/*
Copyright 2026 Lotus Guild

SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
Please see LICENSE in the repository root for full details.
*/

import {
  ConnectionQuality,
  type LocalAudioTrack,
  type LocalTrackPublication,
  type Participant,
  ParticipantEvent,
  type RemoteAudioTrack,
  type RemoteParticipant,
  type Room as LivekitRoom,
  RoomEvent,
  Track,
  type TrackPublication,
} from "livekit-client";

import { type CallViewModel } from "../state/CallViewModel/CallViewModel";
import { widget } from "../widget";
import { LotusWidgetActions } from "./lotusActions";
import { lotusSendToHost } from "./lotusWidget";

export type CallQualityVerdict = "good" | "fair" | "poor" | "unknown";

export interface CallSummary {
  /** Wall-clock time connected to the SFU, ms. */
  durationMs: number;
  /** LiveKit reconnect attempts during the call. */
  reconnects: number;
  /** Time the local connection quality was reported poor/lost, ms. */
  poorMs: number;
  verdict: CallQualityVerdict;
  /** [cinny #253] The breakdown behind the host's "Details" card. */
  details?: CallSummaryDetails;
}

/** [cinny #253] Everything the host's post-call Details card shows. */
export interface CallSummaryDetails {
  /** Other Matrix users seen in the call (`@user:server`), first-seen order. */
  participants: string[];
  /** Most people in the call at once, you included. */
  peakParticipants: number;
  quality: {
    /** Your connection reported poor/lost, ms. */
    youPoorMs: number;
    /** Each other person's connection reported poor/lost, ms (only > 0). */
    othersPoorMs: Record<string, number>;
    /** Everyone, you included, poor at the same time (points at the server). */
    everyonePoorMs: number;
  };
  network: {
    rttMedianMs?: number;
    rttP95Ms?: number;
    /** Your microphone's packets the SFU reported lost, %. */
    outboundLossPct?: number;
    /** Packets lost on the audio you received, %. */
    inboundLossPct?: number;
    jitterMs?: number;
  };
  activity: { speakingMs: number; mutedMs: number; screenshareMs: number };
}

/** Time spent in an on/off state, e.g. muted. */
class Stopwatch {
  private since: number | undefined;

  private total = 0;

  public set(on: boolean, now: number): void {
    if (on && this.since === undefined) this.since = now;
    if (!on && this.since !== undefined) {
      this.total += now - this.since;
      this.since = undefined;
    }
  }

  public get on(): boolean {
    return this.since !== undefined;
  }

  public ms(now: number): number {
    return this.total + (this.since === undefined ? 0 : now - this.since);
  }
}

/** `@user:server:DEVICE` (a LiveKit identity) → `@user:server`. */
export function matrixUserOf(identity: string): string {
  if (!identity.startsWith("@")) return identity;
  const first = identity.indexOf(":");
  const second = first === -1 ? -1 : identity.indexOf(":", first + 1);
  return second === -1 ? identity : identity.slice(0, second);
}

const percentile = (sorted: number[], p: number): number =>
  sorted[Math.min(sorted.length - 1, Math.floor(p * sorted.length))];

/**
 * [cinny #253] Who was in the call, whose connection was poor and when,
 * network numbers, and your own activity. Fed by LiveKit events and periodic
 * stats samples; nothing leaves the frame except the final summary, sent to
 * the host only.
 */
export class CallDetailsTracker {
  // user -> identities (devices) currently in the call
  private readonly devices = new Map<string, Set<string>>();

  private readonly seen: string[] = [];

  private peak = 1;

  private readonly poor = new Map<string, Stopwatch>();

  private readonly youPoor = new Stopwatch();

  private readonly everyonePoor = new Stopwatch();

  private readonly rtts: number[] = [];

  private readonly jitters: number[] = [];

  private readonly sent = new Map<string, { packets: number; lost: number }>();

  private readonly received = new Map<
    string,
    { packets: number; lost: number }
  >();

  private readonly speaking = new Stopwatch();

  private readonly muted = new Stopwatch();

  private readonly sharing = new Stopwatch();

