/**
 * Call — the hub entity in the hub model.
 *
 * A Call owns N legs and bridges their media. For 2-party calls, RTP packets
 * from leg A are forwarded to leg B and vice versa. For N>2 party calls,
 * packets from each leg are forwarded to all other legs (fan-out).
 *
 * Transcoding is applied per-leg when codecs differ.
 */

import { Buffer } from 'node:buffer';
import type { ILeg } from './leg.ts';
import type { TCallState, TCallDirection, ICallStatus } from './types.ts';
import { RtpPortPool } from './rtp-port-pool.ts';
import type { SipLeg } from './sip-leg.ts';

export class Call {
  readonly id: string;
  state: TCallState = 'setting-up';
  direction: TCallDirection;
  readonly createdAt: number;

  callerNumber: string | null = null;
  calleeNumber: string | null = null;
  providerUsed: string | null = null;

  /** All legs in this call. */
  private legs = new Map<string, ILeg>();

  /** Codec payload type for the "native" audio in the call (usually the first SIP leg's codec). */
  private nativeCodec: number | null = null;

  /** Port pool reference for cleanup. */
  private portPool: RtpPortPool;
  private log: (msg: string) => void;
  private onChange: ((call: Call) => void) | null = null;

  constructor(options: {
    id: string;
    direction: TCallDirection;
    portPool: RtpPortPool;
    log: (msg: string) => void;
    onChange?: (call: Call) => void;
  }) {
    this.id = options.id;
    this.direction = options.direction;
    this.createdAt = Date.now();
    this.portPool = options.portPool;
    this.log = options.log;
    this.onChange = options.onChange ?? null;
  }

  // -------------------------------------------------------------------------
  // Leg management
  // -------------------------------------------------------------------------

  /** Add a leg to this call and wire up media forwarding. */
  addLeg(leg: ILeg): void {
    this.legs.set(leg.id, leg);

    // Wire up RTP forwarding: when this leg receives a packet, forward to all other legs.
    leg.onRtpReceived = (data: Buffer) => {
      this.forwardRtp(leg.id, data);
    };

    this.log(`[call:${this.id}] added leg ${leg.id} (${leg.type}), total=${this.legs.size}`);
    this.updateState();
  }

  /** Remove a leg from this call, tear it down, and release its port. */
  removeLeg(legId: string): void {
    const leg = this.legs.get(legId);
    if (!leg) return;

    leg.onRtpReceived = null;
    leg.teardown();
    if (leg.rtpPort) {
      this.portPool.release(leg.rtpPort);
    }
    this.legs.delete(legId);

    this.log(`[call:${this.id}] removed leg ${legId}, total=${this.legs.size}`);
    this.updateState();
  }

  getLeg(legId: string): ILeg | null {
    return this.legs.get(legId) ?? null;
  }

  getLegs(): ILeg[] {
    return [...this.legs.values()];
  }

  getLegByType(type: string): ILeg | null {
    for (const leg of this.legs.values()) {
      if (leg.type === type) return leg;
    }
    return null;
  }

  getLegBySipCallId(sipCallId: string): ILeg | null {
    for (const leg of this.legs.values()) {
      if (leg.sipCallId === sipCallId) return leg;
    }
    return null;
  }

  get legCount(): number {
    return this.legs.size;
  }

  // -------------------------------------------------------------------------
  // Media forwarding (the hub)
  // -------------------------------------------------------------------------

  private forwardRtp(fromLegId: string, data: Buffer): void {
    for (const [id, leg] of this.legs) {
      if (id === fromLegId) continue;
      if (leg.state !== 'connected') continue;

      // For WebRTC legs, sendRtp calls forwardToBrowser which handles transcoding internally.
      // For SIP legs, forward the raw packet (same codec path) or let the leg handle it.
      // The Call hub does NOT transcode — that's the leg's responsibility.
      leg.sendRtp(data);
    }
  }

