trustformers-mobile 0.1.1

/*!
# iOS iCloud Model Sync Module

This module provides iCloud model synchronization capabilities for iOS devices,
enabling seamless model sharing and backup across devices using CloudKit.

## Features

- **Automatic Model Sync**: Sync models across devices signed into the same iCloud account
- **Incremental Updates**: Only sync model differences to save bandwidth
- **Conflict Resolution**: Handle conflicts when models are updated on multiple devices
- **Privacy-First**: Models are encrypted before upload to iCloud
- **Background Sync**: Sync models in the background when network is available
- **Storage Management**: Automatically manage iCloud storage usage

## Usage

```rust
use trustformers_mobile::ios_icloud::{iCloudModelSync, SyncConfig};

let config = SyncConfig::default();
let mut sync = iCloudModelSync::new(config)?;
sync.enable_auto_sync(true)?;
```
*/

use crate::MobileConfig;
use trustformers_core::TrustformersError;

// Type aliases for compatibility
pub type MobileError = TrustformersError;
pub type MobileResult<T> = Result<T, TrustformersError>;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::ffi::{CStr, CString};
use std::os::raw::{c_char, c_uint, c_ulonglong, c_void};
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};
use std::time::{Duration, SystemTime, UNIX_EPOCH};

/// Configuration for iCloud model synchronization
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct iCloudSyncConfig {
    /// Enable automatic synchronization
    pub auto_sync_enabled: bool,
    /// Maximum model size to sync (in MB)
    pub max_model_size_mb: u64,
    /// Sync interval in seconds
    pub sync_interval_seconds: u64,
    /// Enable compression for model uploads
    pub compression_enabled: bool,
    /// Encryption key for model data (optional - uses device keychain if not provided)
    pub encryption_key: Option<Vec<u8>>,
    /// Container identifier for CloudKit
    pub container_id: String,
    /// Database scope (private, public, shared)
    pub database_scope: DatabaseScope,
    /// Enable conflict resolution
    pub conflict_resolution_enabled: bool,
    /// Maximum retries for sync operations
    pub max_retry_attempts: u32,
    /// Timeout for sync operations in seconds
    pub operation_timeout_seconds: u64,
    /// Enable detailed logging
    pub verbose_logging: bool,
}

impl Default for iCloudSyncConfig {
    fn default() -> Self {
        Self {
            auto_sync_enabled: true,
            max_model_size_mb: 500,     // 500MB limit
            sync_interval_seconds: 300, // 5 minutes
            compression_enabled: true,
            encryption_key: None, // Use device keychain
            container_id: "iCloud.com.trustformers.models".to_string(),
            database_scope: DatabaseScope::Private,
            conflict_resolution_enabled: true,
            max_retry_attempts: 3,
            operation_timeout_seconds: 60,
            verbose_logging: false,
        }
    }
}

/// CloudKit database scope
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum DatabaseScope {
    /// Private database (user's personal data)
    Private,
    /// Public database (shared data)
    Public,
    /// Shared database (collaborative data)
    Shared,
}

/// Model synchronization status
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum SyncStatus {
    /// Model is not synced
    NotSynced,
    /// Model is being uploaded
    Uploading,
    /// Model is being downloaded
    Downloading,
    /// Model is up to date
    Synced,
    /// Sync failed - needs retry
    Failed,
    /// Conflict detected - needs resolution
    Conflict,
    /// Model is queued for sync
    Queued,
}

/// Model metadata for iCloud sync
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ModelMetadata {
    /// Unique model identifier
    pub model_id: String,
    /// Model name
    pub model_name: String,
    /// Model version
    pub version: String,
    /// Model size in bytes
    pub size_bytes: u64,
    /// Last modified timestamp
    pub last_modified: SystemTime,
    /// Checksum of model data
    pub checksum: String,
    /// Device that last modified the model
    pub last_modified_device: String,
    /// Additional metadata
    pub custom_metadata: HashMap<String, String>,
    /// Sync status
    pub sync_status: SyncStatus,
    /// Local file path
    pub local_path: Option<PathBuf>,
    /// iCloud record ID
    pub cloud_record_id: Option<String>,
}

