import type { DeepPartial } from '@vben-core/typings';

import type { Preferences } from './types';

import { markRaw, reactive, readonly, watch } from 'vue';

import { StorageManager } from '@vben-core/cache';
import { generatorColorVariables } from '@vben-core/colorful';
import { merge, updateCSSVariables } from '@vben-core/toolkit';

import {
  breakpointsTailwind,
  useBreakpoints,
  useDebounceFn,
} from '@vueuse/core';

import { defaultPreferences } from './config';
import { BUILT_IN_THEME_PRESETS } from './constants';

const STORAGE_KEY = 'preferences';
const STORAGE_KEY_LOCALE = `${STORAGE_KEY}-locale`;
const STORAGE_KEY_THEME = `${STORAGE_KEY}-theme`;

interface initialOptions {
  namespace: string;
  overrides?: DeepPartial<Preferences>;
}

function isDarkTheme(theme: string) {
  let dark = theme === 'dark';
  if (theme === 'auto') {
    dark = window.matchMedia('(prefers-color-scheme: dark)').matches;
  }
  return dark;
}

class PreferenceManager {
  private cache: StorageManager | null = null;
  // private flattenedState: Flatten<Preferences>;
  private initialPreferences: Preferences = defaultPreferences;
  private isInitialized: boolean = false;
  private savePreferences: (preference: Preferences) => void;
  private state: Preferences = reactive<Preferences>({
    ...this.loadPreferences(),
  });
  constructor() {
    this.cache = new StorageManager();
    // this.flattenedState = reactive(flattenObject(this.state));

    this.savePreferences = useDebounceFn(
      (preference: Preferences) => this._savePreferences(preference),
      100,
    );
  }

  /**
   * 保存偏好设置
   * @param {Preferences} preference - 需要保存的偏好设置
   */
  private _savePreferences(preference: Preferences) {
    this.cache?.setItem(STORAGE_KEY, preference);
    this.cache?.setItem(STORAGE_KEY_LOCALE, preference.app.locale);
    this.cache?.setItem(STORAGE_KEY_THEME, preference.theme.mode);
  }

  /**
   * 处理更新的键值
   * 根据更新的键值执行相应的操作。
   *
   * @param {DeepPartial<Preferences>} updates - 部分更新的偏好设置
   */
  private handleUpdates(updates: DeepPartial<Preferences>) {
    const themeUpdates = updates.theme || {};
    const appUpdates = updates.app || {};

    if (themeUpdates && Object.keys(themeUpdates).length > 0) {
      this.updateTheme(this.state);
    }

    if (appUpdates.colorGrayMode || appUpdates.colorWeakMode) {
      this.updateColorMode(this.state);
    }
  }

  /**
   *  从缓存中加载偏好设置。如果缓存中没有找到对应的偏好设置，则返回默认偏好设置。
   */
  private loadCachedPreferences() {
    return this.cache?.getItem<Preferences>(STORAGE_KEY);
  }

  /**
   * 加载偏好设置
   * @returns {Preferences} 加载的偏好设置
   */
  private loadPreferences(): Preferences {
    return this.loadCachedPreferences() || { ...defaultPreferences };
  }

  /**
   * 监听状态和系统偏好设置的变化。
   */
  private setupWatcher() {
    if (this.isInitialized) {
      return;
    }

    // const debounceWaterState = useDebounceFn(() => {
    //   const newFlattenedState = flattenObject(this.state);
    //   for (const k in newFlattenedState) {
    //     const key = k as FlattenObjectKeys<Preferences>;
    //     this.flattenedState[key] = newFlattenedState[key];
    //   }
    //   this.savePreferences(this.state);
    // }, 16);

    // const debounceWaterFlattenedState = useDebounceFn(
    //   (val: Flatten<Preferences>) => {
    //     this.updateState(val);
    //     this.savePreferences(this.state);
    //   },
    //   16,
    // );

    // 监听 state 的变化
    // watch(this.state, debounceWaterState, { deep: true });

    // 监听 flattenedState 的变化并触发 set 方法
    // watch(this.flattenedState, debounceWaterFlattenedState, { deep: true });

    // 监听断点，判断是否移动端
    const breakpoints = useBreakpoints(breakpointsTailwind);
    const isMobile = breakpoints.smaller('md');
    watch(
      () => isMobile.value,
      (val) => {
        this.updatePreferences({
          app: { isMobile: val },
        });
      },
      { immediate: true },
    );

    // 监听系统主题偏好设置变化
    window
      .matchMedia('(prefers-color-scheme: dark)')
      .addEventListener('change', ({ matches: isDark }) => {
        this.updatePreferences({
          theme: { mode: isDark ? 'dark' : 'light' },
        });
        this.updateTheme(this.state);
      });
  }

  /**
   * 更新页面颜色模式（灰色、色弱）
   * @param preference
   */
  private updateColorMode(preference: Preferences) {
    if (preference.app) {
      const { colorGrayMode, colorWeakMode } = preference.app;
      const body = document.body;
      const COLOR_WEAK = 'invert-mode';
      const COLOR_GRAY = 'grayscale-mode';
      colorWeakMode
        ? body.classList.add(COLOR_WEAK)
        : body.classList.remove(COLOR_WEAK);
      colorGrayMode
        ? body.classList.add(COLOR_GRAY)
        : body.classList.remove(COLOR_GRAY);
    }
  }

