Files
filepuff-mcp/internal/server/server.go
T

420 lines
15 KiB
Go

// Package server implements the MCP server for file operations.
package server
import (
"context"
"log/slog"
"os"
"os/signal"
"syscall"
"time"
"github.com/lukaszraczylo/mcp-filepuff/internal/config"
"github.com/lukaszraczylo/mcp-filepuff/internal/edit"
"github.com/lukaszraczylo/mcp-filepuff/internal/lsp"
"github.com/lukaszraczylo/mcp-filepuff/internal/parser"
"github.com/lukaszraczylo/mcp-filepuff/internal/query"
"github.com/lukaszraczylo/mcp-filepuff/internal/search"
"github.com/mark3labs/mcp-go/mcp"
"github.com/mark3labs/mcp-go/server"
)
// MaxConcurrentReads limits concurrent file read operations to prevent memory exhaustion.
const MaxConcurrentReads = 10
// MaxConcurrentQueries limits concurrent AST query operations to prevent CPU exhaustion.
const MaxConcurrentQueries = 5
// ServerShutdownTimeout is the timeout for graceful server shutdown.
const ServerShutdownTimeout = 10 * time.Second
// PreviewLineMaxLength is the maximum length for preview lines before truncation.
const PreviewLineMaxLength = 100
// Server represents the MCP file operations server.
type Server struct {
cfg *config.Config
logger *slog.Logger
mcp *server.MCPServer
searcher *search.Searcher
parser *parser.Registry
matcher *query.Matcher
lspManager *lsp.Manager
editor *edit.Engine
readSem chan struct{} // Semaphore for limiting concurrent file reads
querySem chan struct{} // Semaphore for limiting concurrent AST queries
}
// New creates a new MCP server instance.
func New(cfg *config.Config, logger *slog.Logger) (*Server, error) {
parserRegistry := parser.NewRegistryWithSize(cfg.MaxParseSize)
s := &Server{
cfg: cfg,
logger: logger,
parser: parserRegistry,
matcher: query.NewMatcher(parserRegistry),
editor: edit.NewEngine(parserRegistry),
readSem: make(chan struct{}, MaxConcurrentReads),
querySem: make(chan struct{}, MaxConcurrentQueries),
}
// Initialize searcher
searcher, err := search.New(cfg, logger)
if err != nil {
logger.Warn("ripgrep not available, search functionality disabled", "error", err)
}
s.searcher = searcher
// Initialize LSP manager if enabled
if cfg.EnableLSP {
s.lspManager = lsp.NewManager(cfg.WorkspaceRoot, logger)
}
// Create MCP server
mcpServer := server.NewMCPServer(
"mcp-filepuff",
"1.0.0",
server.WithLogging(),
)
s.mcp = mcpServer
// Register tools
s.registerTools()
return s, nil
}
// registerTools registers all available tools with the MCP server.
