/**
 * 罗盘业务逻辑组合函数
 */

import { computed, ref, readonly, watch, type Ref, isRef } from 'vue';
import type {
  CenterIconData,
  DegreeRingData,
  LayerConfig,
  LuopanConfig,
  LuopanConfigInput,
  Sector,
  SectorLayerConfig,
  ThemeConfig,
  ThemeItem,
  ThemesConfig,
  TextRadialPosition,
} from '../types';
import { polarToXY } from '../utils';
import { parseConfig } from '../configParser';
import { ColorResolver } from '../colorResolver';
import { SectorBuilder } from '../sectorBuilder';
import { buildDegreeRing } from '../degreeRing';
import { loadCenterIcon } from '../centerIcon';

// 只有扇区层会生成扇区几何，其它层仍参与层级顺序。
const isSectorLayer = (layer: LayerConfig): layer is SectorLayerConfig =>
  layer.type !== 'centerIcon' && layer.type !== 'degreeRing';

const HEX_COLOR_RE = /^#([0-9a-fA-F]{3}|[0-9a-fA-F]{6})$/;

const resolveThemeColor = (
  theme: ThemeConfig,
  value: string | undefined,
  fallback: string
) => {
  if (!value) return fallback;
  if (HEX_COLOR_RE.test(value)) return value;
  return theme.colorPalettes[value] ?? fallback;
};

const findDegreeRingLayer = (layers: LayerConfig[]) =>
  layers.find((layer) => layer.type === 'degreeRing');

const findCenterIconLayer = (layers: LayerConfig[]) =>
  layers.find((layer) => layer.type === 'centerIcon');

const THEMES_PATH = '/themes.json';

let cachedThemes: ThemesConfig | null = null;

const isObject = (value: unknown): value is Record<string, unknown> =>
  typeof value === 'object' && value !== null && !Array.isArray(value);

const normalizeThemeItem = (item: Record<string, unknown>): ThemeItem | null => {
  const name = item.name;
  const palettes = item.colorPalettes;
  if (typeof name !== 'string' || !isObject(palettes)) return null;

  const colorPalettes: Record<string, string> = {};
  Object.entries(palettes).forEach(([key, value]) => {
    if (typeof value === 'string') {
      colorPalettes[key] = value;
    }
  });

  if (Object.keys(colorPalettes).length === 0) return null;
  return { name, colorPalettes };
};

const normalizeThemesConfig = (input: unknown): ThemesConfig => {
  if (!isObject(input)) {
    throw new Error('themes.json 必须为对象');
  }
  const rawItems = Array.isArray(input.items) ? input.items : [];
  const items = rawItems
    .filter((item): item is Record<string, unknown> => isObject(item))
    .map((item) => normalizeThemeItem(item))
    .filter((item): item is ThemeItem => Boolean(item));
  if (items.length === 0) {
    throw new Error('themes.json.items 不能为空');
  }
  return {
    default: typeof input.default === 'string' ? input.default : undefined,
    items,
  };
};

const loadThemes = async (): Promise<ThemesConfig> => {
  if (cachedThemes) return cachedThemes;
  const response = await fetch(THEMES_PATH, { cache: 'no-store' });
  if (!response.ok) {
    throw new Error(`主题配置加载失败: ${response.status}`);
  }
  const raw = await response.json();
  cachedThemes = normalizeThemesConfig(raw);
  return cachedThemes;
};

const resolveTheme = async (configObj: LuopanConfigInput): Promise<ThemeConfig> => {
  if (configObj.theme && !configObj.themeRef) {
    return configObj.theme;
  }
  const themes = await loadThemes();
  const themeName = configObj.themeRef ?? themes.default ?? themes.items[0].name;
  const matched = themes.items.find((item) => item.name === themeName);
  if (matched) {
    return { name: matched.name, colorPalettes: matched.colorPalettes };
  }
  if (configObj.theme) {
    return configObj.theme;
  }
  throw new Error(`未找到主题: ${themeName}`);
};

