hey-api-builders/src/generators/builder-generator.ts

A custom plugin for @hey-api/openapi-ts that generates mock data builders with a lightweight custom runtime, Zod integration, or static mock generation.

import type { GeneratedSchemaMeta, MockStrategy } from '../types';
import type { Schema } from '../types';
import { generateZodSchema } from './zod-schema-generator';
import { generateStaticMockCode } from './static-mock-generator';
import { generateWithMethods } from '../core/code-generator';

/**
 * Builder class generation
 */

export interface BuilderGeneratorOptions {
  mockStrategy: MockStrategy;
}

/**
 * Generates a builder class for an enum schema
 */
export function generateEnumBuilder(
  meta: GeneratedSchemaMeta,
  options: BuilderGeneratorOptions
): string {
  const { typeName, schema } = meta;
  const { mockStrategy } = options;

  let code = `export class ${typeName}Builder {\n`;
  code += `  private options: BuilderOptions = {}\n`;
  code += `  setOptions(o: BuilderOptions): this { this.options = o || {}; return this }\n\n`;

  if (mockStrategy === 'static') {
    code += generateStaticEnumBuild(typeName, schema);
  } else if (mockStrategy === 'zod') {
    code += generateZodEnumBuild(typeName, schema);
  } else {
    code += generateCustomEnumBuild(typeName, meta.constName);
  }

  code += `}\n\n`;
  return code;
}

/**
 * Generates a builder class for an object schema
 */
export function generateObjectBuilder(
  meta: GeneratedSchemaMeta,
  options: BuilderGeneratorOptions
): string {
  const { typeName, schema, constName } = meta;
  const { mockStrategy } = options;

  let code = `export class ${typeName}Builder {\n`;
  code += `  private overrides: Partial<types.${typeName}> = {}\n`;
  code += `  private options: BuilderOptions = {}\n`;
  code += `  setOptions(o: BuilderOptions): this { this.options = o || {}; return this }\n`;

  const withMethods = generateWithMethods(schema, typeName);
  if (withMethods) {
    code += withMethods + '\n';
  }

  code += '\n';

  if (mockStrategy === 'static') {
    code += generateStaticObjectBuild(typeName, schema);
  } else if (mockStrategy === 'zod') {
    code += generateZodObjectBuild(typeName, schema);
  } else {
    code += generateCustomObjectBuild(typeName, constName);
  }

  code += `}\n\n`;
  return code;
}

/**
 * Static mock build method for enums
 */
function generateStaticEnumBuild(typeName: string, schema: Schema): string {
  const staticMock = generateStaticMockCode(schema, typeName);
  return `  build(): types.${typeName} {\n    return ${staticMock} as types.${typeName};\n  }\n`;
}

/**
 * Zod mock build method for enums
 */
function generateZodEnumBuild(typeName: string, schema: Schema): string {
  const zodSchemaString = generateZodSchema(schema);
  return (
    `  build(): types.${typeName} {\n` +
    `    const zodSchemaString = \`${zodSchemaString}\`;\n` +
    `    return generateMockFromZodSchema(zodSchemaString, {}, {\n` +
    `      useDefault: this.options.useDefault,\n` +
    `      useExamples: this.options.useExamples,\n` +
    `      alwaysIncludeOptionals: this.options.alwaysIncludeOptionals,\n` +
    `      optionalsProbability: this.options.optionalsProbability,\n` +
    `      omitNulls: this.options.omitNulls\n` +
    `    }) as types.${typeName};\n` +
    `  }\n`
  );
}

/**
 * Custom runtime build method for enums
 */
function generateCustomEnumBuild(typeName: string, constName: string): string {
  return (
    `  build(): types.${typeName} {\n` +
    `    return generateMock<types.${typeName}>(schemas.${constName}, {\n` +
    `      useDefault: this.options.useDefault,\n` +
    `      useExamples: this.options.useExamples,\n` +
    `      alwaysIncludeOptionals: this.options.alwaysIncludeOptionals,\n` +
    `      optionalsProbability: this.options.optionalsProbability,\n` +
    `      omitNulls: this.options.omitNulls\n` +
    `    })\n` +
    `  }\n`
  );
}

/**
 * Static mock build method for objects
 */
function generateStaticObjectBuild(typeName: string, schema: Schema): string {
  const staticMock = generateStaticMockCode(schema, typeName);
  return (
    `  build(): types.${typeName} {\n` +
    `    const baseMock = ${staticMock};\n` +
    `    return { ...baseMock, ...this.overrides } as types.${typeName};\n` +
    `  }\n`
  );
}

/**
 * Zod mock build method for objects
 */
function generateZodObjectBuild(typeName: string, schema: Schema): string {
  const zodSchemaString = generateZodSchema(schema);
  return (
    `  build(): types.${typeName} {\n` +
    `    const zodSchemaString = \`${zodSchemaString}\`;\n` +
    `    return generateMockFromZodSchema(zodSchemaString, this.overrides, {\n` +
    `      useDefault: this.options.useDefault,\n` +
    `      useExamples: this.options.useExamples,\n` +
    `      alwaysIncludeOptionals: this.options.alwaysIncludeOptionals,\n` +
    `      optionalsProbability: this.options.optionalsProbability,\n` +
    `      omitNulls: this.options.omitNulls\n` +
    `    }) as types.${typeName};\n` +
    `  }\n`
  );
}

/**
 * Custom runtime build method for objects
 */
function generateCustomObjectBuild(typeName: string, constName: string): string {
  return (
    `  build(): types.${typeName} {\n` +
    `    const mock = generateMock<types.${typeName}>(schemas.${constName}, {\n` +
    `      useDefault: this.options.useDefault,\n` +
    `      useExamples: this.options.useExamples,\n` +
    `      alwaysIncludeOptionals: this.options.alwaysIncludeOptionals,\n` +
    `      optionalsProbability: this.options.optionalsProbability,\n` +
    `      omitNulls: this.options.omitNulls\n` +
    `    })\n` +
    `    for (const k in this.overrides) {\n` +
    `      if (Object.prototype.hasOwnProperty.call(this.overrides, k)) {\n` +
    `        const typedMock = mock as Record<string, unknown>;\n` +
    `        const typedOverrides = this.overrides as Record<string, unknown>;\n` +
    `        typedMock[k] = typedOverrides[k];\n` +
    `      }\n` +
    `    }\n` +
    `    return mock\n` +
    `  }\n`
  );
}