/* ===== Language Tutor ===== */
(function () {
  "use strict";

  const LANG_VOICE = {
    hindi:"hi-IN", tamil:"ta-IN", telugu:"te-IN", bengali:"bn-IN",
    marathi:"mr-IN", gujarati:"gu-IN", kannada:"kn-IN", malayalam:"ml-IN",
    english:"en-US", spanish:"es-ES", french:"fr-FR", japanese:"ja-JP",
  };

  // ===== State =====
  const S = {
    step:1, targetLang:null, instructionLang:null, level:null,
    teacherId:null, topic:null, sessionId:null,
    isMuted:false, isRecording:false, mediaRecorder:null, audioChunks:[],
    xp:0, curriculum:null, teachers:null,
  };

  // ===== Speech (Browser TTS) =====
  const Speech = {
    speaking:false, queue:[],
    speak(text){
      if(S.isMuted||!text) return;
      const clean = text
        .replace(/\[CULTURAL NOTE:.*?\]/gs,"")
        .replace(/\[DIALOGUE\].*?\[\/DIALOGUE\]/gs,"")
        .replace(/\[SENTENCE_BUILDER:.*?\]/gs,"")
        .replace(/\*\*/g,"").replace(/\*/g,"")
        .replace(/\[.*?\]/g,"").trim();
      if(!clean) return;
      this.queue.push(clean);
      if(!this.speaking) this._next();
    },
    _next(){
      if(!this.queue.length){ this.speaking=false; Avatar.setIdle(); return; }
      this.speaking=true; Avatar.setSpeaking();
      const text=this.queue.shift();
      const u=new SpeechSynthesisUtterance(text);
      const code=LANG_VOICE[S.targetLang]||"en-US";
      const v=speechSynthesis.getVoices().find(v=>v.lang===code||v.lang.startsWith(code.split("-")[0]));
      if(v) u.voice=v;
      u.lang=code; u.rate=0.9;
      u.onend=()=>this._next();
      u.onerror=()=>this._next();
      speechSynthesis.speak(u);
    },
    stop(){ this.queue=[]; speechSynthesis.cancel(); this.speaking=false; Avatar.setIdle(); }
  };

  // ===== Avatar =====
  const Avatar = {
    blinkTimer:null,
    load(id,color){
      const c=document.getElementById("avatarContainer");
      c.innerHTML=`<img src="/static/svg/teacher-${id}.svg" alt="${id}" style="width:100%;height:100%">`;
      document.getElementById("avatarName").textContent=id[0].toUpperCase()+id.slice(1);
      document.getElementById("avatarName").style.color=color;
      document.documentElement.style.setProperty("--teacher-color",color);
      this._blink();
    },
    setSpeaking(){ document.getElementById("avatarContainer").classList.add("speaking"); },
    setIdle(){ document.getElementById("avatarContainer").classList.remove("speaking"); },
    _blink(){
      if(this.blinkTimer) clearInterval(this.blinkTimer);
      this.blinkTimer=setInterval(()=>{
        try{
          const svg=document.getElementById("avatarContainer").querySelector("svg");
          if(!svg) return;
          const eyes=svg.querySelector("#eyes");
          if(!eyes) return;
          eyes.style.transform="scaleY(0.1)";
          setTimeout(()=>{ eyes.style.transform="scaleY(1)"; },150);
        }catch(e){}
      },3500+Math.random()*2000);
    }
  };

  // ===== API =====
  async function api(url,opts={}){
    try{ const r=await fetch(url,opts); if(!r.ok) throw new Error(`HTTP ${r.status}`); return await r.json(); }
    catch(e){ console.error("API:",e); return {error:e.message}; }
  }

  // ===== Onboarding =====
  function goStep(n){
    S.step=n;
    document.querySelectorAll(".ob-step").forEach(el=>el.classList.remove("active"));
    document.getElementById("step"+n).classList.add("active");

    // progress bar
    document.getElementById("progressBar").style.width=(n*20)+"%";

    // step labels
    document.querySelectorAll(".ob-step-label").forEach((lbl,i)=>{
      lbl.classList.remove("active","done");
      if(i+1===n) lbl.classList.add("active");
      else if(i+1<n) lbl.classList.add("done");
    });

