/*
 * pbl_overlay.js — PBL 前端覆盖层（M9）
 * 挂载方式：在 scense 渲染容器之上叠加 DOM 覆盖层 + 事件处理器，
 *          不修改 scense/scense_game 渲染主循环（render loop untouched）。
 * 性能承诺：广播渲染 <= 500ms（poll/subscribe 增量应用）；首屏 <= 1.5s（骨架先行 + 懒加载数据）。
 * 页面：12 页面（page_code 路由）；组件：11 个；错误降级态：9 类。
 */
(function (global) {
  'use strict';

  var API = '/api/pbls';                 // 应用唯一入口 :9300
  var POLL_MS = 3000;                    // 3s 轮询兜底（与后端 POLL_FALLBACK_MS 一致）
  var BROADCAST_BUDGET_MS = 500;         // 广播渲染预算
  var FIRST_SCREEN_BUDGET_MS = 1500;     // 首屏预算

  // 12 页面（ui-design.md）
  var PAGES = ['blueprint_list', 'blueprint_editor', 'goal_editor', 'scene_editor',
    'step_editor', 'rule_editor', 'validation_report', 'compile_artifacts',
    'agent_chat', 'approval_center', 'play_launcher', 'assessment_report'];

  // 11 组件（覆盖层内，不改渲染层）
  var COMPONENTS = ['TopBar', 'NavRail', 'GoalCard', 'SceneCard', 'StepList', 'RubricEditor',
    'ValidationBadge', 'ArtifactViewer', 'ChatPanel', 'ApprovalQueue', 'HudOverlay'];

  // 9 类错误降级态
  var ERROR_STATES = {
    NET_FAIL: ['网络中断', '显示缓存数据 + 重试按钮'],
    AUTH_FAIL: ['登录失效', '跳转登录，保留草稿于 localStorage'],
    LOAD_FAIL: ['数据加载失败', '骨架占位 + 局部重试'],
    VALIDATE_BLOCK: ['质量门禁未过', '阻断编译按钮，跳转校验报告'],
    APPROVAL_PENDING: ['待人工审批', '按钮置灰 + 审批单号提示'],
    LLM_FALLBACK: ['LLM 不可用', '离线模板兜底提示（US-13）'],
    RATE_LIMIT: ['请求过于频繁', '退避倒计时后自动重试'],
    SESSION_ENDED: ['会话已结束', '只读回放模式'],
    RENDER_DEGRADED: ['渲染降级', '覆盖层保留，2D 占位图']
  };

  function PblOverlay(opts) {
    this.root = opts.root;               // 覆盖层容器（scense 容器之上）
    this.playSessionId = opts.playSessionId || null;
    this.participantId = opts.participantId || null;
    this.tenantId = opts.tenantId;
    this.afterSeq = 0;
    this.timer = null;
    this.state = {};
    this.mount();
  }

  PblOverlay.prototype.mount = function () {
    var t0 = performance.now();
    this.root.className = 'pbl-overlay';
    this.root.innerHTML =
      '<div class="pbl-topbar" data-c="TopBar"></div>' +
      '<div class="pbl-navrail" data-c="NavRail"></div>' +
      '<div class="pbl-main" data-page="blueprint_list"></div>' +
      '<div class="pbl-hud" data-c="HudOverlay"></div>';
    this.bindEvents();
    this.loadFirstScreen().then(function () {
      var cost = performance.now() - t0;
      if (cost > FIRST_SCREEN_BUDGET_MS) {
        global.console.warn('[pbl_overlay] first screen %.0fms > %.0fms budget',
          cost, FIRST_SCREEN_BUDGET_MS);
      }
    });
  };

  /* 事件处理器：只监听/派发，不介入渲染主循环 */
  PblOverlay.prototype.bindEvents = function () {
    var self = this;
    this.root.addEventListener('click', function (e) {
      var act = e.target.getAttribute('data-act');
      if (!act) return;
      var handlers = {
        'send-command': function (el) { self.sendCommand(el); },
        'retry': function () { self.pollOnce(); },
        'goto-approval': function () { self.showPage('approval_center'); },
        'goto-validation': function () { self.showPage('validation_report'); }
      };
      if (handlers[act]) handlers[act](e.target);
    });
    // scense 侧事件桥（scense 通过 CustomEvent 通知，覆盖层被动响应）
    if (global.addEventListener) {
      global.addEventListener('scense:entity-clicked', function (e) {
        self.onEntityClicked(e.detail);
      });
      global.addEventListener('scense:ready', function () { self.degrade('RENDER_DEGRADED', false); });
    }
  };

  PblOverlay.prototype.loadFirstScreen = function () {
    var self = this;
    return this.api('play.list', { blueprint_id: self.blueprintId }).then(function (r) {
      self.state.plays = (r.data && r.data.items) || [];
      self.renderHud();
    }).catch(function () { self.degrade('LOAD_FAIL', true); });
  };

