fastmcp_server/providers/

filesystem.rs

//! Filesystem resource provider.
//!
//! Exposes files from a directory as MCP resources with configurable
//! patterns, security controls, and MIME type detection.
//!
//! # Security
//!
//! The provider includes path traversal protection to prevent accessing
//! files outside the configured root directory.
//!
//! # Example
//!
//! ```ignore
//! use fastmcp_server::providers::FilesystemProvider;
//!
//! let provider = FilesystemProvider::new("/data/docs")
//!     .with_prefix("docs")
//!     .with_patterns(&["**/*.md", "**/*.txt"])
//!     .with_exclude(&["**/secret/**", "**/.*"])
//!     .with_recursive(true)
//!     .with_max_size(10 * 1024 * 1024); // 10MB limit
//! ```

use std::path::{Path, PathBuf};

use fastmcp_core::{McpContext, McpError, McpOutcome, McpResult, Outcome};
use fastmcp_protocol::{Resource, ResourceContent, ResourceTemplate};

use crate::handler::{BoxFuture, ResourceHandler, UriParams};

/// Default maximum file size (10 MB).
const DEFAULT_MAX_SIZE: usize = 10 * 1024 * 1024;

/// Errors that can occur when using the filesystem provider.
#[derive(Debug, Clone)]
pub enum FilesystemProviderError {
    /// The requested path would escape the root directory.
    PathTraversal { requested: String },
    /// The file exceeds the maximum allowed size.
    TooLarge { path: String, size: u64, max: usize },
    /// Symlink access was denied.
    SymlinkDenied { path: String },
    /// Symlink target escapes the root directory.
    SymlinkEscapesRoot { path: String },
    /// IO error occurred.
    Io { message: String },
    /// File not found.
    NotFound { path: String },
}

impl std::fmt::Display for FilesystemProviderError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::PathTraversal { requested } => {
                write!(f, "Path traversal attempt blocked: {requested}")
            }
            Self::TooLarge { path, size, max } => {
                write!(f, "File too large: {path} ({size} bytes, max {max} bytes)")
            }
            Self::SymlinkDenied { path } => {
                write!(f, "Symlink access denied: {path}")
            }
            Self::SymlinkEscapesRoot { path } => {
                write!(f, "Symlink target escapes root directory: {path}")
            }
            Self::Io { message } => write!(f, "IO error: {message}"),
            Self::NotFound { path } => write!(f, "File not found: {path}"),
        }
    }
}

impl std::error::Error for FilesystemProviderError {}

impl From<FilesystemProviderError> for McpError {
    fn from(err: FilesystemProviderError) -> Self {
        match err {
            FilesystemProviderError::PathTraversal { .. } => {
                // Security violation - path traversal attempt
                McpError::invalid_request(err.to_string())
            }
            FilesystemProviderError::TooLarge { .. } => McpError::invalid_request(err.to_string()),
            FilesystemProviderError::SymlinkDenied { .. }
            | FilesystemProviderError::SymlinkEscapesRoot { .. } => {
                // Security violation - symlink escape attempt
                McpError::invalid_request(err.to_string())
            }
            FilesystemProviderError::Io { .. } => McpError::internal_error(err.to_string()),
            FilesystemProviderError::NotFound { path } => McpError::resource_not_found(&path),
        }
    }
}

/// A resource provider that exposes filesystem directories.
///
/// Files under the configured root directory are exposed as MCP resources
/// with URIs like `file://{prefix}/{relative_path}`.
///
/// # Security
///
/// - Path traversal attempts (e.g., `../../../etc/passwd`) are blocked
/// - Symlinks can be optionally followed or blocked
/// - Maximum file size limits prevent memory exhaustion
/// - Hidden files (starting with `.`) can be excluded
///
/// # Example
///
/// ```ignore
/// use fastmcp_server::providers::FilesystemProvider;
///
/// let provider = FilesystemProvider::new("/app/data")
///     .with_prefix("data")
///     .with_patterns(&["*.json", "*.yaml"])
///     .with_recursive(true);
/// ```
#[derive(Debug, Clone)]
pub struct FilesystemProvider {
    /// Root directory for file access.
    root: PathBuf,
    /// URI prefix (e.g., "docs" -> "file://docs/...").
    prefix: Option<String>,
    /// Glob patterns to include (empty = all files).
    include_patterns: Vec<String>,
    /// Glob patterns to exclude.
    exclude_patterns: Vec<String>,
    /// Whether to traverse subdirectories.
    recursive: bool,
    /// Maximum file size in bytes.
    max_file_size: usize,
    /// Whether to follow symlinks.
    follow_symlinks: bool,
    /// Description for the resource template.
    description: Option<String>,
}

impl FilesystemProvider {
    /// Creates a new filesystem provider for the given root directory.
    ///
    /// # Arguments
    ///
    /// * `root` - The root directory to expose
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data/docs");
    /// ```
    #[must_use]
    pub fn new(root: impl AsRef<Path>) -> Self {
        Self {
            root: root.as_ref().to_path_buf(),
            prefix: None,
            include_patterns: Vec::new(),
            exclude_patterns: vec![".*".to_string()], // Exclude hidden files by default
            recursive: false,
            max_file_size: DEFAULT_MAX_SIZE,
            follow_symlinks: false,
            description: None,
        }
    }

    /// Sets the URI prefix for resources.
    ///
    /// Files will have URIs like `file://{prefix}/{path}`.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data")
    ///     .with_prefix("mydata");
    /// // Results in URIs like file://mydata/readme.md
    /// ```
    #[must_use]
    pub fn with_prefix(mut self, prefix: impl Into<String>) -> Self {
        self.prefix = Some(prefix.into());
        self
    }

    /// Sets glob patterns to include.
    ///
    /// Only files matching at least one of these patterns will be exposed.
    /// Empty patterns means all files are included.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data")
    ///     .with_patterns(&["*.md", "*.txt", "**/*.json"]);
    /// ```
    #[must_use]
    pub fn with_patterns(mut self, patterns: &[&str]) -> Self {
        self.include_patterns = patterns.iter().map(|s| (*s).to_string()).collect();
        self
    }

    /// Sets glob patterns to exclude.
    ///
    /// Files matching any of these patterns will be excluded.
    /// By default, hidden files (starting with `.`) are excluded.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data")
    ///     .with_exclude(&["**/secret/**", "*.bak"]);
    /// ```
    #[must_use]
    pub fn with_exclude(mut self, patterns: &[&str]) -> Self {
        self.exclude_patterns = patterns.iter().map(|s| (*s).to_string()).collect();
        self
    }

    /// Enables or disables recursive directory traversal.
    ///
    /// When enabled, files in subdirectories are also exposed.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data")
    ///     .with_recursive(true);
    /// ```
    #[must_use]
    pub fn with_recursive(mut self, enabled: bool) -> Self {
        self.recursive = enabled;
        self
    }

    /// Sets the maximum file size in bytes.
    ///
    /// Files larger than this limit will return an error when read.
    /// Default is 10 MB.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data")
    ///     .with_max_size(5 * 1024 * 1024); // 5 MB
    /// ```
    #[must_use]
    pub fn with_max_size(mut self, bytes: usize) -> Self {
        self.max_file_size = bytes;
        self
    }

    /// Enables or disables following symlinks.
    ///
    /// When disabled (default), symlinks are not followed.
    /// When enabled, symlinks are followed but must still point within the root directory.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data")
    ///     .with_follow_symlinks(true);
    /// ```
    #[must_use]
    pub fn with_follow_symlinks(mut self, enabled: bool) -> Self {
        self.follow_symlinks = enabled;
        self
    }

    /// Sets the description for the resource template.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let provider = FilesystemProvider::new("/data")
    ///     .with_description("Documentation files");
    /// ```
    #[must_use]
    pub fn with_description(mut self, description: impl Into<String>) -> Self {
        self.description = Some(description.into());
        self
    }