  /**
   * 更新 CSS 变量
   * @param  preference - 当前偏好设置对象，它的颜色值将被转换成 HSL 格式并设置为 CSS 变量。
   */
  private updateMainColors(preference: Preferences) {
    if (!preference.theme) {
      return;
    }
    const { colorDestructive, colorPrimary, colorSuccess, colorWarning } =
      preference.theme;

    const colorVariables = generatorColorVariables([
      { color: colorPrimary, name: 'primary' },
      { alias: 'warning', color: colorWarning, name: 'yellow' },
      { alias: 'success', color: colorSuccess, name: 'green' },
      { alias: 'destructive', color: colorDestructive, name: 'red' },
    ]);

    if (colorPrimary) {
      document.documentElement.style.setProperty(
        '--primary',
        colorVariables['--primary-600'],
      );
    }

    if (colorVariables['--green-600']) {
      colorVariables['--success'] = colorVariables['--green-600'];
    }
    if (colorVariables['--yellow-600']) {
      colorVariables['--warning'] = colorVariables['--yellow-600'];
    }
    if (colorVariables['--red-600']) {
      colorVariables['--destructive'] = colorVariables['--red-600'];
    }
    updateCSSVariables(colorVariables);
  }

  /**
   *  更新状态
   * 将新的扁平对象转换为嵌套对象，并与当前状态合并。
   * @param {FlattenObject<Preferences>} newValue - 新的扁平对象
   */
  // private updateState(newValue: Flatten<Preferences>) {
  //   const nestObj = nestedObject(newValue, 2);
  //   Object.assign(this.state, merge(nestObj, this.state));
  // }

  /**
   * 更新主题
   * @param preferences - 当前偏好设置对象，它的主题值将被用来设置文档的主题。
   */
  private updateTheme(preferences: Preferences) {
    // 当修改到颜色变量时，更新 css 变量
    const root = document.documentElement;
    if (!root) {
      return;
    }

    const {
      builtinType,
      colorDestructive,
      colorPrimary,
      colorSuccess,
      colorWarning,
      mode,
      radius,
    } = preferences?.theme ?? {};

    if (mode) {
      const dark = isDarkTheme(mode);
      root.classList.toggle('dark', dark);
    }

    if (builtinType) {
      const rootTheme = root.dataset.theme;
      if (rootTheme !== builtinType) {
        root.dataset.theme = builtinType;
      }
    }

    const currentBuiltType = BUILT_IN_THEME_PRESETS.find(
      (item) => item.type === builtinType,
    );

    let builtinTypeColorPrimary: string | undefined = '';

    if (currentBuiltType) {
      const isDark = isDarkTheme(this.state.theme.mode);

      const color = isDark
        ? currentBuiltType.darkPrimaryColor || currentBuiltType.primaryColor
        : currentBuiltType.primaryColor;
      builtinTypeColorPrimary = color || currentBuiltType.color;
    }

    if (
      builtinTypeColorPrimary ||
      colorPrimary ||
      colorDestructive ||
      colorSuccess ||
      colorWarning
    ) {
      preferences.theme.colorPrimary = builtinTypeColorPrimary || colorPrimary;
      this.updateMainColors(preferences);
    }

    if (radius) {
      document.documentElement.style.setProperty('--radius', `${radius}rem`);
    }
  }

  // public getFlatPreferences() {
  //   return this.flattenedState;
  // }

  public getInitialPreferences() {
    return this.initialPreferences;
  }

  public getPreferences() {
    return readonly(this.state);
  }

  /**
   * 覆盖偏好设置
   * overrides  要覆盖的偏好设置
   * namespace  命名空间
   */
  public async initPreferences({ namespace, overrides }: initialOptions) {
    // 是否初始化过
    if (this.isInitialized) {
      return;
    }
    // 初始化存储管理器
    this.cache = new StorageManager({ prefix: namespace });
    // 合并初始偏好设置
    this.initialPreferences = merge({}, overrides, defaultPreferences);

    // 加载并合并当前存储的偏好设置
    const mergedPreference = merge(
      {},
      this.loadCachedPreferences(),
      this.initialPreferences,
    );

    // 更新偏好设置
    this.updatePreferences(mergedPreference);

    this.setupWatcher();
    // 标记为已初始化
    this.isInitialized = true;
  }

  /**
   * 重置偏好设置
   * 偏好设置将被重置为初始值，并从 localStorage 中移除。
   *
   * @example
   * 假设 initialPreferences 为 { theme: 'light', language: 'en' }
   * 当前 state 为 { theme: 'dark', language: 'fr' }
   * this.resetPreferences();
   * 调用后，state 将被重置为 { theme: 'light', language: 'en' }
   * 并且 localStorage 中的对应项将被移除
   */
  resetPreferences() {
    // 将状态重置为初始偏好设置
    Object.assign(this.state, this.initialPreferences);
    // 保存重置后的偏好设置
    this.savePreferences(this.state);
    // 从存储中移除偏好设置项
    [STORAGE_KEY, STORAGE_KEY_THEME, STORAGE_KEY_LOCALE].forEach((key) => {
      this.cache?.removeItem(key);
    });
  }

  /**
   * 更新偏好设置
   * @param updates - 要更新的偏好设置
   */
  public updatePreferences(updates: DeepPartial<Preferences>) {
    const mergedState = merge({}, updates, markRaw(this.state));

    Object.assign(this.state, mergedState);

    // Object.assign(this.flattenedState, flattenObject(this.state));

    // 根据更新的键值执行相应的操作
    this.handleUpdates(updates);
    this.savePreferences(this.state);
  }
}

const preferencesManager = new PreferenceManager();
export { PreferenceManager, isDarkTheme, preferencesManager };