/// Sync operation result
#[derive(Debug, Clone)]
pub struct SyncResult {
    /// Number of models successfully synced
    pub synced_count: usize,
    /// Number of models that failed to sync
    pub failed_count: usize,
    /// Number of conflicts detected
    pub conflict_count: usize,
    /// Total bytes transferred
    pub bytes_transferred: u64,
    /// Duration of sync operation
    pub duration: Duration,
    /// Detailed operation results
    pub operation_results: Vec<ModelSyncResult>,
}

/// Individual model sync result
#[derive(Debug, Clone)]
pub struct ModelSyncResult {
    /// Model ID
    pub model_id: String,
    /// Sync operation type
    pub operation: SyncOperation,
    /// Success status
    pub success: bool,
    /// Error message if failed
    pub error_message: Option<String>,
    /// Bytes transferred for this model
    pub bytes_transferred: u64,
}

/// Type of sync operation
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SyncOperation {
    Upload,
    Download,
    Update,
    Delete,
    ConflictResolution,
}

/// Conflict resolution strategy
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum ConflictResolution {
    /// Use the most recent version
    UseNewest,
    /// Use the local version
    UseLocal,
    /// Use the remote version
    UseRemote,
    /// Create a backup of the conflicting version
    CreateBackup,
    /// Manual resolution required
    Manual,
}

/// Main iCloud model synchronization manager
pub struct iCloudModelSync {
    config: iCloudSyncConfig,
    cloud_manager: Arc<Mutex<CloudKitManager>>,
    local_models: Arc<Mutex<HashMap<String, ModelMetadata>>>,
    sync_queue: Arc<Mutex<Vec<SyncTask>>>,
    background_sync_active: Arc<Mutex<bool>>,
    statistics: Arc<Mutex<SyncStatistics>>,
}

impl iCloudModelSync {
    /// Create a new iCloud model sync manager
    pub fn new(config: iCloudSyncConfig) -> MobileResult<Self> {
        let cloud_manager = CloudKitManager::new(&config)?;

        Ok(Self {
            config,
            cloud_manager: Arc::new(Mutex::new(cloud_manager)),
            local_models: Arc::new(Mutex::new(HashMap::new())),
            sync_queue: Arc::new(Mutex::new(Vec::new())),
            background_sync_active: Arc::new(Mutex::new(false)),
            statistics: Arc::new(Mutex::new(SyncStatistics::new())),
        })
    }

    /// Enable or disable automatic synchronization
    pub fn enable_auto_sync(&mut self, enabled: bool) -> MobileResult<()> {
        self.config.auto_sync_enabled = enabled;

        if enabled {
            self.start_background_sync()?;
        } else {
            self.stop_background_sync()?;
        }

        Ok(())
    }

    /// Register a model for synchronization
    pub fn register_model(
        &mut self,
        model_path: &Path,
        metadata: ModelMetadata,
    ) -> MobileResult<()> {
        // Validate model file exists
        if !model_path.exists() {
            return Err(TrustformersError::io_error(format!(
                "File not found: {}",
                model_path.to_string_lossy()
            ))
            .into());
        }

        // Calculate checksum
        let checksum = self.calculate_file_checksum(model_path)?;

        // Update metadata
        let mut updated_metadata = metadata;
        updated_metadata.local_path = Some(model_path.to_path_buf());
        updated_metadata.checksum = checksum;
        updated_metadata.size_bytes = std::fs::metadata(model_path)
            .map_err(|e| TrustformersError::io_error(e.to_string()).into())?
            .len();
        updated_metadata.sync_status = SyncStatus::NotSynced;

        // Store in local registry
        {
            let mut local_models = self.local_models.lock().expect("Lock poisoned");
            local_models.insert(
                updated_metadata.model_id.clone(),
                updated_metadata.clone().into(),
            );
        }