func (s *Server) registerTools() {
// Register ping tool for health checks
s.mcp.AddTool(
mcp.NewTool("ping",
mcp.WithDescription("Health check - returns pong to verify the server is running.\n\n"+
"Returns: \"pong\" text string."),
mcp.WithReadOnlyHintAnnotation(true),
),
s.handlePing,
)
// Register file_search tool
if s.searcher != nil {
s.mcp.AddTool(
mcp.NewTool("file_search",
mcp.WithDescription("Search for text patterns in files using ripgrep. Supports regex patterns, file type filtering, and context lines.\n\n"+
"Returns: Results grouped by file with match context. Format: \"Found N matches in M files:\" followed by file sections, "+
"each with matching lines prefixed by \"L{line}│\" and context lines prefixed by \" │\".\n\n"+
"Example: {\"pattern\": \"func.*Error\", \"file_types\": [\"go\"], \"max_results\": 20}"),
mcp.WithReadOnlyHintAnnotation(true),
mcp.WithString("pattern",
mcp.Required(),
mcp.Description("The search pattern (regex by default)"),
),
mcp.WithArray("paths",
mcp.Description("Paths to search in (defaults to workspace root)"),
mcp.WithStringItems(),
),
mcp.WithArray("file_types",
mcp.Description("File types to search (e.g., ['go', 'ts', 'py'])"),
mcp.WithStringItems(),
),
mcp.WithBoolean("ignore_case",
mcp.Description("Case insensitive search"),
),
mcp.WithBoolean("regex",
mcp.Description("Treat pattern as regex (default: true)"),
),
mcp.WithNumber("context_lines",
mcp.Description("Number of context lines around matches (default: 2)"),
),
mcp.WithNumber("max_results",
mcp.Description("Maximum number of results to return"),
),
),
s.handleFileSearch,
)
}
// Register file_read tool
s.mcp.AddTool(
mcp.NewTool("file_read",
mcp.WithDescription("Read a file's contents with optional line range and AST symbol summary.\n\n"+
"Returns: File content with numbered lines (format: \" 12│ line text\"). "+
"When include_ast=true: prepends symbol summary (\"**file.go** (N lines, go)\\nSymbols:\\n func Name L12\\n struct Config L45\"). "+
"When symbols_only=true: returns only the symbol summary (~95% fewer tokens). "+
"When max_lines is set: truncates output with \"[... N more lines omitted]\" notice.\n\n"+
"Examples:\n"+
" Full file: {\"path\": \"main.go\"}\n"+
" With AST: {\"path\": \"main.go\", \"include_ast\": true}\n"+
" Symbols only: {\"path\": \"main.go\", \"include_ast\": true, \"symbols_only\": true}\n"+
" Line range: {\"path\": \"main.go\", \"line_start\": 10, \"line_end\": 50}"),
mcp.WithReadOnlyHintAnnotation(true),
mcp.WithString("path",
mcp.Required(),
mcp.Description("Path to the file to read"),
),
mcp.WithNumber("line_start",
mcp.Description("Starting line number (1-indexed)"),
),
mcp.WithNumber("line_end",
mcp.Description("Ending line number (inclusive)"),
),
mcp.WithBoolean("include_ast",
mcp.Description("Include AST symbol summary (functions, classes, types, etc.)"),
),
mcp.WithBoolean("symbols_only",
mcp.Description("Return only symbol summary without file content (token-efficient mode). Requires include_ast=true."),
),
mcp.WithNumber("max_lines",
mcp.Description("Maximum number of lines to return (for token efficiency). Applied after line_start/line_end."),
),
),
s.handleFileRead,
)
// Register ast_query tool
s.mcp.AddTool(
mcp.NewTool("ast_query",
mcp.WithDescription("Search for AST patterns in code files. Use code patterns with $VAR placeholders to match and capture code structures like functions, classes, and types.\n\n"+
"Returns: \"Found N match(es):\" followed by entries in format \"**file:line** (node_type)\" with code blocks "+
"and captured variables ($NAME=value). Returns \"No matches found.\" when no results.\n\n"+
"Examples:\n"+
" Go error funcs: {\"pattern\": \"func $NAME($$$ARGS) error\", \"language\": \"go\"}\n"+
" Python classes: {\"pattern\": \"class $NAME: $$$BODY\", \"language\": \"python\"}\n"+
" Named function: {\"pattern\": \"func $NAME($$$ARGS)\", \"language\": \"go\", \"name_exact\": \"NewServer\"}"),
mcp.WithReadOnlyHintAnnotation(true),
