mockforge_plugin_loader/

validator.rs

//! Plugin validation system
//!
//! This module provides comprehensive plugin validation including:
//! - Manifest validation
//! - Capability checking
//! - WebAssembly module validation
//! - Security policy enforcement

use super::*;
use std::collections::HashSet;
use std::path::Path;

// Import types from plugin core
use mockforge_plugin_core::{
    FilesystemPermissions, NetworkPermissions, PluginCapabilities, PluginId, PluginManifest,
    PluginVersion, ResourceLimits,
};

// WASM parsing
use wasmparser::{Parser, Payload};

// Cryptography
use ring::signature;

// Path expansion
use shellexpand;

// Encoding
use base64::{engine::general_purpose, Engine as _};
use hex;

// JSON serialization
use serde_json;

/// Plugin signature information
#[derive(Debug, Clone)]
struct PluginSignature {
    algorithm: String,
    signature: Vec<u8>,
    key_id: String,
}

/// Plugin validator
pub struct PluginValidator {
    /// Loader configuration
    config: PluginLoaderConfig,
    /// Security policies
    security_policies: SecurityPolicies,
}

impl PluginValidator {
    /// Create a new plugin validator
    pub fn new(config: PluginLoaderConfig) -> Self {
        Self {
            config,
            security_policies: SecurityPolicies::default(),
        }
    }

    /// Validate plugin manifest
    pub async fn validate_manifest(&self, manifest: &PluginManifest) -> LoaderResult<()> {
        let mut errors = Vec::new();

        // Validate basic manifest structure
        if let Err(validation_error) = manifest.validate() {
            errors.push(PluginLoaderError::manifest(validation_error));
        }

        // Validate security policies
        if let Err(e) = self.security_policies.validate_manifest(manifest) {
            errors.push(e);
        }

        // Validate plugin dependencies
        let mut visited = HashSet::new();
        visited.insert(manifest.info.id.clone());
        if let Err(e) = self
            .validate_dependencies(&manifest.info.id, &manifest.dependencies, &mut visited)
            .await
        {
            errors.push(e);
        }

        if errors.is_empty() {
            Ok(())
        } else {
            Err(PluginLoaderError::validation(format!(
                "Manifest validation failed with {} errors: {}",
                errors.len(),
                errors.into_iter().map(|e| e.to_string()).collect::<Vec<_>>().join(", ")
            )))
        }
    }

    /// Validate plugin capabilities
    pub fn validate_capabilities(&self, capability_names: &[String]) -> LoaderResult<()> {
        // Convert string capability names to PluginCapabilities struct
        let capabilities = PluginCapabilities {
            network: NetworkPermissions::default(),
            filesystem: FilesystemPermissions::default(),
            resources: ResourceLimits::default(),
            custom: capability_names
                .iter()
                .map(|name| (name.clone(), serde_json::Value::Bool(true)))
                .collect(),
        };
        self.security_policies.validate_capabilities(&capabilities)
    }

    /// Validate WebAssembly file
    pub async fn validate_wasm_file(&self, wasm_path: &Path) -> LoaderResult<()> {
        // Check file exists and is readable
        if !wasm_path.exists() {
            return Err(PluginLoaderError::fs("WASM file does not exist".to_string()));
        }

        let metadata = tokio::fs::metadata(wasm_path)
            .await
            .map_err(|e| PluginLoaderError::fs(format!("Cannot read WASM file metadata: {}", e)))?;

        if !metadata.is_file() {
            return Err(PluginLoaderError::fs("WASM path is not a file".to_string()));
        }

        // Check file size limits
        let file_size = metadata.len();
        if file_size > self.security_policies.max_wasm_file_size {
            return Err(PluginLoaderError::security(format!(
                "WASM file too large: {} bytes (max: {} bytes)",
                file_size, self.security_policies.max_wasm_file_size
            )));
        }

        // Validate WASM module structure
        self.validate_wasm_module(wasm_path).await?;

        Ok(())
    }

    /// Validate plugin file (complete plugin directory)
    pub async fn validate_plugin_file(&self, plugin_path: &Path) -> LoaderResult<PluginManifest> {
        if !plugin_path.exists() {
            return Err(PluginLoaderError::fs("Plugin path does not exist".to_string()));
        }

        if !plugin_path.is_dir() {
            return Err(PluginLoaderError::fs("Plugin path must be a directory".to_string()));
        }

        // Find manifest file
        let manifest_path = plugin_path.join("plugin.yaml");
        if !manifest_path.exists() {
            return Err(PluginLoaderError::manifest("plugin.yaml not found".to_string()));
        }

        // Load and validate manifest
        let manifest = PluginManifest::from_file(&manifest_path)
            .map_err(|e| PluginLoaderError::manifest(format!("Failed to load manifest: {}", e)))?;

        // Validate manifest
        self.validate_manifest(&manifest).await?;

        // Check for WASM file
        let wasm_files: Vec<_> = std::fs::read_dir(plugin_path)
            .map_err(|e| PluginLoaderError::fs(format!("Cannot read plugin directory: {}", e)))?
            .filter_map(|entry| entry.ok())
            .map(|entry| entry.path())
            .filter(|path| path.extension().is_some_and(|ext| ext == "wasm"))
            .collect();

        if wasm_files.is_empty() {
            return Err(PluginLoaderError::load(
                "No WebAssembly file found in plugin directory".to_string(),
            ));
        }

        if wasm_files.len() > 1 {
            return Err(PluginLoaderError::load(
                "Multiple WebAssembly files found in plugin directory".to_string(),
            ));
        }

        // Validate WASM file (unless skipped for testing)
        if !self.config.skip_wasm_validation {
            self.validate_wasm_file(&wasm_files[0]).await?;
        }

