import {
  AppsV1Api,
  CoreV1Api,
  KubeConfig,
  type V1LabelSelector,
} from "@kubernetes/client-node";
import http, { type IncomingMessage, type RequestOptions } from "node:http";
import https from "node:https";
import { logKubernetesRequest } from "../lib/request-log";
import {
  KubernetesLogError,
  type ContainerLogRequest,
  type KubernetesLogsBackend,
} from "./log-service";

function selector(labels: Readonly<Record<string, string>>): string {
  return Object.entries(labels)
    .sort(([left], [right]) => left.localeCompare(right))
    .map(([key, value]) => `${key}=${value}`)
    .join(",");
}

function matchLabels(
  value: V1LabelSelector | undefined,
): Record<string, string> {
  if (value?.matchExpressions?.length) return {};
  return value?.matchLabels ?? {};
}

function statusCode(error: unknown): number | undefined {
  if (!error || typeof error !== "object") return;
  if ("code" in error && typeof error.code === "number") return error.code;
  if ("statusCode" in error && typeof error.statusCode === "number")
    return error.statusCode;
}

function logError(error: unknown): KubernetesLogError {
  const status = statusCode(error);
  const code =
    error && typeof error === "object" && "code" in error
      ? error.code
      : undefined;
  const transientNetworkCodes = new Set([
    "ECONNRESET", "ETIMEDOUT", "EPIPE", "ECONNREFUSED", "EHOSTUNREACH",
    "ENETUNREACH", "ECONNABORTED", "EAI_AGAIN", "UND_ERR_SOCKET",
    "UND_ERR_CONNECT_TIMEOUT",
  ]);
  const message = error instanceof Error ? error.message : "";
  return new KubernetesLogError(
    error instanceof Error ? error.message : "Kubernetes log request failed",
    typeof code === "string"
      ? transientNetworkCodes.has(code)
      : status === undefined && /socket hang up|socket closed/i.test(message)
        ? true
        : status === undefined || status === 408 || status === 429 || status >= 500,
  );
}

function requestLogs(
  url: URL,
  options: RequestOptions,
  signal: AbortSignal,
): Promise<IncomingMessage> {
  return new Promise((resolve, reject) => {
    const transport = url.protocol === "https:" ? https : http;
    const request = transport.request(
      url,
      { ...options, method: "GET", signal },
      resolve,
    );
    request.once("error", reject);
    request.end();
  });
}

async function responseBody(response: IncomingMessage): Promise<string> {
  const chunks: Buffer[] = [];
  for await (const chunk of response) chunks.push(Buffer.from(chunk));
  return Buffer.concat(chunks).toString("utf8");
}

export class KubernetesLogs implements KubernetesLogsBackend {
  constructor(
    private readonly config: KubeConfig,
    private readonly apps = config.makeApiClient(AppsV1Api),
    private readonly core = config.makeApiClient(CoreV1Api),
  ) {}

  async listDeployments(
    namespace: string,
    labels: Readonly<Record<string, string>>,
  ) {
    try {
      const deployments = await this.apps.listNamespacedDeployment({
        namespace,
        labelSelector: selector(labels),
      });
      return deployments.items.flatMap((deployment) => {
        const name = deployment.metadata?.name;
        const labels = matchLabels(deployment.spec?.selector);
        return name && Object.keys(labels).length
          ? [{ name, selector: labels }]
          : [];
      });
    } catch (error) {
      throw logError(error);
    }
  }

  async getService(namespace: string, name: string) {
    try {
      const service = await this.core.readNamespacedService({
        namespace,
        name,
      });
      return { name, selector: service.spec?.selector ?? {} };
    } catch (error) {
      if (statusCode(error) === 404) return;
      throw logError(error);
    }
  }

  async listPods(namespace: string, labels: Readonly<Record<string, string>>) {
    try {
      const pods = await this.core.listNamespacedPod({
        namespace,
        labelSelector: selector(labels),
      });
      return pods.items.map((pod) => ({
        name: pod.metadata?.name ?? "",
        uid: pod.metadata?.uid ?? "",
        phase: pod.status?.phase,
        containers: (pod.spec?.containers ?? []).map(
          (container) => container.name,
        ),
      }));
    } catch (error) {
      throw logError(error);
    }
  }

  async readContainerLogs(request: ContainerLogRequest): Promise<string> {
    try {
      return await this.core.readNamespacedPodLog({
        namespace: request.namespace,
        name: request.pod,
        container: request.container,
        tailLines: request.tailLines,
        sinceSeconds: request.sinceSeconds,
        timestamps: request.timestamps,
      });
    } catch (error) {
      throw logError(error);
    }
  }

  async *streamContainerLogs(
    request: ContainerLogRequest,
    signal: AbortSignal,
  ): AsyncIterable<Uint8Array> {
    try {
      if (signal.aborted) return;
      const cluster = this.config.getCurrentCluster();
      if (!cluster) throw new Error("No currently active cluster");
      const url = new URL(
        `${cluster.server}/api/v1/namespaces/${encodeURIComponent(request.namespace)}/pods/${encodeURIComponent(request.pod)}/log`,
      );
      url.searchParams.set("container", request.container);
      url.searchParams.set("follow", "true");
      url.searchParams.set("timestamps", String(request.timestamps));
      if (request.tailLines !== undefined)
        url.searchParams.set("tailLines", String(request.tailLines));
      if (request.sinceSeconds !== undefined)
        url.searchParams.set("sinceSeconds", String(request.sinceSeconds));
      if (request.sinceTime !== undefined)
        url.searchParams.set("sinceTime", request.sinceTime);

      const options: RequestOptions = {};
      await this.config.applyToHTTPSOptions(options);
      const response = await logKubernetesRequest(
        {
          method: "GET",
          pathname: url.pathname,
          body: undefined,
          attempt: 1,
        },
        async () => {
          const response = await requestLogs(url, options, signal);
          const status = response.statusCode ?? 0;
          if (status < 200 || status >= 300) {
            const body = await responseBody(response);
            let detail = body.trim();
            try {
              const status = JSON.parse(body) as { message?: unknown };
              if (typeof status.message === "string") detail = status.message;
            } catch {
              // Proxies can return plain text rather than a Kubernetes Status.
            }
            throw new KubernetesLogError(
              `Kubernetes log request failed (HTTP ${status})${detail ? `: ${detail.slice(0, 512)}` : ""}`,
              status === 408 || status === 429 || status >= 500,
            );
          }
          return response;
        },
      );
      for await (const chunk of response)
        yield new Uint8Array(chunk);
    } catch (error) {
      if (!signal.aborted)
        throw error instanceof KubernetesLogError ? error : logError(error);
    }
  }
}