    /// Builds a resource handler from this provider.
    ///
    /// The returned handler can be registered with a server.
    ///
    /// # Example
    ///
    /// ```ignore
    /// let handler = FilesystemProvider::new("/data")
    ///     .with_prefix("docs")
    ///     .build();
    ///
    /// let server = Server::new("demo", "1.0")
    ///     .resource(handler);
    /// ```
    #[must_use]
    pub fn build(self) -> FilesystemResourceHandler {
        FilesystemResourceHandler::new(self)
    }

    /// Validates a path and returns the canonical path if valid.
    ///
    /// Returns an error if:
    /// - The path is absolute
    /// - The path escapes the root directory
    /// - The path is a symlink and symlinks are disabled
    fn validate_path(&self, requested: &str) -> Result<PathBuf, FilesystemProviderError> {
        let requested_path = Path::new(requested);

        // Reject absolute paths in request
        if requested_path.is_absolute() {
            return Err(FilesystemProviderError::PathTraversal {
                requested: requested.to_string(),
            });
        }

        // Build full path
        let full_path = self.root.join(requested_path);

        // Canonicalize to resolve ../ etc.
        // Note: canonicalize requires the path to exist
        let canonical = full_path.canonicalize().map_err(|e| {
            if e.kind() == std::io::ErrorKind::NotFound {
                FilesystemProviderError::NotFound {
                    path: requested.to_string(),
                }
            } else {
                FilesystemProviderError::Io {
                    message: e.to_string(),
                }
            }
        })?;

        // Get canonical root for comparison
        let canonical_root = self
            .root
            .canonicalize()
            .map_err(|e| FilesystemProviderError::Io {
                message: format!("Cannot canonicalize root: {e}"),
            })?;

        // Verify still under root
        if !canonical.starts_with(&canonical_root) {
            return Err(FilesystemProviderError::PathTraversal {
                requested: requested.to_string(),
            });
        }

        // Check symlink
        if full_path.is_symlink() {
            self.check_symlink(&full_path, &canonical_root)?;
        }

        Ok(canonical)
    }

    /// Checks if a symlink is allowed.
    fn check_symlink(
        &self,
        path: &Path,
        canonical_root: &Path,
    ) -> Result<(), FilesystemProviderError> {
        if !self.follow_symlinks {
            return Err(FilesystemProviderError::SymlinkDenied {
                path: path.display().to_string(),
            });
        }

        // Verify symlink target is still under root
        let target = std::fs::read_link(path).map_err(|e| FilesystemProviderError::Io {
            message: e.to_string(),
        })?;

        let resolved = if target.is_absolute() {
            target
        } else {
            path.parent().unwrap_or(Path::new("")).join(&target)
        };

        let canonical_target =
            resolved
                .canonicalize()
                .map_err(|e| FilesystemProviderError::Io {
                    message: e.to_string(),
                })?;

        if !canonical_target.starts_with(canonical_root) {
            return Err(FilesystemProviderError::SymlinkEscapesRoot {
                path: path.display().to_string(),
            });
        }

        Ok(())
    }

    /// Checks if a filename matches the include/exclude patterns.
    fn matches_patterns(&self, relative_path: &str) -> bool {
        // Check exclude patterns first
        for pattern in &self.exclude_patterns {
            if glob_match(pattern, relative_path) {
                return false;
            }
        }

        // If no include patterns, include everything
        if self.include_patterns.is_empty() {
            return true;
        }

        // Check include patterns
        for pattern in &self.include_patterns {
            if glob_match(pattern, relative_path) {
                return true;
            }
        }

        false
    }

    /// Lists files in the directory that match patterns.
    fn list_files(&self) -> Result<Vec<FileEntry>, FilesystemProviderError> {
        let canonical_root = self
            .root
            .canonicalize()
            .map_err(|e| FilesystemProviderError::Io {
                message: format!("Cannot canonicalize root: {e}"),
            })?;

        let mut entries = Vec::new();
        self.walk_directory(&canonical_root, &canonical_root, &mut entries)?;
        Ok(entries)
    }

    /// Recursively walks a directory collecting file entries.
    fn walk_directory(
        &self,
        current: &Path,
        root: &Path,
        entries: &mut Vec<FileEntry>,
    ) -> Result<(), FilesystemProviderError> {
        let read_dir = std::fs::read_dir(current).map_err(|e| FilesystemProviderError::Io {
            message: e.to_string(),
        })?;

        for entry_result in read_dir {
            let entry = entry_result.map_err(|e| FilesystemProviderError::Io {
                message: e.to_string(),
            })?;

            let path = entry.path();
            let file_type = entry.file_type().map_err(|e| FilesystemProviderError::Io {
                message: e.to_string(),
            })?;

            // Handle symlinks
            if file_type.is_symlink() && !self.follow_symlinks {
                continue;
            }

            // Calculate relative path
            let relative = path
                .strip_prefix(root)
                .map_err(|e| FilesystemProviderError::Io {
                    message: e.to_string(),
                })?;
            let relative_str = relative.to_string_lossy().replace('\\', "/");

            if file_type.is_dir() || (file_type.is_symlink() && path.is_dir()) {
                if self.recursive {
                    self.walk_directory(&path, root, entries)?;
                }
            } else if file_type.is_file() || (file_type.is_symlink() && path.is_file()) {
                // Check patterns
                if self.matches_patterns(&relative_str) {
                    let metadata = std::fs::metadata(&path).ok();
                    entries.push(FileEntry {
                        path: path.clone(),
                        relative_path: relative_str,
                        size: metadata.as_ref().map(|m| m.len()),
                        mime_type: detect_mime_type(&path),
                    });
                }
            }
        }

        Ok(())
    }

    /// Returns the URI for a file.
    fn file_uri(&self, relative_path: &str) -> String {
        match &self.prefix {
            Some(prefix) => format!("file://{prefix}/{relative_path}"),
            None => format!("file://{relative_path}"),
        }
    }

    /// Returns the URI template for this provider.
    fn uri_template(&self) -> String {
        match &self.prefix {
            Some(prefix) => format!("file://{prefix}/{{path}}"),
            None => "file://{path}".to_string(),
        }
    }

    /// Extracts the relative path from a URI.
    fn path_from_uri(&self, uri: &str) -> Option<String> {
        let expected_prefix = match &self.prefix {
            Some(p) => format!("file://{p}/"),
            None => "file://".to_string(),
        };

        if uri.starts_with(&expected_prefix) {
            Some(uri[expected_prefix.len()..].to_string())
        } else {
            None
        }
    }

    /// Reads a file and returns its content.
    fn read_file(&self, relative_path: &str) -> Result<FileContent, FilesystemProviderError> {
        // Validate and get canonical path
        let path = self.validate_path(relative_path)?;

        // Check file size
        let metadata = std::fs::metadata(&path).map_err(|e| {
            if e.kind() == std::io::ErrorKind::NotFound {
                FilesystemProviderError::NotFound {
                    path: relative_path.to_string(),
                }
            } else {
                FilesystemProviderError::Io {
                    message: e.to_string(),
                }
            }
        })?;

        if metadata.len() > self.max_file_size as u64 {
            return Err(FilesystemProviderError::TooLarge {
                path: relative_path.to_string(),
                size: metadata.len(),
                max: self.max_file_size,
            });
        }

        // Detect MIME type
        let mime_type = detect_mime_type(&path);

        // Read content
        let content = if is_binary_mime_type(&mime_type) {
            let bytes = std::fs::read(&path).map_err(|e| FilesystemProviderError::Io {
                message: e.to_string(),
            })?;
            FileContent::Binary(bytes)
        } else {
            let text = std::fs::read_to_string(&path).map_err(|e| FilesystemProviderError::Io {
                message: e.to_string(),
            })?;
            FileContent::Text(text)
        };

