/**
 * GeoGraSim V2 — TelemetryClient
 *
 * ESM-Bibliothek für V2-Module. Übernimmt:
 *   - URL-Parameter-Parsing (session_token, mode, difficulty, lang …)
 *   - Profil-Abruf (/api/student/me)
 *   - Runtime-Config (/api/runtime-config)
 *   - Heartbeat-Loop mit Plattform-Frequenz (clamped 10–30s default)
 *   - Stuck-Detection (Default 90s, aus runtime-config)
 *   - Milestone- und Accessibility-Blocker-Events
 *   - State-Save (/api/module/state PUT)
 *   - Result-POST am Ende
 *   - Tab-Close via navigator.sendBeacon
 *   - Mock-Erkennung (?mock=1 in URL)
 *
 * Token-Refresh: Stub vorhanden, echte Implementation folgt mit V2-Login.
 * Bei 401 → Lib redirected zu /v2beta/ (Login).
 *
 * Verwendung im Modul (siehe v2-modules/hallo-welt/public/game.html):
 *
 *   import { TelemetryClient } from '../../../v2-platform/lib/telemetry-client.js';
 *
 *   const tc = new TelemetryClient({
 *     moduleSlug: 'hallo-welt',
 *     moduleVersion: '1.0.0',
 *     specVersion: '1.0',
 *   });
 *   await tc.init();
 *
 *   tc.setPhase('welcome', 'Begrüßung');
 *   tc.milestone('welcome-shown', 'Begrüßung gesehen', 1);
 *   tc.updateScore(score, 100);
 *
 *   await tc.complete({
 *     completed: true,
 *     lehrplanCoverage: { 'AT-GW-1.4.2': 'full' },
 *   });
 */

export class TelemetryClient {
  /**
   * @param {object} options
   * @param {string} options.moduleSlug   — z.B. "hallo-welt"
   * @param {string} options.moduleVersion — z.B. "1.0.0"
   * @param {string} options.specVersion   — z.B. "1.0"
   * @param {number} [options.heartbeatPreferenceS=15] — Modul-Wunsch, wird auf runtime-config-Grenzen geclampt
   * @param {(profile:object) => void} [options.onProfileLoaded]
   * @param {(err:Error) => void} [options.onError]
   * @param {(reason:string) => void} [options.onTokenExpired] — wenn null, default: redirect zu /v2beta/
   * @param {(info:{idleS:number,phase:string}) => void} [options.onStuck] — UI-Hook: Banner einblenden
   * @param {() => void} [options.onUnstuck] — UI-Hook: Banner ausblenden, wenn wieder Aktivität
   */
  constructor(options) {
    if (!options?.moduleSlug || !options?.moduleVersion || !options?.specVersion) {
      throw new Error('TelemetryClient: moduleSlug, moduleVersion, specVersion sind Pflicht.');
    }
    this.opts = {
      heartbeatPreferenceS: 15,
      ...options,
    };

    // URL-Parameter parsen
    const params = new URLSearchParams(location.search);
    this.session = {
      sessionToken: params.get('session_token') || '',
      studentId:   parseInt(params.get('student_id') || '0', 10),
      classId:     parseInt(params.get('class_id')   || '0', 10),
      mode:        params.get('mode')       || 'free',
      difficulty:  params.get('difficulty') || 'L1',
      lang:        params.get('lang')       || 'de-AT-standard',
      resume:      params.get('resume')     === '1',
      isMock:      params.get('mock')       === '1',
    };

    if (!this.session.sessionToken) {
      throw new Error('TelemetryClient: kein session_token in URL.');
    }

    // API-Base: Mock oder Echt
    // Pfad: von v2-modules/<slug>/public/game.html drei Ebenen hoch nach Repo-Root
    this.apiBase = this.session.isMock
      ? '../../../v2-platform/mock/api'
      : '../../../v2-platform/php/api';

    // Runtime-State
    this.profile = null;
    this.config = null;
    this.phase = null;
    this.phaseLabel = null;
    this.step = null;
    this.score = 0;
    this.scoreMax = 0;
    this.startTs = Date.now();
    this.phaseStartTs = Date.now();
    this.lastActivityTs = Date.now();
    this._heartbeatTimer = null;
    this._stuckTimer = null;
    this._stuckActive = false;
    this._activityHandlers = null;
    this._destroyed = false;
  }

  // ─── INIT ──────────────────────────────────────────────────────────

  async init() {
    // 1) runtime-config holen
    this.config = await this._fetch('runtime-config.php', { method: 'GET' });

    // 2) Profil holen
    const profileRes = await this._fetch('student/me.php', { method: 'GET' });
    this.profile = profileRes;
    this.opts.onProfileLoaded?.(profileRes);