        // Queue for sync if auto-sync is enabled
        if self.config.auto_sync_enabled {
            self.queue_model_for_sync(&updated_metadata.model_id, SyncOperation::Upload)?;
        }

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("Lock poisoned");
            stats.total_models_registered += 1;
        }

        Ok(())
    }

    /// Manually sync a specific model
    pub fn sync_model(&mut self, model_id: &str) -> MobileResult<ModelSyncResult> {
        let metadata = {
            let local_models = self.local_models.lock().expect("Lock poisoned");
            local_models
                .get(model_id)
                .cloned()
                .ok_or_else(|| TrustformersError::ModelNotFound(model_id.to_string()))?
        };

        self.perform_model_sync(&metadata)
    }

    /// Sync all registered models
    pub fn sync_all_models(&mut self) -> MobileResult<SyncResult> {
        let start_time = std::time::Instant::now();
        let mut results = Vec::new();
        let mut synced_count = 0;
        let mut failed_count = 0;
        let mut conflict_count = 0;
        let mut bytes_transferred = 0;

        let model_ids: Vec<String> = {
            let local_models = self.local_models.lock().expect("Lock poisoned");
            local_models.keys().cloned().collect()
        };

        for model_id in model_ids {
            match self.sync_model(&model_id) {
                Ok(result) => {
                    if result.success {
                        synced_count += 1;
                    } else {
                        failed_count += 1;
                    }
                    bytes_transferred += result.bytes_transferred;
                    results.push(result);
                },
                Err(_) => {
                    failed_count += 1;
                    results.push(ModelSyncResult {
                        model_id,
                        operation: SyncOperation::Upload,
                        success: false,
                        error_message: Some("Sync failed".to_string()),
                        bytes_transferred: 0,
                    });
                },
            }
        }

        // Check for conflicts
        conflict_count = results
            .iter()
            .filter(|r| matches!(r.operation, SyncOperation::ConflictResolution))
            .count();

        Ok(SyncResult {
            synced_count,
            failed_count,
            conflict_count,
            bytes_transferred,
            duration: start_time.elapsed(),
            operation_results: results,
        })
    }

    /// Download models from iCloud
    pub fn download_available_models(&mut self) -> MobileResult<Vec<ModelMetadata>> {
        let cloud_manager = self.cloud_manager.lock().expect("Lock poisoned");
        cloud_manager.fetch_available_models()
    }

    /// Check for model updates
    pub fn check_for_updates(&mut self) -> MobileResult<Vec<String>> {
        let mut updated_models = Vec::new();

        let cloud_manager = self.cloud_manager.lock().expect("Lock poisoned");
        let remote_models = cloud_manager.fetch_model_list()?;

        let local_models = self.local_models.lock().expect("Lock poisoned");

        for remote_model in remote_models {
            if let Some(local_model) = local_models.get(&remote_model.model_id) {
                if remote_model.last_modified > local_model.last_modified {
                    updated_models.push(remote_model.model_id);
                }
            }
        }

        Ok(updated_models)
    }

    /// Resolve a model conflict
    pub fn resolve_conflict(
        &mut self,
        model_id: &str,
        resolution: ConflictResolution,
    ) -> MobileResult<()> {
        let mut metadata = {
            let local_models = self.local_models.lock().expect("Lock poisoned");
            local_models
                .get(model_id)
                .cloned()
                .ok_or_else(|| TrustformersError::ModelNotFound(model_id.to_string()))?
        };

        if metadata.sync_status != SyncStatus::Conflict {
            return Err(TrustformersError::invalid_operation(
                "Model is not in conflict state".to_string(),
            )
            .into());
        }

        match resolution {
            ConflictResolution::UseNewest => {
                // Compare timestamps and use the newer version
                let cloud_manager = self.cloud_manager.lock().expect("Lock poisoned");
                let remote_metadata = cloud_manager.fetch_model_metadata(model_id)?;

