/**
* YAML serializer for mcpGraph configuration
* Handles both deserialization (load/parse) and serialization (save/dump)
*/
import { load, dump } from "js-yaml";
import { readFileSync, writeFileSync } from "node:fs";
import { mcpGraphConfigSchema } from "./schema.js";
import type { McpGraphConfig } from "../types/config.js";
import { logger } from "../logger.js";
import { validateConfigExpressions } from "./expression-validator.js";
/**
* Parse YAML configuration file into McpGraphConfig object
* @param filePath - Path to the YAML configuration file
* @returns McpGraphConfig object
*/
export function parseYamlConfig(filePath: string): McpGraphConfig {
try {
const fileContents = readFileSync(filePath, "utf-8");
const parsed = load(fileContents) as unknown;
// Validate against schema
const validated = mcpGraphConfigSchema.parse(parsed);
// Validate expression syntax (JSONata and JSON Logic)
const expressionErrors = validateConfigExpressions(validated as McpGraphConfig);
if (expressionErrors.length > 0) {
const errorMessages = expressionErrors.map(
(e) => ` - Node "${e.nodeId}": ${e.message}`
).join("\n");
const error = new Error(
`Configuration validation failed - expression syntax errors:\n${errorMessages}`
);
logger.error(error.message);
throw error;
}
return validated as McpGraphConfig;
} catch (error) {
if (error instanceof Error) {
logger.error(`Failed to parse YAML config: ${error.message}`);
throw error;
}
throw new Error("Unknown error parsing YAML config");
}
}
/**
* Write McpGraphConfig object to YAML file
* @param filePath - Path to the YAML configuration file
* @param config - McpGraphConfig object to write
* Only servers with _source: 'graph' are serialized (external servers are excluded)
*/
export function writeYamlConfig(filePath: string, config: McpGraphConfig): void {
try {
// Create a copy for serialization, filtering out external servers
const configToWrite: McpGraphConfig = {
...config,
mcpServers: undefined,
};
if (config.mcpServers) {
for (const [name, serverConfig] of Object.entries(config.mcpServers)) {
// Only include servers from graph file (or undefined source, for backwards compatibility)
if (serverConfig._source !== 'external') {
// Create clean copy without _source metadata
const { _source, ...cleanConfig } = serverConfig;
if (!configToWrite.mcpServers) {
configToWrite.mcpServers = {};
}
configToWrite.mcpServers[name] = cleanConfig;
}
}
}
// Use js-yaml dump with readable formatting
const yamlString = dump(configToWrite, {
indent: 2,
lineWidth: -1, // No line wrapping
noRefs: true, // Don't use YAML references
sortKeys: false, // Preserve key order
});
writeFileSync(filePath, yamlString, "utf-8");
logger.info(`Saved configuration to: ${filePath}`);
} catch (error) {
if (error instanceof Error) {
logger.error(`Failed to write YAML config: ${error.message}`);
throw error;
}
throw new Error("Unknown error writing YAML config");
}
}