    // 3) Activity-Tracking starten
    this._activityHandlers = {
      activity: () => { this.lastActivityTs = Date.now(); this._clearStuck(); },
      visibility: () => {
        if (document.visibilityState === 'visible') {
          this.lastActivityTs = Date.now();
        }
      },
    };
    ['click', 'touchstart', 'keydown'].forEach(e =>
      document.addEventListener(e, this._activityHandlers.activity, { passive: true })
    );
    document.addEventListener('visibilitychange', this._activityHandlers.visibility);

    // 4) Tab-Close-Beacon registrieren
    addEventListener('beforeunload', () => this._sendFinalBeacon());

    // 5) Heartbeat-Loop starten
    this._startHeartbeat();

    // 6) Stuck-Check starten
    this._startStuckChecker();

    return this;
  }

  // ─── PHASE / SCORE ─────────────────────────────────────────────────

  setPhase(phase, phaseLabel = null, step = null) {
    this.phase = phase;
    this.phaseLabel = phaseLabel || phase;
    this.step = step;
    this.phaseStartTs = Date.now();
    this.lastActivityTs = Date.now();
    this._clearStuck();
    // sofort Heartbeat senden, damit Lehrperson den Wechsel sieht
    this._sendHeartbeat();
  }

  updateScore(score, scoreMax = null) {
    this.score = score;
    if (scoreMax !== null) this.scoreMax = scoreMax;
  }

  // ─── EVENTS ────────────────────────────────────────────────────────

  /**
   * Milestone emittieren.
   * @param {string} id     — muss in manifest.telemetryMilestones deklariert sein
   * @param {string} label  — sichtbarer Text
   * @param {number} [scoreDelta=0]
   */
  milestone(id, label, scoreDelta = 0) {
    this.score += scoreDelta;
    return this._post('telemetry.php', {
      type: 'milestone',
      milestoneId: id,
      milestoneLabel: label,
      scoreDelta,
      currentScore: this.score,
      phase: this.phase,
    });
  }

  /**
   * Accessibility-Blocker — wenn Modul für aktuelle Schüler*in nicht weiterspielbar ist.
   * @param {object} info
   * @param {'visual-required'|'audio-required'|'mouse-required'|'motor-required'} info.blockerType
   * @param {string} info.hint
   */
  accessibilityBlocker({ blockerType, hint }) {
    return this._post('telemetry.php', {
      type: 'accessibility-blocker',
      blockerType,
      hint,
      phase: this.phase,
      phaseLabel: this.phaseLabel,
    });
  }

  // ─── STATE (Resume-Daten) ──────────────────────────────────────────

  async saveState(state, summary = '') {
    return this._post('module/state.php', {
      moduleSlug: this.opts.moduleSlug,
      state,
      summary,
    }, 'PUT');
  }

  // ─── ABSCHLUSS ─────────────────────────────────────────────────────

  /**
   * Ergebnis bei Modul-Abschluss senden + Cleanup.
   * Modul ruft das EINMAL pro Sitzung, danach destroy().
   */
  async complete(result) {
    const body = {
      moduleSlug: this.opts.moduleSlug,
      moduleVersion: this.opts.moduleVersion,
      specVersion: this.opts.specVersion,
      completed: true,
      abandoned: false,
      score: this.score,
      scoreMax: this.scoreMax || 100,
      durationS: this.elapsedTotalS(),
      difficulty: this.session.difficulty,
      mode: this.session.mode,
      milestonesReached: [],
      lehrplanCoverage: {},
      ts: new Date().toISOString(),
      ...result,
    };
    const res = await this._post('result.php', body);
    return res;
  }

  /**
   * Cleanup: Timer stoppen, Event-Listener entfernen.
   * Wird von complete() / exit() automatisch aufgerufen.
   */
  destroy() {
    if (this._destroyed) return;
    this._destroyed = true;
    if (this._heartbeatTimer) clearInterval(this._heartbeatTimer);
    if (this._stuckTimer)     clearInterval(this._stuckTimer);
    if (this._activityHandlers) {
      ['click', 'touchstart', 'keydown'].forEach(e =>
        document.removeEventListener(e, this._activityHandlers.activity)
      );
      document.removeEventListener('visibilitychange', this._activityHandlers.visibility);
    }
  }

  /**
   * Modul-Abbruch (z.B. User klickt ✕).
   */
  exit(reason = 'user-exit') {
    this._post('telemetry.php', {
      type: 'milestone',
      milestoneId: 'module-aborted',
      milestoneLabel: `Modul abgebrochen (${reason})`,
      phase: this.phase,
    });
    this.destroy();
  }

  // ─── UTILS für Modul-Code ──────────────────────────────────────────

  elapsedTotalS() { return Math.floor((Date.now() - this.startTs) / 1000); }
  elapsedPhaseS() { return Math.floor((Date.now() - this.phaseStartTs) / 1000); }