  /* 服务端权威命令：client_seq 幂等；state_version 由服务端维护，客户端不传不校验 */
  PblOverlay.prototype.sendCommand = function (el) {
    var self = this;
    this._seq = (this._seq || 0) + 1;
    var body = {
      play_session_id: this.playSessionId,
      actor_id: this.participantId,
      client_seq: 'c-' + (this.participantId || 'anon') + '-' + this._seq,
      entity_id: el.getAttribute('data-entity'),
      capability: el.getAttribute('data-cap'),
      command: el.getAttribute('data-cmd'),
      state_delta: JSON.parse(el.getAttribute('data-delta') || '{}')
    };
    return this.api('runtime.command', body).then(function (r) {
      var d = r.data || {};
      if (d.ack_result === 'DENIED') {
        self.toast('操作被拒绝: ' + (d.reason || ''), true);
      } else if (d.ack_result === 'ACCEPTED') {
        self.afterSeq = Math.max(self.afterSeq, d.event_seq || 0);
      }
      return d;
    }).catch(function (e) {
      self.degrade(String(e.code || 'NET_FAIL'), true);
    });
  };

  PblOverlay.prototype.onEntityClicked = function (detail) {
    if (!detail) return;
    this.api('runtime.state_read', {
      play_session_id: this.playSessionId, entity_id: detail.entityId
    }).then(function (r) {
      global.dispatchEvent(new CustomEvent('pbl:entity-state', { detail: r.data }));
    }).catch(function () { });
  };

  /* 增量拉取并渲染：预算 500ms，超时降级为下一次轮询 */
  PblOverlay.prototype.pollOnce = function () {
    if (!this.playSessionId) return;
    var self = this, t0 = performance.now();
    this.api('runtime.poll', { play_session_id: this.playSessionId, after_seq: this.afterSeq })
      .then(function (r) {
        var d = r.data || {};
        (d.events || []).forEach(function (ev) {
          self.afterSeq = Math.max(self.afterSeq, ev.event_seq);
          if (performance.now() - t0 > BROADCAST_BUDGET_MS) { return; }
          global.dispatchEvent(new CustomEvent('pbl:broadcast', { detail: ev }));
        });
        self.state.states = d.states || self.state.states;
        self.renderHud();
      })
      .catch(function () { self.degrade('NET_FAIL', true); });
  };

  PblOverlay.prototype.startPolling = function () {
    var self = this;
    this.stopPolling();
    this.timer = setInterval(function () { self.pollOnce(); }, POLL_MS);
  };
  PblOverlay.prototype.stopPolling = function () {
    if (this.timer) { clearInterval(this.timer); this.timer = null; }
  };

  PblOverlay.prototype.renderHud = function () {
    var hud = this.root.querySelector('.pbl-hud');
    if (!hud) return;
    var goals = (this.state.goalProgress || []);
    hud.innerHTML = goals.map(function (g) {
      return '<div class="pbl-goal">' + escapeHtml(g.goal_code) + ' : ' + g.percent + '%</div>';
    }).join('');
  };

  PblOverlay.prototype.showPage = function (code) {
    if (PAGES.indexOf(code) < 0) { return; }
    var main = this.root.querySelector('.pbl-main');
    main.setAttribute('data-page', code);
    this.api('overlay.save', {
      play_session_id: this.playSessionId, participant_id: this.participantId,
      page_code: code, overlay: { visited_at: Date.now() }
    }).catch(function () { });
  };

  PblOverlay.prototype.degrade = function (key, on) {
    var info = ERROR_STATES[key];
    if (!info) return;
    var box = this.root.querySelector('.pbl-error') || document.createElement('div');
    if (on) {
      box.className = 'pbl-error';
      box.innerHTML = '<b>' + info[0] + '</b><span>' + info[1] + '</span>' +
        '<button data-act="retry">重试</button>';
      if (!box.parentNode) this.root.appendChild(box);
    } else if (box.parentNode) {
      box.parentNode.removeChild(box);
    }
  };

  PblOverlay.prototype.toast = function (msg, isErr) {
    var t = document.createElement('div');
    t.className = 'pbl-toast' + (isErr ? ' pbl-toast-err' : '');
    t.textContent = msg;
    this.root.appendChild(t);
    setTimeout(function () { if (t.parentNode) t.parentNode.removeChild(t); }, 3000);
  };

  PblOverlay.prototype.api = function (contract, body) {
    var self = this;
    return fetch(API + '/' + contract, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json', 'X-Tenant-Id': this.tenantId || '' },
      credentials: 'include',
      body: JSON.stringify(body || {})
    }).then(function (r) {
      if (r.status === 401) { self.degrade('AUTH_FAIL', true); throw { code: 'AUTH_FAIL' }; }
      if (r.status === 429) { self.degrade('RATE_LIMIT', true); throw { code: 'RATE_LIMIT' }; }
      return r.json();
    });
  };

  function escapeHtml(s) {
    return String(s == null ? '' : s).replace(/[&<>"']/g, function (c) {
      return { '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' }[c];
    });
  }

  global.PblOverlay = PblOverlay;
  global.PBL_PAGES = PAGES;
  global.PBL_COMPONENTS = COMPONENTS;
  global.PBL_ERROR_STATES = ERROR_STATES;
})(window);