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 { specUrl, specContent } = body;

    let spec = specContent || '';

    // Fetch spec from URL if provided
    if (specUrl && !spec) {
      try {
        const res = await fetch(specUrl, { headers: { Accept: 'application/json, text/yaml, text/plain, */*' } });
        spec = await res.text();
      } catch (e) {
        return Response.json({ error: 'Failed to fetch spec from URL' }, { status: 400 });
      }
    }

    if (!spec || spec.length < 50) {
      return Response.json({ error: 'Please provide a valid OpenAPI spec (URL or content)' }, { status: 400 });
    }

    // Load our mcp-api-analyzer skill
    const analyzerSkill = loadSkill('mcp-api-analyzer');

    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: 'Starting analysis...', percent: 10 });

          const response = await getClient().messages.create({
            model: 'claude-sonnet-4-5-20250514',
            max_tokens: 8192,
            system: analyzerSkill + '\n\nIMPORTANT: Return your analysis as a JSON object wrapped in ```json code fences. The JSON must have this structure: { "service": string, "baseUrl": string, "toolGroups": [{ "name": string, "tools": [{ "name": string, "description": string, "method": "GET"|"POST"|"PUT"|"PATCH"|"DELETE", "endpoint": string, "inputSchema": { "type": "object", "properties": {}, "required": [] } }] }], "authFlow": { "type": "api_key"|"oauth2"|"bearer" }, "appCandidates": [{ "name": string, "pattern": string, "description": string }] }',
            messages: [{
              role: 'user',
              content: `Analyze this API specification and produce the structured analysis:\n\n${spec.substring(0, 50000)}`
            }],
          });

          send('progress', { step: 'Analysis complete', percent: 90 });

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

          // Try to extract JSON from the response
          const jsonMatch = text.match(/```json\s*([\s\S]*?)```/) || text.match(/\{[\s\S]*\}/);
          let analysis = null;
          if (jsonMatch) {
            try {
              analysis = JSON.parse(jsonMatch[1] || jsonMatch[0]);
            } catch {
              analysis = { rawText: text };
            }
          } else {
            analysis = { rawText: text };
          }

          // Emit tools one by one
          if (analysis.toolGroups) {
            for (const group of analysis.toolGroups) {
              for (const tool of group.tools || []) {
                send('tool_found', { ...tool, groupName: group.name });
                await new Promise(r => setTimeout(r, 200)); // stagger for UX
              }
            }
          }

          send('complete', { analysis });
          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 });
  }
}