import type { ValidationAcceptor, ValidationChecks } from 'langium';
import {
  AgentlangAstType,
  isStandaloneStatement,
  ModuleDefinition,
  SchemaDef,
} from './generated/ast.js';
import type { AgentlangServices } from './agentlang-module.js';

/**
 * Register custom validation checks.
 */
export function registerValidationChecks(services: AgentlangServices) {
  const registry = services.validation.ValidationRegistry;
  const validator = services.validation.AgentlangValidator;
  const checks: ValidationChecks<AgentlangAstType> = {
    ModuleDefinition: validator.checkUniqueDefs,
    SchemaDef: validator.checkUniqueAttributes,
  };
  registry.register(checks, validator);
}

/**
 * Implementation of custom validations.
 */
export class AgentlangValidator {
  // our new validation function for defs
  checkUniqueDefs(module: ModuleDefinition, accept: ValidationAcceptor): void {
    // create a set of visited functions
    // and report an error when we see one we've already seen
    const reported = new Set();
    module.defs.forEach(d => {
      if (!isStandaloneStatement(d)) {
        if (d.$type != 'WorkflowDefinition' && reported.has(d.name)) {
          accept('error', `Definition has non-unique name '${d.name}'.`, {
            node: d,
            property: 'name',
          });
        }
        reported.add(d.name);
      }
    });
  }

  checkUniqueAttributes(def: SchemaDef, accept: ValidationAcceptor): void {
    // create a set of visited functions
    // and report an error when we see one we've already seen
    const reported = new Set();
    def.schema.attributes.forEach(a => {
      if (reported.has(a.name)) {
        accept('error', `'${def.name} " - attribute has non-unique name '${a.name}'.`, {
          node: a,
          property: 'name',
        });
      }
      reported.add(a.name);
    });
  }
}