/**
 * pi-statusline - MCP server info (private module)
 *
 * Reads the number of configured/connected MCP servers from the agent dir,
 * with a short TTL cache.
 */

import * as fs from 'node:fs';
import * as path from 'node:path';
import { getAgentDir } from '@earendil-works/pi-coding-agent';

export interface McpInfo {
  total: number;
  connected: number;
}

let mcpCache: { data: McpInfo; ts: number } | null = null;
// TTL rationale: mcp.json / mcp-cache.json change only when servers are
// configured or connected; 30s bounds the two small file reads to 2/min
// while keeping the footer count honest enough for a status display.
const MCP_CACHE_TTL_MS = 30000;

interface McpCacheStats {
  hits: number;
  misses: number;
}

const mcpCacheStats: McpCacheStats = { hits: 0, misses: 0 };

export function getMcpStats(): McpCacheStats {
  return { ...mcpCacheStats };
}

export function getMcpInfo(): McpInfo {
  if (mcpCache && Date.now() - mcpCache.ts < MCP_CACHE_TTL_MS) {
    mcpCacheStats.hits++;

    return mcpCache.data;
  }

  mcpCacheStats.misses++;

  const agentDir = getAgentDir();
  const mcpConfigPath = path.join(agentDir, 'mcp.json');
  const mcpCachePath = path.join(agentDir, 'mcp-cache.json');

  let total = 0;
  let connected = 0;

  try {
    const config = JSON.parse(fs.readFileSync(mcpConfigPath, 'utf-8'));

    total = Object.keys(config.mcpServers || {}).length;
  } catch {
    /* mcp.json not found */
  }

  try {
    const cache = JSON.parse(fs.readFileSync(mcpCachePath, 'utf-8'));
    const servers: Record<string, any> = cache.servers || {};

    connected = Object.values(servers).filter((s) => Array.isArray(s.tools) && s.tools.length > 0).length;
  } catch {
    /* cache not found */
  }

  const data = { total, connected };

  mcpCache = { data, ts: Date.now() };

  return data;
}