mcp.WithString("pattern",
mcp.Required(),
mcp.Description("Code pattern with placeholders: $NAME (single), $$$ARGS (multiple), $_ (wildcard). Examples: 'func $NAME($$$ARGS) error', 'class $NAME { $$$BODY }'"),
),
mcp.WithString("language",
mcp.Required(),
mcp.Description("Target language: go, typescript, javascript, python, c, cpp, html, vue, elixir, rust"),
),
mcp.WithArray("paths",
mcp.Description("Paths to search in (defaults to workspace root)"),
mcp.WithStringItems(),
),
mcp.WithString("name_matches",
mcp.Description("Regex pattern to filter by name"),
),
mcp.WithString("name_exact",
mcp.Description("Exact name to match"),
),
mcp.WithArray("kind_in",
mcp.Description("Node types to match (e.g., function_declaration, class_declaration)"),
mcp.WithStringItems(),
),
mcp.WithNumber("max_results",
mcp.Description("Maximum number of results to return (default: 100)"),
),
),
s.handleASTQuery,
)
// Register LSP-based tools if LSP is enabled
if s.lspManager != nil {
// Register symbol_at tool
s.mcp.AddTool(
mcp.NewTool("symbol_at",
mcp.WithDescription("Get information about the symbol at a specific position in a file. Returns type, documentation, and definition location using LSP when available.\n\n"+
"Returns: \"**Symbol Information**\" followed by hover/type information from LSP, or \"**Symbol Information** (AST fallback)\" "+
"with node type and text when LSP unavailable. Returns \"No symbol information available at this position.\" when nothing is found.\n\n"+
"Example: {\"file\": \"server.go\", \"line\": 45, \"column\": 6}"),
mcp.WithReadOnlyHintAnnotation(true),
mcp.WithString("file",
mcp.Required(),
mcp.Description("Path to the file"),
),
mcp.WithNumber("line",
mcp.Required(),
mcp.Description("Line number (1-indexed)"),
),
mcp.WithNumber("column",
mcp.Required(),
mcp.Description("Column number (1-indexed)"),
),
),
s.handleSymbolAt,
)
// Register find_definition tool
s.mcp.AddTool(
mcp.NewTool("find_definition",
mcp.WithDescription("Find the definition of the symbol at a specific position. Uses LSP to locate where a function, variable, type, etc. is defined.\n\n"+
"Returns: \"Found N definition(s):\" with entries showing \"**file:line:column**\" and a 3-line code preview "+
"with the target line marked by \">\". Returns \"No definition found.\" when the symbol has no definition.\n\n"+
"Example: {\"file\": \"handler.go\", \"line\": 23, \"column\": 10}"),
mcp.WithReadOnlyHintAnnotation(true),
mcp.WithString("file",
mcp.Required(),
mcp.Description("Path to the file"),
),
mcp.WithNumber("line",
mcp.Required(),
mcp.Description("Line number (1-indexed)"),
),
mcp.WithNumber("column",
mcp.Required(),
mcp.Description("Column number (1-indexed)"),
),
),
s.handleFindDefinition,
)
// Register find_references tool
s.mcp.AddTool(
mcp.NewTool("find_references",
mcp.WithDescription("Find all references to the symbol at a specific position. Uses LSP to locate all usages of a function, variable, type, etc.\n\n"+
"Returns: \"Found N reference(s):\" grouped by file, each showing \"**file** (count)\" with locations as "+
"\"L{line}:{column}\". Returns \"No references found.\" when no usages exist.\n\n"+
"Example: {\"file\": \"types.go\", \"line\": 5, \"column\": 6}"),
mcp.WithReadOnlyHintAnnotation(true),
mcp.WithString("file",
mcp.Required(),
mcp.Description("Path to the file"),
),
mcp.WithNumber("line",
mcp.Required(),
mcp.Description("Line number (1-indexed)"),
),
mcp.WithNumber("column",
mcp.Required(),
mcp.Description("Column number (1-indexed)"),
),
mcp.WithBoolean("include_declaration",
mcp.Description("Include the declaration in results (default: true)"),
),
),
s.handleFindReferences,
)
}
// Register edit tools
s.mcp.AddTool(
mcp.NewTool("edit_apply",
mcp.WithDescription("Apply an edit to a file. Uses AST-aware editing for code files (Go, TypeScript, JavaScript, Python, C, C++, Rust) with syntax validation, and text-based editing for other files (Markdown, JSON, YAML, config files, etc.).\n\n"+