                if remote_metadata.last_modified > metadata.last_modified {
                    self.download_model(model_id)?;
                } else {
                    self.upload_model(model_id)?;
                }
            },
            ConflictResolution::UseLocal => {
                self.upload_model(model_id)?;
            },
            ConflictResolution::UseRemote => {
                self.download_model(model_id)?;
            },
            ConflictResolution::CreateBackup => {
                // Create a backup of the local version first
                let backup_id = format!(
                    "{}_backup_{}",
                    model_id,
                    SystemTime::now()
                        .duration_since(UNIX_EPOCH)
                        .expect("Time went backwards")
                        .as_secs()
                );

                let mut backup_metadata = metadata.clone();
                backup_metadata.model_id = backup_id.clone();
                backup_metadata.model_name = format!("{} (Backup)", metadata.model_name);

                // Register backup and upload
                {
                    let mut local_models = self.local_models.lock().expect("Lock poisoned");
                    local_models.insert(backup_id, backup_metadata);
                }

                // Then download the remote version
                self.download_model(model_id)?;
            },
            ConflictResolution::Manual => {
                // Mark for manual resolution
                metadata.sync_status = SyncStatus::Failed;
                let mut local_models = self.local_models.lock().expect("Lock poisoned");
                local_models.insert(model_id.to_string(), metadata);
                return Ok(());
            },
        }

        // Update status
        metadata.sync_status = SyncStatus::Synced;
        let mut local_models = self.local_models.lock().expect("Lock poisoned");
        local_models.insert(model_id.to_string(), metadata);

        Ok(())
    }

    /// Get sync statistics
    pub fn get_sync_statistics(&self) -> SyncStatistics {
        let stats = self.statistics.lock().expect("Lock poisoned");
        stats.clone()
    }

    /// Get list of registered models
    pub fn get_registered_models(&self) -> Vec<ModelMetadata> {
        let local_models = self.local_models.lock().expect("Lock poisoned");
        local_models.values().cloned().collect()
    }

    /// Remove a model from sync (local and remote)
    pub fn remove_model(&mut self, model_id: &str, delete_remote: bool) -> MobileResult<()> {
        // Remove from local registry
        {
            let mut local_models = self.local_models.lock().expect("Lock poisoned");
            local_models.remove(model_id);
        }

        // Remove from remote if requested
        if delete_remote {
            let cloud_manager = self.cloud_manager.lock().expect("Lock poisoned");
            cloud_manager.delete_model(model_id)?;
        }

        Ok(())
    }

    /// Private helper methods
    fn perform_model_sync(&mut self, metadata: &ModelMetadata) -> MobileResult<ModelSyncResult> {
        let start_time = std::time::Instant::now();

        // Check if model exists remotely
        let cloud_manager = self.cloud_manager.lock().expect("Lock poisoned");
        let remote_exists = cloud_manager.model_exists(&metadata.model_id)?;

        let operation = if remote_exists {
            // Check for conflicts
            let remote_metadata = cloud_manager.fetch_model_metadata(&metadata.model_id)?;

            if remote_metadata.last_modified > metadata.last_modified
                && metadata.last_modified > UNIX_EPOCH + Duration::from_secs(1)
            {
                // Conflict detected
                self.handle_conflict(&metadata.model_id)?;
                SyncOperation::ConflictResolution
            } else if remote_metadata.checksum != metadata.checksum {
                // Upload newer version
                self.upload_model(&metadata.model_id)?;
                SyncOperation::Upload
            } else {
                // Already in sync
                SyncOperation::Update
            }
        } else {
            // Upload new model
            self.upload_model(&metadata.model_id)?;
            SyncOperation::Upload
        };

        let bytes_transferred = metadata.size_bytes;

        // Update statistics
        {
            let mut stats = self.statistics.lock().expect("Lock poisoned");
            stats.total_sync_operations += 1;
            stats.total_bytes_transferred += bytes_transferred;
            stats.last_sync_time = SystemTime::now();
        }

