const OFFLINE_MAP_DIR_KEY = 'OFFLINE_MAP_DIR__';
const OFFLINE_MAP_SERVER_DIR_KEY = 'OFFLINE_MAP_SERVER_DIR__';
export const OFFLINE_MAP_DIR_CHANGED_EVENT = 'offline-map-dir-changed';
const LOCAL_MAP_PROTOCOL = 'localmap://';

function isValidOfflineMapPath(value: string) {
  const text = String(value || '').trim();
  if (!text) return false;
  if (text === '[object Object]') return false;
  if (text === 'null' || text === 'undefined') return false;
  return (
    /^[a-zA-Z]:[\\/]/.test(text) ||
    text.startsWith('/') ||
    text.startsWith('file://') ||
    text.startsWith(LOCAL_MAP_PROTOCOL)
  );
}

function normalizePath(value: string) {
  const text = String(value || '').trim();
  if (!isValidOfflineMapPath(text)) return '';
  return text.replace(/[\\/]+$/, '');
}

export function getOfflineMapDir() {
  try {
    const serverDir = normalizePath(window.localStorage.getItem(OFFLINE_MAP_SERVER_DIR_KEY) || '');
    if (serverDir) return serverDir;
    return normalizePath(window.localStorage.getItem(OFFLINE_MAP_DIR_KEY) || '');
  } catch {
    return '';
  }
}

export function getManualOfflineMapDir() {
  try {
    return normalizePath(window.localStorage.getItem(OFFLINE_MAP_DIR_KEY) || '');
  } catch {
    return '';
  }
}

export function getServerOfflineMapDir() {
  try {
    return normalizePath(window.localStorage.getItem(OFFLINE_MAP_SERVER_DIR_KEY) || '');
  } catch {
    return '';
  }
}

export function setOfflineMapDir(path: string) {
  const normalized = normalizePath(path);
  try {
    if (!normalized) {
      window.localStorage.removeItem(OFFLINE_MAP_DIR_KEY);
      window.dispatchEvent(new CustomEvent(OFFLINE_MAP_DIR_CHANGED_EVENT, { detail: '' }));
      return;
    }
    window.localStorage.setItem(OFFLINE_MAP_DIR_KEY, normalized);
    window.dispatchEvent(new CustomEvent(OFFLINE_MAP_DIR_CHANGED_EVENT, { detail: normalized }));
  } catch {}
}

export function clearOfflineMapDir() {
  setOfflineMapDir('');
}

export function setServerOfflineMapDir(path: string) {
  const normalized = normalizePath(path);
  try {
    if (!normalized) {
      window.localStorage.removeItem(OFFLINE_MAP_SERVER_DIR_KEY);
      window.dispatchEvent(new CustomEvent(OFFLINE_MAP_DIR_CHANGED_EVENT, { detail: getOfflineMapDir() }));
      return;
    }
    window.localStorage.setItem(OFFLINE_MAP_SERVER_DIR_KEY, normalized);
    window.dispatchEvent(new CustomEvent(OFFLINE_MAP_DIR_CHANGED_EVENT, { detail: normalized }));
  } catch {}
}

export function buildFileUrl(filePath: string) {
  const normalized = normalizePath(filePath).replace(/\\/g, '/');
  if (!normalized) return '';
  if (new RegExp(`^${LOCAL_MAP_PROTOCOL}`, 'i').test(normalized)) return normalized;
  if (/^file:\/\//i.test(normalized)) return toLocalMapUrl(normalized);
  if (/^[a-zA-Z]:/.test(normalized)) {
    return encodeURI(`${LOCAL_MAP_PROTOCOL}/${normalized}`);
  }
  return encodeURI(`${LOCAL_MAP_PROTOCOL}${normalized.startsWith('/') ? '' : '/'}${normalized}`);
}

export function getOfflineMapPmtilesUrl(fileName = 'china.pmtiles') {
  const dir = getOfflineMapDir();
  if (!dir) return '';
  return buildFileUrl(`${dir}/${fileName}`);
}

export function getOfflineMapFileUrl(fileName: string) {
  const dir = getOfflineMapDir();
  if (!dir || !fileName) return '';
  return buildFileUrl(`${dir}/${fileName}`);
}

export function getOfflineMapFilePath(fileName: string) {
  const dir = getOfflineMapDir();
  if (!dir || !fileName) return '';
  return normalizePath(`${dir}/${fileName}`);
}

export function toLocalMapUrl(value: string) {
  const text = String(value || '').trim();
  if (!text) return '';
  if (new RegExp(`^${LOCAL_MAP_PROTOCOL}`, 'i').test(text)) return text;
  if (/^file:\/\//i.test(text)) {
    try {
      const url = new URL(text);
      const pathname = decodeURIComponent(url.pathname || '');
      const normalized = /^[\\/][a-zA-Z]:/.test(pathname) ? pathname.slice(1) : pathname;
      return buildFileUrl(normalized);
    } catch {
      return text;
    }
  }
  if (/^[a-zA-Z]:/.test(text) || text.startsWith('/')) {
    return buildFileUrl(text);
  }
  return text;
}

export class ElectronPmtilesSource {
  filePath: string;

  constructor(filePath: string) {
    this.filePath = normalizePath(filePath);
  }

  getKey() {
    return this.filePath;
  }

  async getBytes(offset: number, length: number) {
    const ipcRenderer = (window as any)?.electron?.ipcRenderer;
    if (!ipcRenderer?.invoke || !this.filePath || !length) {
      return { data: new ArrayBuffer(0) };
    }
    const payload =
      (await ipcRenderer.invoke('controller/os/readBinaryFileRange', {
        filePath: this.filePath,
        offset,
        length,
      })) || {};
    const base64 = String(payload?.data || '');
    const size = Number(payload?.size || 0);
    if (!base64 || !size) {
      return { data: new ArrayBuffer(0) };
    }
    const binary = window.atob(base64);
    const bytes = new Uint8Array(binary.length);
    for (let index = 0; index < binary.length; index += 1) {
      bytes[index] = binary.charCodeAt(index);
    }
    return { data: bytes.buffer };
  }
}