/**
 * Selfbot live-stream backend (default).
 *
 * Streams the VNC X display (:1) into the voice channel as a real Discord
 * "Go Live" broadcast. Discord blocks video from *bot* accounts, so this path
 * requires a USER account token (a "selfbot"), which violates Discord ToS and
 * can get the account banned. Use a throwaway/burner account, never your main.
 *
 * Dependencies are optional (native) and dynamically imported so the core bot
 * installs/runs without them:
 *   bun add discord.js-selfbot-v13 @dank074/discord-video-stream
 *   bun pm trust @dank074/node-av node-datachannel   # build native deps
 *
 * API targets @dank074/discord-video-stream v6 (verified against its d.ts):
 *   new Streamer(client) -> joinVoice(guildId, channelId)
 *   prepareStream(input, opts, signal) -> { command, output }
 *   playStream(output, streamer, { type: "go-live" }, signal)
 */
import { spawn, type ChildProcess } from "node:child_process";
import type { AppConfig } from "../config.ts";
import type { ScreenStreamer, StreamContext } from "./index.ts";
import { VncKeepalive, resolveVncPassword, vncPortForDisplay } from "./vnc-keepalive.ts";

export class SelfbotStreamer implements ScreenStreamer {
  readonly kind = "selfbot" as const;
  private streamer: any = null;
  private capture: ChildProcess | null = null;
  private keepalive: VncKeepalive | null = null;
  private controller: AbortController | null = null;
  private active = false;

  constructor(private config: AppConfig) {}

  isActive() {
    return this.active;
  }

  /**
   * Wait a randomised, human-plausible amount of time. Resolves immediately if
   * the stream is aborted (stop()) mid-wait, so teardown never hangs on a pause.
   */
  private humanPause(minMs: number, maxMs: number, signal?: AbortSignal): Promise<void> {
    const ms = Math.floor(minMs + Math.random() * Math.max(0, maxMs - minMs));
    return new Promise((resolve) => {
      if (signal?.aborted) return resolve();
      const onAbort = () => {
        clearTimeout(timer);
        resolve();
      };
      const timer = setTimeout(() => {
        signal?.removeEventListener("abort", onAbort);
        resolve();
      }, ms);
      signal?.addEventListener("abort", onAbort, { once: true });
    });
  }

  private async loadLib() {
    let selfbot: any, vs: any;
    try {
      selfbot = await import("discord.js-selfbot-v13");
      // Optional native dep; resolved at runtime only.
      // @ts-ignore - optional dependency, may be absent until `bun add`ed
      vs = await import("@dank074/discord-video-stream");
    } catch (e) {
      throw new Error(
        "셀프봇 송출 의존성이 없습니다. 설치: bun add discord.js-selfbot-v13 @dank074/discord-video-stream\n" +
          `원본 오류: ${(e as Error).message}`,
      );
    }
    if (!vs.Streamer || !vs.prepareStream || !vs.playStream) {
      throw new Error(
        "@dank074/discord-video-stream v6 API(Streamer/prepareStream/playStream)를 찾지 못했습니다. " +
          "package.json 버전을 ^6.0.0으로 맞추세요.",
      );
    }
    return { selfbot, vs };
  }

  async start(ctx: StreamContext): Promise<string> {
    if (this.active) return "이미 송출 중입니다.";
    if (!this.config.selfbotToken) {
      return "DISCORD_SELFBOT_TOKEN이 설정되지 않았습니다 (.env). 버너 계정 토큰을 넣어주세요.";
    }
    if (!ctx.voiceChannelId) {
      return "셀프봇 송출은 음성 채널 안에서 호출해야 합니다.";
    }
    // Lock the starting state BEFORE any await: the human-pause delays below
    // mean start() is in-flight for several seconds, so a second /stream call
    // must be rejected by the `this.active` guard above, and the status must
    // read "starting" rather than idle during the wait. Keep controller /
    // streamer / capture as LOCAL refs so an interleaved stop() (which nulls the
    // instance fields) can't turn our own continuation into a null dereference.
    this.active = true;
    const controller = (this.controller = new AbortController());
    const signal = controller.signal;
    let streamer: any = null;
    let capture: ChildProcess | null = null;
    let keepalive: VncKeepalive | null = null;

    try {
      const { selfbot, vs } = await this.loadLib();
      const { Streamer, prepareStream, playStream } = vs;
      signal.throwIfAborted();

      streamer = this.streamer = new Streamer(new selfbot.Client());
      await streamer.client.login(this.config.selfbotToken);
      signal.throwIfAborted();

