import JSZip from 'jszip';
import {
  type DiceFace,
  type DrinkmarbleAssets,
  getAssets,
  setBackgroundAsset,
  setChessmanAsset,
  setDiceFaceAsset,
} from './asset-storage';

const PACK_VERSION = 1;
const DICE_FACES: DiceFace[] = [1, 2, 3, 4, 5, 6];

type PackManifest = {
  version: number;
  app: 'drinkmarble';
  files: {
    background?: string;
    chessman?: string;
    dice?: Partial<Record<DiceFace, string>>;
  };
};

async function srcToBlob(src: string): Promise<Blob> {
  const res = await fetch(src);
  if (!res.ok) {
    throw new Error(`이미지를 읽지 못했습니다: ${src}`);
  }
  return res.blob();
}

function extFromBlob(blob: Blob, fallback = 'png') {
  const type = blob.type;
  if (type.includes('jpeg') || type.includes('jpg')) return 'jpg';
  if (type.includes('webp')) return 'webp';
  if (type.includes('png')) return 'png';
  return fallback;
}

function downloadBlob(blob: Blob, filename: string) {
  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = filename;
  a.click();
  URL.revokeObjectURL(url);
}

async function blobToDataUrl(blob: Blob): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.onerror = () => reject(new Error('파일을 읽을 수 없습니다.'));
    reader.onload = () => resolve(String(reader.result));
    reader.readAsDataURL(blob);
  });
}

/**
 * 현재 적용 중인 애셋(커스텀 또는 기본 public)을 ZIP으로 내보낸다.
 * drinkmarble-pack.zip
 * ├── manifest.json
 * ├── background.*
 * ├── chessman.*
 * └── dice/1.* … 6.*
 */
export async function exportAssetPack(assets: DrinkmarbleAssets = getAssets()) {
  const zip = new JSZip();
  const files: PackManifest['files'] = {};

  const bgBlob = await srcToBlob(assets.background);
  const bgName = `background.${extFromBlob(bgBlob)}`;
  zip.file(bgName, bgBlob);
  files.background = bgName;

  const manBlob = await srcToBlob(assets.chessman);
  const manName = `chessman.${extFromBlob(manBlob)}`;
  zip.file(manName, manBlob);
  files.chessman = manName;

  files.dice = {};
  for (const face of DICE_FACES) {
    const faceBlob = await srcToBlob(assets.dice[face]);
    const faceName = `dice/${face}.${extFromBlob(faceBlob)}`;
    zip.file(faceName, faceBlob);
    files.dice[face] = faceName;
  }

  const manifest: PackManifest = {
    version: PACK_VERSION,
    app: 'drinkmarble',
    files,
  };
  zip.file('manifest.json', JSON.stringify(manifest, null, 2));

  const zipBlob = await zip.generateAsync({ type: 'blob' });
  const stamp = new Date().toISOString().slice(0, 19).replace(/[:T]/g, '-');
  downloadBlob(zipBlob, `drinkmarble-pack-${stamp}.zip`);
}

/**
 * ZIP 팩을 읽어 localStorage에 반영한다.
 * manifest.json이 없으면 관례적 파일명(background.*, chessman.*, dice/1.*)을 시도한다.
 */
export async function importAssetPack(file: File): Promise<DrinkmarbleAssets> {
  if (!file.name.toLowerCase().endsWith('.zip')) {
    throw new Error('ZIP 파일만 가져올 수 있습니다.');
  }

  const zip = await JSZip.loadAsync(file);
  const manifestFile = zip.file('manifest.json');
  let manifest: PackManifest | null = null;

  if (manifestFile) {
    const text = await manifestFile.async('string');
    const parsed = JSON.parse(text) as PackManifest;
    if (parsed.app && parsed.app !== 'drinkmarble') {
      throw new Error('Drinkmarble 팩이 아닙니다.');
    }
    manifest = parsed;
  }

  const findEntry = (path: string) => {
    const exact = zip.file(path);
    if (exact) return exact;
    const lower = path.toLowerCase();
    const match = Object.keys(zip.files).find(
      (name) => !zip.files[name].dir && name.toLowerCase() === lower,
    );
    return match ? zip.file(match) : null;
  };

  const resolvePath = (preferred?: string, fallbacks: string[] = []) => {
    const candidates = [preferred, ...fallbacks].filter(Boolean) as string[];
    for (const path of candidates) {
      const entry = findEntry(path);
      if (entry) return entry;
    }
    // 확장자만 다른 경우
    for (const path of candidates) {
      const base = path.replace(/\.[^.]+$/, '');
      const match = Object.keys(zip.files).find(
        (name) =>
          !zip.files[name].dir &&
          name.replace(/\.[^.]+$/, '').toLowerCase() === base.toLowerCase(),
      );
      if (match) return zip.file(match);
    }
    return null;
  };

  const bgEntry = resolvePath(manifest?.files.background, [
    'background.jpg',
    'background.jpeg',
    'background.png',
    'background.webp',
  ]);
  const manEntry = resolvePath(manifest?.files.chessman, [
    'chessman.jpg',
    'chessman.jpeg',
    'chessman.png',
    'chessman.webp',
  ]);

  let imported = 0;

  if (bgEntry) {
    setBackgroundAsset(await blobToDataUrl(await bgEntry.async('blob')));
    imported += 1;
  }
  if (manEntry) {
    setChessmanAsset(await blobToDataUrl(await manEntry.async('blob')));
    imported += 1;
  }

  for (const face of DICE_FACES) {
    const faceEntry = resolvePath(manifest?.files.dice?.[face], [
      `dice/${face}.jpg`,
      `dice/${face}.jpeg`,
      `dice/${face}.png`,
      `dice/${face}.webp`,
    ]);
    if (faceEntry) {
      setDiceFaceAsset(face, await blobToDataUrl(await faceEntry.async('blob')));
      imported += 1;
    }
  }

  if (imported === 0) {
    throw new Error('팩에서 사용할 이미지를 찾지 못했습니다.');
  }

  return getAssets();
}