        Ok(content)
    }
}

/// A file entry from directory listing.
#[derive(Debug)]
struct FileEntry {
    #[allow(dead_code)]
    path: PathBuf,
    relative_path: String,
    #[allow(dead_code)]
    size: Option<u64>,
    mime_type: String,
}

/// File content (text or binary).
enum FileContent {
    Text(String),
    Binary(Vec<u8>),
}

/// Resource handler implementation for the filesystem provider.
pub struct FilesystemResourceHandler {
    provider: FilesystemProvider,
    /// Cached file list for static resources.
    cached_resources: Vec<Resource>,
}

impl FilesystemResourceHandler {
    /// Creates a new handler from a provider.
    fn new(provider: FilesystemProvider) -> Self {
        // Pre-compute the list of resources
        let cached_resources = match provider.list_files() {
            Ok(entries) => entries
                .into_iter()
                .map(|entry| Resource {
                    uri: provider.file_uri(&entry.relative_path),
                    name: entry.relative_path.clone(),
                    description: None,
                    mime_type: Some(entry.mime_type),
                    icon: None,
                    version: None,
                    tags: vec![],
                })
                .collect(),
            Err(_) => Vec::new(),
        };

        Self {
            provider,
            cached_resources,
        }
    }
}

impl ResourceHandler for FilesystemResourceHandler {
    fn definition(&self) -> Resource {
        // Return a synthetic "root" resource for the provider
        Resource {
            uri: self.provider.uri_template(),
            name: self
                .provider
                .prefix
                .clone()
                .unwrap_or_else(|| "files".to_string()),
            description: self.provider.description.clone(),
            mime_type: None,
            icon: None,
            version: None,
            tags: vec![],
        }
    }

    fn template(&self) -> Option<ResourceTemplate> {
        Some(ResourceTemplate {
            uri_template: self.provider.uri_template(),
            name: self
                .provider
                .prefix
                .clone()
                .unwrap_or_else(|| "files".to_string()),
            description: self.provider.description.clone(),
            mime_type: None,
            icon: None,
            version: None,
            tags: vec![],
        })
    }

    fn read(&self, _ctx: &McpContext) -> McpResult<Vec<ResourceContent>> {
        // For template resources, read() without params returns the file list
        let files = self.provider.list_files()?;

        let listing = files
            .iter()
            .map(|f| format!("{}: {}", f.relative_path, f.mime_type))
            .collect::<Vec<_>>()
            .join("\n");

        Ok(vec![ResourceContent {
            uri: self.provider.uri_template(),
            mime_type: Some("text/plain".to_string()),
            text: Some(listing),
            blob: None,
        }])
    }

    fn read_with_uri(
        &self,
        _ctx: &McpContext,
        uri: &str,
        params: &UriParams,
    ) -> McpResult<Vec<ResourceContent>> {
        // Extract path from URI or params
        let relative_path = if let Some(path) = params.get("path") {
            path.clone()
        } else if let Some(path) = self.provider.path_from_uri(uri) {
            path
        } else {
            return Err(McpError::invalid_params("Missing path parameter"));
        };

        let content = self.provider.read_file(&relative_path)?;

        let resource_content = match content {
            FileContent::Text(text) => ResourceContent {
                uri: uri.to_string(),
                mime_type: Some(detect_mime_type(Path::new(&relative_path))),
                text: Some(text),
                blob: None,
            },
            FileContent::Binary(bytes) => {
                let base64_str = base64_encode(&bytes);

                ResourceContent {
                    uri: uri.to_string(),
                    mime_type: Some(detect_mime_type(Path::new(&relative_path))),
                    text: None,
                    blob: Some(base64_str),
                }
            }
        };

        Ok(vec![resource_content])
    }

    fn read_async_with_uri<'a>(
        &'a self,
        ctx: &'a McpContext,
        uri: &'a str,
        params: &'a UriParams,
    ) -> BoxFuture<'a, McpOutcome<Vec<ResourceContent>>> {
        Box::pin(async move {
            match self.read_with_uri(ctx, uri, params) {
                Ok(v) => Outcome::Ok(v),
                Err(e) => Outcome::Err(e),
            }
        })
    }
}

impl std::fmt::Debug for FilesystemResourceHandler {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("FilesystemResourceHandler")
            .field("provider", &self.provider)
            .field("cached_resources", &self.cached_resources.len())
            .finish()
    }
}

/// Detects the MIME type for a file based on its extension.
fn detect_mime_type(path: &Path) -> String {
    let extension = path
        .extension()
        .and_then(|e| e.to_str())
        .map(str::to_lowercase);

    match extension.as_deref() {
        // Text formats
        Some("txt") => "text/plain",
        Some("md" | "markdown") => "text/markdown",
        Some("html" | "htm") => "text/html",
        Some("css") => "text/css",
        Some("csv") => "text/csv",
        Some("xml") => "application/xml",

        // Programming languages
        Some("rs") => "text/x-rust",
        Some("py") => "text/x-python",
        Some("js" | "mjs") => "text/javascript",
        Some("ts" | "mts") => "text/typescript",
        Some("json") => "application/json",
        Some("yaml" | "yml") => "application/yaml",
        Some("toml") => "application/toml",
        Some("sh" | "bash") => "text/x-shellscript",
        Some("c") => "text/x-c",
        Some("cpp" | "cc" | "cxx") => "text/x-c++",
        Some("h" | "hpp") => "text/x-c-header",
        Some("java") => "text/x-java",
        Some("go") => "text/x-go",
        Some("rb") => "text/x-ruby",
        Some("php") => "text/x-php",
        Some("swift") => "text/x-swift",
        Some("kt" | "kts") => "text/x-kotlin",
        Some("sql") => "text/x-sql",

        // Images
        Some("png") => "image/png",
        Some("jpg" | "jpeg") => "image/jpeg",
        Some("gif") => "image/gif",
        Some("svg") => "image/svg+xml",
        Some("webp") => "image/webp",
        Some("ico") => "image/x-icon",
        Some("bmp") => "image/bmp",

        // Binary/Documents
        Some("pdf") => "application/pdf",
        Some("zip") => "application/zip",
        Some("gz" | "gzip") => "application/gzip",
        Some("tar") => "application/x-tar",
        Some("wasm") => "application/wasm",
        Some("exe") => "application/octet-stream",
        Some("dll") => "application/octet-stream",
        Some("so") => "application/octet-stream",
        Some("bin") => "application/octet-stream",

        // Default
        _ => "application/octet-stream",
    }
    .to_string()
}

/// Checks if a MIME type represents binary content.
fn is_binary_mime_type(mime_type: &str) -> bool {
    mime_type.starts_with("image/")
        || mime_type.starts_with("audio/")
        || mime_type.starts_with("video/")
        || mime_type == "application/octet-stream"
        || mime_type == "application/pdf"
        || mime_type == "application/zip"
        || mime_type == "application/gzip"
        || mime_type == "application/x-tar"
        || mime_type == "application/wasm"
}

