'use server'

import { streamText } from 'ai'
import { NextRequest, NextResponse } from 'next/server'
import type { ChatRequest } from '@/lib/types'
import { getConfiguredModel } from '@/lib/openrouter'
import { getAgentDefinition } from '@/lib/agents/factory'
import { getFlags } from '@/lib/flags'

/**
 * POST /api/chat
 * Stream chat responses from the selected agent
 *
 * Request body:
 * - message: User message
 * - agentId: Selected agent (agent-1, agent-2, or custom-{uuid})
 * - sessionId: Session ID for conversation tracking
 * - timestamp: Request timestamp
 * - images?: Base64 encoded images (optional)
 * - systemPrompt?: For custom agents, the agent's system prompt
 *
 * Response:
 * - Server-Sent Events (SSE) stream with text and tool calls
 */
export async function POST(request: NextRequest) {
  try {
    // Parse request body
    const body = (await request.json()) as Partial<ChatRequest> & {
      systemPrompt?: string
    }

    const { message, agentId, sessionId, timestamp, images, systemPrompt } = body

    // Validate required fields
    if (!message) {
      return NextResponse.json(
        { error: 'Message is required' },
        { status: 400 }
      )
    }

    if (!agentId) {
      return NextResponse.json(
        { error: 'Agent ID is required' },
        { status: 400 }
      )
    }

    // Check feature flags
    const flags = getFlags()
    if (images && images.length > 0 && !flags.IMAGE_UPLOADS_ENABLED) {
      return NextResponse.json(
        {
          error: 'Image uploads are not enabled',
          hint: 'Contact administrator to enable this feature',
        },
        { status: 403 }
      )
    }

    // Log request
    console.log(`[chat] Agent: ${agentId}, Session: ${sessionId}, Message length: ${message.length}`)

    // Load agent definition
    const agent = await getAgentDefinition(agentId, {
      systemPrompt: systemPrompt || '',
      tools: undefined, // Tools come from agent definition
    })

    // Build message array with context
    const messageContent = buildMessageContent(message, images)
    const messages: Parameters<typeof streamText>[0]['messages'] = [
      {
        role: 'user',
        content: messageContent as any,
      },
    ]

    // Get configured model
    const model = getConfiguredModel()

    // Debug: Log tools being passed to streamText
    const toolsToPass = agent.tools || {}
    console.log(`[chat] Tools available for agent ${agentId}:`, Object.keys(toolsToPass))

    // Stream response from agent
    const result = streamText({
      model,
      system: agent.systemPrompt,
      tools: toolsToPass,
      messages,
      temperature: agent.temperature,
      // Note: maxTokens is not used in streamText - it uses maxRetries, retry logic, etc
      onFinish: (event) => {
        console.log(`[chat] Response completed for agent ${agentId}`)
      },
    })

    // Return as text stream response (Server-Sent Events format)
    return result.toTextStreamResponse()
  } catch (error) {
    console.error('[chat] Error:', error)
    const message = error instanceof Error ? error.message : 'Unknown error'
    return NextResponse.json(
      {
        error: 'Failed to process message',
        hint: message,
      },
      { status: 500 }
    )
  }
}

/**
 * Build message content with text and images
 * Supports both text-only and multimodal messages
 */
function buildMessageContent(
  text: string,
  images?: string[]
): string | Array<{ type: 'text' | 'image'; text?: string; image?: string; mimeType?: string }> {
  // Text only
  if (!images || images.length === 0) {
    return text
  }

  // Multimodal message with images
  const content: Array<{ type: 'text' | 'image'; text?: string; image?: string; mimeType?: string }> = [
    {
      type: 'text',
      text,
    },
  ]

  for (const base64Image of images) {
    // Determine MIME type from base64 prefix
    let mimeType = 'image/jpeg'
    if (base64Image.includes('data:image/png')) {
      mimeType = 'image/png'
    } else if (base64Image.includes('data:image/gif')) {
      mimeType = 'image/gif'
    } else if (base64Image.includes('data:image/webp')) {
      mimeType = 'image/webp'
    }

    // Extract base64 data (remove data URL prefix if present)
    const imageData = base64Image.includes(',')
      ? base64Image.split(',')[1]
      : base64Image

    content.push({
      type: 'image',
      image: imageData,
      mimeType,
    })
  }

  return content
}