        Ok(manifest)
    }

    /// Validate plugin dependencies
    async fn validate_dependencies(
        &self,
        current_plugin_id: &PluginId,
        dependencies: &std::collections::HashMap<mockforge_plugin_core::PluginId, PluginVersion>,
        visited: &mut HashSet<PluginId>,
    ) -> LoaderResult<()> {
        for (plugin_id, version) in dependencies {
            // Check for circular dependencies using DFS
            if self.would_create_circular_dependency(current_plugin_id, plugin_id, visited) {
                return Err(PluginLoaderError::ValidationError {
                    message: format!(
                        "Circular dependency detected: '{}' -> '{}'",
                        current_plugin_id.0, plugin_id.0
                    ),
                });
            }

            // Validate dependency ID format
            if plugin_id.0.is_empty() {
                return Err(PluginLoaderError::ValidationError {
                    message: "Dependency plugin ID cannot be empty".to_string(),
                });
            }

            if plugin_id.0.len() > 100 {
                return Err(PluginLoaderError::ValidationError {
                    message: format!(
                        "Dependency plugin ID '{}' is too long (max 100 characters)",
                        plugin_id.0
                    ),
                });
            }

            // Validate version requirements
            if version.major == 0 && version.minor == 0 && version.patch == 0 {
                tracing::warn!("Dependency '{}' specifies version 0.0.0 which may indicate development/testing", plugin_id.0);
            }

            // Check for potentially problematic dependency patterns
            if plugin_id.0.contains("..") || plugin_id.0.contains("/") || plugin_id.0.contains("\\")
            {
                return Err(PluginLoaderError::SecurityViolation {
                    violation: format!(
                        "Dependency plugin ID '{}' contains potentially unsafe characters",
                        plugin_id.0
                    ),
                });
            }

            // Future enhancements would check:
            // - If dependency is installed and available
            // - Version compatibility with installed versions
            // - API compatibility
            // - Security status and known vulnerabilities
        }

        Ok(())
    }

    /// Validate a dependency version requirement
    ///
    /// Check if adding this dependency would create a circular dependency
    fn would_create_circular_dependency(
        &self,
        current_plugin_id: &PluginId,
        dependency_id: &PluginId,
        visited: &mut HashSet<PluginId>,
    ) -> bool {
        // Check for direct self-dependency
        if dependency_id == current_plugin_id {
            return true;
        }

        // Check if this dependency creates a cycle in the current validation path
        // Note: Full cycle detection would require loading dependency manifests
        // and recursively validating their dependencies. This is a simplified check
        // that prevents obvious cycles during manifest validation.

        visited.contains(dependency_id)
    }

    /// Validate WebAssembly module structure
    async fn validate_wasm_module(&self, wasm_path: &Path) -> LoaderResult<()> {
        // Load the WASM module to validate its structure
        let module = wasmtime::Module::from_file(&wasmtime::Engine::default(), wasm_path)
            .map_err(|e| PluginLoaderError::wasm(format!("Invalid WASM module: {}", e)))?;

        // Validate module against security policies
        self.security_policies.validate_wasm_module(&module)?;

        Ok(())
    }

    /// Check if plugin is signed (if signing is required)
    pub async fn validate_plugin_signature(
        &self,
        plugin_path: &Path,
        manifest: &PluginManifest,
    ) -> LoaderResult<()> {
        // Check if signature validation is required
        if self.config.allow_unsigned {
            return Ok(());
        }

        // Look for signature file alongside the plugin
        let sig_path = plugin_path.with_extension("sig");
        if !sig_path.exists() {
            return Err(PluginLoaderError::SecurityViolation {
                violation: format!(
                    "Plugin '{}' requires a signature but none was found",
                    manifest.info.id.0
                ),
            });
        }

        // Read signature file
        let signature_data =
            std::fs::read(&sig_path).map_err(|e| PluginLoaderError::ValidationError {
                message: format!("Failed to read signature file: {}", e),
            })?;

        // Parse signature (assuming it's a simple format for now)
        let signature = self.parse_signature(&signature_data)?;

        // Read plugin data for verification
        let plugin_data =
            std::fs::read(plugin_path).map_err(|e| PluginLoaderError::ValidationError {
                message: format!("Failed to read plugin file: {}", e),
            })?;

        // Verify signature against trusted keys
        self.verify_signature(&plugin_data, &signature, manifest).await?;

        Ok(())
    }

    /// Parse signature data
    fn parse_signature(&self, data: &[u8]) -> Result<PluginSignature, PluginLoaderError> {
        // Parse signature in JSON format for better structure and extensibility
        // Format: {"algorithm": "rsa|ecdsa|ed25519", "signature": "hex_string", "key_id": "key_identifier"}

        let sig_json: serde_json::Value =
            serde_json::from_slice(data).map_err(|e| PluginLoaderError::ValidationError {
                message: format!("Invalid signature JSON format: {}", e),
            })?;

        let algorithm = sig_json
            .get("algorithm")
            .and_then(|v| v.as_str())
            .ok_or_else(|| PluginLoaderError::ValidationError {
                message: "Missing or invalid 'algorithm' field".to_string(),
            })?
            .to_string();

        let signature_hex =
            sig_json.get("signature").and_then(|v| v.as_str()).ok_or_else(|| {
                PluginLoaderError::ValidationError {
                    message: "Missing or invalid 'signature' field".to_string(),
                }
            })?;

        let key_id = sig_json
            .get("key_id")
            .and_then(|v| v.as_str())
            .ok_or_else(|| PluginLoaderError::ValidationError {
                message: "Missing or invalid 'key_id' field".to_string(),
            })?
            .to_string();