/// Standard base64 alphabet.
const BASE64_CHARS: &[u8; 64] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/// Encodes bytes to standard base64.
fn base64_encode(data: &[u8]) -> String {
    let mut result = String::with_capacity((data.len() + 2) / 3 * 4);

    for chunk in data.chunks(3) {
        let b0 = chunk[0] as usize;
        let b1 = chunk.get(1).copied().unwrap_or(0) as usize;
        let b2 = chunk.get(2).copied().unwrap_or(0) as usize;

        let combined = (b0 << 16) | (b1 << 8) | b2;

        result.push(BASE64_CHARS[(combined >> 18) & 0x3F] as char);
        result.push(BASE64_CHARS[(combined >> 12) & 0x3F] as char);

        if chunk.len() > 1 {
            result.push(BASE64_CHARS[(combined >> 6) & 0x3F] as char);
        } else {
            result.push('=');
        }

        if chunk.len() > 2 {
            result.push(BASE64_CHARS[combined & 0x3F] as char);
        } else {
            result.push('=');
        }
    }

    result
}

/// Simple glob pattern matching.
///
/// Supports:
/// - `*` - matches any sequence of characters (except `/`)
/// - `**` - matches any sequence of characters (including `/`)
/// - `?` - matches any single character
fn glob_match(pattern: &str, path: &str) -> bool {
    glob_match_recursive(pattern, path)
}

/// Recursive glob matching implementation.
fn glob_match_recursive(pattern: &str, path: &str) -> bool {
    let mut pattern_chars = pattern.chars().peekable();
    let mut path_chars = path.chars().peekable();

    while let Some(p) = pattern_chars.next() {
        match p {
            '*' => {
                // Check for **
                if pattern_chars.peek() == Some(&'*') {
                    pattern_chars.next(); // consume second *

                    // Skip optional / after **
                    if pattern_chars.peek() == Some(&'/') {
                        pattern_chars.next();
                    }

                    let remaining_pattern: String = pattern_chars.collect();

                    // ** matches zero or more path segments
                    // Try matching from current position and all subsequent positions
                    let remaining_path: String = path_chars.collect();

                    // Try matching with empty ** (zero segments)
                    if glob_match_recursive(&remaining_pattern, &remaining_path) {
                        return true;
                    }

                    // Try matching with ** consuming characters one at a time
                    for i in 0..=remaining_path.len() {
                        if glob_match_recursive(&remaining_pattern, &remaining_path[i..]) {
                            return true;
                        }
                    }
                    return false;
                }

                // Single * - match anything except /
                let remaining_pattern: String = pattern_chars.collect();
                let remaining_path: String = path_chars.collect();

                // Try matching with * consuming 0, 1, 2, ... characters (but not /)
                for i in 0..=remaining_path.len() {
                    // Check if the portion we're consuming contains /
                    if remaining_path[..i].contains('/') {
                        break;
                    }
                    if glob_match_recursive(&remaining_pattern, &remaining_path[i..]) {
                        return true;
                    }
                }
                return false;
            }
            '?' => {
                // Match any single character
                if path_chars.next().is_none() {
                    return false;
                }
            }
            c => {
                // Literal character
                if path_chars.next() != Some(c) {
                    return false;
                }
            }
        }
    }

    // Pattern exhausted - path should also be exhausted
    path_chars.next().is_none()
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::collections::HashMap;
    use std::path::Path;
    use std::sync::atomic::{AtomicU64, Ordering};
    use std::time::{SystemTime, UNIX_EPOCH};

    static TEST_DIR_SEQ: AtomicU64 = AtomicU64::new(1);

    struct TestDir {
        path: PathBuf,
    }

    impl TestDir {
        fn new(label: &str) -> Self {
            let mut path = std::env::temp_dir();
            let seq = TEST_DIR_SEQ.fetch_add(1, Ordering::SeqCst);
            let nanos = SystemTime::now()
                .duration_since(UNIX_EPOCH)
                .expect("system clock before epoch")
                .as_nanos();
            path.push(format!(
                "fastmcp-fs-tests-{label}-{}-{seq}-{nanos}",
                std::process::id()
            ));
            std::fs::create_dir_all(&path).expect("create temp test dir");
            Self { path }
        }

        fn join(&self, relative: &str) -> PathBuf {
            self.path.join(relative)
        }

        fn path(&self) -> &Path {
            &self.path
        }
    }

    impl Drop for TestDir {
        fn drop(&mut self) {
            let _ = std::fs::remove_dir_all(&self.path);
        }
    }

    fn write_text(path: &Path, content: &str) {
        if let Some(parent) = path.parent() {
            std::fs::create_dir_all(parent).expect("create parent dir");
        }
        std::fs::write(path, content).expect("write text file");
    }

    fn write_bytes(path: &Path, bytes: &[u8]) {
        if let Some(parent) = path.parent() {
            std::fs::create_dir_all(parent).expect("create parent dir");
        }
        std::fs::write(path, bytes).expect("write binary file");
    }

    #[test]
    fn test_glob_match_star() {
        assert!(glob_match("*.md", "readme.md"));
        assert!(glob_match("*.md", "CHANGELOG.md"));
        assert!(!glob_match("*.md", "readme.txt"));
        assert!(!glob_match("*.md", "dir/readme.md")); // * doesn't match /
    }

    #[test]
    fn test_glob_match_double_star() {
        assert!(glob_match("**/*.md", "readme.md"));
        assert!(glob_match("**/*.md", "docs/readme.md"));
        assert!(glob_match("**/*.md", "docs/api/readme.md"));
        assert!(!glob_match("**/*.md", "readme.txt"));
    }

    #[test]
    fn test_glob_match_question() {
        assert!(glob_match("file?.txt", "file1.txt"));
        assert!(glob_match("file?.txt", "fileA.txt"));
        assert!(!glob_match("file?.txt", "file12.txt"));
    }

    #[test]
    fn test_glob_match_hidden() {
        assert!(glob_match(".*", ".hidden"));
        assert!(glob_match(".*", ".gitignore"));
        assert!(!glob_match(".*", "visible"));
    }

    #[test]
    fn test_detect_mime_type() {
        assert_eq!(detect_mime_type(Path::new("file.md")), "text/markdown");
        assert_eq!(detect_mime_type(Path::new("file.json")), "application/json");
        assert_eq!(detect_mime_type(Path::new("file.rs")), "text/x-rust");
        assert_eq!(detect_mime_type(Path::new("file.png")), "image/png");
        assert_eq!(
            detect_mime_type(Path::new("file.unknown")),
            "application/octet-stream"
        );
    }

    #[test]
    fn test_is_binary_mime_type() {
        assert!(is_binary_mime_type("image/png"));
        assert!(is_binary_mime_type("application/pdf"));
        assert!(!is_binary_mime_type("text/plain"));
        assert!(!is_binary_mime_type("application/json"));
    }

    #[test]
    fn test_provider_list_files_respects_patterns_and_recursion() {
        let root = TestDir::new("list-recursive");
        write_text(&root.join("README.md"), "# readme");
        write_text(&root.join("notes.txt"), "notes");
        write_text(&root.join("nested/info.md"), "# nested");
        write_text(&root.join("nested/code.rs"), "fn main() {}");

        let provider = FilesystemProvider::new(root.path())
            .with_patterns(&["**/*.md", "**/*.txt"])
            .with_recursive(true);

        let files = provider.list_files().expect("list files");
        let mut relative_paths = files
            .iter()
            .map(|entry| entry.relative_path.as_str())
            .collect::<Vec<_>>();
        relative_paths.sort_unstable();

        assert_eq!(
            relative_paths,
            vec!["README.md", "nested/info.md", "notes.txt"]
        );
    }

    #[test]
    fn test_provider_list_files_non_recursive_skips_subdirectories() {
        let root = TestDir::new("list-flat");
        write_text(&root.join("root.md"), "root");
        write_text(&root.join("nested/child.md"), "child");

        let provider = FilesystemProvider::new(root.path())
            .with_patterns(&["**/*.md"])
            .with_recursive(false);

        let files = provider.list_files().expect("list files");
        let relative_paths = files
            .iter()
            .map(|entry| entry.relative_path.as_str())
            .collect::<Vec<_>>();
        assert_eq!(relative_paths, vec!["root.md"]);
    }

