# BackendParserService

**Kind:** Service

**Source:** [`atloria-monorepo/apps/backend-parser/src/backend-parser.service.ts`](https://github.com/sherkety/atloria/blob/main/atloria-monorepo/apps/backend-parser/src/backend-parser.service.ts#L31)

Backend Parser Service

Provides a unified interface for all backend parsers.
Automatically selects the appropriate parser based on file type.

`BackendParserService` provides a single entry point for parsing backend source files in the Atloria monorepo. It detects the input file type, selects the matching backend parser, and returns a consistent parsing result for downstream consumers such as documentation, analysis, or code-generation workflows.

## Methods

| Method | Signature | Returns | Description |
|---|---|---|---|
| `onModuleInit` | `onModuleInit()` | `Promise<void>` |  |
| `onModuleDestroy` | `onModuleDestroy()` | `Promise<void>` |  |
| `initialize` | `initialize(config: ParserConfig)` | `Promise<void>` | Initialize all parsers with configuration |
| `getParsers` | `getParsers()` | `IParser[]` | Get all registered parsers |
| `getParser` | `getParser(name: string)` | `IParser | undefined` | Get parser by name |
| `findParserForFile` | `findParserForFile(filePath: string)` | `IParser | undefined` | Find appropriate parser for a file |
| `parseFile` | `parseFile(filePath: string, content: string)` | `Promise<ParseResult>` | Parse a single file using the appropriate parser |
| `parseFiles` | `parseFiles(files: ParseFileInput[])` | `Promise<ParseResult[]>` | Parse multiple files |
| `parseFilesGrouped` | `parseFilesGrouped(files: ParseFileInput[])` | `Promise<ParseResult[]>` | Parse files grouped by parser type for efficiency |
| `getSupportedPatterns` | `getSupportedPatterns()` | `string[]` | Get supported file patterns from all parsers |
| `getParserMetadata` | `getParserMetadata()` | `Array<{
    name: string;
    version: string;
    supportedPatterns: string[];
  }>` | Get parser metadata for registration |

## Dependencies

- `NestjsParser`
- `ExpressParser`
- `FastAPIParser`
- `DjangoParser`

## Where it refuses work

- `BackendParserService` stops the work with an early return when `!parser`.

## Diagram

```mermaid
sequenceDiagram
  participant Client as Calling Service
  participant ParserService as BackendParserService
  participant Selector as Parser Selection
  participant Parser as Backend-Specific Parser

  Client->>ParserService: parse(filePath, sourceCode)
  ParserService->>Selector: Determine parser from file type
  Selector-->>ParserService: Matching parser
  ParserService->>Parser: parse(sourceCode, filePath)
  Parser-->>ParserService: Parsed entity metadata
  ParserService-->>Client: Unified parse result
```

## Usage

```ts
import { BackendParserService } from './backend-parser.service';

async function parseBackendFile(
  parserService: BackendParserService,
  filePath: string,
  sourceCode: string,
) {
  const result = await parserService.parse(filePath, sourceCode);

  console.log(result);
  return result;
}

// In a NestJS service or controller, inject BackendParserService
// through the constructor and pass the target file contents.
```

## AI Coding Instructions

- Route all backend source parsing through `BackendParserService` rather than instantiating individual parsers directly.
- Add support for new backend file types by registering a dedicated parser and updating the service’s file-type selection logic.
- Keep parser outputs consistent so consumers can handle results without knowing which parser processed the file.
- Handle unsupported extensions and malformed source code explicitly; return actionable errors instead of silently selecting a fallback parser.
- Preserve NestJS dependency-injection patterns when adding parser dependencies or extending this service.

## Relationships

- DEPENDS_ON → `nestjsparser`
- DEPENDS_ON → `expressparser`
- DEPENDS_ON → `fastapiparser`
- DEPENDS_ON → `djangoparser`

## Referenced By

- `AppModule` (MODULE_PROVIDES)
- `AppModule` (MODULE_EXPORTS)