import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { z } from 'zod';
import { runGxi, escapeSchemeString, ERROR_MARKER } from '../gxi.js';
const RESULT_MARKER = 'GERBIL-MCP-IMPORT:';
// Curated list of commonly-used standard library modules to scan.
// Kept as a Scheme list literal to avoid per-module subprocess overhead.
export const STD_MODULES = [
':std/iter',
':std/sugar',
':std/test',
':std/error',
':std/format',
':std/sort',
':std/text/json',
':std/text/csv',
':std/text/utf8',
':std/pregexp',
':std/net/request',
':std/net/httpd',
':std/net/websocket',
':std/net/ssl',
':std/io',
':std/os/socket',
':std/misc/channel',
':std/misc/threads',
':std/misc/string',
':std/misc/list',
':std/misc/list-builder',
':std/misc/queue',
':std/misc/deque',
':std/misc/rbtree',
':std/misc/pqueue',
':std/misc/sync',
':std/coroutine',
':std/generic',
':std/foreign',
':std/crypto',
':std/actor',
':std/db/postgresql',
':std/db/sqlite',
':std/srfi/1',
':std/srfi/13',
];
export function registerSuggestImportsTool(server: McpServer): void {
server.registerTool(
'gerbil_suggest_imports',
{
title: 'Suggest Imports',
description:
'Find which standard library module exports a given symbol. ' +
'Scans common :std/* modules and reports matching import statements. ' +
'For less common modules, use gerbil_apropos + gerbil_module_exports as a fallback.',
annotations: {
readOnlyHint: true,
idempotentHint: true,
},
inputSchema: {
symbol: z
.string()
.describe(
'Symbol to find the import for (e.g. "for/collect", "read-json", "hash-ref")',
),
},
},
async ({ symbol }) => {
const escapedSym = escapeSchemeString(symbol);
const expr = buildSuggestExpr(escapedSym);
const result = await runGxi(['(import :gerbil/expander)', expr], { timeout: 60_000 });
if (result.timedOut) {
return {
content: [
{
type: 'text' as const,
text: 'Import search timed out after 60 seconds.',
},
],
isError: true,
};
}
if (result.exitCode === 127) {
return {
content: [
{
type: 'text' as const,
text: 'gxi not found. Ensure Gerbil is installed and gxi is in PATH.',
},
],
isError: true,
};
}
const stdout = result.stdout;
const errorIdx = stdout.indexOf(ERROR_MARKER);
if (errorIdx !== -1) {
const errorMsg = stdout.slice(errorIdx + ERROR_MARKER.length).trim();
return {
content: [
{
type: 'text' as const,
text: `Error searching for "${symbol}":\n${errorMsg}`,
},
],
isError: true,
};
}
// Parse GERBIL-MCP-IMPORT:module-path lines
const importLines = stdout
.split('\n')
.filter((l) => l.startsWith(RESULT_MARKER));
const modules = importLines.map((l) =>
l.slice(RESULT_MARKER.length).trim(),
);
if (modules.length === 0) {
return {
content: [
{
type: 'text' as const,
text:
`Symbol "${symbol}" not found in common standard library modules.\n\n` +
`Try using gerbil_apropos to search more broadly, then gerbil_module_exports to check specific modules.`,
},
],
};
}
const sections: string[] = [
`Symbol "${symbol}" is exported by:`,
'',
];
for (const mod of modules) {
sections.push(` (import ${mod})`);
}
return {
content: [{ type: 'text' as const, text: sections.join('\n') }],
};
},
);
}
function buildSuggestExpr(escapedSym: string): string {
const moduleList = STD_MODULES.map((m) => `(quote ${m})`).join(' ');
return [
'(with-catch',
' (lambda (e)',
` (display "${ERROR_MARKER}\\n")`,
' (display-exception e (current-output-port)))',
' (lambda ()',
` (let* ((target (string->symbol "${escapedSym}"))`,
` (modules (list ${moduleList})))`,
' (for-each',
' (lambda (mod-sym)',
' (with-catch',
' (lambda (e) (void))',
' (lambda ()',
' (let* ((mod (import-module mod-sym #f #t))',
' (exports (module-context-export mod)))',
' (for-each',
' (lambda (ex)',
' (when (eq? (module-export-name ex) target)',
` (display "${RESULT_MARKER}")`,
' (display mod-sym)',
' (newline)))',
' exports)))))',
' modules))))',
].join(' ');
}
