compress-payload.ts

type SyncPayload = {
  changes: {
    participants: {
      updated: {id: string, check_in_date: string | null}[]
    }
  },
  timestamp: number
}

type CompressedPayload = {
  c: string,
  timestamp: number
}

function compressPayload(payload: SyncPayload): CompressedPayload {
  function compressId(id: string) {
    return (+id).toString(36) // comprime número de 7 dígitos para 5
  }

  function compressDate(date: string | null) {
    if (date === null) return ""
    // converte a data para número e reduz a quantidade de dígitos
    return " " + new Date(date).getTime().toString(36)
  }

  const c = payload.changes.participants.updated
    .map(u => compressId(u.id) + compressDate(u.check_in_date))
    .join("|") // separar cada participante com pipe

  return {
    c,
    timestamp: payload.timestamp
  }
}

function decompressPayload(payload: CompressedPayload): SyncPayload {
  function decompressId(id: string) {
    return Number.parseInt(id, 36).toString()
  }

  function decompressDate(date: string) {
    return new Date(Number.parseInt(date, 36)).toUTCString()
  }

  const updated = payload.c.split("|").map(p => {
    const [id, date] = p.split(" ")
    return {
      id: decompressId(id),
      check_in_date: date ? decompressDate(date) : null
    }
  })

  return {
    changes: {
      participants: {
        updated
      }
    },
    timestamp: payload.timestamp
  }
}

// substituir por um payload maior de 10K inscritos
const payload = {
  "changes": {
    "events": {
      "created": [],
      "updated": [],
      "deleted": []
    },
    "participants": {
      "created": [],
      "updated": [
        {
          "id": "5175639",
          "check_in_date": "Wed, 18 Sep 2024 13:27:41 GMT"
        },
        {
          "id": "5175640",
          "check_in_date": null
        },
        {
          "id": "5175641",
          "check_in_date": new Date().toUTCString()
        }
      ],
      "deleted": []
    }
  },
  "timestamp": 1726666068808
}

const compressed = compressPayload(payload)
const sizeBefore = JSON.stringify(payload).length
const sizeAfter = JSON.stringify(compressed).length
const percentageReduction = Math.round((1 - sizeAfter / sizeBefore) * 100)
const times = Math.round(sizeBefore / sizeAfter)
console.log(compressed)
console.log("Bytes antes de comprimir:", sizeBefore)
console.log("Bytes depois de comprimir:", sizeAfter)
console.log(`Redução de ${percentageReduction}% ou ${times} vezes menor`)

// validar se após compress e decompress, os valores continuam os mesmos
const decompressed = decompressPayload(compressed)
if (JSON.stringify(decompressed.changes.participants.updated) ===
    JSON.stringify(payload.changes.participants.updated.map(
      updated => ({id: updated.id, check_in_date: updated.check_in_date})))) {
  console.log("payload VÁLIDO")
} else {
  console.log("payload inválido")
}