import type { RefComponentMountAdapter } from '../types/refComponentMount';
import type { UrlListenerAdapter } from '../types/urlListener';
import type {
  MergeNativeRuntimeAdapterInput,
  NativeRuntimeAdapterState,
} from '../types/nativeRuntimeAdapter';

let nativeRuntimeState: NativeRuntimeAdapterState | null = null;

/**
 * 读取当前 native 适配器状态。
 * @returns 已注册状态；未注册时为 null
 */
function getNativeRuntimeAdapter(): NativeRuntimeAdapterState | null {
  if (!nativeRuntimeState) {
    return null;
  }
  return { ...nativeRuntimeState };
}

/**
 * 是否已注册 native 运行时适配器（mergeNativeAdapter 传入非 null 对象后即为 true）。
 * @returns 是否已注册
 */
function isNativeRuntimeAdapterRegistered(): boolean {
  return nativeRuntimeState !== null;
}

/**
 * 命令式挂载是否已通过 native 适配器声明为支持（refComponentMount 为非 null 对象）。
 * @returns 是否支持
 */
function isNativeRefComponentMountSupported(): boolean {
  const mount = nativeRuntimeState?.refComponentMount;
  return mount != null && typeof mount === 'object';
}

/**
 * 命令式挂载是否已通过 native 适配器声明为不支持（refComponentMount === null）。
 * @returns 是否明确不支持
 */
function isNativeRefComponentMountDisabled(): boolean {
  return nativeRuntimeState != null && nativeRuntimeState.refComponentMount === null;
}

/**
 * URL 监听是否已通过 native 适配器声明为支持。
 * @returns 是否支持
 */
function isNativeUrlListenerSupported(): boolean {
  const url = nativeRuntimeState?.urlListener;
  return url != null && typeof url === 'object';
}

/**
 * URL 监听是否已通过 native 适配器声明为不支持。
 * @returns 是否明确不支持
 */
function isNativeUrlListenerDisabled(): boolean {
  return nativeRuntimeState != null && nativeRuntimeState.urlListener === null;
}

/**
 * 解析 native 适配器中的 refComponentMount 字段。
 * @returns unset | none | 适配器
 */
function resolveNativeRefComponentMount():
  | { kind: 'unset' }
  | { kind: 'none' }
  | { kind: 'adapter', adapter: RefComponentMountAdapter } {
  if (!nativeRuntimeState || nativeRuntimeState.refComponentMount === undefined) {
    return { kind: 'unset' };
  }
  if (nativeRuntimeState.refComponentMount === null) {
    return { kind: 'none' };
  }
  return { kind: 'adapter', adapter: nativeRuntimeState.refComponentMount };
}

/**
 * 解析 native 适配器中的 urlListener 字段。
 * @returns unset | none | 适配器
 */
function resolveNativeUrlListener():
  | { kind: 'unset' }
  | { kind: 'none' }
  | { kind: 'adapter', adapter: UrlListenerAdapter } {
  if (!nativeRuntimeState || nativeRuntimeState.urlListener === undefined) {
    return { kind: 'unset' };
  }
  if (nativeRuntimeState.urlListener === null) {
    return { kind: 'none' };
  }
  return { kind: 'adapter', adapter: nativeRuntimeState.urlListener };
}

/**
 * 注册 / 更新 / 清空非浏览器运行时统一适配器。
 * @param input - 适配器片段；传 null 清空
 * @returns 当前状态快照
 */
function mergeNativeAdapter(
  input: MergeNativeRuntimeAdapterInput | null,
): NativeRuntimeAdapterState | null {
  if (input === null) {
    nativeRuntimeState = null;
    return null;
  }
  const next: NativeRuntimeAdapterState = { ...(nativeRuntimeState || {}) };
  if (input.id !== undefined) {
    next.id = input.id;
  }
  if (input.refComponentMount !== undefined) {
    next.refComponentMount = input.refComponentMount;
  }
  if (input.urlListener !== undefined) {
    next.urlListener = input.urlListener;
  }
  nativeRuntimeState = next;
  if (
    nativeRuntimeState.refComponentMount === undefined
    && nativeRuntimeState.urlListener === undefined
    && nativeRuntimeState.id === undefined
  ) {
    nativeRuntimeState = null;
  }
  return getNativeRuntimeAdapter();
}

/**
 * 重置 native 运行时适配器（主要用于测试）。
 */
function resetNativeAdapter(): void {
  mergeNativeAdapter(null);
}

/**
 * 仅清除 native 适配器中的 refComponentMount 字段。
 */
function clearNativeRefComponentMount(): void {
  if (!nativeRuntimeState) {
    return;
  }
  delete nativeRuntimeState.refComponentMount;
  if (
    nativeRuntimeState.urlListener === undefined
    && nativeRuntimeState.id === undefined
  ) {
    nativeRuntimeState = null;
  }
}

/**
 * 仅清除 native 适配器中的 urlListener 字段。
 */
function clearNativeUrlListener(): void {
  if (!nativeRuntimeState) {
    return;
  }
  delete nativeRuntimeState.urlListener;
  if (
    nativeRuntimeState.refComponentMount === undefined
    && nativeRuntimeState.id === undefined
  ) {
    nativeRuntimeState = null;
  }
}

export {
  mergeNativeAdapter,
  resetNativeAdapter,
  getNativeRuntimeAdapter,
  isNativeRuntimeAdapterRegistered,
  isNativeRefComponentMountSupported,
  isNativeRefComponentMountDisabled,
  isNativeUrlListenerSupported,
  isNativeUrlListenerDisabled,
  resolveNativeRefComponentMount,
  resolveNativeUrlListener,
  clearNativeRefComponentMount,
  clearNativeUrlListener,
};