@helia/verified-fetch/src/plugins/plugin-base.ts

A fetch-like API for obtaining verified & trustless IPFS content on the web

import type { VerifiedFetchPlugin, PluginContext, PluginOptions } from './types.js'
import type { Logger } from '@libp2p/interface'

/**
 * Base class for verified-fetch plugins. This class provides a basic implementation of the `FetchHandlerPlugin`
 * interface.
 *
 * Subclasses must implement the `id` property and the `canHandle` and `handle` methods.
 * Subclasses may override the `codes` and `log` properties.
 *
 * If your plugin adds/edits the context supplied in `handle`, you should increment the `context.modified` property.
 */
export abstract class BasePlugin implements VerifiedFetchPlugin {
  readonly codes: number[] = []
  readonly pluginOptions: PluginOptions
  abstract readonly id: string
  protected _log?: Logger

  get log (): Logger {
    // instantiate the logger lazily because it depends on the id, which is not set until after the constructor is called
    if (this._log == null) {
      this._log = this.pluginOptions.logger.forComponent(this.id)
    }
    return this._log
  }

  constructor (options: PluginOptions) {
    this.pluginOptions = options
  }

  abstract canHandle (context: PluginContext): boolean

  abstract handle (context: PluginContext): Promise<Response | null>
}