      // Act like a person, not a bot: take a breath after coming online before
      // navigating into the voice channel, then settle in for a few seconds
      // before hitting "Go Live". Randomised so the cadence isn't
      // fingerprintable. throwIfAborted() after each pause unwinds into the
      // catch below if stop() lands mid-wait, so we never join/go-live on a
      // torn-down streamer.
      await this.humanPause(2500, 4500, signal);
      signal.throwIfAborted();
      await streamer.joinVoice(ctx.guildId, ctx.voiceChannelId);
      await this.humanPause(6000, 10000, signal);
      signal.throwIfAborted();

      const [w, h] = this.config.vncResolution.split("x").map((n) => parseInt(n, 10));

      // Capture the VNC X display with the SYSTEM ffmpeg (which reliably has
      // x11grab), then pipe that stream into the library. Relying on the lib's
      // bundled libav for the x11grab input device is not portable; piping the
      // system ffmpeg is. (Verified live against a real voice channel.)
      //
      // The SYSTEM ffmpeg produces the final, Discord-ready H264 in one pass:
      // target bitrate (-b:v/-maxrate), no B-frames (WebRTC requires this), a
      // 1s keyframe interval, and yuv420p. The library then only REMUXES it
      // (noTranscoding below) so there is no second decode/scale/encode. With
      // streamHw on (default) this single encode runs on the GPU (h264_nvenc,
      // RTX 5050); otherwise it falls back to software x264.
      const hw = this.config.streamHw;
      const kbps = this.config.vncBitrateKbps;
      // The library advertises a hardcoded max_bitrate of 10 Mbps to Discord
      // (BaseMediaConnection: `max_bitrate: 10000 * 1000`). If the encoder bursts
      // above that negotiated ceiling, WebRTC congestion control drops packets
      // and the viewer sees stutter. Cap -maxrate at 10 Mbps to stay within it.
      const LIB_MAX_BITRATE_KBPS = 10000;
      const maxKbps = Math.min(Math.round(kbps * 1.5), LIB_MAX_BITRATE_KBPS);
      const captureCodecArgs = hw
        ? ["-c:v", "h264_nvenc", "-preset", "p4", "-tune", "ll", "-forced-idr", "1"]
        : ["-c:v", "libx264", "-preset", "ultrafast", "-tune", "zerolatency"];
      // Optionally pull desktop audio (the default sink's PipeWire/Pulse monitor)
      // so the broadcast has sound. We add it as a second input and mux AAC into
      // the mpegts; the library re-encodes it to Opus for Discord. ffmpeg needs
      // XDG_RUNTIME_DIR (inherited) to reach the pulse socket. -map is required
      // once there are two inputs.
      const audioOn = this.config.streamAudio;
      const audioInput = audioOn ? ["-f", "pulse", "-i", this.config.streamAudioSource] : [];
      const audioMap = audioOn ? ["-map", "0:v:0", "-map", "1:a:0"] : [];
      const audioCodec = audioOn ? ["-c:a", "aac", "-b:a", "160k", "-ar", "48000", "-ac", "2"] : [];
      capture = this.capture = spawn("ffmpeg", [
        "-loglevel", "error",
        "-thread_queue_size", "1024",
        "-f", "x11grab",
        "-framerate", String(this.config.vncFramerate),
        "-video_size", this.config.vncResolution,
        "-i", this.config.vncDisplay,
        ...(audioOn ? ["-thread_queue_size", "1024"] : []),
        ...audioInput,
        ...audioMap,
        ...captureCodecArgs,
        "-b:v", `${kbps}k`, "-maxrate", `${maxKbps}k`, "-bufsize", `${kbps}k`,
        "-bf", "0",
        "-pix_fmt", "yuv420p",
        "-g", String(this.config.vncFramerate),
        ...audioCodec,
        "-f", "mpegts", "pipe:1",
      ]);
      capture.stderr?.on("data", (d) => {
        if (!signal.aborted) console.error("[selfbot x11grab]", d.toString().trim());
      });

