import { AxiosError } from "axios";
import { GraphQLServerError } from "./graphql/types.js";
import { HTTPError } from "../../utils/http-client.js";

/**
 * Represents GraphQL specific errors (validation, missing fields, etc.)
 */
export class GraphQLError extends Error {
  constructor(
    message: string,
    public errors: GraphQLServerError[]
  ) {
    super(message);
    this.name = "GraphQLError";
  }
}

/**
 * Centralized error handling for API requests.
 * Transforms various error types into standardized HTTPError or GraphQLError.
 */
export class ErrorHandler {
  /**
   * Transforms any error into a standardized HTTPError or GraphQLError and throws it.
   * Never returns - always throws an error.
   *
   * @throws {HTTPError|GraphQLError} Standardized error with appropriate details
   */
  static handle(error: unknown): never {
    if (error instanceof GraphQLError) {
      throw error;
    }

    // Handle HTTPError (already processed by http-client)
    if (error instanceof HTTPError) {
      // For GraphQL responses with errors in the data
      if (
        error.data &&
        typeof error.data === "object" &&
        "errors" in error.data &&
        Array.isArray((error.data as any).errors) &&
        (error.data as any).errors.length > 0
      ) {
        const graphqlError = new GraphQLError(
          "GraphQL Error",
          (error.data as { errors: GraphQLServerError[] }).errors
        );
        throw graphqlError;
      }
      throw error; // Re-throw the original HTTPError
    }

    // Handle raw AxiosError (direct usage, not through http-client)
    if (error instanceof AxiosError) {
      // For GraphQL responses with errors
      if (
        error.response?.data?.errors &&
        Array.isArray(error.response.data.errors) &&
        error.response.data.errors.length > 0
      ) {
        const graphqlError = new GraphQLError(
          "GraphQL Error",
          error.response.data.errors as GraphQLServerError[]
        );
        throw graphqlError;
      }

      // For HTTP errors - create HTTPError and log with response data
      const httpError = new HTTPError(
        error.message,
        error.response?.status || 500,
        error.code,
        error.response?.data
      );
      throw httpError;
    }

    // For other errors
    const httpError = new HTTPError(
      error instanceof Error ? error.message : "An unknown error occurred",
      500
    );
    throw httpError;
  }
}