/**
* Copyright (c) 2026 Ivan Iraci <ivan.iraci@professioneit.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
import * as fs from 'fs/promises';
import * as path from 'path';
import * as os from 'os';
import type { Config, LSPServerConfig } from './types.js';
import { DEFAULT_CONFIG, DEFAULT_SERVERS } from './constants.js';
// ============================================================================
// Configuration Loading
// ============================================================================
/**
* Configuration file locations (in order of priority).
*/
function getConfigPaths(): string[] {
const home = os.homedir();
const xdgConfig = process.env.XDG_CONFIG_HOME ?? path.join(home, '.config');
return [
// Current directory
path.join(process.cwd(), '.lsp-mcp.json'),
path.join(process.cwd(), 'lsp-mcp.json'),
// XDG config directory
path.join(xdgConfig, 'lsp-mcp', 'config.json'),
// Home directory
path.join(home, '.lsp-mcp.json'),
];
}
/**
* Try to read a JSON file.
*/
async function tryReadJson(filePath: string): Promise<unknown | null> {
try {
const content = await fs.readFile(filePath, 'utf-8');
return JSON.parse(content);
} catch {
return null;
}
}
/**
* Merge server configurations.
* User servers override built-in servers with the same ID.
*/
function mergeServers(
builtIn: LSPServerConfig[],
user: LSPServerConfig[]
): LSPServerConfig[] {
const merged = new Map<string, LSPServerConfig>();
// Add built-in servers
for (const server of builtIn) {
merged.set(server.id, server);
}
// Override/add user servers
for (const server of user) {
merged.set(server.id, server);
}
return Array.from(merged.values());
}
/**
* Validate a server configuration.
*/
function validateServerConfig(server: unknown): server is LSPServerConfig {
if (!server || typeof server !== 'object') {
return false;
}
const s = server as Record<string, unknown>;
return (
typeof s.id === 'string' &&
Array.isArray(s.extensions) &&
s.extensions.every((e) => typeof e === 'string') &&
Array.isArray(s.languageIds) &&
s.languageIds.every((l) => typeof l === 'string') &&
typeof s.command === 'string' &&
Array.isArray(s.args) &&
s.args.every((a) => typeof a === 'string')
);
}
/**
* Load configuration from file or environment.
*/
export async function loadConfig(): Promise<Config> {
const config: Config = {
...DEFAULT_CONFIG,
servers: [...DEFAULT_SERVERS],
};
// Try to load config file
const configPaths = getConfigPaths();
let userConfig: Record<string, unknown> | null = null;
for (const configPath of configPaths) {
const loaded = await tryReadJson(configPath);
if (loaded && typeof loaded === 'object') {
userConfig = loaded as Record<string, unknown>;
break;
}
}
// Apply user configuration
if (userConfig) {
// Merge servers
if (Array.isArray(userConfig.servers)) {
const validServers = userConfig.servers.filter(validateServerConfig);
config.servers = mergeServers(DEFAULT_SERVERS, validServers);
}
// Apply other settings
if (typeof userConfig.requestTimeout === 'number') {
config.requestTimeout = userConfig.requestTimeout;
}
if (typeof userConfig.autoStart === 'boolean') {
config.autoStart = userConfig.autoStart;
}
if (typeof userConfig.logLevel === 'string') {
const level = userConfig.logLevel as string;
if (['debug', 'info', 'warn', 'error'].includes(level)) {
config.logLevel = level as Config['logLevel'];
}
}
if (typeof userConfig.idleTimeout === 'number') {
config.idleTimeout = userConfig.idleTimeout;
}
}
// Environment variable overrides
if (process.env.LSP_MCP_LOG_LEVEL) {
const level = process.env.LSP_MCP_LOG_LEVEL;
if (['debug', 'info', 'warn', 'error'].includes(level)) {
config.logLevel = level as Config['logLevel'];
}
}
if (process.env.LSP_MCP_REQUEST_TIMEOUT) {
const timeout = parseInt(process.env.LSP_MCP_REQUEST_TIMEOUT, 10);
if (!isNaN(timeout) && timeout > 0) {
config.requestTimeout = timeout;
}
}
return config;
}
/**
* Get server config by ID.
*/
export function getServerConfig(
config: Config,
serverId: string
): LSPServerConfig | undefined {
return config.servers.find((s) => s.id === serverId);
}
/**
* Find server config by file extension.
*/
export function findServerByExtension(
config: Config,
extension: string
): LSPServerConfig | undefined {
return config.servers.find((s) => s.extensions.includes(extension));
}
/**
* Find server config by language ID.
*/
export function findServerByLanguageId(
config: Config,
languageId: string
): LSPServerConfig | undefined {
return config.servers.find((s) => s.languageIds.includes(languageId));
}
