const express = require('express');
const path = require('path');
const yaml = require('js-yaml');

const app = express();
const PORT = process.env.PORT || 3000;

app.use(express.static(path.join(__dirname, 'public')));
app.use(express.json({ limit: '2mb' }));

app.get('/api/health', (req, res) => {
  res.json({ status: 'ok' });
});

function buildGraphFromPaths(pathsObject) {
  const httpMethods = new Set(['get','put','post','delete','options','head','patch','trace']);
  const nodeIdSet = new Set();
  const linkKeySet = new Set();
  const nodes = [];
  const links = [];
  const endpoints = [];

  for (const pathKey of Object.keys(pathsObject || {})) {
    const pathItem = pathsObject[pathKey] || {};
    // Collect endpoints
    for (const method of Object.keys(pathItem)) {
      const lower = method.toLowerCase();
      if (httpMethods.has(lower)) {
        endpoints.push({ method: lower.toUpperCase(), path: pathKey });
      }
    }
    // Build nodes/links from URL segments
    const segments = pathKey.split('/').filter(Boolean);
    if (segments.length === 0) continue;

    // Ensure nodes
    for (const seg of segments) {
      if (!nodeIdSet.has(seg)) {
        nodeIdSet.add(seg);
        nodes.push({ id: seg });
      }
    }

    // Create sequential links along the path
    for (let i = 0; i < segments.length - 1; i++) {
      const source = segments[i];
      const target = segments[i + 1];
      const key = `${source}|${target}`;
      if (!linkKeySet.has(key)) {
        linkKeySet.add(key);
        links.push({ source, target });
      }
    }
  }

  return { nodes, links, endpoints };
}

app.post('/api/parse', (req, res) => {
  try {
    const { yaml: yamlText } = req.body || {};
    if (typeof yamlText !== 'string' || yamlText.trim() === '') {
      return res.status(400).json({ error: 'Missing yaml string in body' });
    }
    const spec = yaml.load(yamlText);
    if (!spec || typeof spec !== 'object') {
      return res.status(400).json({ error: 'Invalid YAML content' });
    }

    const pathsObject = spec.paths || {};
    const graph = buildGraphFromPaths(pathsObject);
    res.json({ graph, info: { title: spec.info && spec.info.title, version: spec.info && spec.info.version } });
  } catch (err) {
    res.status(400).json({ error: err.message || 'Failed to parse YAML' });
  }
});

app.listen(PORT, () => {
  console.log(`Server listening on http://localhost:${PORT}`);
});