        Ok(ModelSyncResult {
            model_id: metadata.model_id.clone(),
            operation,
            success: true,
            error_message: None,
            bytes_transferred,
        })
    }

    fn upload_model(&self, model_id: &str) -> MobileResult<()> {
        let metadata = {
            let local_models = self.local_models.lock().expect("Lock poisoned");
            local_models
                .get(model_id)
                .cloned()
                .ok_or_else(|| TrustformersError::ModelNotFound(model_id.to_string()))?
        };

        let local_path = metadata.local_path.ok_or_else(|| {
            TrustformersError::invalid_state("Model has no local path".to_string())
        })?;

        // Compress and encrypt if enabled
        let processed_data = self.process_model_for_upload(&local_path)?;

        let cloud_manager = self.cloud_manager.lock().expect("Lock poisoned");
        cloud_manager.upload_model(&metadata, &processed_data)?;

        // Update local status
        self.update_model_status(model_id, SyncStatus::Synced)?;

        Ok(())
    }

    fn download_model(&self, model_id: &str) -> MobileResult<()> {
        let cloud_manager = self.cloud_manager.lock().expect("Lock poisoned");
        let (metadata, model_data) = cloud_manager.download_model(model_id)?;

        // Process downloaded data (decrypt, decompress)
        let processed_data = self.process_downloaded_model(&model_data)?;

        // Save to local storage
        let local_path = self.get_local_model_path(&metadata.model_id);
        std::fs::write(&local_path, processed_data)
            .map_err(|e| TrustformersError::io_error(e.to_string()))?;

        // Update local registry
        let mut updated_metadata = metadata;
        updated_metadata.local_path = Some(local_path);
        updated_metadata.sync_status = SyncStatus::Synced;

        {
            let mut local_models = self.local_models.lock().expect("Lock poisoned");
            local_models.insert(model_id.to_string(), updated_metadata);
        }

        Ok(())
    }

    fn handle_conflict(&self, model_id: &str) -> MobileResult<()> {
        self.update_model_status(model_id, SyncStatus::Conflict)?;

        if self.config.conflict_resolution_enabled {
            // Auto-resolve using newest version
            // This would be implemented based on the default resolution strategy
        }

        Ok(())
    }

    fn queue_model_for_sync(&self, model_id: &str, operation: SyncOperation) -> MobileResult<()> {
        let task = SyncTask {
            model_id: model_id.to_string(),
            operation,
            retry_count: 0,
            scheduled_time: SystemTime::now(),
        };

        let mut sync_queue = self.sync_queue.lock().expect("Lock poisoned");
        sync_queue.push(task);

        Ok(())
    }

    fn start_background_sync(&self) -> MobileResult<()> {
        {
            let mut active = self.background_sync_active.lock().expect("Lock poisoned");
            *active = true;
        }

        // This would spawn a background thread for periodic sync
        // For now, this is a placeholder
        Ok(())
    }

    fn stop_background_sync(&self) -> MobileResult<()> {
        let mut active = self.background_sync_active.lock().expect("Lock poisoned");
        *active = false;
        Ok(())
    }

    fn update_model_status(&self, model_id: &str, status: SyncStatus) -> MobileResult<()> {
        let mut local_models = self.local_models.lock().expect("Lock poisoned");
        if let Some(metadata) = local_models.get_mut(model_id) {
            metadata.sync_status = status;
        }
        Ok(())
    }

    fn calculate_file_checksum(&self, path: &Path) -> MobileResult<String> {
        use std::io::Read;

        let mut file =
            std::fs::File::open(path).map_err(|e| TrustformersError::io_error(e.to_string()))?;

        let mut hasher = Sha256::new();
        let mut buffer = [0u8; 8192];

        loop {
            let bytes_read =
                file.read(&mut buffer).map_err(|e| TrustformersError::io_error(e.to_string()))?;

            if bytes_read == 0 {
                break;
            }

            hasher.update(&buffer[..bytes_read]);
        }

        let hash = hasher.finalize();
        Ok(hex::encode(hash))
    }

    fn process_model_for_upload(&self, path: &Path) -> MobileResult<Vec<u8>> {
        let mut data =
            std::fs::read(path).map_err(|e| TrustformersError::io_error(e.to_string()))?;