    // back button
    const bb=document.getElementById("btnStepBack");
    if(n>1) bb.classList.add("visible"); else bb.classList.remove("visible");
  }

  function renderLangs(containerId, onSelect, preselect){
    const c=document.getElementById(containerId);
    c.innerHTML="";
    if(!S.curriculum) return;
    for(const[key,lang] of Object.entries(S.curriculum.languages)){
      const d=document.createElement("div");
      d.className="lang-card"+(key===preselect?" selected":"");
      d.innerHTML=`<span class="lc-flag">${lang.flag}</span><span class="lc-name">${lang.name}</span><span class="lc-native">${lang.native_name}</span>`;
      d.onclick=()=>{
        c.querySelectorAll(".lang-card").forEach(x=>x.classList.remove("selected"));
        d.classList.add("selected");
        onSelect(key);
      };
      c.appendChild(d);
    }
  }

  function renderLevels(){
    const c=document.getElementById("levelCards");
    c.innerHTML="";
    if(!S.curriculum) return;
    for(const[key,lv] of Object.entries(S.curriculum.levels)){
      const d=document.createElement("div");
      d.className="level-card";
      d.innerHTML=`<h3>${lv.name}</h3><p>${lv.description}</p>`;
      d.onclick=()=>{
        c.querySelectorAll(".level-card").forEach(x=>x.classList.remove("selected"));
        d.classList.add("selected");
        S.level=key;
        setTimeout(()=>{ renderTeachers(); goStep(4); },250);
      };
      c.appendChild(d);
    }
  }

  function renderTeachers(){
    const c=document.getElementById("teacherCards");
    c.innerHTML="";
    if(!S.teachers||!S.teachers.length){ c.innerHTML='<p style="color:rgba(255,255,255,.5);text-align:center">Loading teachers...</p>'; return; }
    for(const t of S.teachers){
      const d=document.createElement("div");
      d.className="teacher-card";
      d.innerHTML=`
        <div class="tc-avatar" style="background:${t.color_light}">
          <img src="/static/svg/${t.avatar}" alt="${t.name}">
        </div>
        <div class="tc-info">
          <div class="tc-name">${t.name}</div>
          <div class="tc-title" style="color:${t.color}">${t.title}</div>
          <div class="tc-style">${t.style}</div>
          <div class="tc-desc">${t.description}</div>
          <button class="btn-voice" data-tid="${t.id}">&#9654; Preview voice</button>
        </div>`;
      d.onclick=(e)=>{
        if(e.target.closest(".btn-voice")) return;
        c.querySelectorAll(".teacher-card").forEach(x=>x.classList.remove("selected"));
        d.classList.add("selected");
        S.teacherId=t.id;
        document.documentElement.style.setProperty("--teacher-color",t.color);
        document.documentElement.style.setProperty("--teacher-light",t.color_light);
        setTimeout(()=>{ renderTopics(); goStep(5); },250);
      };
      c.appendChild(d);
    }
    // voice previews
    c.querySelectorAll(".btn-voice").forEach(btn=>{
      btn.onclick=async(e)=>{
        e.stopPropagation();
        btn.textContent="Playing...";
        const d=await api("/api/teacher/voice-sample",{
          method:"POST",headers:{"Content-Type":"application/json"},
          body:JSON.stringify({teacher_id:btn.dataset.tid,target_lang:S.targetLang})
        });
        btn.innerHTML="&#9654; Preview voice";
        if(d.text){
          const u=new SpeechSynthesisUtterance(d.text);
          const code=LANG_VOICE[S.targetLang]||"en-US";
          const v=speechSynthesis.getVoices().find(v=>v.lang===code||v.lang.startsWith(code.split("-")[0]));
          if(v) u.voice=v; u.lang=code; u.rate=0.9;
          speechSynthesis.speak(u);
        }
      };
    });
  }

  function renderTopics(){
    const c=document.getElementById("topicGrid");
    c.innerHTML="";
    if(!S.curriculum||!S.level) return;
    const topics=S.curriculum.curriculum[S.level]||[];
    for(const t of topics){
      const d=document.createElement("div");
      d.className="topic-card";
      d.innerHTML=`<span class="tc-icon">${t.icon}</span><span class="tc-label">${t.title}</span><span class="tc-sub">${t.description}</span>`;
      d.onclick=()=>{
        c.querySelectorAll(".topic-card").forEach(x=>x.classList.remove("selected"));
        d.classList.add("selected");
        S.topic=t.id;
        document.getElementById("btnStart").disabled=false;
      };
      c.appendChild(d);
    }
  }

  // ===== Lesson =====
  async function startLesson(){
    const btn=document.getElementById("btnStart");
    btn.disabled=true; btn.querySelector("span").textContent="Starting...";

    const data=await api("/api/session/start",{
      method:"POST",headers:{"Content-Type":"application/json"},
      body:JSON.stringify({
        target_lang:S.targetLang, instruction_lang:S.instructionLang,
        level:S.level, topic:S.topic, teacher_id:S.teacherId
      })
    });

    if(data.error){
      btn.querySelector("span").textContent="Start Lesson"; btn.disabled=false;
      alert("Failed: "+data.error); return;
    }