  // -------------------------------------------------------------------------
  // State management
  // -------------------------------------------------------------------------

  private updateState(): void {
    if (this.state === 'terminated' || this.state === 'terminating') return;

    const legs = [...this.legs.values()];
    if (legs.length === 0) {
      this.state = 'terminated';
    } else if (legs.every((l) => l.state === 'terminated')) {
      this.state = 'terminated';
    } else if (legs.some((l) => l.state === 'connected') && legs.filter((l) => l.state !== 'terminated').length >= 2) {
      // If a system leg is connected, report voicemail/ivr state for the dashboard.
      const systemLeg = legs.find((l) => l.type === 'system');
      if (systemLeg) {
        // Keep voicemail/ivr state if already set; otherwise set connected.
        if (this.state !== 'voicemail' && this.state !== 'ivr') {
          this.state = 'connected';
        }
      } else {
        this.state = 'connected';
      }
    } else if (legs.some((l) => l.state === 'ringing')) {
      this.state = 'ringing';
    } else {
      this.state = 'setting-up';
    }

    this.onChange?.(this);
  }

  /** Notify the call that a leg's state has changed. */
  notifyLegStateChange(_leg: ILeg): void {
    this.updateState();
  }

  // -------------------------------------------------------------------------
  // Hangup
  // -------------------------------------------------------------------------

  /** Tear down all legs and terminate the call. */
  hangup(): void {
    if (this.state === 'terminated' || this.state === 'terminating') return;
    this.state = 'terminating';
    this.log(`[call:${this.id}] hanging up (${this.legs.size} legs)`);

    for (const [id, leg] of this.legs) {
      // Send BYE/CANCEL for SIP legs (system legs have no SIP signaling).
      if (leg.type === 'sip-device' || leg.type === 'sip-provider') {
        (leg as SipLeg).sendHangup();
      }
      leg.teardown();
      if (leg.rtpPort) {
        this.portPool.release(leg.rtpPort);
      }
    }
    this.legs.clear();

    this.state = 'terminated';
    this.onChange?.(this);
  }

  /**
   * Handle a BYE from one leg — tear down the other legs.
   * Called by CallManager when a SipLeg receives a BYE.
   */
  handleLegTerminated(terminatedLegId: string): void {
    const terminatedLeg = this.legs.get(terminatedLegId);
    if (!terminatedLeg) return;

    // Remove the terminated leg.
    terminatedLeg.onRtpReceived = null;
    if (terminatedLeg.rtpPort) {
      this.portPool.release(terminatedLeg.rtpPort);
    }
    this.legs.delete(terminatedLegId);

    // If this is a 2-party call, hang up the other leg too.
    if (this.legs.size <= 1) {
      for (const [id, leg] of this.legs) {
        // Send BYE/CANCEL for SIP legs (system legs just get torn down).
        if (leg.type === 'sip-device' || leg.type === 'sip-provider') {
          (leg as SipLeg).sendHangup();
        }
        leg.teardown();
        if (leg.rtpPort) {
          this.portPool.release(leg.rtpPort);
        }
      }
      this.legs.clear();
      this.state = 'terminated';
      this.log(`[call:${this.id}] terminated`);
      this.onChange?.(this);
    } else {
      this.log(`[call:${this.id}] leg ${terminatedLegId} removed, ${this.legs.size} remaining`);
      this.updateState();
    }
  }

  // -------------------------------------------------------------------------
  // Transfer
  // -------------------------------------------------------------------------

  /**
   * Detach a leg from this call (without tearing it down).
   * The leg can then be added to another call.
   */
  detachLeg(legId: string): ILeg | null {
    const leg = this.legs.get(legId);
    if (!leg) return null;

    leg.onRtpReceived = null;
    this.legs.delete(legId);

    this.log(`[call:${this.id}] detached leg ${legId}`);
    this.updateState();
    return leg;
  }

  // -------------------------------------------------------------------------
  // Status
  // -------------------------------------------------------------------------

  getStatus(): ICallStatus {
    return {
      id: this.id,
      state: this.state,
      direction: this.direction,
      callerNumber: this.callerNumber,
      calleeNumber: this.calleeNumber,
      providerUsed: this.providerUsed,
      createdAt: this.createdAt,
      duration: Math.floor((Date.now() - this.createdAt) / 1000),
      legs: [...this.legs.values()].map((l) => l.getStatus()),
    };
  }
}