import type { RudderContext } from '../core/context.js';
import { uuidv4 } from '../core/uuid.js';
import { RudderHttpError, RudderModuleError } from '../client/RudderError.js';
import type {
  CallModuleFunctionClientResponse,
  CallModuleFunctionRequest,
  ModuleErrorResponse,
} from '../generated/modules.js';

export interface ModuleCallOptions {
  /** Version the caller was built against; sent as `X-Rudder-Module-Version: <module>@<version>`. */
  moduleVersion?: string;
}

/**
 * ModulesDomain — calls module functions. Usually reached through a client
 * generated by `rudder client generate`, not directly.
 */
export class ModulesDomain {
  constructor(private readonly ctx: RudderContext) {}

  /**
   * Calls `module.fn` and returns its `result`. Each call gets one
   * Idempotency-Key reused across retries (network errors, 5xx, 409 `conflict`).
   * Rejects with {@link RudderModuleError} on 422.
   */
  async call<T = unknown>(
    module: string,
    fn: string,
    args?: unknown,
    options?: ModuleCallOptions,
  ): Promise<T> {
    const headers: Record<string, string> = { 'Idempotency-Key': uuidv4() };
    if (options?.moduleVersion) {
      headers['X-Rudder-Module-Version'] = `${module}@${options.moduleVersion}`;
    }
    const path = `/sdk/v1/modules/${encodeURIComponent(module)}/${encodeURIComponent(fn)}`;
    try {
      const response = await this.ctx.request<CallModuleFunctionClientResponse>(
        'POST',
        path,
        { args: args ?? {} } satisfies CallModuleFunctionRequest,
        { headers, retry: true },
      );
      return response?.result as T;
    } catch (err) {
      if (err instanceof RudderHttpError && err.status === 422 && err.code) {
        let payload: Partial<ModuleErrorResponse> = {};
        try {
          payload = JSON.parse(err.body);
        } catch {
          // err.code came from this body, so it is JSON; keep the fallback anyway.
        }
        throw new RudderModuleError(err.statusText, err.body, { ...payload, code: err.code });
      }
      throw err;
    }
  }
}