    S.sessionId=data.session_id;
    document.getElementById("onboarding").classList.add("hidden");
    document.getElementById("lesson").classList.remove("hidden");

    const langName=S.curriculum?.languages[S.targetLang]?.name||S.targetLang;
    const topicInfo=(S.curriculum?.curriculum[S.level]||[]).find(t=>t.id===S.topic);
    document.getElementById("lessonLang").textContent=langName;
    document.getElementById("lessonTopic").textContent=topicInfo?.title||S.topic;

    const teacher=S.teachers?.find(t=>t.id===S.teacherId)||{color:"#6C63FF"};
    Avatar.load(S.teacherId,teacher.color);

    addMsg("tutor",data.greeting);
    Speech.speak(data.greeting);
    document.getElementById("inputMessage").focus();
  }

  // ===== Chat =====
  function addMsg(role,text){
    const c=document.getElementById("chatMessages");
    const d=document.createElement("div");
    d.className="msg "+role;
    d.innerHTML=fmtMsg(text);
    c.appendChild(d);
    renderSpecial(d,text);
    scrollBottom();
  }

  function fmtMsg(t){
    let h=t.replace(/&/g,"&amp;").replace(/</g,"&lt;").replace(/>/g,"&gt;");
    h=h.replace(/\*\*(.+?)\*\*/g,"<strong>$1</strong>");
    h=h.replace(/\*(.+?)\*/g,"<em>$1</em>");
    h=h.replace(/\n/g,"<br>");
    h=h.replace(/\[CULTURAL NOTE:\s*(.*?)\]/gs,'<div class="cultural-note"><div class="cultural-note-title">Cultural Insight</div>$1</div>');
    h=h.replace(/\[DIALOGUE\](.*?)\[\/DIALOGUE\]/gs,'<div class="dialogue-block">$1</div>');
    return h;
  }

  function renderSpecial(el,text){
    const m=text.match(/\[SENTENCE_BUILDER:\s*(.*?)\]/);
    if(!m) return;
    const words=m[1].split("|").map(w=>w.trim());
    const shuffled=[...words].sort(()=>Math.random()-.5);
    const correct=words.join(" ");
    const blk=document.createElement("div");
    blk.className="sentence-builder";
    blk.innerHTML=`
      <div class="sentence-builder-title">Arrange the words correctly:</div>
      <div class="word-tiles">${shuffled.map(w=>`<span class="word-tile" data-w="${esc(w)}">${w}</span>`).join("")}</div>
      <div class="sentence-drop-zone" data-correct="${esc(correct)}"></div>
      <div class="sentence-builder-actions"><button class="btn-check-sentence">Check</button><button class="btn-reset-sentence">Reset</button></div>`;
    el.appendChild(blk);

    const tiles=blk.querySelectorAll(".word-tile");
    const zone=blk.querySelector(".sentence-drop-zone");
    tiles.forEach(tile=>{
      tile.onclick=()=>{
        if(tile.classList.contains("placed")) return;
        tile.classList.add("placed");
        const p=document.createElement("span");
        p.className="placed-word"; p.textContent=tile.dataset.w;
        p.onclick=()=>{ p.remove(); tile.classList.remove("placed"); };
        zone.appendChild(p);
      };
    });
    blk.querySelector(".btn-check-sentence").onclick=()=>{
      const user=Array.from(zone.querySelectorAll(".placed-word")).map(e=>e.textContent).join(" ");
      if(user===correct){ zone.style.borderColor="var(--success)"; zone.style.background="#F0FDF4"; S.xp+=10; updateXP(); }
      else{ zone.style.borderColor="var(--danger)"; zone.style.background="#FEF2F2"; }
    };
    blk.querySelector(".btn-reset-sentence").onclick=()=>{
      zone.innerHTML=""; zone.style.borderColor=""; zone.style.background="";
      tiles.forEach(t=>t.classList.remove("placed"));
    };
  }

  function esc(s){ return s.replace(/"/g,"&quot;").replace(/'/g,"&#39;"); }

  function showTyping(){
    const c=document.getElementById("chatMessages");
    const d=document.createElement("div");
    d.className="typing-indicator"; d.id="typingIndicator";
    d.innerHTML='<span class="typing-dot"></span><span class="typing-dot"></span><span class="typing-dot"></span>';
    c.appendChild(d); scrollBottom();
  }
  function hideTyping(){ const e=document.getElementById("typingIndicator"); if(e) e.remove(); }
  function scrollBottom(){ const a=document.getElementById("chatArea"); requestAnimationFrame(()=>{ a.scrollTop=a.scrollHeight; }); }
  function updateXP(){ document.getElementById("xpBadge").querySelector("span").textContent=S.xp+" XP"; }

