import Anthropic from '@anthropic-ai/sdk';
import { readFileSync } from 'fs';
import { join } from 'path';

function getClient() { return new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY! }); }

function loadSkill(name: string): string {
  const skillsDir = join(process.cwd(), '../../packages/ai-pipeline/skills/data');
  return readFileSync(join(skillsDir, `${name}.md`), 'utf-8');
}

export async function POST(request: Request) {
  try {
    const body = await request.json();
    const { analysis, tools, serviceName } = body;

    if (!analysis && !tools) {
      return Response.json({ error: 'Provide analysis or tools config' }, { status: 400 });
    }

    // Load our server-builder + server-development skills
    const builderSkill = loadSkill('mcp-server-builder');
    const devSkill = loadSkill('mcp-server-development');
    const systemPrompt = builderSkill + '\n\n---\n\n' + devSkill;

    const encoder = new TextEncoder();
    const stream = new ReadableStream({
      async start(controller) {
        try {
          const send = (event: string, data: unknown) => {
            controller.enqueue(encoder.encode(`event: ${event}\ndata: ${JSON.stringify(data)}\n\n`));
          };

          send('progress', { step: 'Generating MCP server...', percent: 10 });

          const response = await getClient().messages.create({
            model: 'claude-sonnet-4-5-20250514',
            max_tokens: 16384,
            system: systemPrompt + '\n\nIMPORTANT: Generate a complete, working MCP server. Output each file in this format:\n\n--- FILE: path/to/file ---\n```typescript\n// file content\n```\n\nGenerate at minimum: src/index.ts, package.json, tsconfig.json, README.md, .env.example',
            messages: [{
              role: 'user',
              content: `Generate a complete MCP server for "${serviceName || 'custom'}" based on this analysis:\n\n${JSON.stringify(analysis || { tools })}\n\nThe server should compile with TypeScript and use the MCP SDK ^1.26.0.`
            }],
          });

          send('progress', { step: 'Parsing generated files...', percent: 80 });

          const text = response.content
            .filter((b): b is Anthropic.TextBlock => b.type === 'text')
            .map(b => b.text)
            .join('');

          // Parse files from the output
          const files: { path: string; content: string }[] = [];
          const filePattern = /--- FILE: (.+?) ---\s*```(?:typescript|json|markdown|ts|md)?\s*([\s\S]*?)```/g;
          let match;
          while ((match = filePattern.exec(text)) !== null) {
            files.push({ path: match[1].trim(), content: match[2].trim() });
            send('file_ready', { path: match[1].trim(), preview: match[2].trim().substring(0, 200) });
          }

          // If no file pattern found, try to extract code blocks
          if (files.length === 0) {
            const codeBlocks = text.match(/```(?:typescript|ts|json)\s*([\s\S]*?)```/g) || [];
            if (codeBlocks.length > 0) {
              files.push({
                path: 'src/index.ts',
                content: codeBlocks[0].replace(/```(?:typescript|ts)?\s*/, '').replace(/```$/, '').trim()
              });
              send('file_ready', { path: 'src/index.ts', preview: 'Main server file' });
            }
          }

          send('complete', {
            files,
            totalFiles: files.length,
            rawOutput: files.length === 0 ? text : undefined
          });
          controller.close();
        } catch (err: unknown) {
          const msg = err instanceof Error ? err.message : 'Unknown error';
          controller.enqueue(encoder.encode(`event: error\ndata: ${JSON.stringify({ message: msg })}\n\n`));
          controller.close();
        }
      }
    });

    return new Response(stream, {
      headers: {
        'Content-Type': 'text/event-stream',
        'Cache-Control': 'no-cache',
        Connection: 'keep-alive',
      },
    });
  } catch (err: unknown) {
    const msg = err instanceof Error ? err.message : 'Unknown error';
    return Response.json({ error: msg }, { status: 500 });
  }
}