"Returns: \"**Edit Applied Successfully**\" followed by a unified diff of the changes made. "+
"For code files, validates syntax before writing — returns an error if the edit would produce invalid syntax.\n\n"+
"Examples:\n"+
" AST mode: {\"file\": \"main.go\", \"operation\": \"replace\", \"selector_kind\": \"function_declaration\", \"selector_name\": \"Hello\", \"new_content\": \"func Hello() {\\n\\treturn\\n}\"}\n"+
" Text mode: {\"file\": \"README.md\", \"operation\": \"replace\", \"selector_text\": \"## Old Header\", \"new_content\": \"## New Header\"}\n"+
" Line range: {\"file\": \"config.yaml\", \"operation\": \"replace\", \"selector_line\": 5, \"selector_line_end\": 10, \"new_content\": \"key: value\"}"),
mcp.WithString("file",
mcp.Required(),
mcp.Description("Path to the file to edit"),
),
mcp.WithString("operation",
mcp.Required(),
mcp.Description("Edit operation: replace, insert_before, insert_after, delete"),
),
mcp.WithString("new_content",
mcp.Description("New content (required for replace/insert operations)"),
),
// AST-mode selectors (for code files)
mcp.WithString("selector_kind",
mcp.Description("AST node type to match (e.g., function_declaration, class_declaration). For code files only."),
),
mcp.WithString("selector_name",
mcp.Description("Name of the symbol to match. For code files only."),
),
// Shared selectors
mcp.WithNumber("selector_line",
mcp.Description("Line number (1-indexed). For AST mode: narrows search. For text mode: start of line range."),
),
mcp.WithNumber("selector_index",
mcp.Description("Index of the match to use if multiple matches found (default: 0)"),
),
// Text-mode selectors (for non-code files or explicit text matching)
mcp.WithNumber("selector_line_end",
mcp.Description("End line number for range selection (text mode). Used with selector_line."),
),
mcp.WithString("selector_text",
mcp.Description("Exact text to match (text mode). Must be unique or use selector_index."),
),
mcp.WithString("selector_pattern",
mcp.Description("Regex pattern to match (text mode). Must be unique or use selector_index."),
),
),
s.handleEditApply,
)
}
// handlePing handles the ping health check tool.
func (s *Server) handlePing(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
return mcp.NewToolResultText("pong"), nil
}
// Run starts the MCP server and blocks until shutdown.
func (s *Server) Run(ctx context.Context) error {
// Set up signal handling for graceful shutdown
ctx, cancel := context.WithCancel(ctx)
defer cancel()
sigChan := make(chan os.Signal, 1)
signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
defer signal.Stop(sigChan)
// Channel to communicate server errors
errChan := make(chan error, 1)
// Start server in goroutine
go func() {
s.logger.Info("starting MCP server",
"workspace", s.cfg.WorkspaceRoot,
"lsp_enabled", s.cfg.EnableLSP,
)
errChan <- server.ServeStdio(s.mcp)
}()
// Wait for either signal or server error
select {
case sig := <-sigChan:
s.logger.Info("received shutdown signal", "signal", sig)
// Create timeout context for shutdown
shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), ServerShutdownTimeout)
defer shutdownCancel()
// Call graceful shutdown
if err := s.Shutdown(shutdownCtx); err != nil {
s.logger.Error("error during shutdown", "error", err)
return err
}
s.logger.Info("server shutdown complete")
return nil
case err := <-errChan:
// Server stopped on its own
return err
case <-ctx.Done():
// Context cancelled externally
shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), ServerShutdownTimeout)
defer shutdownCancel()
if err := s.Shutdown(shutdownCtx); err != nil {
s.logger.Error("error during shutdown", "error", err)
}
return ctx.Err()
}
}
// Shutdown gracefully shuts down the server.
func (s *Server) Shutdown(ctx context.Context) error {
s.logger.Info("shutting down MCP server")
// Close LSP manager
if s.lspManager != nil {
_ = s.lspManager.Close()
}
// Close parser registry
if s.parser != nil {
s.parser.Close()
}
return nil
}