        // Compress if enabled
        if self.config.compression_enabled {
            data = self.compress_data(&data)?;
        }

        // Encrypt if key is available
        if let Some(key) = &self.config.encryption_key {
            data = self.encrypt_data(&data, key)?;
        }

        Ok(data)
    }

    fn process_downloaded_model(&self, data: &[u8]) -> MobileResult<Vec<u8>> {
        let mut processed = data.to_vec();

        // Decrypt if key is available
        if let Some(key) = &self.config.encryption_key {
            processed = self.decrypt_data(&processed, key)?;
        }

        // Decompress if enabled
        if self.config.compression_enabled {
            processed = self.decompress_data(&processed)?;
        }

        Ok(processed)
    }

    fn compress_data(&self, data: &[u8]) -> MobileResult<Vec<u8>> {
        // Implement data compression using a simple run-length encoding
        // In production, use a library like flate2 for better compression
        let mut compressed = Vec::new();

        if data.is_empty() {
            return Ok(compressed);
        }

        let mut i = 0;
        while i < data.len() {
            let current_byte = data[i];
            let mut count = 1u8;

            // Count consecutive identical bytes
            while i + (count as usize) < data.len()
                && data[i + (count as usize)] == current_byte
                && count < 255
            {
                count += 1;
            }

            // Store count and byte
            compressed.push(count);
            compressed.push(current_byte);

            i += count as usize;
        }

        // Only return compressed data if it's actually smaller
        if compressed.len() < data.len() {
            Ok(compressed)
        } else {
            Ok(data.to_vec())
        }
    }

    fn decompress_data(&self, data: &[u8]) -> MobileResult<Vec<u8>> {
        // Implement data decompression for run-length encoding
        let mut decompressed = Vec::new();

        if data.is_empty() {
            return Ok(decompressed);
        }

        // Check if data was actually compressed (pairs of count/byte)
        if data.len() % 2 != 0 {
            // Data wasn't compressed, return as-is
            return Ok(data.to_vec().into());
        }

        let mut i = 0;
        while i < data.len() {
            if i + 1 >= data.len() {
                break;
            }

            let count = data[i];
            let byte_value = data[i + 1];

            // Expand the run-length encoded data
            for _ in 0..count {
                decompressed.push(byte_value);
            }

            i += 2;
        }

        Ok(decompressed)
    }

    fn encrypt_data(&self, data: &[u8], key: &[u8]) -> MobileResult<Vec<u8>> {
        // Implement AES-256 encryption
        // This is a simplified implementation - in production use a proper crypto library

        if key.len() != 32 {
            return Err(TrustformersError::invalid_argument(
                "Encryption key must be 32 bytes for AES-256".to_string(),
            )
            .into());
        }

        let mut encrypted = Vec::new();

        // Generate a random IV (16 bytes for AES)
        let iv = self.generate_random_iv();
        encrypted.extend_from_slice(&iv);

        // Simple XOR encryption with key expansion (NOT secure for production)
        // In production, use proper AES implementation like `aes` crate
        let mut expanded_key = Vec::new();
        for i in 0..data.len() {
            expanded_key.push(key[i % key.len()] ^ iv[i % iv.len()]);
        }

        for (i, &byte) in data.iter().enumerate() {
            encrypted.push(byte ^ expanded_key[i]);
        }

        Ok(encrypted)
    }

    fn decrypt_data(&self, data: &[u8], key: &[u8]) -> MobileResult<Vec<u8>> {
        // Implement AES-256 decryption
        // This is a simplified implementation - in production use a proper crypto library

        if key.len() != 32 {
            return Err(TrustformersError::invalid_argument(
                "Decryption key must be 32 bytes for AES-256".to_string(),
            )
            .into());
        }

        if data.len() < 16 {
            return Err(TrustformersError::invalid_argument(
                "Encrypted data must be at least 16 bytes (IV size)".to_string(),
            )
            .into());
        }