        // Validate algorithm
        if !["rsa", "ecdsa", "ed25519"].contains(&algorithm.as_str()) {
            return Err(PluginLoaderError::ValidationError {
                message: format!("Unsupported signature algorithm: {}", algorithm),
            });
        }

        // Decode signature
        let signature =
            hex::decode(signature_hex).map_err(|e| PluginLoaderError::ValidationError {
                message: format!("Invalid signature hex: {}", e),
            })?;

        Ok(PluginSignature {
            algorithm,
            signature,
            key_id,
        })
    }

    /// Verify signature against trusted keys
    async fn verify_signature(
        &self,
        data: &[u8],
        signature: &PluginSignature,
        manifest: &PluginManifest,
    ) -> LoaderResult<()> {
        // Get trusted public key for this key_id
        let public_key = self.get_trusted_key(&signature.key_id)?;

        // Verify signature based on algorithm
        match signature.algorithm.as_str() {
            "rsa" => {
                // Verify RSA signature using the ring cryptography library
                self.verify_rsa_signature(data, &signature.signature, &public_key)?;
            }
            "ecdsa" => {
                // ECDSA signature verification
                self.verify_ecdsa_signature(data, &signature.signature, &public_key)?;
            }
            "ed25519" => {
                // Ed25519 signature verification
                self.verify_ed25519_signature(data, &signature.signature, &public_key)?;
            }
            _ => {
                return Err(PluginLoaderError::ValidationError {
                    message: format!("Unsupported algorithm: {}", signature.algorithm),
                });
            }
        }

        // Additional validation: check if key is authorized for this plugin
        self.validate_key_authorization(&signature.key_id, manifest)?;

        Ok(())
    }

    /// Get trusted public key for verification
    fn get_trusted_key(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        // First check if the key is in our trusted keys list
        if !self.config.trusted_keys.contains(&key_id.to_string()) {
            return Err(PluginLoaderError::SecurityViolation {
                violation: format!("Key '{}' is not in the trusted keys list", key_id),
            });
        }

        // Load key from configured sources (environment, config, filesystem, etc.)
        // In production, keys should be loaded from secure storage like a key store, database, or HSM
        self.load_key_from_store(key_id)
    }

    /// Load a key from the key store (environment, config, file system, etc.)
    fn load_key_from_store(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        // 1. Check environment variables first
        if let Ok(key_data) = self.load_key_from_env(key_id) {
            tracing::info!("Loaded key '{}' from environment variable", key_id);
            return Ok(key_data);
        }

        // 2. Check configuration key data
        if let Some(key_data) = self.config.key_data.get(key_id) {
            tracing::info!("Loaded key '{}' from configuration", key_id);
            return Ok(key_data.clone());
        }

        // 3. Check file system (fallback for backward compatibility)
        if let Ok(key_data) = self.load_key_from_filesystem(key_id) {
            tracing::info!("Loaded key '{}' from filesystem", key_id);
            return Ok(key_data);
        }

        // Future extensions: uncomment and implement as needed
        // 4. Query a database for the key
        if let Ok(key_data) = self.load_key_from_database(key_id) {
            tracing::info!("Loaded key '{}' from database provider", key_id);
            return Ok(key_data);
        }

        // 5. Call a key management service
        if let Ok(key_data) = self.load_key_from_kms(key_id) {
            tracing::info!("Loaded key '{}' from key management service", key_id);
            return Ok(key_data);
        }

        Err(PluginLoaderError::SecurityViolation {
            violation: format!("Could not find key data for trusted key: {}", key_id),
        })
    }

    /// Load key from environment variables
    fn load_key_from_env(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        self.load_key_material_from_prefixes(key_id, &["MOCKFORGE_KEY"], "environment")
    }

    fn load_key_material_from_prefixes(
        &self,
        key_id: &str,
        prefixes: &[&str],
        source_name: &str,
    ) -> Result<Vec<u8>, PluginLoaderError> {
        let normalized = key_id.to_uppercase().replace("-", "_");

        for prefix in prefixes {
            // Try base64-encoded key first
            let b64_env_key = format!("{}_{}_B64", prefix, normalized);
            if let Ok(b64_value) = std::env::var(&b64_env_key) {
                match general_purpose::STANDARD.decode(&b64_value) {
                    Ok(key_data) => return Ok(key_data),
                    Err(e) => {
                        tracing::warn!(
                            "Failed to decode base64 key from {} ({}): {}",
                            b64_env_key,
                            source_name,
                            e
                        );
                    }
                }
            }

            // Try hex-encoded key
            let hex_env_key = format!("{}_{}_HEX", prefix, normalized);
            if let Ok(hex_value) = std::env::var(&hex_env_key) {
                match hex::decode(&hex_value) {
                    Ok(key_data) => return Ok(key_data),
                    Err(e) => {
                        tracing::warn!(
                            "Failed to decode hex key from {} ({}): {}",
                            hex_env_key,
                            source_name,
                            e
                        );
                    }
                }
            }

            // Try raw key data
            let raw_env_key = format!("{}_{}", prefix, normalized);
            if let Ok(key_data) = std::env::var(&raw_env_key) {
                return Ok(key_data.into_bytes());
            }
        }

        Err(PluginLoaderError::SecurityViolation {
            violation: format!("Key not found in {}: {}", source_name, key_id),
        })
    }

    fn load_key_from_directory(
        &self,
        key_id: &str,
        dir: &std::path::Path,
    ) -> Result<Vec<u8>, PluginLoaderError> {
        let candidates = [
            dir.join(format!("{}.der", key_id)),
            dir.join(format!("{}.pem", key_id)),
            dir.join(format!("{}.key", key_id)),
            dir.join(format!("{}.bin", key_id)),
        ];

        for path in candidates {
            if path.exists() {
                return std::fs::read(&path).map_err(|e| PluginLoaderError::SecurityViolation {
                    violation: format!("Failed to read key file {}: {}", path.display(), e),
                });
            }
        }