  public constructor(private readonly now: () => number = () => Date.now()) {}

  /** Idempotent per device: safe to call for everyone already present too. */
  public remoteJoined(identity: string): void {
    const user = matrixUserOf(identity);
    let ids = this.devices.get(user);
    if (!ids) this.devices.set(user, (ids = new Set()));
    ids.add(identity);
    if (!this.seen.includes(user)) this.seen.push(user);
    this.peak = Math.max(this.peak, this.devices.size + 1);
    this.updateEveryone();
  }

  public remoteLeft(identity: string): void {
    const user = matrixUserOf(identity);
    const ids = this.devices.get(user);
    ids?.delete(identity);
    if (!ids || ids.size === 0) {
      this.devices.delete(user);
      this.poor.get(user)?.set(false, this.now());
    }
    this.updateEveryone();
  }

  /** `identity` undefined = the local participant. */
  public setQuality(
    identity: string | undefined,
    quality: ConnectionQuality,
  ): void {
    if (quality === ConnectionQuality.Unknown) return;
    const bad =
      quality === ConnectionQuality.Poor || quality === ConnectionQuality.Lost;
    if (identity === undefined) this.youPoor.set(bad, this.now());
    else {
      const user = matrixUserOf(identity);
      let sw = this.poor.get(user);
      if (!sw) this.poor.set(user, (sw = new Stopwatch()));
      sw.set(bad, this.now());
    }
    this.updateEveryone();
  }

  private updateEveryone(): void {
    const others = [...this.devices.keys()];
    const all =
      this.youPoor.on &&
      others.length > 0 &&
      others.every((u) => this.poor.get(u)?.on);
    this.everyonePoor.set(all, this.now());
  }

  public addRtt(seconds: number | undefined): void {
    if (typeof seconds === "number" && Number.isFinite(seconds) && seconds >= 0)
      this.rtts.push(seconds * 1000);
  }

  public addJitter(seconds: number | undefined): void {
    if (typeof seconds === "number" && Number.isFinite(seconds) && seconds >= 0)
      this.jitters.push(seconds * 1000);
  }

  /** Cumulative counters for one sent/received track (latest value wins). */
  public setSent(key: string, packets?: number, lost?: number): void {
    if (typeof packets === "number")
      this.sent.set(key, { packets, lost: Math.max(0, lost ?? 0) });
  }

  public setReceived(key: string, packets?: number, lost?: number): void {
    if (typeof packets === "number")
      this.received.set(key, { packets, lost: Math.max(0, lost ?? 0) });
  }

  public setSpeaking(on: boolean): void {
    this.speaking.set(on, this.now());
  }

  public setMuted(on: boolean): void {
    this.muted.set(on, this.now());
  }

  public setScreensharing(on: boolean): void {
    this.sharing.set(on, this.now());
  }

  public details(): CallSummaryDetails {
    const now = this.now();
    const othersPoorMs: Record<string, number> = {};
    for (const [user, sw] of this.poor) {
      const ms = sw.ms(now);
      if (ms > 0) othersPoorMs[user] = ms;
    }
    const lossPct = (
      m: Map<string, { packets: number; lost: number }>,
    ): number | undefined => {
      let packets = 0;
      let lost = 0;
      for (const v of m.values()) {
        packets += v.packets;
        lost += v.lost;
      }
      return packets + lost > 0
        ? Math.round((lost / (packets + lost)) * 1000) / 10
        : undefined;
    };
    const rtts = [...this.rtts].sort((a, b) => a - b);
    const network: CallSummaryDetails["network"] = {};
    if (rtts.length) {
      network.rttMedianMs = Math.round(percentile(rtts, 0.5));
      network.rttP95Ms = Math.round(percentile(rtts, 0.95));
    }
    const out = lossPct(this.sent);
    if (out !== undefined) network.outboundLossPct = out;
    const inn = lossPct(this.received);
    if (inn !== undefined) network.inboundLossPct = inn;
    if (this.jitters.length)
      network.jitterMs = Math.round(
        this.jitters.reduce((a, b) => a + b, 0) / this.jitters.length,
      );
    return {
      participants: [...this.seen],
      peakParticipants: this.peak,
      quality: {
        youPoorMs: this.youPoor.ms(now),
        othersPoorMs,
        everyonePoorMs: this.everyonePoor.ms(now),
      },
      network,
      activity: {
        speakingMs: this.speaking.ms(now),
        mutedMs: this.muted.ms(now),
        screenshareMs: this.sharing.ms(now),
      },
    };
  }
}

