/**
 * rag.js — 智能问答页(RAG + SSE 流式)
 */

const RagPage = {
  state: {
    question: '', template: 'simple', answer: '', citations: [], streaming: false, error: null,
    thinking: '',          // thinking 内容
    thinkingEnabled: true, // thinking 开关(从 API 加载)
  },

  render() {
    const templates = [
      { value: 'simple', label: '通俗解释' },
      { value: 'professional', label: '专业分析' },
      { value: 'compare', label: '对比条文' },
    ];
    return `
      <div class="p-4 md:p-6 max-w-4xl mx-auto">
        <h2 class="text-lg font-semibold mb-4">智能问答</h2>

        <!-- 输入区 -->
        <div class="bg-white rounded-xl border border-gray-200 p-4 mb-4">
          <textarea id="rag-input" rows="3" placeholder="输入你的问题,如:个人信息保护法对敏感个人信息有什么规定?"
            class="w-full rounded-lg border border-gray-200 px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-gray-900 resize-none"
            maxlength="1000" oninput="RagPage.onInput()">${this.state.question}</textarea>
          <div class="flex items-center justify-between mt-3">
            <div class="flex gap-2">
              ${templates.map(t => `
                <button onclick="RagPage.setTemplate('${t.value}')"
                  class="px-3 py-1.5 text-xs rounded-lg ${this.state.template === t.value ? 'bg-gray-900 text-white' : 'bg-gray-100 text-gray-600 hover:bg-gray-200'}">
                  ${t.label}
                </button>`).join('')}
            </div>
            <div class="flex items-center gap-3">
              <span class="text-xs text-gray-400">${this.state.question.length}/1000</span>
              <button id="rag-submit" onclick="RagPage.submit()" class="px-4 py-2 bg-gray-900 text-white text-sm rounded-lg hover:bg-gray-800 disabled:opacity-50">
                提问
              </button>
            </div>
          </div>
        </div>

        <!-- 答案区 -->
        <div id="rag-answer">
          ${UI.emptyState('提问开始对话', '系统将检索相关法规条文并由 AI 生成带引用的答案')}
        </div>
      </div>`;
  },

  init() {
    // 加载 LLM 参数(用于 thinking 状态显示)
    this.loadLLMParams();
  },

  async loadLLMParams() {
    try {
      const resp = await API.get('/api/prompts');
      this.state.thinkingEnabled = resp.data.llm_params.thinking_enabled;
    } catch (e) {
      console.error('加载 LLM 参数失败:', e);
    }
  },

  onInput() {
    const input = document.getElementById('rag-input');
    if (input) this.state.question = input.value;
  },

  setTemplate(t) {
    this.state.template = t;
    const content = document.getElementById('content');
    content.innerHTML = this.render();
  },

  async submit() {
    const input = document.getElementById('rag-input');
    if (input) this.state.question = input.value.trim();
    if (!this.state.question || this.state.streaming) return;

    this.state.answer = '';
    this.state.thinking = '';
    this.state.citations = [];
    this.state.streaming = true;
    this.state.error = null;
    this.renderAnswer();

    try {
      const resp = await fetch('/api/rag', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          question: this.state.question,
          template: this.state.template,
        }),
      });

      if (!resp.ok) {
        const err = await resp.json().catch(() => ({ detail: resp.statusText }));
        throw new Error(err.detail || `HTTP ${resp.status}`);
      }