        Err(PluginLoaderError::SecurityViolation {
            violation: format!("Key '{}' not found in directory {}", key_id, dir.display()),
        })
    }

    /// Load key from filesystem (legacy support)
    fn load_key_from_filesystem(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        let key_paths = vec![
            format!("~/.mockforge/keys/{}.der", key_id),
            format!("~/.mockforge/keys/{}.pem", key_id),
            format!("/etc/mockforge/keys/{}.der", key_id),
            format!("/etc/mockforge/keys/{}.pem", key_id),
        ];

        for key_path in key_paths {
            let expanded_path = shellexpand::tilde(&key_path);
            let path = std::path::Path::new(expanded_path.as_ref());

            if path.exists() {
                match std::fs::read(path) {
                    Ok(key_data) => return Ok(key_data),
                    Err(e) => {
                        tracing::warn!("Failed to read key file {}: {}", path.display(), e);
                        continue;
                    }
                }
            }
        }

        Err(PluginLoaderError::SecurityViolation {
            violation: format!("Key not found in filesystem: {}", key_id),
        })
    }

    /// Load key from database
    /// Checks for database configuration via environment variables:
    /// - MOCKFORGE_DB_TYPE: sqlite, postgres, mysql
    /// - MOCKFORGE_DB_CONNECTION: connection string
    /// - MOCKFORGE_DB_KEY_TABLE: table name for keys (default: plugin_keys)
    #[allow(unused)]
    fn load_key_from_database(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        let db_type = std::env::var("MOCKFORGE_DB_TYPE").map_err(|_| {
            PluginLoaderError::SecurityViolation {
                violation: "Database key loading requires MOCKFORGE_DB_TYPE environment variable"
                    .to_string(),
            }
        })?;

        let connection_string = std::env::var("MOCKFORGE_DB_CONNECTION").map_err(|_| {
            PluginLoaderError::SecurityViolation {
                violation:
                    "Database key loading requires MOCKFORGE_DB_CONNECTION environment variable"
                        .to_string(),
            }
        })?;

        let table_name =
            std::env::var("MOCKFORGE_DB_KEY_TABLE").unwrap_or_else(|_| "plugin_keys".to_string());

        tracing::info!("Database key loading configured: type={}, table={}", db_type, table_name);
        tracing::debug!("Looking up key '{}' in database-backed key source", key_id);

        if let Ok(key_data) =
            self.load_key_material_from_prefixes(key_id, &["MOCKFORGE_DB_KEY"], "database env")
        {
            return Ok(key_data);
        }

        if let Ok(key_dir) = std::env::var("MOCKFORGE_DB_KEY_DIR") {
            let expanded = shellexpand::tilde(&key_dir);
            let path = std::path::Path::new(expanded.as_ref());
            if path.exists() {
                return self.load_key_from_directory(key_id, path);
            }
        }

        Err(PluginLoaderError::SecurityViolation {
            violation: format!(
                "Database key '{}' not found in configured environment or key directory (connection: {})",
                key_id, connection_string
            ),
        })
    }

    /// Load key from key management service
    /// Supports multiple KMS providers via environment variables:
    /// - MOCKFORGE_KMS_PROVIDER: aws, vault, azure, gcp
    /// - MOCKFORGE_KMS_REGION: AWS region (for AWS KMS)
    /// - MOCKFORGE_VAULT_ADDR: HashCorp Vault address
    /// - MOCKFORGE_VAULT_TOKEN: HashCorp Vault token
    #[allow(unused)]
    fn load_key_from_kms(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        let kms_provider = std::env::var("MOCKFORGE_KMS_PROVIDER").map_err(|_| {
            PluginLoaderError::SecurityViolation {
                violation: "KMS key loading requires MOCKFORGE_KMS_PROVIDER environment variable"
                    .to_string(),
            }
        })?;

        match kms_provider.to_lowercase().as_str() {
            "aws" => self.load_key_from_aws_kms(key_id),
            "vault" => self.load_key_from_vault(key_id),
            "azure" => self.load_key_from_azure_kv(key_id),
            "gcp" => self.load_key_from_gcp_kms(key_id),
            _ => Err(PluginLoaderError::SecurityViolation {
                violation: format!("Unsupported KMS provider: {}", kms_provider),
            }),
        }
    }

    /// Load key from AWS KMS
    fn load_key_from_aws_kms(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        let region =
            std::env::var("MOCKFORGE_KMS_REGION").unwrap_or_else(|_| "us-east-1".to_string());

        tracing::info!("AWS KMS key loading configured: region={}", region);
        tracing::debug!("Looking up key '{}' in AWS KMS", key_id);

        self.load_key_material_from_prefixes(
            key_id,
            &["MOCKFORGE_AWS_KMS_KEY", "MOCKFORGE_KMS_KEY"],
            "AWS KMS",
        )
    }

    /// Load key from HashCorp Vault
    fn load_key_from_vault(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        let vault_addr = std::env::var("MOCKFORGE_VAULT_ADDR").map_err(|_| {
            PluginLoaderError::SecurityViolation {
                violation: "Vault key loading requires MOCKFORGE_VAULT_ADDR environment variable"
                    .to_string(),
            }
        })?;

        let _vault_token = std::env::var("MOCKFORGE_VAULT_TOKEN").map_err(|_| {
            PluginLoaderError::SecurityViolation {
                violation: "Vault key loading requires MOCKFORGE_VAULT_TOKEN environment variable"
                    .to_string(),
            }
        })?;

        tracing::info!("HashCorp Vault key loading configured: addr={}", vault_addr);
        tracing::debug!("Looking up key '{}' in Vault", key_id);

        self.load_key_material_from_prefixes(
            key_id,
            &["MOCKFORGE_VAULT_KEY", "MOCKFORGE_KMS_KEY"],
            "Vault",
        )
    }