/**
 * [Gitea #143] Per-call connection quality, kept in memory for the local
 * participant only and summarised once at hangup. Nothing is stored or sent
 * anywhere but to the host at the end.
 */
export class CallQualityTracker {
  private startedAt: number | undefined;

  private poorSince: number | undefined;

  private poorMs = 0;

  private reconnects = 0;

  private sampled = false;

  public constructor(private readonly now: () => number = () => Date.now()) {}

  public start(): void {
    if (this.startedAt === undefined) this.startedAt = this.now();
  }

  public setQuality(quality: ConnectionQuality): void {
    if (quality === ConnectionQuality.Unknown) return;
    this.sampled = true;
    const bad =
      quality === ConnectionQuality.Poor || quality === ConnectionQuality.Lost;
    if (bad && this.poorSince === undefined) this.poorSince = this.now();
    if (!bad && this.poorSince !== undefined) {
      this.poorMs += this.now() - this.poorSince;
      this.poorSince = undefined;
    }
  }

  public reconnect(): void {
    this.reconnects += 1;
  }

  public summary(): CallSummary {
    const end = this.now();
    const durationMs =
      this.startedAt === undefined ? 0 : Math.max(0, end - this.startedAt);
    const poorMs =
      this.poorMs + (this.poorSince === undefined ? 0 : end - this.poorSince);
    let verdict: CallQualityVerdict = "unknown";
    if (this.sampled && durationMs > 0) {
      const poorShare = poorMs / durationMs;
      if (poorShare < 0.05 && this.reconnects <= 1) verdict = "good";
      else if (poorShare < 0.25 && this.reconnects <= 3) verdict = "fair";
      else verdict = "poor";
    }
    return { durationMs, reconnects: this.reconnects, poorMs, verdict };
  }
}

/**
 * Track the local participant's LiveKit connection quality and reconnects
 * for the life of the in-call view, and send `io.lotus.call_summary` to the
 * host once — on the first SFU disconnect or on teardown, whichever comes
 * first — so the host can show "41 min · connection was good" at hangup.
 */
export function startLotusCallSummary(vm: CallViewModel): () => void {
  if (!widget) return () => undefined;
  const tracker = new CallQualityTracker();
  const details = new CallDetailsTracker();
  let sent = false;
  const send = (): void => {
    if (sent) return;
    sent = true;
    clearInterval(sampler);
    lotusSendToHost(LotusWidgetActions.CallSummary, {
      ...tracker.summary(),
      details: details.details(),
    });
  };

  // [cinny #253] Network numbers: sample sender/receiver stats every 5 s.
  const sample = async (room: LivekitRoom): Promise<void> => {
    const mic = room.localParticipant.getTrackPublication(
      Track.Source.Microphone,
    )?.track as LocalAudioTrack | undefined;
    const s = await mic?.getSenderStats?.().catch(() => undefined);
    if (s) {
      details.addRtt(s.roundTripTime);
      details.setSent(`${room.name}:mic`, s.packetsSent, s.packetsLost);
    }
    for (const p of room.remoteParticipants.values()) {
      for (const pub of p.audioTrackPublications.values()) {
        const t = pub.track as RemoteAudioTrack | undefined;
        const r = await t?.getReceiverStats?.().catch(() => undefined);
        if (r) {
          details.addJitter(r.jitter);
          details.setReceived(
            `${room.name}:${p.identity}:${pub.trackSid}`,
            r.packetsReceived,
            r.packetsLost,
          );
        }
      }
    }
  };
  const sampler = setInterval(() => {
    for (const room of listeners.keys())
      void sample(room).catch(() => undefined);
  }, 5_000);