      // SSE 流式读取
      const reader = resp.body.getReader();
      const decoder = new TextDecoder();
      let buffer = '';

      while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        buffer += decoder.decode(value, { stream: true });
        const lines = buffer.split('\n');
        buffer = lines.pop(); // 保留不完整的行

        for (const line of lines) {
          if (!line.startsWith('data: ')) continue;
          try {
            const evt = JSON.parse(line.slice(6));
            if (evt.type === 'answer') {
              this.state.answer += evt.content;
              this.renderAnswer();
            } else if (evt.type === 'thinking') {
              this.state.thinking += evt.content;
              this.renderAnswer();
            } else if (evt.type === 'params') {
              this.state.thinkingEnabled = evt.thinking_enabled;
            } else if (evt.type === 'citations') {
              this.state.citations = evt.clauses || [];
              this.renderAnswer();
            } else if (evt.type === 'no_result') {
              this.state.error = evt.message;
              this.renderAnswer();
            } else if (evt.type === 'error') {
              this.state.error = evt.message;
              this.renderAnswer();
            } else if (evt.type === 'done') {
              // 完成
            }
          } catch (e) { /* 忽略解析错误 */ }
        }
      }
      this.state.streaming = false;
      this.renderAnswer();
    } catch (e) {
      this.state.streaming = false;
      this.state.error = e.message;
      this.renderAnswer();
    }
  },

  renderAnswer() {
    const el = document.getElementById('rag-answer');
    if (!el) return;

    if (this.state.error) {
      el.innerHTML = UI.errorState(this.state.error, 'RagPage.submit()');
      return;
    }

    if (!this.state.answer && !this.state.citations.length && this.state.streaming) {
      el.innerHTML = `<div class="flex items-center justify-center py-16 gap-3 text-gray-400">${UI.spinner(20)}<span class="text-sm">检索法规并生成答案中...</span></div>`;
      return;
    }

    if (!this.state.answer && !this.state.thinking && !this.state.citations.length) {
      el.innerHTML = UI.emptyState('提问开始对话', '系统将检索相关法规条文并由 AI 生成带引用的答案');
      return;
    }

    // thinking 折叠区(仅 thinking 开启且有内容时显示)
    const thinkingHtml = this.state.thinking
      ? `<details class="mb-4 group">
          <summary class="cursor-pointer flex items-center gap-2 text-xs text-gray-400 hover:text-gray-600 py-2">
            <svg class="w-3 h-3 transition-transform group-open:rotate-90" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><polyline points="9 18 15 12 9 6"/></svg>
            <span>Thinking 思考过程</span>
            <span class="text-gray-300">${this.state.thinking.length} 字</span>
            ${this.state.streaming && !this.state.answer ? '<span class="text-emerald-500">思考中...</span>' : ''}
          </summary>
          <div class="mt-2 p-3 bg-gray-50 rounded-lg border border-gray-100 max-h-96 overflow-y-auto scroll-thin">
            <pre class="text-xs text-gray-500 whitespace-pre-wrap font-mono leading-relaxed">${this._escapeHtml(this.state.thinking)}</pre>
          </div>
        </details>`
      : '';

    const answerHtml = this.state.answer
      ? `<div class="md-content text-sm leading-relaxed ${this.state.streaming ? 'stream-cursor' : ''}">${marked.parse(this.state.answer)}</div>`
      : (this.state.streaming && this.state.thinking ? '<div class="text-xs text-gray-400 py-2">等待生成答案...</div>' : '');
    const citationsHtml = this.state.citations.length
      ? `<div class="mt-6 pt-4 border-t border-gray-200"><div class="text-xs font-semibold text-gray-500 mb-3">引用条文(${this.state.citations.length})</div>${this.state.citations.map(c => UI.clauseCard(c)).join('')}</div>`
      : '';

    el.innerHTML = `
      <div class="bg-white rounded-xl border border-gray-200 p-4">
        <div class="text-xs font-semibold text-gray-500 mb-3">AI 回答</div>
        ${thinkingHtml}
        ${answerHtml}
        ${this.state.streaming ? `<div class="flex items-center gap-2 mt-3 text-xs text-gray-400">${UI.spinner(14)} 生成中...</div>` : ''}
        ${citationsHtml}
      </div>`;
  },

  _escapeHtml(text) {
    const div = document.createElement('div');
    div.textContent = text;
    return div.innerHTML;
  },
};