    #[test]
    fn test_validate_path_rejects_absolute_and_parent_escape() {
        let root = TestDir::new("validate-path");
        write_text(&root.join("safe.txt"), "safe");

        let outside_file = root
            .path()
            .parent()
            .expect("temp dir has parent")
            .join("outside-fastmcp-provider-test.txt");
        write_text(&outside_file, "outside");

        let provider = FilesystemProvider::new(root.path());

        // Use a platform-appropriate absolute path: on Windows
        // `/tmp/absolute.txt` is *not* absolute (no drive letter), so the
        // hard-coded Unix string fails to exercise the absolute-path
        // rejection branch and the assertion below misfires.
        let absolute_input = if cfg!(windows) {
            r"C:\Windows\System32\absolute.txt"
        } else {
            "/tmp/absolute.txt"
        };
        let absolute = provider.validate_path(absolute_input);
        assert!(matches!(
            absolute,
            Err(FilesystemProviderError::PathTraversal { .. })
        ));

        let escape = provider.validate_path("../outside-fastmcp-provider-test.txt");
        assert!(matches!(
            escape,
            Err(FilesystemProviderError::PathTraversal { .. })
        ));

        let ok = provider.validate_path("safe.txt").expect("safe path");
        assert!(ok.ends_with("safe.txt"));
    }

    #[test]
    fn test_read_file_text_binary_and_size_limit() {
        let root = TestDir::new("read-file");
        write_text(&root.join("doc.txt"), "hello world");
        write_bytes(&root.join("blob.bin"), &[0x00, 0x7F, 0xAA, 0x55]);
        write_bytes(&root.join("large.bin"), &[0u8; 8]);

        let provider = FilesystemProvider::new(root.path()).with_max_size(32);

        let text = provider.read_file("doc.txt").expect("read text");
        assert!(matches!(text, FileContent::Text(ref t) if t == "hello world"));

        let binary = provider.read_file("blob.bin").expect("read binary");
        assert!(matches!(binary, FileContent::Binary(ref b) if b == &[0x00, 0x7F, 0xAA, 0x55]));

        let size_limited = FilesystemProvider::new(root.path()).with_max_size(4);
        let too_large = size_limited.read_file("large.bin");
        assert!(matches!(
            too_large,
            Err(FilesystemProviderError::TooLarge { path, size: 8, max: 4 })
                if path == "large.bin"
        ));
    }

    #[test]
    fn test_handler_read_listing_and_read_with_uri() {
        let root = TestDir::new("handler-read");
        write_text(&root.join("docs/readme.md"), "# docs");

        let handler = FilesystemProvider::new(root.path())
            .with_prefix("docs")
            .with_patterns(&["**/*.md"])
            .with_recursive(true)
            .with_description("Documentation")
            .build();

        let ctx = McpContext::new(asupersync::Cx::for_testing(), 1);

        let definition = handler.definition();
        assert_eq!(definition.uri, "file://docs/{path}");
        assert_eq!(definition.name, "docs");
        assert_eq!(definition.description.as_deref(), Some("Documentation"));

        let template = handler.template().expect("resource template");
        assert_eq!(template.uri_template, "file://docs/{path}");

        let listing = handler.read(&ctx).expect("read listing");
        let listing_text = listing[0].text.as_deref().expect("listing text");
        assert!(listing_text.contains("docs/readme.md: text/markdown"));

        let mut params = HashMap::new();
        params.insert("path".to_string(), "docs/readme.md".to_string());
        let content = handler
            .read_with_uri(&ctx, "file://docs/docs/readme.md", &params)
            .expect("read with params");
        assert_eq!(content[0].text.as_deref(), Some("# docs"));

        let empty_params = HashMap::new();
        let content_from_uri = handler
            .read_with_uri(&ctx, "file://docs/docs/readme.md", &empty_params)
            .expect("read using uri path");
        assert_eq!(content_from_uri[0].text.as_deref(), Some("# docs"));

        let invalid = handler.read_with_uri(&ctx, "file://wrong-prefix/readme.md", &empty_params);
        assert!(invalid.is_err());
    }

    #[test]
    fn test_handler_read_async_with_uri() {
        let root = TestDir::new("handler-async");
        write_text(&root.join("notes.md"), "async content");

        let handler = FilesystemProvider::new(root.path())
            .with_patterns(&["*.md"])
            .build();
        let ctx = McpContext::new(asupersync::Cx::for_testing(), 9);

        let mut params = HashMap::new();
        params.insert("path".to_string(), "notes.md".to_string());
        let outcome =
            fastmcp_core::block_on(handler.read_async_with_uri(&ctx, "file://notes.md", &params));
        match outcome {
            Outcome::Ok(content) => {
                assert_eq!(content.len(), 1);
                assert_eq!(content[0].text.as_deref(), Some("async content"));
            }
            other => panic!("unexpected async outcome: {other:?}"),
        }
    }

    #[test]
    fn test_base64_encode_padding_variants() {
        assert_eq!(base64_encode(b""), "");
        assert_eq!(base64_encode(b"f"), "Zg==");
        assert_eq!(base64_encode(b"fo"), "Zm8=");
        assert_eq!(base64_encode(b"foo"), "Zm9v");
    }

    #[cfg(unix)]
    #[test]
    fn test_symlink_validation_denied_and_escape() {
        use std::os::unix::fs::symlink;

        let root = TestDir::new("symlink-root");
        let outside = TestDir::new("symlink-outside");

        write_text(&root.join("inside.txt"), "inside");
        write_text(&outside.join("outside.txt"), "outside");

        let inside_link = root.join("inside-link.txt");
        let escape_link = root.join("escape-link.txt");
        symlink(root.join("inside.txt"), &inside_link).expect("create inside symlink");
        symlink(outside.join("outside.txt"), &escape_link).expect("create escape symlink");

        let deny_provider = FilesystemProvider::new(root.path()).with_follow_symlinks(false);
        let denied = deny_provider.validate_path("inside-link.txt");
        assert!(matches!(
            denied,
            Err(FilesystemProviderError::SymlinkDenied { .. })
        ));

        let allow_provider = FilesystemProvider::new(root.path()).with_follow_symlinks(true);
        let canonical_root = root.path().canonicalize().expect("canonical root");
        let escaped = allow_provider.check_symlink(&escape_link, &canonical_root);
        assert!(matches!(
            escaped,
            Err(FilesystemProviderError::SymlinkEscapesRoot { .. })
        ));
    }

    // ── FilesystemProviderError ────────────────────────────────────

    #[test]
    fn error_path_traversal_display() {
        let err = FilesystemProviderError::PathTraversal {
            requested: "../etc/passwd".to_string(),
        };
        let msg = err.to_string();
        assert!(msg.contains("Path traversal attempt blocked"));
        assert!(msg.contains("../etc/passwd"));
    }

    #[test]
    fn error_too_large_display() {
        let err = FilesystemProviderError::TooLarge {
            path: "big.bin".to_string(),
            size: 50_000_000,
            max: 10_000_000,
        };
        let msg = err.to_string();
        assert!(msg.contains("File too large"));
        assert!(msg.contains("big.bin"));
        assert!(msg.contains("50000000"));
        assert!(msg.contains("10000000"));
    }

    #[test]
    fn error_symlink_denied_display() {
        let err = FilesystemProviderError::SymlinkDenied {
            path: "link.txt".to_string(),
        };
        assert!(err.to_string().contains("Symlink access denied"));
    }

    #[test]
    fn error_symlink_escapes_root_display() {
        let err = FilesystemProviderError::SymlinkEscapesRoot {
            path: "evil-link".to_string(),
        };
        assert!(err.to_string().contains("Symlink target escapes root"));
    }

    #[test]
    fn error_io_display() {
        let err = FilesystemProviderError::Io {
            message: "permission denied".to_string(),
        };
        assert!(err.to_string().contains("IO error"));
        assert!(err.to_string().contains("permission denied"));
    }

