const SYSTEM_PROMPT = `你是一个专业的旅行规划助手。你需要根据用户的需求规划行程。

## 重要：输出格式
你必须直接输出 JSON，不要包含任何 markdown 代码块标记（如 \`\`\`json），不要在 JSON 前后添加任何额外文字。

JSON 格式如下：
{
  "thinking": "你的思考过程",
  "schemes": [
    {
      "name": "方案名称",
      "route": "路线描述",
      "days": 4,
      "totalKm": 1200,
      "totalDriveTime": 12,
      "budget": "¥3000",
      "highlights": ["亮点1", "亮点2"],
      "points": [
        {
          "name": "地点名称",
          "lat": 25.04,
          "lng": 102.71,
          "day": "Day 1",
          "badge": "START",
          "icon": "🏙️",
          "desc": "简短描述",
          "km": "0km",
          "driveTime": "—",
          "schedule": [{"time": "上午", "content": "行程"}],
          "foods": ["美食"],
          "hotel": "住宿",
          "tips": "注意事项"
        }
      ]
    }
  ]
}

注意：
1. points 第一个用 START badge，中间用 D1/D2，最后一个用 END
2. lat/lng 必须是真实中国地理坐标
3. 至少 2 个方案，最多 3 个
4. 直接输出 JSON，不要其他内容`

export async function chatWithAI(userMessage, onThinking = null) {
  const response = await fetch('/api/chat', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      messages: [
        { role: 'system', content: SYSTEM_PROMPT },
        { role: 'user', content: userMessage }
      ],
      stream: true
    })
  })
  
  if (!response.ok) {
    const error = await response.json().catch(() => ({}))
    throw new Error(error.error?.message || `API 请求失败: ${response.status}`)
  }
  
  const reader = response.body.getReader()
  const decoder = new TextDecoder()
  let fullContent = ''
  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() || ''
    
    for (const line of lines) {
      const trimmed = line.trim()
      if (!trimmed || !trimmed.startsWith('data:')) continue
      
      const data = trimmed.slice(5).trim()
      if (data === '[DONE]') break
      
      try {
        const parsed = JSON.parse(data)
        const chunk = parsed.choices?.[0]?.delta?.content || ''
        if (chunk) {
          fullContent += chunk
          if (onThinking) onThinking(fullContent)
        }
      } catch (e) {
        // Skip malformed JSON chunks
      }
    }
  }
  
  return parseAIResponse(fullContent)
}

function parseAIResponse(content) {
  // Remove markdown code block markers if present
  let cleaned = content.trim()
  
  // Remove ```json ... ``` or ``` ... ```
  const codeBlockMatch = cleaned.match(/```(?:json)?\s*([\s\S]*?)```/)
  if (codeBlockMatch) {
    cleaned = codeBlockMatch[1].trim()
  }
  
  // Remove any <thinking>...</thinking> tags
  cleaned = cleaned.replace(/<thinking>[\s\S]*?<\/thinking>/g, '').trim()
  
  // Try to find JSON object
  // Find the first { and last } to extract the JSON
  const firstBrace = cleaned.indexOf('{')
  const lastBrace = cleaned.lastIndexOf('}')
  
  if (firstBrace === -1 || lastBrace === -1 || lastBrace <= firstBrace) {
    throw new Error('AI 未返回有效的 JSON 数据')
  }
  
  const jsonStr = cleaned.substring(firstBrace, lastBrace + 1)
  
  try {
    const parsed = JSON.parse(jsonStr)
    
    // Validate required fields
    if (!parsed.schemes || !Array.isArray(parsed.schemes) || parsed.schemes.length === 0) {
      throw new Error('AI 返回结果缺少 schemes')
    }
    
    return parsed
  } catch (e) {
    if (e.message.includes('缺少 schemes')) throw e
    console.error('JSON parse error:', e)
    console.error('Raw content:', cleaned.substring(0, 200))
    throw new Error('AI 返回的 JSON 格式有误，请重试')
  }
}