import {
  FlowExternalDbIntegrationConfig,
  FlowIntegrationContext,
  FlowIntegrationResult,
} from "../types/flow";
import { FlowExternalDbConnectionService } from "./flowExternalDbConnectionService";
import { Pool } from "pg";

/**
 * 플로우 외부 DB 연동 실행 서비스
 * 외부 데이터베이스에 대한 작업(INSERT, UPDATE, DELETE, CUSTOM QUERY) 수행
 */
export class FlowExternalDbIntegrationService {
  private connectionService: FlowExternalDbConnectionService;

  constructor() {
    this.connectionService = new FlowExternalDbConnectionService();
  }

  /**
   * 외부 DB 연동 실행
   */
  async execute(
    context: FlowIntegrationContext,
    config: FlowExternalDbIntegrationConfig
  ): Promise<FlowIntegrationResult> {
    const startTime = Date.now();

    try {
      // 1. 연결 정보 조회
      const connection = await this.connectionService.findById(
        config.connectionId
      );
      if (!connection) {
        return {
          success: false,
          error: {
            code: "CONNECTION_NOT_FOUND",
            message: `외부 DB 연결 정보를 찾을 수 없습니다 (ID: ${config.connectionId})`,
          },
        };
      }

      if (!connection.isActive) {
        return {
          success: false,
          error: {
            code: "CONNECTION_INACTIVE",
            message: `외부 DB 연결이 비활성화 상태입니다 (${connection.name})`,
          },
        };
      }

      // 2. 쿼리 생성 (템플릿 변수 치환)
      const query = this.buildQuery(config, context);

      // 3. 실행
      const pool = await this.connectionService.getConnectionPool(connection);
      const result = await this.executeQuery(pool, query);

      const executionTime = Date.now() - startTime;

      return {
        success: true,
        message: `외부 DB 작업 성공 (${config.operation}, ${executionTime}ms)`,
        data: result,
        rollbackInfo: {
          query: this.buildRollbackQuery(config, context, result),
          connectionId: config.connectionId,
        },
      };
    } catch (error: any) {
      const executionTime = Date.now() - startTime;

      return {
        success: false,
        error: {
          code: "EXTERNAL_DB_ERROR",
          message: error.message || "외부 DB 작업 실패",
          details: {
            operation: config.operation,
            tableName: config.tableName,
            executionTime,
            originalError: error,
          },
        },
      };
    }
  }

  /**
   * 쿼리 실행
   */
  private async executeQuery(
    pool: Pool,
    query: { sql: string; params: any[] }
  ): Promise<any> {
    const client = await pool.connect();
    try {
      const result = await client.query(query.sql, query.params);
      return result.rows;
    } finally {
      client.release();
    }
  }

  /**
   * 쿼리 빌드 (템플릿 변수 치환 포함)
   */
  private buildQuery(
    config: FlowExternalDbIntegrationConfig,
    context: FlowIntegrationContext
  ): { sql: string; params: any[] } {
    let sql = "";
    const params: any[] = [];
    let paramIndex = 1;

    switch (config.operation) {
      case "update":
        return this.buildUpdateQuery(config, context, paramIndex);
      case "insert":
        return this.buildInsertQuery(config, context, paramIndex);
      case "delete":
        return this.buildDeleteQuery(config, context, paramIndex);
      case "custom":
        return this.buildCustomQuery(config, context);
      default:
        throw new Error(`지원하지 않는 작업: ${config.operation}`);
    }
  }

  /**
   * UPDATE 쿼리 빌드
   */
  private buildUpdateQuery(
    config: FlowExternalDbIntegrationConfig,
    context: FlowIntegrationContext,
    startIndex: number
  ): { sql: string; params: any[] } {
    if (!config.updateFields || Object.keys(config.updateFields).length === 0) {
      throw new Error("UPDATE 작업에는 updateFields가 필요합니다");
    }

    if (
      !config.whereCondition ||
      Object.keys(config.whereCondition).length === 0
    ) {
      throw new Error("UPDATE 작업에는 whereCondition이 필요합니다");
    }

    const setClauses: string[] = [];
    const params: any[] = [];
    let paramIndex = startIndex;

    // SET 절 생성
    for (const [key, value] of Object.entries(config.updateFields)) {
      setClauses.push(`${key} = $${paramIndex}`);
      params.push(this.replaceVariables(value, context));
      paramIndex++;
    }

    // WHERE 절 생성
    const whereClauses: string[] = [];
    for (const [key, value] of Object.entries(config.whereCondition)) {
      whereClauses.push(`${key} = $${paramIndex}`);
      params.push(this.replaceVariables(value, context));
      paramIndex++;
    }

    const sql = `UPDATE ${config.tableName} SET ${setClauses.join(", ")} WHERE ${whereClauses.join(" AND ")}`;

    return { sql, params };
  }

  /**
   * INSERT 쿼리 빌드
   */
  private buildInsertQuery(
    config: FlowExternalDbIntegrationConfig,
    context: FlowIntegrationContext,
    startIndex: number
  ): { sql: string; params: any[] } {
    if (!config.updateFields || Object.keys(config.updateFields).length === 0) {
      throw new Error("INSERT 작업에는 updateFields가 필요합니다");
    }