      // Keep a VNC client attached for the life of the stream. TigerVNC only
      // flushes its framebuffer at full rate while a client pulls updates; the
      // Discord broadcast reads that framebuffer with x11grab (not as a VNC
      // client), so without this the captured screen would idle at ~1.5 fps and
      // the stream would look badly choppy. Fail-open: a missing password just
      // skips it. Matched to the stream framerate so motion stays smooth.
      const vncPw = resolveVncPassword();
      if (vncPw) {
        keepalive = this.keepalive = new VncKeepalive({
          host: "127.0.0.1",
          port: vncPortForDisplay(this.config.vncDisplay),
          password: vncPw,
          fps: this.config.vncFramerate,
        });
        keepalive.start();
      }

      const { command, output } = prepareStream(
        capture.stdout,
        {
          // The capture above is already a Discord-ready H264 elementary stream,
          // so the library only remuxes it (no second encode). width/height/
          // frameRate are passed for signalling; encoding options are ignored
          // on the copy path.
          width: w || 1920,
          height: h || 1080,
          frameRate: this.config.vncFramerate,
          videoCodec: "H264",
          noTranscoding: true,
        },
        signal,
      );
      command.on("error", (err: Error) => {
        if (!signal.aborted) console.error("[selfbot] ffmpeg error:", err);
      });
      signal.throwIfAborted();

      playStream(output, streamer, { type: "go-live" }, signal)
        .catch((err: Error) => {
          if (!signal.aborted) console.error("[selfbot] playStream:", err);
        })
        .finally(() => {
          // The stream ended on its own (Discord closed the Go-Live, the voice
          // UDP dropped, or ffmpeg exited) rather than via stop(). If we are
          // still the current attempt, tear the pipeline DOWN: kill the capture
          // ffmpeg and leave voice. Otherwise the x11grab->nvenc encoder keeps
          // running forever feeding a pipe nobody reads, pinning a CPU core
          // while no media is actually transmitted. Skip if a concurrent
          // stop()/start() already replaced the controller (it owns teardown).
          if (this.controller !== controller) return;
          try {
            capture?.kill("SIGKILL");
          } catch {
            /* ignore */
          }
          try {
            keepalive?.stop();
          } catch {
            /* ignore */
          }
          try {
            streamer?.leaveVoice?.();
            streamer?.client?.destroy?.();
          } catch {
            /* ignore */
          }
          if (this.capture === capture) this.capture = null;
          if (this.keepalive === keepalive) this.keepalive = null;
          if (this.streamer === streamer) this.streamer = null;
          this.controller = null;
          this.active = false;
        });

      return "🔴 셀프봇으로 VNC 화면을 음성채널에 실시간 송출 중입니다 (Go Live).";
    } catch (e) {
      // Startup was aborted (stop() during a pause) or failed. Tear down using
      // our LOCAL refs, then clear instance state only if it still points at us
      // (a concurrent stop()/start() may already have replaced it).
      try {
        capture?.kill("SIGKILL");
      } catch {
        /* ignore */
      }
      try {
        keepalive?.stop();
      } catch {
        /* ignore */
      }
      try {
        streamer?.leaveVoice?.();
        streamer?.client?.destroy?.();
      } catch {
        /* ignore */
      }
      // Only release the lock / clear instance state if WE are still the
      // current attempt. If a concurrent stop()+start() already replaced the
      // controller, a newer start() owns `active` — clearing it here would
      // unlock it mid-startup and let a third start() race in.
      if (this.controller === controller) {
        if (this.capture === capture) this.capture = null;
        if (this.keepalive === keepalive) this.keepalive = null;
        if (this.streamer === streamer) this.streamer = null;
        this.controller = null;
        this.active = false;
      }
      if (signal.aborted) return "송출을 시작하는 중에 중지했습니다.";
      throw e;
    }
  }

  async stop(): Promise<void> {
    this.controller?.abort();
    this.controller = null;
    try {
      this.capture?.kill("SIGKILL");
    } catch {
      /* ignore */
    }
    this.capture = null;
    try {
      this.keepalive?.stop();
    } catch {
      /* ignore */
    }
    this.keepalive = null;
    try {
      this.streamer?.leaveVoice?.();
      this.streamer?.client?.destroy?.();
    } catch {
      /* ignore */
    }
    this.streamer = null;
    this.active = false;
  }
}