# ParserRegistryService

**Kind:** Service

**Source:** [`atloria-monorepo/apps/config-docs-parser/src/services/parser-registry.service.ts`](https://github.com/sherkety/atloria/blob/main/atloria-monorepo/apps/config-docs-parser/src/services/parser-registry.service.ts#L30)

`ParserRegistryService` is a NestJS service that manages the configured set of `IParser` implementations used to parse configuration documentation files. It initializes and disposes parser resources during module lifecycle events, discovers parsers that support a file, selects the best match, and delegates parsing to that parser.

## Methods

| Method | Signature | Returns | Description |
|---|---|---|---|
| `onModuleInit` | `onModuleInit()` | `Promise<void>` |  |
| `onModuleDestroy` | `onModuleDestroy()` | `Promise<void>` |  |
| `configure` | `configure(config: ParserRegistryConfig)` | `Promise<void>` | Configure and initialize the registry with custom settings |
| `getAllParsers` | `getAllParsers()` | `IParser[]` | Get all registered parsers |
| `getParser` | `getParser(name: string)` | `IParser | undefined` | Get a parser by name |
| `hasParser` | `hasParser(name: string)` | `boolean` | Check if a parser is registered |
| `getParserNames` | `getParserNames()` | `string[]` | Get parser names |
| `findParsersForFile` | `findParsersForFile(filePath: string)` | `IParser[]` | Find all parsers that can handle a given file |
| `findBestParser` | `findBestParser(filePath: string)` | `IParser | undefined` | Find the best parser for a file (first match) |
| `parseFile` | `parseFile(filePath: string, content: string)` | `Promise<ParseResult>` | Parse a file using the best available parser |
| `parseFiles` | `parseFiles(files: ParseFileRequest[])` | `Promise<ParseResult[]>` | Parse multiple files, automatically selecting the correct parser for each |
| `getAllSupportedPatterns` | `getAllSupportedPatterns()` | `string[]` | Get all supported file patterns across all parsers |
| `getStats` | `getStats()` | `{
    parserCount: number;
    parsers: Array<{ name: string; version: string; patterns: string[] }>;
    totalPatterns: number;
  }` | Get registry statistics |
| `destroyAll` | `destroyAll()` | `Promise<void>` | Destroy all parsers and clear the registry |
| `isInitialized` | `isInitialized()` | `boolean` | Check if the registry is initialized |

## Dependencies

- `MarkdownParser`
- `MdxParser`
- `EnvParser`
- `YamlParser`
- `JsonConfigParser`

## Where it refuses work

- `ParserRegistryService` stops the work with `Error` when `!this.initialized` — “ParserRegistry not initialized. Call configure() first.”, in 2 places.
- `ParserRegistryService` stops the work with an early return when `!parser`.

## Diagram

```mermaid
sequenceDiagram
    participant App as NestJS Module
    participant Registry as ParserRegistryService
    participant Parser as IParser
    participant File as Source File

    App->>Registry: onModuleInit()
    Registry->>Registry: configure()
    Registry->>Parser: initialize/configure parsers

    App->>Registry: parseFile(file)
    Registry->>Registry: findParsersForFile(file)
    Registry->>Registry: findBestParser(parsers)
    Registry->>Parser: parse(file)
    Parser->>File: read and analyze content
    Parser-->>Registry: ParseResult
    Registry-->>App: ParseResult

    App->>Registry: onModuleDestroy()
    Registry->>Parser: dispose/cleanup resources
```

## Usage

```ts
import { Injectable } from '@nestjs/common';
import { ParserRegistryService } from './services/parser-registry.service';

@Injectable()
export class DocumentationImportService {
  constructor(
    private readonly parserRegistry: ParserRegistryService,
  ) {}

  async importFile(filePath: string) {
    const parser = this.parserRegistry.findBestParser(filePath);

    if (!parser) {
      throw new Error(
        `No parser is registered for "${filePath}". Available parsers: ${this.parserRegistry
          .getParserNames()
          .join(', ')}`,
      );
    }

    const result = await this.parserRegistry.parseFile(filePath);

    return result;
  }
}
```

## AI Coding Instructions

- Use `ParserRegistryService` as the single entry point for parser discovery and file parsing; avoid directly selecting parser implementations in consumers.
- Ensure new `IParser` implementations are registered through the service configuration flow so they are available after `onModuleInit()`.
- Call `findBestParser()` or `hasParser()` before parsing when handling optional or user-provided file types.
- Preserve parser selection behavior when adding parsers, especially when multiple parsers may support the same file extension or format.
- Do not manually invoke lifecycle methods; NestJS calls `onModuleInit()` and `onModuleDestroy()` as part of module startup and shutdown.

## Relationships

- DEPENDS_ON → `markdownparser`
- DEPENDS_ON → `mdxparser`
- DEPENDS_ON → `envparser`
- DEPENDS_ON → `yamlparser`
- DEPENDS_ON → `jsonconfigparser`

## Referenced By

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