hyperpubee/lib/core/embedding.js

Self-publishing over the decentralised internet

const { isValidHyperHash, isValidPubeeLocation } = require('./utils')
const { EmbeddingValidationError } = require('../exceptions')
const { applyDiffToText } = require('./diff-patch')

class Embedding {
  constructor ({ referencedHash, referencedLocation, patch }) {
    if (!isValidHyperHash(referencedHash)) {
      throw new EmbeddingValidationError(
        `referencedHash must be a valid hypercore hash (${referencedHash})`
      )
    }

    this.referencedHash = referencedHash

    if (!isValidPubeeLocation(referencedLocation)) {
      throw new EmbeddingValidationError(
        `Invalid referenced location (${referencedLocation})`
      )
    }
    this.referencedLocation = referencedLocation

    validatePatch(patch)
    this.patch = JSON.parse(JSON.stringify(patch))
  }

  applyPatch (text) {
    return applyDiffToText(this.patch, text)
  }
}

function validatePatch (patch) {
  if (!Array.isArray(patch)) {
    throw new EmbeddingValidationError(
      'patch must be an array (use empty array if none to apply)'
    )
  }

  for (const diffElem of patch) {
    const error = new Error(
      `Invalid patch structure for element '${JSON.stringify(diffElem)}'`
    )

    if (diffElem.length !== 2) {
      throw error
    }

    if (![0, -1, 1].includes(diffElem[0])) {
      throw error
    }

    if (typeof (diffElem[1]) !== 'string') {
      throw error
    }
  }
}

function validateEmbedding (embedding) {
  // Creating a new embedding runs all validation tests
  // (throws when finding an issue)
  new Embedding(embedding) // eslint-disable-line no-new
}

module.exports = {
  validateEmbedding,
  Embedding
}