import { Injectable, Logger } from '@nestjs/common';
import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'fs';
import { join } from 'path';

type RuntimeSettings = {
  /** When false, SuperAdmin stops SMS alerts to managers */
  adminSmsEnabled: boolean;
};

const DEFAULTS: RuntimeSettings = {
  adminSmsEnabled: true,
};

@Injectable()
export class RuntimeSettingsService {
  private readonly logger = new Logger(RuntimeSettingsService.name);
  private readonly filePath = join(process.cwd(), 'data', 'runtime-settings.json');
  private cache: RuntimeSettings | null = null;

  getAdminSmsEnabled(): boolean {
    return this.read().adminSmsEnabled !== false;
  }

  setAdminSmsEnabled(enabled: boolean) {
    const next = { ...this.read(), adminSmsEnabled: Boolean(enabled) };
    this.write(next);
    this.logger.log(`Admin SMS alerts ${next.adminSmsEnabled ? 'enabled' : 'disabled'}`);
    return next;
  }

  getPublic() {
    return {
      adminSmsEnabled: this.getAdminSmsEnabled(),
    };
  }

  private read(): RuntimeSettings {
    if (this.cache) return this.cache;
    try {
      if (!existsSync(this.filePath)) {
        this.cache = { ...DEFAULTS };
        return this.cache;
      }
      const raw = JSON.parse(readFileSync(this.filePath, 'utf8')) as Partial<RuntimeSettings>;
      this.cache = {
        adminSmsEnabled: raw.adminSmsEnabled !== false,
      };
      return this.cache;
    } catch (error: any) {
      this.logger.warn(`Failed to read runtime settings: ${error?.message || error}`);
      this.cache = { ...DEFAULTS };
      return this.cache;
    }
  }

  private write(settings: RuntimeSettings) {
    const dir = join(process.cwd(), 'data');
    if (!existsSync(dir)) mkdirSync(dir, { recursive: true });
    writeFileSync(this.filePath, JSON.stringify(settings, null, 2), 'utf8');
    this.cache = settings;
  }
}