import { Injectable } from '@nestjs/common';
import { PrometheusService } from '../prometheus.service';
import { MenuItem } from './menu.interface';
import * as fs from 'fs/promises';
import * as path from 'path';

@Injectable()
export class MenuService {
  constructor(private readonly prometheusService: PrometheusService) { }

  private readonly menuOverridesPath = path.join(process.cwd(), 'data', 'menu.json');

  async saveMenuToFile(): Promise<void> {
    const menu = await this.getFullMenu();
    await fs.mkdir(path.dirname(this.menuOverridesPath), { recursive: true });
    await fs.writeFile(this.menuOverridesPath, JSON.stringify(menu, null, 2), 'utf-8');
  }

  async getFullMenu(): Promise<MenuItem> {
    const dynamicItems = await this.generateDynamicItems();
    const baseMenu = this.injectDynamicItems(this.getStaticStructure(), dynamicItems);
    const overrides = await this.loadOverrides();
    return this.applyOverrides(baseMenu, overrides);
  }

  private applyOverrides(menu: MenuItem, overrides: Partial<MenuItem>[]): MenuItem {
    const overrideMap = new Map(overrides.map(o => [o.id, o]));

    const apply = (item: MenuItem): MenuItem => {
      const override = overrideMap.get(item.id);
      const updated = override ? { ...item, ...override } : item;

      if (updated.items) {
        updated.items = updated.items.map(apply);
      }

      return updated;
    };

    return apply(menu);
  }

  private async loadOverrides(): Promise<Partial<MenuItem>[]> {
    try {
      const content = await fs.readFile(this.menuOverridesPath, 'utf-8');
      const parsed = JSON.parse(content);
      return parsed.overrides || [];
    } catch (e) {
      return []; // если файл не существует
    }
  }

  private getStaticStructure(): MenuItem {
    return {
      title: "ЗВКС",
      id: "root",
      items: [
        {
          title: "ВКС",
          id: "vks",
          items: [
            {
              title: "Медиа серверы",
              id: "media_servers",
              items: []
            }
          ]
        }
      ]
    };
  }

  private async generateDynamicItems(): Promise<MenuItem[]> {
    const metricNames = await this.prometheusService.fetchAllMetrics();

    // Получаем все серии для каждой метрики
    const allSeries = (
      await Promise.all(
        metricNames.map(async name => {
          const series = await this.prometheusService.fetchMetricSeries(name);
          return series.map(s => ({
            metric: name,
            labels: s
          }));
        })
      )
    ).flat();

    // Загружаем мета-информацию по каждой метрике
    const metadataMap = new Map<string, string>(); // metric -> help

    await Promise.all(
      metricNames.map(async metric => {
        try {
          const meta = await this.prometheusService.fetchMetricMetadata(metric);
          if (meta?.help) {
            metadataMap.set(metric, meta.help);
          }
        } catch (e) {
          console.warn(`No metadata for metric ${metric}`);
        }
      })
    );

    const isGarbageDevice = (device: string) =>
      device.startsWith('/dev') ||
      device.startsWith('/proc') ||
      device.startsWith('/sys') ||
      device.startsWith('/rootfs') ||
      device.startsWith('/var') ||
      device.startsWith('overlay') ||
      device.startsWith('br') ||
      device.startsWith('docker0') ||
      device.startsWith('ens18') ||
      device.startsWith('sda') ||
      device.startsWith('sr0') ||
      device.startsWith('tmpfs') ||
      device.startsWith('veth') ||
      device.startsWith('gvfsd') ||
      device.startsWith('lo') ||
      device.startsWith('/run');

    const isGarbageInstance = (instance: string) =>
      instance.includes('192.168.2.34:9049');

    const filteredSeries = allSeries.filter(({ labels }) => {
      const device = labels.device;
      const instance = labels.instance;

      return (!device || !isGarbageDevice(device)) &&
        (!instance || !isGarbageInstance(instance));
    });
    const devices = this.extractUniqueEntities(filteredSeries, 'device');

    return devices.map(device => ({
      id: `device_${device}`,
      title: `Graviton S2082I (${device})`,
      items: this.generateModuleItems(device, allSeries, metadataMap),
      isDynamic: true
    }));
  }

  private extractUniqueEntities(metrics: any[], field: string): string[] {
    const entities = new Set<string>();
    metrics.forEach(meta => {
      if (meta.labels?.[field]) {
        entities.add(meta.labels[field]);
      }
    });
    return Array.from(entities);
  }

  private generateModuleItems(
    device: string,
    seriesData: { metric: string; labels: Record<string, string> }[],
    metadataMap: Map<string, string>
  ): MenuItem[] {
    const modules = new Set<string>();

    seriesData.forEach(({ labels }) => {
      if (labels.device === device && labels.source_id) {
        modules.add(labels.source_id);
      }
    });

    return Array.from(modules).map(module => ({
      id: `module_${device}_${module}`,
      title: `Module ${module.replace('module$', '')}`,
      items: this.generateMetricItems(device, module, seriesData, metadataMap),
      isDynamic: true
    }));
  }

  private generateMetricItems(
    device: string,
    module: string,
    seriesData: { metric: string; labels: Record<string, string> }[],
    metadataMap: Map<string, string>
  ): MenuItem[] {
    const filtered = seriesData.filter(
      ({ labels }) => labels.device === device && labels.source_id === module
    );

    const uniqueMetrics = new Set(filtered.map(entry => entry.metric));

    return Array.from(uniqueMetrics).map(metric => {
      const description = metadataMap.get(metric) || metric;

      return {
        id: `metric_${device}_${module}_${metric}`,
        title: description,
        metric,
        filters: {
          device,
          source_id: module
        },
        isDynamic: true
      };
    });
  }

  private injectDynamicItems(menu: MenuItem, dynamicItems: MenuItem[]): MenuItem {
    if (menu.id === 'media_servers') {
      return { ...menu, items: dynamicItems };
    }

    return {
      ...menu,
      items: menu.items?.map(item => this.injectDynamicItems(item, dynamicItems)) || []
    };
  }

  async updateMenuItem(id: string, update: Partial<MenuItem>): Promise<MenuItem> {
    const fullMenu = await this.getFullMenu();
    const item = this.findMenuItem(fullMenu, id);

    if (!item) throw new Error('Menu item not found');
    Object.assign(item, update);

    return item;
  }

  async saveOverrides(overrides: Partial<MenuItem>[]): Promise<void> {
    await fs.writeFile(this.menuOverridesPath, JSON.stringify({ overrides }, null, 2), 'utf-8');
  }

  private findMenuItem(menu: MenuItem, id: string): MenuItem | null {
    if (menu.id === id) return menu;

    if (menu.items) {
      for (const item of menu.items) {
        const found = this.findMenuItem(item, id);
        if (found) return found;
      }
    }

    return null;
  }
}