/**
 * 罗盘逻辑 Hook
 * @param configPathOrObject 配置文件路径或配置对象
 * @param textRadialPositionRef 文字径向位置的响应式引用（可选）
 * @returns 罗盘相关的计算属性和方法
 */
type LuopanConfigSource = string | LuopanConfigInput;

export function useLuopan(
  configPathOrObject: LuopanConfigSource | Ref<LuopanConfigSource>,
  textRadialPositionRef?: Ref<TextRadialPosition>
) {
  const config = ref<LuopanConfig | null>(null);
  const sectors = ref<Sector[]>([]);
  const degreeRing = ref<DegreeRingData | null>(null);
  const centerIcon = ref<CenterIconData | null>(null);
  const loading = ref(false);
  const error = ref<Error | null>(null);

  const textRadialPosition = computed(
    () => textRadialPositionRef?.value ?? 'middle'
  );

  const configSource = isRef(configPathOrObject)
    ? configPathOrObject
    : ref(configPathOrObject);

  const buildSectors = (configObj: LuopanConfig) => {
    const resolver = new ColorResolver(configObj.theme, configObj.background);
    const builder = new SectorBuilder(resolver, {
      textRadialPosition: textRadialPosition.value,
      insetDistance: configObj.insetDistance,
    });
    // 层索引与配置顺序一致（`centerIcon`/`degreeRing` 仍占位）。
    return configObj.layers.flatMap((layer, index) =>
      isSectorLayer(layer) ? builder.buildLayer(layer, index) : []
    );
  };

  const loadConfig = async () => {
    try {
      loading.value = true;
      error.value = null;

      let configObj: LuopanConfigInput;
      const configInput = configSource.value;
      if (typeof configInput === 'string') {
        const jsonText = await fetch(configInput).then((res) => res.text());
        configObj = parseConfig(jsonText);
      } else {
        configObj = configInput;
      }

      const resolvedTheme = await resolveTheme(configObj);
      const resolvedBackground = resolveThemeColor(
        resolvedTheme,
        configObj.background,
        '#000000'
      );
      const resolvedStrokeColor = resolveThemeColor(
        resolvedTheme,
        configObj.strokeColor,
        '#1f2937'
      );

      const resolvedConfig: LuopanConfig = {
        ...configObj,
        theme: resolvedTheme,
        background: resolvedBackground,
        strokeColor: resolvedStrokeColor,
        strokeWidth: typeof configObj.strokeWidth === 'number'
          ? configObj.strokeWidth
          : undefined,
        strokeOpacity: typeof configObj.strokeOpacity === 'number'
          ? configObj.strokeOpacity
          : undefined,
        insetDistance: typeof configObj.insetDistance === 'number'
          ? configObj.insetDistance
          : undefined,
      };

      config.value = resolvedConfig;
      sectors.value = buildSectors(resolvedConfig);

      const degreeRingLayer = findDegreeRingLayer(resolvedConfig.layers);
      degreeRing.value = degreeRingLayer
        ? buildDegreeRing(degreeRingLayer.degreeRing)
        : null;

      const centerIconLayer = findCenterIconLayer(resolvedConfig.layers);
      centerIcon.value = centerIconLayer
        ? await loadCenterIcon(centerIconLayer.centerIcon)
        : null;
    } catch (err) {
      error.value = err as Error;
    } finally {
      loading.value = false;
    }
  };

  // 文字位置切换后仅重建扇区
  watch(textRadialPosition, () => {
    if (config.value) {
      sectors.value = buildSectors(config.value);
    }
  });

  watch(configSource, () => {
    loadConfig();
  });

  loadConfig();

  const sectorLayers = computed(() =>
    config.value ? config.value.layers.filter(isSectorLayer) : []
  );

  const rings = computed(() => sectorLayers.value.map((layer) => layer.rOuter));

  const anglesDeg = computed(() => {
    const firstLayer = sectorLayers.value[0];
    if (!firstLayer || firstLayer.divisions <= 0) return [];

    const step = 360 / firstLayer.divisions;
    const start = firstLayer.startAngle ?? 0;
    return Array.from({ length: firstLayer.divisions + 1 }, (_, i) => start + i * step);
  });

  const outerMost = computed(() => {
    if (!config.value) return 0;

    // 取扇区层与刻度环中的最大半径。
    const radii = sectorLayers.value.map((layer) => layer.rOuter);
    const degreeRingLayer = findDegreeRingLayer(config.value.layers);
    if (degreeRingLayer) {
      radii.push(degreeRingLayer.degreeRing.rOuter);
    }

    const maxRadius = radii.length > 0 ? Math.max(...radii) : 0;
    if (maxRadius > 0) return maxRadius;

    return typeof config.value.outerRadius === 'number' ? config.value.outerRadius : 0;
  });

  return {
    config: readonly(config),
    sectors: readonly(sectors),
    degreeRing: readonly(degreeRing),
    centerIcon: readonly(centerIcon),
    anglesDeg,
    rings,
    outerMost,
    toXY: polarToXY,
    loading: readonly(loading),
    error: readonly(error),
    reload: loadConfig,
  };
}

/**
 * 返回类型定义
 */
export type UseLuopanReturn = ReturnType<typeof useLuopan>;