    #[test]
    fn error_not_found_display() {
        let err = FilesystemProviderError::NotFound {
            path: "missing.txt".to_string(),
        };
        assert!(err.to_string().contains("File not found"));
        assert!(err.to_string().contains("missing.txt"));
    }

    #[test]
    fn error_debug() {
        let err = FilesystemProviderError::PathTraversal {
            requested: "x".to_string(),
        };
        let debug = format!("{:?}", err);
        assert!(debug.contains("PathTraversal"));
    }

    #[test]
    fn error_clone() {
        let err = FilesystemProviderError::NotFound {
            path: "a.txt".to_string(),
        };
        let cloned = err.clone();
        assert!(cloned.to_string().contains("a.txt"));
    }

    #[test]
    fn error_std_error() {
        let err = FilesystemProviderError::Io {
            message: "oops".to_string(),
        };
        let std_err: &dyn std::error::Error = &err;
        assert!(std_err.to_string().contains("oops"));
    }

    // ── From<FilesystemProviderError> for McpError ─────────────────

    #[test]
    fn error_into_mcp_error_path_traversal() {
        let err = FilesystemProviderError::PathTraversal {
            requested: "x".to_string(),
        };
        let mcp: McpError = err.into();
        assert!(mcp.message.contains("Path traversal"));
    }

    #[test]
    fn error_into_mcp_error_too_large() {
        let err = FilesystemProviderError::TooLarge {
            path: "x".to_string(),
            size: 100,
            max: 10,
        };
        let mcp: McpError = err.into();
        assert!(mcp.message.contains("File too large"));
    }

    #[test]
    fn error_into_mcp_error_symlink_denied() {
        let err = FilesystemProviderError::SymlinkDenied {
            path: "x".to_string(),
        };
        let mcp: McpError = err.into();
        assert!(mcp.message.contains("Symlink access denied"));
    }

    #[test]
    fn error_into_mcp_error_symlink_escapes() {
        let err = FilesystemProviderError::SymlinkEscapesRoot {
            path: "x".to_string(),
        };
        let mcp: McpError = err.into();
        assert!(mcp.message.contains("Symlink target escapes"));
    }

    #[test]
    fn error_into_mcp_error_io() {
        let err = FilesystemProviderError::Io {
            message: "disk fail".to_string(),
        };
        let mcp: McpError = err.into();
        assert!(mcp.message.contains("IO error"));
    }

    #[test]
    fn error_into_mcp_error_not_found() {
        let err = FilesystemProviderError::NotFound {
            path: "gone.txt".to_string(),
        };
        let mcp: McpError = err.into();
        assert!(mcp.message.contains("gone.txt"));
    }

    // ── FilesystemProvider construction and builders ───────────────

    #[test]
    fn provider_new_defaults() {
        let root = TestDir::new("defaults");
        let provider = FilesystemProvider::new(root.path());
        assert_eq!(provider.root, root.path().to_path_buf());
        assert!(provider.prefix.is_none());
        assert!(provider.include_patterns.is_empty());
        assert_eq!(provider.exclude_patterns, vec![".*".to_string()]);
        assert!(!provider.recursive);
        assert_eq!(provider.max_file_size, DEFAULT_MAX_SIZE);
        assert!(!provider.follow_symlinks);
        assert!(provider.description.is_none());
    }

    #[test]
    fn provider_with_prefix() {
        let provider = FilesystemProvider::new("/tmp").with_prefix("myprefix");
        assert_eq!(provider.prefix, Some("myprefix".to_string()));
    }

    #[test]
    fn provider_with_patterns() {
        let provider = FilesystemProvider::new("/tmp").with_patterns(&["*.md", "*.txt"]);
        assert_eq!(provider.include_patterns, vec!["*.md", "*.txt"]);
    }

    #[test]
    fn provider_with_exclude() {
        let provider = FilesystemProvider::new("/tmp").with_exclude(&["*.bak", "*.tmp"]);
        // Default hidden file pattern should be replaced
        assert_eq!(provider.exclude_patterns, vec!["*.bak", "*.tmp"]);
    }

    #[test]
    fn provider_with_recursive() {
        let provider = FilesystemProvider::new("/tmp").with_recursive(true);
        assert!(provider.recursive);
    }

    #[test]
    fn provider_with_max_size() {
        let provider = FilesystemProvider::new("/tmp").with_max_size(1024);
        assert_eq!(provider.max_file_size, 1024);
    }

    #[test]
    fn provider_with_follow_symlinks() {
        let provider = FilesystemProvider::new("/tmp").with_follow_symlinks(true);
        assert!(provider.follow_symlinks);
    }

    #[test]
    fn provider_with_description() {
        let provider = FilesystemProvider::new("/tmp").with_description("My files");
        assert_eq!(provider.description, Some("My files".to_string()));
    }

    #[test]
    fn provider_debug() {
        let provider = FilesystemProvider::new("/tmp").with_prefix("dbg");
        let debug = format!("{:?}", provider);
        assert!(debug.contains("FilesystemProvider"));
        assert!(debug.contains("dbg"));
    }

    #[test]
    fn provider_clone() {
        let provider = FilesystemProvider::new("/tmp")
            .with_prefix("cloned")
            .with_recursive(true)
            .with_max_size(5000);
        let cloned = provider.clone();
        assert_eq!(cloned.prefix, Some("cloned".to_string()));
        assert!(cloned.recursive);
        assert_eq!(cloned.max_file_size, 5000);
    }

    // ── URI methods ───────────────────────────────────────────────

    #[test]
    fn file_uri_with_prefix() {
        let provider = FilesystemProvider::new("/tmp").with_prefix("docs");
        assert_eq!(provider.file_uri("readme.md"), "file://docs/readme.md");
    }

    #[test]
    fn file_uri_without_prefix() {
        let provider = FilesystemProvider::new("/tmp");
        assert_eq!(provider.file_uri("readme.md"), "file://readme.md");
    }

    #[test]
    fn uri_template_with_prefix() {
        let provider = FilesystemProvider::new("/tmp").with_prefix("data");
        assert_eq!(provider.uri_template(), "file://data/{path}");
    }

    #[test]
    fn uri_template_without_prefix() {
        let provider = FilesystemProvider::new("/tmp");
        assert_eq!(provider.uri_template(), "file://{path}");
    }

    #[test]
    fn path_from_uri_with_prefix() {
        let provider = FilesystemProvider::new("/tmp").with_prefix("docs");
        assert_eq!(
            provider.path_from_uri("file://docs/readme.md"),
            Some("readme.md".to_string())
        );
    }

    #[test]
    fn path_from_uri_without_prefix() {
        let provider = FilesystemProvider::new("/tmp");
        assert_eq!(
            provider.path_from_uri("file://readme.md"),
            Some("readme.md".to_string())
        );
    }

    #[test]
    fn path_from_uri_wrong_prefix() {
        let provider = FilesystemProvider::new("/tmp").with_prefix("docs");
        assert_eq!(provider.path_from_uri("file://other/readme.md"), None);
    }

    #[test]
    fn path_from_uri_completely_wrong() {
        let provider = FilesystemProvider::new("/tmp").with_prefix("docs");
        assert_eq!(provider.path_from_uri("http://example.com"), None);
    }

    // ── matches_patterns ──────────────────────────────────────────

    #[test]
    fn matches_patterns_no_includes_no_excludes() {
        let provider = FilesystemProvider::new("/tmp").with_exclude(&[]);
        assert!(provider.matches_patterns("anything.txt"));
        assert!(provider.matches_patterns(".hidden"));
    }

    #[test]
    fn matches_patterns_excludes_only() {
        let provider = FilesystemProvider::new("/tmp"); // default excludes .*
        assert!(provider.matches_patterns("visible.txt"));
        assert!(!provider.matches_patterns(".hidden"));
    }