  const listeners = new Map<LivekitRoom, () => void>();
  const attach = (room: LivekitRoom): void => {
    const onQuality = (
      quality: ConnectionQuality,
      participant: Participant,
    ): void => {
      if (participant.isLocal) tracker.setQuality(quality);
      details.setQuality(
        participant.isLocal ? undefined : participant.identity,
        quality,
      );
    };
    // LiveKit doesn't send ParticipantConnected for people already in the
    // room when we connect, and the mic isn't published yet at attach time:
    // record both once the connection is up.
    const onConnected = (): void => {
      tracker.start();
      for (const p of room.remoteParticipants.values())
        details.remoteJoined(p.identity);
      details.setMuted(!room.localParticipant.isMicrophoneEnabled);
    };
    const onReconnecting = (): void => tracker.reconnect();
    const onDisconnected = (): void => send();
    const onJoined = (p: RemoteParticipant): void =>
      details.remoteJoined(p.identity);
    const onLeft = (p: RemoteParticipant): void =>
      details.remoteLeft(p.identity);
    const isLocalMic = (pub: TrackPublication, p: Participant): boolean =>
      p.isLocal && pub.source === Track.Source.Microphone;
    const onMuted = (pub: TrackPublication, p: Participant): void => {
      if (isLocalMic(pub, p)) details.setMuted(true);
    };
    const onUnmuted = (pub: TrackPublication, p: Participant): void => {
      if (isLocalMic(pub, p)) details.setMuted(false);
    };
    const onLocalPublished = (pub: LocalTrackPublication): void => {
      if (pub.source === Track.Source.ScreenShare)
        details.setScreensharing(true);
      if (pub.source === Track.Source.Microphone) details.setMuted(pub.isMuted);
    };
    const onLocalUnpublished = (pub: LocalTrackPublication): void => {
      if (pub.source === Track.Source.ScreenShare)
        details.setScreensharing(false);
    };
    const onSpeaking = (speaking: boolean): void =>
      details.setSpeaking(speaking);
    room.on(RoomEvent.ConnectionQualityChanged, onQuality);
    room.on(RoomEvent.Connected, onConnected);
    room.on(RoomEvent.Reconnecting, onReconnecting);
    room.on(RoomEvent.Disconnected, onDisconnected);
    room.on(RoomEvent.ParticipantConnected, onJoined);
    room.on(RoomEvent.ParticipantDisconnected, onLeft);
    room.on(RoomEvent.TrackMuted, onMuted);
    room.on(RoomEvent.TrackUnmuted, onUnmuted);
    room.on(RoomEvent.LocalTrackPublished, onLocalPublished);
    room.on(RoomEvent.LocalTrackUnpublished, onLocalUnpublished);
    room.localParticipant.on(ParticipantEvent.IsSpeakingChanged, onSpeaking);
    if (room.state === "connected") onConnected();
    listeners.set(room, () => {
      room.off(RoomEvent.ConnectionQualityChanged, onQuality);
      room.off(RoomEvent.Connected, onConnected);
      room.off(RoomEvent.Reconnecting, onReconnecting);
      room.off(RoomEvent.Disconnected, onDisconnected);
      room.off(RoomEvent.ParticipantConnected, onJoined);
      room.off(RoomEvent.ParticipantDisconnected, onLeft);
      room.off(RoomEvent.TrackMuted, onMuted);
      room.off(RoomEvent.TrackUnmuted, onUnmuted);
      room.off(RoomEvent.LocalTrackPublished, onLocalPublished);
      room.off(RoomEvent.LocalTrackUnpublished, onLocalUnpublished);
      room.localParticipant.off(ParticipantEvent.IsSpeakingChanged, onSpeaking);
    });
  };

  const sub = vm.allConnections$.subscribe((data) => {
    const next = data.getConnections().map((c) => c.livekitRoom);
    for (const [room, off] of listeners) {
      if (!next.includes(room)) {
        off();
        listeners.delete(room);
      }
    }
    for (const room of next) if (!listeners.has(room)) attach(room);
  });

  return () => {
    sub.unsubscribe();
    for (const off of listeners.values()) off();
    listeners.clear();
    send();
  };
}