as const,
        },
      ];
    })();
  }
  return siteOgFontsPromise;
}

/** Rehber / sayfa OG: ClarityCity + Cal Sans + Bricolage. */
export function loadRehberOgFonts(): Promise<OgFont[]> {
  if (!rehberOgFontsPromise) {
    rehberOgFontsPromise = (async () => {
      const [clarityBold, calSans, light, semiBold, extraBold] =
        await Promise.all([
          loadFont("ClarityCity-Bold.ttf"),
          latinPair(
            "Cal Sans",
            400,
            "cal-sans-latin-400-normal.woff",
            "cal-sans-latin-ext-400-normal.woff",
          ),
          latinPair(
            "Bricolage Grotesque",
            300,
            "bricolage-grotesque-latin-300-normal.woff",
            "bricolage-grotesque-latin-ext-300-normal.woff",
          ),
          latinPair(
            "Bricolage Grotesque",
            600,
            "bricolage-grotesque-latin-600-normal.woff",
            "bricolage-grotesque-latin-ext-600-normal.woff",
          ),
          latinPair(
            "Bricolage Grotesque",
            800,
            "bricolage-grotesque-latin-800-normal.woff",
            "bricolage-grotesque-latin-ext-800-normal.woff",
          ),
        ]);

      // Sitede italic kullanılıyor; ayrı italic dosya yok — aynı kesimi italic olarak kaydet.
      const extraBoldItalic = extraBold.map((font) => ({
        ...font,
        style: "italic" as const,
      }));

      return [
        {
          name: "Clarity City",
          data: clarityBold,
          weight: 700,
          style: "normal" as const,
        },
        ...calSans,
        ...light,
        ...semiBold,
        ...extraBold,
        ...extraBoldItalic,
      ];
    })();
  }
  return rehberOgFontsPromise;
}