    #[test]
    fn matches_patterns_includes_only() {
        let provider = FilesystemProvider::new("/tmp")
            .with_exclude(&[])
            .with_patterns(&["*.md"]);
        assert!(provider.matches_patterns("readme.md"));
        assert!(!provider.matches_patterns("readme.txt"));
    }

    #[test]
    fn matches_patterns_exclude_takes_priority() {
        let provider = FilesystemProvider::new("/tmp")
            .with_patterns(&["*.md"])
            .with_exclude(&["secret.md"]);
        assert!(provider.matches_patterns("readme.md"));
        assert!(!provider.matches_patterns("secret.md"));
    }

    // ── validate_path edge cases ──────────────────────────────────

    #[test]
    fn validate_path_not_found() {
        let root = TestDir::new("validate-notfound");
        let provider = FilesystemProvider::new(root.path());
        let result = provider.validate_path("nonexistent.txt");
        assert!(matches!(
            result,
            Err(FilesystemProviderError::NotFound { .. })
        ));
    }

    // ── read_file edge cases ──────────────────────────────────────

    #[test]
    fn read_file_not_found() {
        let root = TestDir::new("read-notfound");
        let provider = FilesystemProvider::new(root.path());
        let result = provider.read_file("missing.txt");
        assert!(matches!(
            result,
            Err(FilesystemProviderError::NotFound { .. })
        ));
    }

    // ── detect_mime_type extended ──────────────────────────────────

    #[test]
    fn detect_mime_type_text_formats() {
        assert_eq!(detect_mime_type(Path::new("f.txt")), "text/plain");
        assert_eq!(detect_mime_type(Path::new("f.html")), "text/html");
        assert_eq!(detect_mime_type(Path::new("f.htm")), "text/html");
        assert_eq!(detect_mime_type(Path::new("f.css")), "text/css");
        assert_eq!(detect_mime_type(Path::new("f.csv")), "text/csv");
        assert_eq!(detect_mime_type(Path::new("f.xml")), "application/xml");
        assert_eq!(detect_mime_type(Path::new("f.markdown")), "text/markdown");
    }

    #[test]
    fn detect_mime_type_programming_languages() {
        assert_eq!(detect_mime_type(Path::new("f.py")), "text/x-python");
        assert_eq!(detect_mime_type(Path::new("f.js")), "text/javascript");
        assert_eq!(detect_mime_type(Path::new("f.mjs")), "text/javascript");
        assert_eq!(detect_mime_type(Path::new("f.ts")), "text/typescript");
        assert_eq!(detect_mime_type(Path::new("f.mts")), "text/typescript");
        assert_eq!(detect_mime_type(Path::new("f.yaml")), "application/yaml");
        assert_eq!(detect_mime_type(Path::new("f.yml")), "application/yaml");
        assert_eq!(detect_mime_type(Path::new("f.toml")), "application/toml");
        assert_eq!(detect_mime_type(Path::new("f.sh")), "text/x-shellscript");
        assert_eq!(detect_mime_type(Path::new("f.bash")), "text/x-shellscript");
        assert_eq!(detect_mime_type(Path::new("f.c")), "text/x-c");
        assert_eq!(detect_mime_type(Path::new("f.cpp")), "text/x-c++");
        assert_eq!(detect_mime_type(Path::new("f.cc")), "text/x-c++");
        assert_eq!(detect_mime_type(Path::new("f.cxx")), "text/x-c++");
        assert_eq!(detect_mime_type(Path::new("f.h")), "text/x-c-header");
        assert_eq!(detect_mime_type(Path::new("f.hpp")), "text/x-c-header");
        assert_eq!(detect_mime_type(Path::new("f.java")), "text/x-java");
        assert_eq!(detect_mime_type(Path::new("f.go")), "text/x-go");
        assert_eq!(detect_mime_type(Path::new("f.rb")), "text/x-ruby");
        assert_eq!(detect_mime_type(Path::new("f.php")), "text/x-php");
        assert_eq!(detect_mime_type(Path::new("f.swift")), "text/x-swift");
        assert_eq!(detect_mime_type(Path::new("f.kt")), "text/x-kotlin");
        assert_eq!(detect_mime_type(Path::new("f.kts")), "text/x-kotlin");
        assert_eq!(detect_mime_type(Path::new("f.sql")), "text/x-sql");
    }

    #[test]
    fn detect_mime_type_images() {
        assert_eq!(detect_mime_type(Path::new("f.jpg")), "image/jpeg");
        assert_eq!(detect_mime_type(Path::new("f.jpeg")), "image/jpeg");
        assert_eq!(detect_mime_type(Path::new("f.gif")), "image/gif");
        assert_eq!(detect_mime_type(Path::new("f.svg")), "image/svg+xml");
        assert_eq!(detect_mime_type(Path::new("f.webp")), "image/webp");
        assert_eq!(detect_mime_type(Path::new("f.ico")), "image/x-icon");
        assert_eq!(detect_mime_type(Path::new("f.bmp")), "image/bmp");
    }

    #[test]
    fn detect_mime_type_binary() {
        assert_eq!(detect_mime_type(Path::new("f.pdf")), "application/pdf");
        assert_eq!(detect_mime_type(Path::new("f.zip")), "application/zip");
        assert_eq!(detect_mime_type(Path::new("f.gz")), "application/gzip");
        assert_eq!(detect_mime_type(Path::new("f.gzip")), "application/gzip");
        assert_eq!(detect_mime_type(Path::new("f.tar")), "application/x-tar");
        assert_eq!(detect_mime_type(Path::new("f.wasm")), "application/wasm");
        assert_eq!(
            detect_mime_type(Path::new("f.exe")),
            "application/octet-stream"
        );
        assert_eq!(
            detect_mime_type(Path::new("f.dll")),
            "application/octet-stream"
        );
        assert_eq!(
            detect_mime_type(Path::new("f.so")),
            "application/octet-stream"
        );
        assert_eq!(
            detect_mime_type(Path::new("f.bin")),
            "application/octet-stream"
        );
    }

    #[test]
    fn detect_mime_type_no_extension() {
        assert_eq!(
            detect_mime_type(Path::new("Makefile")),
            "application/octet-stream"
        );
    }

    // ── is_binary_mime_type extended ───────────────────────────────

    #[test]
    fn is_binary_mime_type_audio_video() {
        assert!(is_binary_mime_type("audio/mpeg"));
        assert!(is_binary_mime_type("video/mp4"));
    }

    #[test]
    fn is_binary_mime_type_archives() {
        assert!(is_binary_mime_type("application/zip"));
        assert!(is_binary_mime_type("application/gzip"));
        assert!(is_binary_mime_type("application/x-tar"));
        assert!(is_binary_mime_type("application/wasm"));
        assert!(is_binary_mime_type("application/octet-stream"));
    }

    #[test]
    fn is_binary_mime_type_text_types_false() {
        assert!(!is_binary_mime_type("text/html"));
        assert!(!is_binary_mime_type("text/markdown"));
        assert!(!is_binary_mime_type("application/yaml"));
        assert!(!is_binary_mime_type("application/toml"));
    }

    // ── base64_encode extended ────────────────────────────────────

    #[test]
    fn base64_encode_hello_world() {
        assert_eq!(base64_encode(b"Hello, World!"), "SGVsbG8sIFdvcmxkIQ==");
    }

    #[test]
    fn base64_encode_binary_sequence() {
        // Known value: bytes [0, 1, 2] → AAEC
        assert_eq!(base64_encode(&[0, 1, 2]), "AAEC");
    }

    // ── glob_match edge cases ─────────────────────────────────────

    #[test]
    fn glob_match_exact() {
        assert!(glob_match("readme.md", "readme.md"));
        assert!(!glob_match("readme.md", "other.md"));
    }