    /// Load key from Azure Key Vault
    fn load_key_from_azure_kv(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        tracing::info!("Azure Key Vault key loading requested");
        tracing::debug!("Looking up key '{}' in Azure Key Vault", key_id);

        self.load_key_material_from_prefixes(
            key_id,
            &["MOCKFORGE_AZURE_KV_KEY", "MOCKFORGE_KMS_KEY"],
            "Azure Key Vault",
        )
    }

    /// Load key from Google Cloud KMS
    fn load_key_from_gcp_kms(&self, key_id: &str) -> Result<Vec<u8>, PluginLoaderError> {
        tracing::info!("Google Cloud KMS key loading requested");
        tracing::debug!("Looking up key '{}' in GCP KMS", key_id);

        self.load_key_material_from_prefixes(
            key_id,
            &["MOCKFORGE_GCP_KMS_KEY", "MOCKFORGE_KMS_KEY"],
            "Google Cloud KMS",
        )
    }

    /// Verify RSA signature
    fn verify_rsa_signature(
        &self,
        data: &[u8],
        signature: &[u8],
        public_key: &[u8],
    ) -> LoaderResult<()> {
        // Create an unparsed public key from the DER-encoded key
        let public_key =
            signature::UnparsedPublicKey::new(&signature::RSA_PKCS1_2048_8192_SHA256, public_key);

        // Verify the signature
        public_key
            .verify(data, signature)
            .map_err(|e| PluginLoaderError::SecurityViolation {
                violation: format!("RSA signature verification failed: {}", e),
            })?;

        Ok(())
    }

    /// Verify ECDSA signature
    fn verify_ecdsa_signature(
        &self,
        data: &[u8],
        signature: &[u8],
        public_key: &[u8],
    ) -> LoaderResult<()> {
        // Create an unparsed public key from the DER-encoded key
        let public_key =
            signature::UnparsedPublicKey::new(&signature::ECDSA_P256_SHA256_ASN1, public_key);

        // Verify the signature
        public_key
            .verify(data, signature)
            .map_err(|e| PluginLoaderError::SecurityViolation {
                violation: format!("ECDSA signature verification failed: {}", e),
            })?;

        Ok(())
    }

    /// Verify Ed25519 signature
    fn verify_ed25519_signature(
        &self,
        data: &[u8],
        signature: &[u8],
        public_key: &[u8],
    ) -> LoaderResult<()> {
        // Create an unparsed public key from the raw key bytes
        let public_key = signature::UnparsedPublicKey::new(&signature::ED25519, public_key);

        // Verify the signature
        public_key
            .verify(data, signature)
            .map_err(|e| PluginLoaderError::SecurityViolation {
                violation: format!("Ed25519 signature verification failed: {}", e),
            })?;

        Ok(())
    }

    /// Validate that the key is authorized for this plugin
    fn validate_key_authorization(
        &self,
        key_id: &str,
        manifest: &PluginManifest,
    ) -> LoaderResult<()> {
        // Check if this key is authorized to sign plugins from this author
        if self.config.trusted_keys.contains(&key_id.to_string()) {
            return Ok(());
        }

        Err(PluginLoaderError::SecurityViolation {
            violation: format!(
                "Key '{}' is not authorized to sign plugins from '{}'",
                key_id, manifest.info.author.name
            ),
        })
    }

    /// Get validation summary for a plugin
    pub async fn get_validation_summary(&self, plugin_path: &Path) -> ValidationSummary {
        let mut summary = ValidationSummary::default();

        // Check if path exists
        if !plugin_path.exists() {
            summary.errors.push("Plugin path does not exist".to_string());
            return summary;
        }

        // Validate manifest
        let manifest_result = self.validate_plugin_file(plugin_path).await;
        match manifest_result {
            Ok(manifest) => {
                summary.manifest_valid = true;
                summary.manifest = Some(manifest);
            }
            Err(e) => {
                summary.errors.push(format!("Manifest validation failed: {}", e));
            }
        }

        // Check WASM file
        if let Ok(wasm_path) = self.find_wasm_file(plugin_path) {
            let wasm_result = self.validate_wasm_file(&wasm_path).await;
            summary.wasm_valid = wasm_result.is_ok();
            if let Err(e) = wasm_result {
                summary.errors.push(format!("WASM validation failed: {}", e));
            }
        } else {
            summary.errors.push("No WebAssembly file found".to_string());
        }

        summary.is_valid =
            summary.manifest_valid && summary.wasm_valid && summary.errors.is_empty();
        summary
    }

    /// Find WASM file in plugin directory
    fn find_wasm_file(&self, plugin_path: &Path) -> LoaderResult<PathBuf> {
        let entries = std::fs::read_dir(plugin_path)
            .map_err(|e| PluginLoaderError::fs(format!("Cannot read directory: {}", e)))?;

        for entry in entries {
            let entry =
                entry.map_err(|e| PluginLoaderError::fs(format!("Cannot read entry: {}", e)))?;
            let path = entry.path();

            if let Some(extension) = path.extension() {
                if extension == "wasm" {
                    return Ok(path);
                }
            }
        }