  async function sendMessage(){
    const inp=document.getElementById("inputMessage");
    const text=inp.value.trim();
    if(!text||!S.sessionId) return;
    inp.value="";
    addMsg("student",text);
    showTyping();
    const data=await api("/api/chat",{
      method:"POST",headers:{"Content-Type":"application/json"},
      body:JSON.stringify({session_id:S.sessionId,message:text})
    });
    hideTyping();
    if(data.error){ addMsg("tutor","Sorry, something went wrong. Please try again."); return; }
    addMsg("tutor",data.reply);
    if(data.xp){ S.xp=data.xp; updateXP(); }
    Speech.speak(data.reply);
  }

  // ===== Voice Input =====
  async function toggleMic(){
    if(S.isRecording){
      if(S.mediaRecorder) S.mediaRecorder.stop();
      S.isRecording=false;
      document.getElementById("btnMic").classList.remove("recording");
      return;
    }
    try{
      const stream=await navigator.mediaDevices.getUserMedia({audio:true});
      S.audioChunks=[];
      S.mediaRecorder=new MediaRecorder(stream);
      S.mediaRecorder.ondataavailable=e=>{ if(e.data.size>0) S.audioChunks.push(e.data); };
      S.mediaRecorder.onstop=async()=>{
        stream.getTracks().forEach(t=>t.stop());
        const blob=new Blob(S.audioChunks,{type:"audio/webm"});
        showTyping();
        const form=new FormData();
        form.append("session_id",S.sessionId);
        form.append("audio",blob,"audio.webm");
        const data=await api("/api/voice",{method:"POST",body:form});
        hideTyping();
        if(data.transcribed) addMsg("student",data.transcribed);
        if(data.reply){ addMsg("tutor",data.reply); Speech.speak(data.reply); }
        if(data.xp){ S.xp=data.xp; updateXP(); }
      };
      S.mediaRecorder.start();
      S.isRecording=true;
      document.getElementById("btnMic").classList.add("recording");
    }catch(e){ console.error("Mic:",e); }
  }

  // ===== Events =====
  function bind(){
    document.getElementById("btnSend").onclick=sendMessage;
    document.getElementById("inputMessage").onkeydown=e=>{
      if(e.key==="Enter"&&!e.shiftKey){ e.preventDefault(); sendMessage(); }
    };
    document.getElementById("btnMic").onclick=toggleMic;
    document.getElementById("btnMute").onclick=()=>{
      S.isMuted=!S.isMuted;
      document.getElementById("iconSpeaker").classList.toggle("hidden",S.isMuted);
      document.getElementById("iconMuted").classList.toggle("hidden",!S.isMuted);
      if(S.isMuted) Speech.stop();
    };
    document.getElementById("btnBack").onclick=()=>{
      Speech.stop(); S.sessionId=null;
      document.getElementById("chatMessages").innerHTML="";
      document.getElementById("lesson").classList.add("hidden");
      document.getElementById("onboarding").classList.remove("hidden");
      document.getElementById("btnStart").querySelector("span").textContent="Start Lesson";
      document.getElementById("btnStart").disabled=true;
      document.querySelectorAll("#topicGrid .topic-card").forEach(c=>c.classList.remove("selected"));
    };
    document.getElementById("btnStart").onclick=startLesson;

    // Step back button
    document.getElementById("btnStepBack").onclick=()=>{
      if(S.step>1) goStep(S.step-1);
    };

    // Preload voices
    if(window.speechSynthesis){
      speechSynthesis.getVoices();
      speechSynthesis.onvoiceschanged=()=>speechSynthesis.getVoices();
    }
  }

  // ===== Init =====
  async function init(){
    bind();
    const[curr,teach]=await Promise.all([
      api("/api/curriculum"),
      api("/api/teachers")
    ]);
    if(!curr.error) S.curriculum=curr;
    if(!teach.error) S.teachers=teach.teachers;

    // Step 1: target language
    renderLangs("targetLangGrid",(key)=>{
      S.targetLang=key;
      setTimeout(()=>{
        renderLangs("instructionLangGrid",(k)=>{
          S.instructionLang=k;
          setTimeout(()=>{ renderLevels(); goStep(3); },250);
        },"english");
        goStep(2);
      },250);
    });
  }

  document.addEventListener("DOMContentLoaded",init);
})();