    #[test]
    fn glob_match_empty_pattern_empty_path() {
        assert!(glob_match("", ""));
    }

    #[test]
    fn glob_match_star_empty() {
        assert!(glob_match("*", ""));
        assert!(glob_match("*", "anything"));
    }

    #[test]
    fn glob_match_double_star_alone() {
        assert!(glob_match("**", ""));
        assert!(glob_match("**", "a/b/c"));
    }

    #[test]
    fn glob_match_mixed_pattern() {
        assert!(glob_match("src/*.rs", "src/main.rs"));
        assert!(!glob_match("src/*.rs", "src/sub/main.rs"));
        assert!(glob_match("src/**/*.rs", "src/sub/main.rs"));
    }

    // ── FilesystemResourceHandler ─────────────────────────────────

    #[test]
    fn handler_debug() {
        let root = TestDir::new("handler-debug");
        write_text(&root.join("a.txt"), "hello");
        let handler = FilesystemProvider::new(root.path()).build();
        let debug = format!("{:?}", handler);
        assert!(debug.contains("FilesystemResourceHandler"));
        assert!(debug.contains("provider"));
    }

    #[test]
    fn handler_definition_without_prefix() {
        let root = TestDir::new("handler-no-prefix");
        let handler = FilesystemProvider::new(root.path()).build();
        let def = handler.definition();
        assert_eq!(def.name, "files");
        assert_eq!(def.uri, "file://{path}");
        assert!(def.description.is_none());
    }

    #[test]
    fn handler_template_without_prefix() {
        let root = TestDir::new("handler-tmpl-no-prefix");
        let handler = FilesystemProvider::new(root.path()).build();
        let tmpl = handler.template().unwrap();
        assert_eq!(tmpl.uri_template, "file://{path}");
        assert_eq!(tmpl.name, "files");
    }

    #[test]
    fn handler_cached_resources_populated() {
        let root = TestDir::new("handler-cached");
        write_text(&root.join("one.txt"), "1");
        write_text(&root.join("two.md"), "2");
        let handler = FilesystemProvider::new(root.path())
            .with_exclude(&[])
            .build();
        // cached_resources should have entries for the files
        assert!(handler.cached_resources.len() >= 2);
    }

    #[test]
    fn handler_read_with_uri_missing_path_param() {
        let root = TestDir::new("handler-missing-param");
        let handler = FilesystemProvider::new(root.path())
            .with_prefix("p")
            .build();
        let ctx = McpContext::new(asupersync::Cx::for_testing(), 1);
        let empty_params = HashMap::new();
        // URI doesn't match prefix either
        let result = handler.read_with_uri(&ctx, "file://wrong/x", &empty_params);
        assert!(result.is_err());
    }

    #[test]
    fn handler_read_binary_file_returns_blob() {
        let root = TestDir::new("handler-binary");
        write_bytes(&root.join("data.bin"), &[0xDE, 0xAD, 0xBE, 0xEF]);

        let handler = FilesystemProvider::new(root.path())
            .with_exclude(&[])
            .build();
        let ctx = McpContext::new(asupersync::Cx::for_testing(), 1);
        let mut params = HashMap::new();
        params.insert("path".to_string(), "data.bin".to_string());
        let result = handler
            .read_with_uri(&ctx, "file://data.bin", &params)
            .unwrap();
        assert!(result[0].text.is_none());
        assert!(result[0].blob.is_some());
    }

    // ── list_files with exclude ───────────────────────────────────

    #[test]
    fn list_files_excludes_hidden_by_default() {
        let root = TestDir::new("list-hidden");
        write_text(&root.join("visible.txt"), "v");
        write_text(&root.join(".hidden"), "h");

        let provider = FilesystemProvider::new(root.path());
        let files = provider.list_files().unwrap();
        let paths: Vec<&str> = files.iter().map(|e| e.relative_path.as_str()).collect();
        assert!(paths.contains(&"visible.txt"));
        assert!(!paths.contains(&".hidden"));
    }

    #[test]
    fn list_files_no_patterns_includes_all() {
        let root = TestDir::new("list-all");
        write_text(&root.join("a.txt"), "a");
        write_text(&root.join("b.rs"), "b");

        let provider = FilesystemProvider::new(root.path()).with_exclude(&[]);
        let files = provider.list_files().unwrap();
        assert!(files.len() >= 2);
    }

    // ── DEFAULT_MAX_SIZE ──────────────────────────────────────────

    #[test]
    fn default_max_size_is_10mb() {
        assert_eq!(DEFAULT_MAX_SIZE, 10 * 1024 * 1024);
    }

    // ── FileEntry ─────────────────────────────────────────────────

    #[test]
    fn file_entry_debug() {
        let entry = FileEntry {
            path: PathBuf::from("/tmp/test.txt"),
            relative_path: "test.txt".to_string(),
            size: Some(42),
            mime_type: "text/plain".to_string(),
        };
        let debug = format!("{:?}", entry);
        assert!(debug.contains("test.txt"));
        assert!(debug.contains("42"));
    }

    // ── Provider builder chaining ─────────────────────────────────

    #[test]
    fn provider_builder_chaining() {
        let root = TestDir::new("builder-chain");
        let provider = FilesystemProvider::new(root.path())
            .with_prefix("chain")
            .with_patterns(&["*.md"])
            .with_exclude(&["*.bak"])
            .with_recursive(true)
            .with_max_size(2048)
            .with_follow_symlinks(true)
            .with_description("Chain test");

        assert_eq!(provider.prefix, Some("chain".to_string()));
        assert_eq!(provider.include_patterns, vec!["*.md"]);
        assert_eq!(provider.exclude_patterns, vec!["*.bak"]);
        assert!(provider.recursive);
        assert_eq!(provider.max_file_size, 2048);
        assert!(provider.follow_symlinks);
        assert_eq!(provider.description, Some("Chain test".to_string()));
    }

    // ── Additional coverage ─────────────────────────────────────────

    #[test]
    fn detect_mime_type_case_insensitive() {
        assert_eq!(detect_mime_type(Path::new("README.MD")), "text/markdown");
        assert_eq!(detect_mime_type(Path::new("photo.JPG")), "image/jpeg");
        assert_eq!(detect_mime_type(Path::new("data.JSON")), "application/json");
    }

    #[test]
    fn glob_match_question_mark_at_end_fails_when_no_char() {
        assert!(!glob_match("file?", "file"));
        assert!(glob_match("file?", "fileA"));
    }

    #[test]
    fn base64_encode_round_trips_with_std_decoder() {
        use base64::Engine as _;
        let data = b"The quick brown fox jumps over the lazy dog";
        let encoded = base64_encode(data);
        let decoded = base64::engine::general_purpose::STANDARD
            .decode(&encoded)
            .expect("valid base64");
        assert_eq!(decoded, data);
    }

    #[test]
    fn handler_empty_root_has_no_cached_resources() {
        let root = TestDir::new("handler-empty");
        let handler = FilesystemProvider::new(root.path()).build();
        assert!(handler.cached_resources.is_empty());
    }

    #[test]
    fn list_files_nonexistent_root_returns_error() {
        let provider = FilesystemProvider::new("/nonexistent-fastmcp-test-dir-xyz");
        let result = provider.list_files();
        assert!(result.is_err());
    }

    #[test]
    fn read_file_path_traversal_blocked() {
        let root = TestDir::new("read-traversal");
        write_text(&root.join("safe.txt"), "ok");
        let provider = FilesystemProvider::new(root.path());
        let result = provider.read_file("../../../etc/passwd");
        assert!(matches!(
            result,
            Err(FilesystemProviderError::PathTraversal { .. }
                | FilesystemProviderError::NotFound { .. })
        ));
    }
}