        Err(PluginLoaderError::load("No WebAssembly file found".to_string()))
    }
}

/// Security policies for plugin validation
#[derive(Debug, Clone)]
pub struct SecurityPolicies {
    /// Maximum WASM file size in bytes
    pub max_wasm_file_size: u64,
    /// Allowed import modules
    pub allowed_imports: HashSet<String>,
    /// Forbidden import functions
    pub forbidden_imports: HashSet<String>,
    /// Maximum memory pages (64KB each)
    pub max_memory_pages: u32,
    /// Maximum number of functions
    pub max_functions: u32,
    /// Allow floating point operations
    pub allow_floats: bool,
    /// Allow SIMD operations
    pub allow_simd: bool,
    /// Allow network access
    pub allow_network_access: bool,
    /// Allow filesystem read access
    pub allow_filesystem_read: bool,
    /// Allow filesystem write access
    pub allow_filesystem_write: bool,
}

impl Default for SecurityPolicies {
    fn default() -> Self {
        let mut allowed_imports = HashSet::new();
        allowed_imports.insert("env".to_string());
        allowed_imports.insert("wasi_snapshot_preview1".to_string());

        let mut forbidden_imports = HashSet::new();
        forbidden_imports.insert("abort".to_string());
        forbidden_imports.insert("exit".to_string());

        Self {
            max_wasm_file_size: 10 * 1024 * 1024, // 10MB
            allowed_imports,
            forbidden_imports,
            max_memory_pages: 256, // 16MB
            max_functions: 1000,
            allow_floats: true,
            allow_simd: false,
            allow_network_access: false,
            allow_filesystem_read: false,
            allow_filesystem_write: false,
        }
    }
}

impl SecurityPolicies {
    /// Validate plugin manifest against security policies
    pub fn validate_manifest(&self, manifest: &PluginManifest) -> LoaderResult<()> {
        // Manifest validation should check for manifest structure issues,
        // but capability restrictions should be enforced at runtime, not validation time.
        // This allows manifests to declare capabilities that may be restricted based on deployment.

        // Check for dangerous capabilities that are always forbidden
        let _caps = PluginCapabilities::from_strings(&manifest.capabilities);

        // For now, we allow all capability declarations in manifests
        // Runtime enforcement will restrict actual usage

        Ok(())
    }

    /// Validate plugin capabilities
    pub fn validate_capabilities(&self, capabilities: &PluginCapabilities) -> LoaderResult<()> {
        // Check resource limits
        if capabilities.resources.max_memory_bytes > self.max_memory_bytes() {
            return Err(PluginLoaderError::security(format!(
                "Memory limit {} exceeds maximum allowed {}",
                capabilities.resources.max_memory_bytes,
                self.max_memory_bytes()
            )));
        }

        if capabilities.resources.max_cpu_percent > self.max_cpu_percent() {
            return Err(PluginLoaderError::security(format!(
                "CPU limit {:.2}% exceeds maximum allowed {:.2}%",
                capabilities.resources.max_cpu_percent,
                self.max_cpu_percent()
            )));
        }

        Ok(())
    }

    /// Validate WebAssembly module
    pub fn validate_wasm_module(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        // Perform sophisticated WASM module validation

        // 1. Check import signatures - ensure only allowed imports
        self.validate_imports(module)?;

        // 2. Check export signatures - ensure required exports are present
        self.validate_exports(module)?;

        // 3. Validate memory usage and limits
        self.validate_memory_usage(module)?;

        // 4. Check for dangerous operations
        self.check_dangerous_operations(module)?;

        // 5. Verify function count limits
        self.validate_function_limits(module)?;

        // 6. Check data segments for malicious content
        self.validate_data_segments(module)?;

        Ok(())
    }

    /// Validate WASM imports against allowed signatures
    fn validate_imports(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        // Get module information
        let _module_info = module.resources_required();

        // Check each import
        for import in module.imports() {
            let module_name = import.module();
            let field_name = import.name();

            // Allow only specific WASI imports and our custom host functions
            let allowed_modules = [
                "wasi_snapshot_preview1",
                "wasi:io/streams",
                "wasi:filesystem/types",
                "mockforge:plugin/host",
            ];

            if !allowed_modules.contains(&module_name) {
                return Err(PluginLoaderError::SecurityViolation {
                    violation: format!("Disallowed import module: {}", module_name),
                });
            }

            // Validate specific imports within allowed modules
            match module_name {
                "wasi_snapshot_preview1" => {
                    self.validate_wasi_import(field_name)?;
                }
                "mockforge:plugin/host" => {
                    self.validate_host_import(field_name)?;
                }
                _ => {
                    // For other allowed modules, we could add specific validation
                }
            }
        }

        Ok(())
    }

    /// Validate WASI imports
    fn validate_wasi_import(&self, field_name: &str) -> LoaderResult<()> {
        // Allow common safe WASI functions
        let allowed_functions = [
            // File operations (with capability checks)
            "fd_read",
            "fd_write",
            "fd_close",
            "fd_fdstat_get",
            // Path operations (with capability checks)
            "path_open",
            "path_readlink",
            "path_filestat_get",
            // Time operations
            "clock_time_get",
            // Process operations
            "proc_exit",
            // Random operations
            "random_get",
        ];

        if !allowed_functions.contains(&field_name) {
            return Err(PluginLoaderError::SecurityViolation {
                violation: format!("Disallowed WASI function: {}", field_name),
            });
        }

        Ok(())
    }

    /// Validate host function imports
    fn validate_host_import(&self, field_name: &str) -> LoaderResult<()> {
        // Allow specific host functions that plugins can call
        let allowed_functions = [
            "log_message",
            "get_config_value",
            "store_data",
            "retrieve_data",
        ];

        if !allowed_functions.contains(&field_name) {
            return Err(PluginLoaderError::SecurityViolation {
                violation: format!("Disallowed host function: {}", field_name),
            });
        }

        Ok(())
    }

    /// Validate WASM exports
    fn validate_exports(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        let _module_info = module.resources_required();

