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`

const QUICK_PLAN_PROMPT = `你是一个专业的旅行规划助手。根据用户指定的目的地和天数，快速生成 3 个不同的旅行方案。

## 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，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，如：昆明→大理→丽江→香格里拉",
      "days": 5,
      "totalKm": 800,
      "totalDriveTime": 10,
      "budget": "¥3000",
      "highlights": ["亮点1", "亮点2", "亮点3"],
      "daysDetail": [
        {
          "location": "当日所在地",
          "desc": "当日行程描述",
          "spots": ["景点1", "景点2", "景点3"]
        }
      ],
      "tips": "旅行贴士，如最佳季节、注意事项、必备物品等",
      "points": [
        {
          "name": "地点名称",
          "lat": 25.04,
          "lng": 102.71,
          "day": "Day 1",
          "badge": "START",
          "icon": "🏙️",
          "desc": "该地点简短描述",
          "km": "0km",
          "driveTime": "—",
          "schedule": [{"time": "上午", "content": "行程安排"}],
          "foods": ["当地美食"],
          "hotel": "推荐住宿",
          "tips": "注意事项"
        }
      ]
    }
  ]
}

要求：
1. 3 个方案风格不同（如：经典路线、深度游、小众路线）
2. lat/lng 必须是真实中国地理坐标
3. 行程安排要合理，每天 1-2 个地点
4. daysDetail 数组长度必须等于 days，每天一个对象
5. 直接输出 JSON，不要其他内容`

const CUSTOM_PLAN_PROMPT = `你是一个专业的旅行规划助手。用户已经输入了他/她的行程安排，你需要：
1. 解析用户的行程安排
2. 评估行程是否合理（时间是否充裕、路线是否顺畅、景点搭配是否合理）
3. 如果不合理，给出优化建议和优化后的方案
4. 同时也生成一个按用户原始输入直接生成的方案

## 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，不要在 JSON 前后添加任何额外文字。

JSON 格式如下：
{
  "thinking": "你的分析过程",
  "evaluation": {
    "isReasonable": true,
    "summary": "整体评价：行程基本合理/存在以下问题...",
    "suggestions": ["建议1：某天行程太紧，建议...", "建议2：A到B距离较远，建议..."]
  },
  "optimizedScheme": {
    "name": "优化方案",
    "route": "优化后的路线",
    "days": 4,
    "totalKm": 800,
    "totalDriveTime": 10,
    "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": "描述",
        "km": "0km",
        "driveTime": "—",
        "schedule": [{"time": "上午", "content": "行程"}],
        "foods": ["美食"],
        "hotel": "住宿",
        "tips": "注意事项"
      }
    ]
  },
  "originalScheme": {
    "name": "原始方案（按你的输入生成）",
    "route": "原始路线",
    "days": 4,
    "totalKm": 900,
    "totalDriveTime": 12,
    "budget": "¥3500",
    "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": "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. lat/lng 必须是真实中国地理坐标
2. optimizedScheme 和 originalScheme 都要包含完整的 points 数组
3. 即使行程合理也要生成两个方案（优化版和原版）
4. 直接输出 JSON，不要其他内容`

export async function chatWithAI(userMessage, onThinking = null) {
  // Use Express API server directly (port 3001) instead of Vite proxy
  const apiUrl = import.meta.env.DEV ? 'http://localhost:3001/api/chat' : '/api/chat'
  const response = await fetch(apiUrl, {
    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 reasoningContent = ''
  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 delta = parsed.choices?.[0]?.delta || {}
        // Support both reasoning_content (thinking models) and content
        if (delta.reasoning_content) {
          reasoningContent += delta.reasoning_content
          if (onThinking) onThinking(reasoningContent)
        }
        const chunk = delta.content || ''
        if (chunk) {
          fullContent += chunk
          if (onThinking) onThinking(fullContent || reasoningContent)
        }
      } catch (e) {
        // Skip malformed JSON chunks
      }
    }
  }
  
  return parseAIResponse(fullContent || reasoningContent)
}

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')
  }
}

// Shared streaming function
async function streamAIRequest(messages, onThinking = null) {
  const apiUrl = import.meta.env.DEV ? 'http://localhost:3001/api/chat' : '/api/chat'
  console.log('[streamAI] Fetching:', apiUrl)
  const response = await fetch(apiUrl, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ messages, stream: true })
  })
  console.log('[streamAI] Response status:', response.status)
  
  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 reasoningContent = ''
  let buffer = ''
  let chunkCount = 0
  let lastUpdate = Date.now()
  
  while (true) {
    const { done, value } = await reader.read()
    if (done) {
      console.log('[streamAI] Done, total chunks:', chunkCount)
      break
    }
    
    chunkCount++
    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 delta = parsed.choices?.[0]?.delta || {}
        if (delta.reasoning_content) {
          reasoningContent += delta.reasoning_content
          if (onThinking) {
            onThinking(reasoningContent)
            if (Date.now() - lastUpdate > 2000) {
              console.log('[streamAI] reasoning_length:', reasoningContent.length)
              lastUpdate = Date.now()
            }
          }
        }
        const chunk = delta.content || ''
        if (chunk) fullContent += chunk
      } catch (e) {
        // Skip malformed JSON
      }
    }
  }
  
  console.log('[streamAI] fullContent:', fullContent.length, 'reasoningContent:', reasoningContent.length)
  return fullContent || reasoningContent
}

function parseJSONFromContent(content) {
  let cleaned = content.trim()
  const codeBlockMatch = cleaned.match(/```(?:json)?\s*([\s\S]*?)```/)
  if (codeBlockMatch) cleaned = codeBlockMatch[1].trim()
  cleaned = cleaned.replace(/<thinking>[\s\S]*?<\/thinking>/g, '').trim()
  
  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 {
    return JSON.parse(jsonStr)
  } catch (e) {
    console.error('JSON parse error:', e)
    throw new Error('AI 返回的 JSON 格式有误，请重试')
  }
}

export async function quickPlan(userInput, onThinking = null) {
  const userMessage = `目的地：${userInput.destination}
出行天数：${userInput.days}天
出发日期：${userInput.startDate}
出行方式：${userInput.transport}
其他需求：${userInput.extraNeeds}

请为我生成 3 个不同风格的旅行方案。`

  const content = await streamAIRequest([
    { role: 'system', content: QUICK_PLAN_PROMPT },
    { role: 'user', content: userMessage }
  ], onThinking)
  
  const parsed = parseJSONFromContent(content)
  
  if (!parsed.schemes || !Array.isArray(parsed.schemes) || parsed.schemes.length === 0) {
    throw new Error('AI 返回结果缺少 schemes')
  }
  
  return parsed
}

export async function customPlan(userInput, onThinking = null) {
  const userMessage = `我的行程安排：
${userInput.itinerary}

出行方式：${userInput.transport}
同行人员：${userInput.companions}

请评估我的行程是否合理，并给出优化建议和两个方案（优化版和原版）。`

  const content = await streamAIRequest([
    { role: 'system', content: CUSTOM_PLAN_PROMPT },
    { role: 'user', content: userMessage }
  ], onThinking)
  
  const parsed = parseJSONFromContent(content)
  
  if (!parsed.evaluation) {
    throw new Error('AI 返回结果缺少 evaluation')
  }
  
  return parsed
}