import db from '../config/database';
import { RedisService } from '../utils/RedisService';

export interface AppConfig {
  key: string;
  value: any;
  description?: string;
  isEnabled: boolean;
}

export class ConfigService {
  private static TABLE_NAME = 'cf_config';
  private static HISTORY_TABLE = 'cf_config_history';

  /**
   * [CORE_DEV_06/16] 初始化配置表与历史表
   */
  static async initTable() {
    const exists = await db.schema.hasTable(this.TABLE_NAME);
    if (!exists) {
      await db.schema.createTable(this.TABLE_NAME, (table) => {
        table.string('key').notNullable();
        table.string('tenantId').defaultTo('SYSTEM').index();
        table.json('value');
        table.string('description');
        table.boolean('isEnabled').defaultTo(true);
        table.integer('version').defaultTo(1); // [CORE_DEV_16] 版本控制
        table.timestamps(true, true);
        table.primary(['key', 'tenantId']);
      });
      // ... (seed data remains same)
    }

    const historyExists = await db.schema.hasTable(this.HISTORY_TABLE);
    if (!historyExists) {
      await db.schema.createTable(this.HISTORY_TABLE, (table) => {
        table.increments('id').primary();
        table.string('key').notNullable();
        table.string('tenantId').notNullable();
        table.json('value');
        table.integer('version').notNullable();
        table.string('changeLog');
        table.timestamp('created_at').defaultTo(db.fn.now());
        table.index(['key', 'tenantId']);
      });
    }
  }

  /**
   * [CORE_DEV_16] 更新配置并保存历史版本
   */
  static async updateConfig(key: string, data: Partial<AppConfig> & { changeLog?: string }, tenantId: string = 'SYSTEM') {
    const current = await this.getConfig(key, tenantId);
    const newVersion = (current?.version || 0) + 1;

    const updateData: any = { ...data, version: newVersion };
    delete updateData.changeLog;

    if (data.value) updateData.value = JSON.stringify(data.value);

    await db.transaction(async (trx) => {
      // 1. 更新主表
      await trx(this.TABLE_NAME).where({ key, tenantId }).update(updateData);

      // 2. 插入历史记录
      await trx(this.HISTORY_TABLE).insert({
        key,
        tenantId,
        value: updateData.value || JSON.stringify(current?.value),
        version: newVersion,
        changeLog: data.changeLog || 'Automated update'
      });
    });

    // [CORE_DEV_12] 分布式配置热更新通知
    await RedisService.publishConfigChange(tenantId, key, data.value || data.isEnabled);
  }

  /**
   * [CORE_DEV_16] 配置版本回滚
   */
  static async rollbackConfig(key: string, version: number, tenantId: string = 'SYSTEM') {
    const history = await db(this.HISTORY_TABLE).where({ key, tenantId, version }).first();
    if (!history) throw new Error(`Version ${version} not found for config ${key}`);

    await this.updateConfig(key, { 
      value: typeof history.value === 'string' ? JSON.parse(history.value) : history.value,
      changeLog: `Rollback to version ${version}`
    }, tenantId);
  }

  static async isFeatureEnabled(key: string, tenantId: string = 'SYSTEM'): Promise<boolean> {
    const config = await this.getConfig(key, tenantId);
    return config ? config.isEnabled : false;
  }
}