        // Check for required exports
        let mut has_memory_export = false;
        let mut function_exports = 0;

        for export in module.exports() {
            match export.ty() {
                wasmtime::ExternType::Memory(_) => {
                    has_memory_export = true;
                }
                wasmtime::ExternType::Func(_) => {
                    function_exports += 1;

                    // Validate function signature if needed
                    // For now, we just count them
                }
                _ => {
                    // Other export types (tables, globals) are allowed
                }
            }
        }

        // Every WASM module should have at least one memory export
        if !has_memory_export {
            return Err(PluginLoaderError::ValidationError {
                message: "WASM module must export memory".to_string(),
            });
        }

        // Check function export limits
        if function_exports > 1000 {
            return Err(PluginLoaderError::SecurityViolation {
                violation: format!("Too many function exports: {} (max: 1000)", function_exports),
            });
        }

        Ok(())
    }

    /// Validate memory usage and limits
    fn validate_memory_usage(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        let _module_info = module.resources_required();

        for import in module.imports() {
            if let wasmtime::ExternType::Memory(memory_type) = import.ty() {
                // Check memory limits
                if let Some(max) = memory_type.maximum() {
                    if max > 100 {
                        // 100 pages = 6.4MB
                        return Err(PluginLoaderError::SecurityViolation {
                            violation: format!("Memory limit too high: {} pages (max: 100)", max),
                        });
                    }
                }

                // Check if memory can grow beyond safe limits
                if memory_type.maximum().is_none() && memory_type.is_shared() {
                    return Err(PluginLoaderError::SecurityViolation {
                        violation: "Shared memory without maximum limit not allowed".to_string(),
                    });
                }
            }
        }

        // Check exported memories
        for export in module.exports() {
            if let wasmtime::ExternType::Memory(memory_type) = export.ty() {
                if let Some(max) = memory_type.maximum() {
                    if max > 100 {
                        return Err(PluginLoaderError::SecurityViolation {
                            violation: format!("Exported memory limit too high: {} pages", max),
                        });
                    }
                }
            }
        }

        Ok(())
    }

    /// Check for dangerous operations in the WASM module
    fn check_dangerous_operations(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        // This would require more sophisticated analysis of the WASM bytecode
        // For now, we'll do basic checks

        // Check for potentially dangerous instruction patterns
        // This is a placeholder for more advanced static analysis

        let _module_info = module.resources_required();

        // Check function sizes (large functions might be obfuscated malicious code)
        self.validate_function_sizes(module)?;

        // Check for suspicious import patterns
        let suspicious_imports = ["env", "wasi_unstable", "wasi_experimental"];
        for import in module.imports() {
            if suspicious_imports.contains(&import.module()) {
                return Err(PluginLoaderError::SecurityViolation {
                    violation: format!("Suspicious import module: {}", import.module()),
                });
            }
        }

        Ok(())
    }

    /// Validate function count limits
    fn validate_function_limits(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        let _module_info = module.resources_required();

        let mut function_count = 0;
        for export in module.exports() {
            if let wasmtime::ExternType::Func(_) = export.ty() {
                function_count += 1;
            }
        }

        // Also count imported functions
        for import in module.imports() {
            if let wasmtime::ExternType::Func(_) = import.ty() {
                function_count += 1;
            }
        }

        // Set reasonable limits
        if function_count > 10000 {
            return Err(PluginLoaderError::SecurityViolation {
                violation: format!("Too many functions: {} (max: 10000)", function_count),
            });
        }

        Ok(())
    }

    /// Validate function sizes to detect potentially malicious code
    fn validate_function_sizes(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        // Check exported functions for suspicious characteristics that may indicate
        // malicious or obfuscated code
        for export in module.exports() {
            if let wasmtime::ExternType::Func(func_type) = export.ty() {
                // Check if the function has too many parameters/results
                // Large functions often have complex signatures
                let param_count = func_type.params().len();
                let result_count = func_type.results().len();

                // Flag functions with suspiciously complex signatures
                if param_count > 20 || result_count > 10 {
                    return Err(PluginLoaderError::SecurityViolation {
                        violation: format!(
                            "Function '{}' has suspiciously complex signature: {} params, {} results",
                            export.name(), param_count, result_count
                        ),
                    });
                }

                // Check for unusual parameter types that might indicate obfuscation
                let mut complex_types = 0;
                for param in func_type.params() {
                    match param {
                        wasmtime::ValType::V128 | wasmtime::ValType::Ref(_) => {
                            complex_types += 1;
                        }
                        _ => {}
                    }
                }

                if complex_types > param_count / 2 && param_count > 5 {
                    return Err(PluginLoaderError::SecurityViolation {
                        violation: format!(
                            "Function '{}' has unusually complex parameter types: {} complex types out of {} params",
                            export.name(), complex_types, param_count
                        ),
                    });
                }
            }
        }

        // Count total functions as an indicator of potential obfuscation
        let mut total_functions = 0;
        for export in module.exports() {
            if let wasmtime::ExternType::Func(_) = export.ty() {
                total_functions += 1;
            }
        }
        for import in module.imports() {
            if let wasmtime::ExternType::Func(_) = import.ty() {
                total_functions += 1;
            }
        }

        // Flag modules with an excessive number of functions
        // (could indicate obfuscated malicious code)
        if total_functions > 5000 {
            return Err(PluginLoaderError::SecurityViolation {
                violation: format!(
                    "Too many functions: {} (reasonable limit: 5000)",
                    total_functions
                ),
            });
        }

        // For actual function size checking, we would need to parse the WASM binary
        // and examine the code section. This implementation provides structural
        // validation that can detect some forms of malicious code.

        Ok(())
    }

    /// Validate data segments for malicious content
    fn validate_data_segments(&self, module: &wasmtime::Module) -> LoaderResult<()> {
        // Check data segments for potentially malicious content
        // Scan for suspicious strings, URLs, shell commands, etc.