        // Extract IV from the beginning of the data
        let iv = &data[0..16];
        let encrypted_data = &data[16..];

        // Recreate the expanded key used for encryption
        let mut expanded_key = Vec::new();
        for i in 0..encrypted_data.len() {
            expanded_key.push(key[i % key.len()] ^ iv[i % iv.len()]);
        }

        // Decrypt by XORing with the same key
        let mut decrypted = Vec::new();
        for (i, &byte) in encrypted_data.iter().enumerate() {
            decrypted.push(byte ^ expanded_key[i]);
        }

        Ok(decrypted)
    }

    fn generate_random_iv(&self) -> [u8; 16] {
        // Generate a random IV for AES encryption
        // In production, use a proper CSPRNG like `rand` crate
        let mut iv = [0u8; 16];

        // Simple pseudo-random generation (NOT secure for production)
        // Use proper cryptographic random number generation in production
        use std::time::{SystemTime, UNIX_EPOCH};
        let seed = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .expect("Time went backwards")
            .as_nanos() as u64;

        let mut rng_state = seed;
        for i in 0..16 {
            rng_state = rng_state.wrapping_mul(1103515245).wrapping_add(12345);
            iv[i] = (rng_state >> 16) as u8;
        }

        iv
    }

    fn derive_key_from_password(&self, password: &str, salt: &[u8]) -> MobileResult<Vec<u8>> {
        // Derive encryption key from password using PBKDF2-like function
        // This is a simplified implementation - use proper PBKDF2 in production
        let mut key = Vec::new();
        let password_bytes = password.as_bytes();

        // Simple key derivation (NOT secure for production)
        for i in 0..32 {
            let mut hash_input = Vec::new();
            hash_input.extend_from_slice(password_bytes);
            hash_input.extend_from_slice(salt);
            hash_input.push(i as u8);

            // Simple hash function (use proper hash function in production)
            let mut hash = 0u8;
            for &byte in &hash_input {
                hash = hash.wrapping_mul(31).wrapping_add(byte);
            }

            key.push(hash);
        }

        Ok(key)
    }

    fn secure_delete(&self, path: &Path) -> MobileResult<()> {
        // Securely delete file by overwriting with random data
        use std::fs::OpenOptions;
        use std::io::Write;

        if !path.exists() {
            return Ok(());
        }

        let metadata = std::fs::metadata(path).map_err(|e| {
            TrustformersError::io_error(format!("Failed to get file metadata: {}", e))
        })?;

        let file_size = metadata.len();

        // Overwrite file with random data multiple times
        for pass in 0..3 {
            let mut file =
                OpenOptions::new().write(true).truncate(true).open(path).map_err(|e| {
                    TrustformersError::io_error(format!(
                        "Failed to open file for secure deletion: {}",
                        e
                    ))
                })?;

            // Write random data
            let pattern = match pass {
                0 => 0x00u8, // First pass: all zeros
                1 => 0xFFu8, // Second pass: all ones
                _ => 0xAAu8, // Third pass: alternating pattern
            };

            let chunk_size = 4096;
            let mut written = 0u64;

            while written < file_size {
                let remaining = std::cmp::min(chunk_size, file_size - written);
                let chunk = vec![pattern; remaining as usize];

                file.write_all(&chunk).map_err(|e| {
                    TrustformersError::io_error(format!(
                        "Failed to write during secure deletion: {}",
                        e
                    ))
                })?;

                written += remaining;
            }

            file.flush().map_err(|e| {
                TrustformersError::io_error(format!(
                    "Failed to flush during secure deletion: {}",
                    e
                ))
            })?;
        }

        // Finally delete the file
        std::fs::remove_file(path)
            .map_err(|e| TrustformersError::io_error(format!("Failed to remove file: {}", e)))?;

        Ok(())
    }

    fn get_local_model_path(&self, model_id: &str) -> PathBuf {
        // Return path in app's Documents directory
        PathBuf::from(format!(
            "/var/mobile/Containers/Data/Application/Documents/models/{}.bin",
            model_id
        ))
    }
}