  // ─── INTERN ────────────────────────────────────────────────────────

  _startHeartbeat() {
    const min = this.config?.heartbeat?.minIntervalS || 10;
    const max = this.config?.heartbeat?.maxIntervalS || 30;
    const clamped = Math.min(max, Math.max(min, this.opts.heartbeatPreferenceS));
    this._heartbeatTimer = setInterval(() => {
      // Bei Inaktivität > 60s nichts senden (User wahrscheinlich AFK)
      if (Date.now() - this.lastActivityTs > 60_000) return;
      this._sendHeartbeat();
    }, clamped * 1000);
    // Initial-Heartbeat
    setTimeout(() => this._sendHeartbeat(), 100);
  }

  _sendHeartbeat() {
    return this._post('telemetry.php', {
      type: 'heartbeat',
      phase: this.phase || 'init',
      phaseLabel: this.phaseLabel || 'Initialisierung',
      step: this.step,
      currentScore: this.score || undefined,
      scoreMax: this.scoreMax || undefined,
      timeInPhaseS: this.elapsedPhaseS(),
      totalTimeS: this.elapsedTotalS(),
    });
  }

  _startStuckChecker() {
    const threshold = this.config?.stuck?.thresholdS || 90;
    this._stuckTimer = setInterval(() => {
      if (this._stuckActive) return;
      if (document.visibilityState !== 'visible') return;
      const idleS = Math.floor((Date.now() - this.lastActivityTs) / 1000);
      if (idleS >= threshold) {
        this._stuckActive = true;
        const info = { idleS, phase: this.phase };
        this._post('telemetry.php', {
          type: 'stuck',
          phase: this.phase,
          phaseLabel: this.phaseLabel,
          step: this.step,
          idleS,
          hint: `Inaktiv in Phase '${this.phase}' seit ${idleS}s`,
        });
        this.opts.onStuck?.(info);
      }
    }, 10_000);
  }

  _clearStuck() {
    if (this._stuckActive) {
      this._stuckActive = false;
      this.opts.onUnstuck?.();
    }
  }

  // ─── HTTP ──────────────────────────────────────────────────────────

  async _fetch(endpoint, opts = {}) {
    const url = `${this.apiBase}/${endpoint}`;
    const res = await fetch(url, {
      method: opts.method || 'GET',
      headers: {
        Authorization: `Bearer ${this.session.sessionToken}`,
        ...(opts.body ? { 'Content-Type': 'application/json' } : {}),
      },
      body: opts.body ? JSON.stringify(opts.body) : undefined,
    });
    if (res.status === 401) {
      this._handleTokenExpired('401-on-' + endpoint);
      throw new Error(`401 Unauthorized auf ${endpoint}`);
    }
    if (!res.ok) {
      const err = new Error(`HTTP ${res.status} auf ${endpoint}`);
      this.opts.onError?.(err);
      throw err;
    }
    return res.json();
  }

  /**
   * Telemetry-Post mit milder Fehlertoleranz (silent retry max 1×, dann verwerfen).
   */
  async _post(endpoint, body, method = 'POST') {
    const full = {
      moduleSlug: this.opts.moduleSlug,
      moduleVersion: this.opts.moduleVersion,
      ts: new Date().toISOString(),
      ...body,
    };
    try {
      return await this._fetch(endpoint, { method, body: full });
    } catch (e) {
      // Telemetry blockiert Modul nicht — Fehler still verschluckt
      return null;
    }
  }

  _handleTokenExpired(reason) {
    if (this.opts.onTokenExpired) {
      this.opts.onTokenExpired(reason);
    } else {
      // Default: zurück zur V2-Login-Seite
      // Aber: nur wenn nicht in iframe (Mock-Test-Harness lädt im iframe)
      if (window.parent === window) {
        location.href = '/v2beta/';
      } else {
        console.warn(`[TelemetryClient] Token expired (${reason}). Im iframe — kein Auto-Redirect.`);
      }
    }
  }

  _sendFinalBeacon() {
    if (!navigator.sendBeacon || this._destroyed) return;
    const body = JSON.stringify({
      type: 'heartbeat',
      moduleSlug: this.opts.moduleSlug,
      moduleVersion: this.opts.moduleVersion,
      phase: 'tab-closed',
      phaseLabel: 'Tab geschlossen',
      currentScore: this.score || undefined,
      scoreMax: this.scoreMax || undefined,
      timeInPhaseS: this.elapsedPhaseS(),
      totalTimeS: this.elapsedTotalS(),
      ts: new Date().toISOString(),
    });
    navigator.sendBeacon(
      `${this.apiBase}/telemetry.php?session_token=${encodeURIComponent(this.session.sessionToken)}`,
      new Blob([body], { type: 'application/json' })
    );
  }
}