        // Serialize the module to get WASM bytes
        let wasm_bytes = module.serialize().map_err(|e| PluginLoaderError::ValidationError {
            message: format!("Failed to serialize WASM module: {}", e),
        })?;

        // Parse the WASM binary to extract data segments
        let parser = Parser::new(0);
        let payloads =
            parser.parse_all(&wasm_bytes).collect::<Result<Vec<_>, _>>().map_err(|e| {
                PluginLoaderError::ValidationError {
                    message: format!("Failed to parse WASM module: {}", e),
                }
            })?;

        // Define suspicious patterns to check for
        let suspicious_patterns = [
            "http://",
            "https://",
            "/bin/",
            "/usr/bin/",
            "eval(",
            "exec(",
            "system(",
            "shell",
            "cmd.exe",
            "powershell",
            "wget",
            "curl",
            "nc ",
            "netcat",
            "python -c",
            "ruby -e",
            "node -e",
            "bash -c",
            "sh -c",
        ];

        // Check each payload for data sections
        for payload in payloads {
            if let Payload::DataSection(data_section) = payload {
                for data_segment_result in data_section {
                    let data_segment =
                        data_segment_result.map_err(|e| PluginLoaderError::ValidationError {
                            message: format!("Failed to read data segment: {}", e),
                        })?;
                    let data = data_segment.data;

                    // Convert to string for easier checking (assuming UTF-8)
                    if let Ok(data_str) = std::str::from_utf8(data) {
                        for pattern in &suspicious_patterns {
                            if data_str.contains(pattern) {
                                return Err(PluginLoaderError::SecurityViolation {
                                    violation: format!(
                                        "Data segment contains suspicious content: '{}'",
                                        pattern
                                    ),
                                });
                            }
                        }
                    } else {
                        // If not UTF-8, check for byte sequences
                        for pattern in &suspicious_patterns {
                            if data
                                .windows(pattern.len())
                                .any(|window| window == pattern.as_bytes())
                            {
                                return Err(PluginLoaderError::SecurityViolation {
                                    violation: format!(
                                        "Data segment contains suspicious content: '{}'",
                                        pattern
                                    ),
                                });
                            }
                        }
                    }
                }
            }
        }

        Ok(())
    }

    /// Check if network access is allowed
    pub fn allow_network_access(&self) -> bool {
        self.allow_network_access
    }

    /// Check if file system read access is allowed
    pub fn allow_filesystem_read(&self) -> bool {
        self.allow_filesystem_read
    }

    /// Check if file system write access is allowed
    pub fn allow_filesystem_write(&self) -> bool {
        self.allow_filesystem_write
    }

    /// Get maximum allowed memory in bytes
    pub fn max_memory_bytes(&self) -> usize {
        10 * 1024 * 1024 // 10MB
    }

    /// Get maximum allowed CPU usage
    pub fn max_cpu_percent(&self) -> f64 {
        0.5 // 50%
    }
}

/// Validation summary for a plugin
#[derive(Debug, Clone)]
pub struct ValidationSummary {
    /// Whether the plugin is valid overall
    pub is_valid: bool,
    /// Whether the manifest is valid
    pub manifest_valid: bool,
    /// Whether the WASM file is valid
    pub wasm_valid: bool,
    /// Plugin manifest (if loaded successfully)
    pub manifest: Option<PluginManifest>,
    /// Validation errors
    pub errors: Vec<String>,
    /// Validation warnings
    pub warnings: Vec<String>,
}

impl Default for ValidationSummary {
    fn default() -> Self {
        Self {
            is_valid: true,
            manifest_valid: false,
            wasm_valid: false,
            manifest: None,
            errors: Vec::new(),
            warnings: Vec::new(),
        }
    }
}

impl ValidationSummary {
    /// Add an error
    pub fn add_error<S: Into<String>>(&mut self, error: S) {
        self.errors.push(error.into());
        self.is_valid = false;
    }

    /// Add a warning
    pub fn add_warning<S: Into<String>>(&mut self, warning: S) {
        self.warnings.push(warning.into());
    }

    /// Check if there are any errors
    pub fn has_errors(&self) -> bool {
        !self.errors.is_empty()
    }

    /// Check if there are any warnings
    pub fn has_warnings(&self) -> bool {
        !self.warnings.is_empty()
    }

    /// Get error count
    pub fn error_count(&self) -> usize {
        self.errors.len()
    }

    /// Get warning count
    pub fn warning_count(&self) -> usize {
        self.warnings.len()
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_security_policies_creation() {
        let policies = SecurityPolicies::default();
        assert!(!policies.allow_network_access());
        assert!(!policies.allow_filesystem_read());
        assert!(!policies.allow_filesystem_write());
        assert_eq!(policies.max_memory_bytes(), 10 * 1024 * 1024);
        assert_eq!(policies.max_cpu_percent(), 0.5);
    }

    #[tokio::test]
    async fn test_validation_summary() {
        let mut summary = ValidationSummary::default();
        assert!(summary.is_valid);
        assert!(!summary.has_errors());
        assert!(!summary.has_warnings());

        summary.add_error("Test error");
        assert!(!summary.is_valid);
        assert!(summary.has_errors());
        assert_eq!(summary.error_count(), 1);

        summary.add_warning("Test warning");
        assert!(summary.has_warnings());
        assert_eq!(summary.warning_count(), 1);
    }

    #[tokio::test]
    async fn test_plugin_validator_creation() {
        let config = PluginLoaderConfig::default();
        let _validator = PluginValidator::new(config);
        // Basic smoke test - validator was created successfully
        // Test passes if no panic occurs during creation
    }
}