    const columns: string[] = [];
    const placeholders: string[] = [];
    const params: any[] = [];
    let paramIndex = startIndex;

    for (const [key, value] of Object.entries(config.updateFields)) {
      columns.push(key);
      placeholders.push(`$${paramIndex}`);
      params.push(this.replaceVariables(value, context));
      paramIndex++;
    }

    const sql = `INSERT INTO ${config.tableName} (${columns.join(", ")}) VALUES (${placeholders.join(", ")}) RETURNING *`;

    return { sql, params };
  }

  /**
   * DELETE 쿼리 빌드
   */
  private buildDeleteQuery(
    config: FlowExternalDbIntegrationConfig,
    context: FlowIntegrationContext,
    startIndex: number
  ): { sql: string; params: any[] } {
    if (
      !config.whereCondition ||
      Object.keys(config.whereCondition).length === 0
    ) {
      throw new Error("DELETE 작업에는 whereCondition이 필요합니다");
    }

    const whereClauses: string[] = [];
    const params: any[] = [];
    let paramIndex = startIndex;

    for (const [key, value] of Object.entries(config.whereCondition)) {
      whereClauses.push(`${key} = $${paramIndex}`);
      params.push(this.replaceVariables(value, context));
      paramIndex++;
    }

    const sql = `DELETE FROM ${config.tableName} WHERE ${whereClauses.join(" AND ")}`;

    return { sql, params };
  }

  /**
   * CUSTOM 쿼리 빌드
   */
  private buildCustomQuery(
    config: FlowExternalDbIntegrationConfig,
    context: FlowIntegrationContext
  ): { sql: string; params: any[] } {
    if (!config.customQuery) {
      throw new Error("CUSTOM 작업에는 customQuery가 필요합니다");
    }

    // 템플릿 변수 치환
    const sql = this.replaceVariables(config.customQuery, context);

    // 커스텀 쿼리는 파라미터를 직접 관리
    // 보안을 위해 가능하면 파라미터 바인딩 사용 권장
    return { sql, params: [] };
  }

  /**
   * 템플릿 변수 치환
   */
  private replaceVariables(value: any, context: FlowIntegrationContext): any {
    if (typeof value !== "string") {
      return value;
    }

    let result = value;

    // {{dataId}} 치환
    result = result.replace(/\{\{dataId\}\}/g, String(context.dataId));

    // {{currentUser}} 치환
    result = result.replace(/\{\{currentUser\}\}/g, context.currentUser);

    // {{currentTimestamp}} 치환
    result = result.replace(
      /\{\{currentTimestamp\}\}/g,
      new Date().toISOString()
    );

    // {{flowId}} 치환
    result = result.replace(/\{\{flowId\}\}/g, String(context.flowId));

    // {{stepId}} 치환
    result = result.replace(/\{\{stepId\}\}/g, String(context.stepId));

    // {{tableName}} 치환
    if (context.tableName) {
      result = result.replace(/\{\{tableName\}\}/g, context.tableName);
    }

    // context.variables의 커스텀 변수 치환
    for (const [key, val] of Object.entries(context.variables)) {
      const regex = new RegExp(`\\{\\{${key}\\}\\}`, "g");
      result = result.replace(regex, String(val));
    }

    // NOW() 같은 SQL 함수는 그대로 반환
    if (result === "NOW()" || result.startsWith("CURRENT_")) {
      return result;
    }

    return result;
  }

  /**
   * 롤백 쿼리 생성
   */
  private buildRollbackQuery(
    config: FlowExternalDbIntegrationConfig,
    context: FlowIntegrationContext,
    result: any
  ): { sql: string; params: any[] } | null {
    // 롤백 쿼리 생성 로직 (복잡하므로 실제 구현 시 상세 설계 필요)
    // 예: INSERT -> DELETE, UPDATE -> 이전 값으로 UPDATE

    switch (config.operation) {
      case "insert":
        // INSERT를 롤백하려면 삽입된 레코드를 DELETE
        if (result && result[0] && result[0].id) {
          return {
            sql: `DELETE FROM ${config.tableName} WHERE id = $1`,
            params: [result[0].id],
          };
        }
        break;
      case "delete":
        // DELETE 롤백은 매우 어려움 (원본 데이터 필요)
        console.warn("DELETE 작업의 롤백은 지원하지 않습니다");
        break;
      case "update":
        // UPDATE 롤백을 위해서는 이전 값을 저장해야 함
        console.warn("UPDATE 작업의 롤백은 현재 구현되지 않았습니다");
        break;
      default:
        break;
    }

    return null;
  }

  /**
   * 롤백 실행
   */
  async rollback(
    connectionId: number,
    rollbackQuery: { sql: string; params: any[] }
  ): Promise<void> {
    const connection = await this.connectionService.findById(connectionId);
    if (!connection) {
      throw new Error(
        `롤백 실패: 연결 정보를 찾을 수 없습니다 (ID: ${connectionId})`
      );
    }

    const pool = await this.connectionService.getConnectionPool(connection);
    await this.executeQuery(pool, rollbackQuery);
  }
}