/**
 * Serializes OTLP payloads into HTTP request bodies.
 *
 * Signal exporters build trace, metric, and log data structures in memory. This
 * module provides the service that turns those structures into JSON or protobuf
 * HTTP bodies before they are posted to an OTLP collector.
 *
 * @stability unstable
 * @since 4.0.0
 */
import * as Context from "../Context.ts"
import * as HttpBody from "../http/HttpBody.ts"
import * as Layer from "../Layer.ts"
import * as otlpProtobuf from "./internal/otlpProtobuf.ts"
import type { LogsData } from "./OtlpLogger.ts"
import type { MetricsData } from "./OtlpMetrics.ts"
import type { TraceData } from "./OtlpTracer.ts"

/**
 * Service for serializing OTLP traces, metrics, and logs into HTTP request
 * bodies.
 *
 * @stability unstable
 * @category services
 * @since 4.0.0
 */
export class OtlpSerialization extends Context.Service<OtlpSerialization, {
  readonly traces: (data: TraceData) => HttpBody.HttpBody
  readonly metrics: (data: MetricsData) => HttpBody.HttpBody
  readonly logs: (data: LogsData) => HttpBody.HttpBody
}>()("effect/observability/OtlpSerialization") {}

// OTLP/JSON writes NaN and Infinity as strings, but JSON.stringify writes null
const nonFiniteToString = (_key: string, value: unknown) =>
  typeof value === "number" && !Number.isFinite(value) ? String(value) : value

const jsonBody = (data: unknown): HttpBody.HttpBody => {
  const json = JSON.stringify(data)
  return HttpBody.text(json.includes("null") ? JSON.stringify(data, nonFiniteToString) : json, "application/json")
}

/**
 * Provides `OtlpSerialization` using OTLP/HTTP JSON bodies.
 *
 * **Details**
 *
 * `NaN`, `Infinity` and `-Infinity` are written as the strings OTLP/JSON
 * expects, not as `null`.
 *
 * @stability unstable
 * @category layers
 * @since 4.0.0
 */
export const layerJson = Layer.succeed(OtlpSerialization, {
  traces: (spans) => jsonBody(spans),
  metrics: (metrics) => jsonBody(metrics),
  logs: (logs) => jsonBody(logs)
})

/**
 * Provides `OtlpSerialization` using protobuf-encoded OTLP bodies with the
 * `application/x-protobuf` content type.
 *
 * @stability unstable
 * @category layers
 * @since 4.0.0
 */
export const layerProtobuf = Layer.succeed(OtlpSerialization, {
  traces: (spans) =>
    HttpBody.uint8Array(
      otlpProtobuf.encodeTracesData(spans as any),
      "application/x-protobuf"
    ),
  metrics: (metrics) =>
    HttpBody.uint8Array(
      otlpProtobuf.encodeMetricsData(metrics as any),
      "application/x-protobuf"
    ),
  logs: (logs) =>
    HttpBody.uint8Array(
      otlpProtobuf.encodeLogsData(logs as any),
      "application/x-protobuf"
    )
})