'use strict';

const fs = require('fs');
const path = require('path');
const os = require('os');

/**
 * Resolve the OpsxDB Go MCP binary path.
 * Order: OPSXDB_MCP_BIN → PATH → common install locations.
 * @returns {string|null}
 */
function resolveBinary() {
  const envBin = process.env.OPSXDB_MCP_BIN;
  if (envBin && isExecutable(envBin)) return path.resolve(envBin);

  const onPath = findOnPath('opsxdb-mcp');
  if (onPath) return onPath;

  const home = os.homedir();
  const candidates = [
    path.join(home, 'devops', 'opsxdb', 'bin', 'opsxdb-mcp'),
    path.join(home, '.opsxdb', 'bin', 'opsxdb-mcp'),
    path.join(home, '.local', 'bin', 'opsxdb-mcp'),
    '/usr/local/bin/opsxdb-mcp',
    '/opt/homebrew/bin/opsxdb-mcp',
  ];
  for (const c of candidates) {
    if (isExecutable(c)) return c;
  }
  return null;
}

function findOnPath(name) {
  const pathEnv = process.env.PATH || '';
  for (const dir of pathEnv.split(path.delimiter)) {
    if (!dir) continue;
    const p = path.join(dir, name);
    if (isExecutable(p)) return p;
    if (process.platform === 'win32' && isExecutable(p + '.exe')) return p + '.exe';
  }
  return null;
}

function isExecutable(filePath) {
  try {
    const st = fs.statSync(filePath);
    if (!st.isFile()) return false;
    fs.accessSync(filePath, fs.constants.X_OK);
    return true;
  } catch {
    return false;
  }
}

function missingBinaryMessage() {
  return `opsxdb-mcp: Go binary not found.

This npm package (@rlwj-lab/opsxdb-mcp) is a Node launcher for the OpsxDB
MCP server (stdio). The real server is a Go binary named opsxdb-mcp.

Build it from the opsxdb repo:

  cd server && go build -o ../bin/opsxdb-mcp ./cmd/opsxdb-mcp

Then either:
  - put bin/opsxdb-mcp on your PATH, or
  - export OPSXDB_MCP_BIN=/absolute/path/to/opsxdb-mcp

Cursor / Claude Desktop example:

  {
    "mcpServers": {
      "opsxdb": {
        "command": "npx",
        "args": ["-y", "@rlwj-lab/opsxdb-mcp"],
        "env": {
          "OPSXDB_MCP_BIN": "/absolute/path/to/opsxdb-mcp"
        }
      }
    }
  }

Config files (same as native binary):
  ~/.opsxdb/mcp.json
  ~/.opsxdb/connections.json
`;
}

module.exports = {
  resolveBinary,
  missingBinaryMessage,
};