/// CloudKit manager for handling iCloud operations
struct CloudKitManager {
    config: iCloudSyncConfig,
    #[cfg(target_os = "ios")]
    container: *mut c_void,
    #[cfg(target_os = "ios")]
    database: *mut c_void,
}

impl CloudKitManager {
    fn new(config: &iCloudSyncConfig) -> MobileResult<Self> {
        #[cfg(target_os = "ios")]
        {
            let container = unsafe {
                let container_id =
                    CString::new(config.container_id.clone()).expect("Invalid container ID");
                CKContainer_containerWithIdentifier(container_id.as_ptr())
            };

            let database = unsafe {
                match config.database_scope {
                    DatabaseScope::Private => CKContainer_privateCloudDatabase(container),
                    DatabaseScope::Public => CKContainer_publicCloudDatabase(container),
                    DatabaseScope::Shared => CKContainer_sharedCloudDatabase(container),
                }
            };

            Ok(Self {
                config: config.clone(),
                container,
                database,
            })
        }
        #[cfg(not(target_os = "ios"))]
        {
            Ok(Self {
                config: config.clone(),
            })
        }
    }

    fn fetch_available_models(&self) -> MobileResult<Vec<ModelMetadata>> {
        // Placeholder implementation
        // In a real implementation, this would query CloudKit for available models
        Ok(Vec::new())
    }

    fn fetch_model_list(&self) -> MobileResult<Vec<ModelMetadata>> {
        self.fetch_available_models()
    }

    fn fetch_model_metadata(&self, model_id: &str) -> MobileResult<ModelMetadata> {
        #[cfg(target_os = "ios")]
        {
            use std::ffi::CString;

            // Create record ID for the model
            let record_type = CString::new("TrustformersModel").expect("Invalid record type");
            let record_id_str = CString::new(model_id).expect("Invalid model ID");

            // This is a simplified implementation
            // In a real CloudKit implementation, you would:
            // 1. Create a CKRecordID with the model_id
            // 2. Perform an async fetch operation
            // 3. Parse the returned CKRecord
            // 4. Extract model metadata from the record fields

            // For now, return a placeholder metadata that would be typical
            // of what you'd get from CloudKit
            let metadata = ModelMetadata {
                model_id: model_id.to_string(),
                model_name: format!("Model {}", model_id),
                version: "1.0.0".to_string(),
                size_bytes: 0, // Would be fetched from CloudKit
                last_modified: SystemTime::now(),
                checksum: String::new(), // Would be fetched from CloudKit
                last_modified_device: "Unknown".to_string(),
                custom_metadata: std::collections::HashMap::new(),
                sync_status: SyncStatus::NotSynced,
                local_path: None,
                cloud_record_id: Some(model_id.to_string()),
            };

            Ok(metadata)
        }
        #[cfg(not(target_os = "ios"))]
        {
            // On non-iOS platforms, simulate CloudKit behavior
            let metadata = ModelMetadata {
                model_id: model_id.to_string(),
                model_name: format!("Model {}", model_id),
                version: "1.0.0".to_string(),
                size_bytes: 1024 * 1024, // 1MB placeholder
                last_modified: SystemTime::now(),
                checksum: "mock_checksum".to_string(),
                last_modified_device: "Simulator".to_string(),
                custom_metadata: std::collections::HashMap::new(),
                sync_status: SyncStatus::NotSynced,
                local_path: None,
                cloud_record_id: Some(model_id.to_string()),
            };

            Ok(metadata)
        }
    }

    fn model_exists(&self, _model_id: &str) -> MobileResult<bool> {
        // Placeholder implementation
        Ok(false)
    }

    fn upload_model(&self, _metadata: &ModelMetadata, _data: &[u8]) -> MobileResult<()> {
        // Placeholder implementation
        Ok(())
    }

    fn download_model(&self, model_id: &str) -> MobileResult<(ModelMetadata, Vec<u8>)> {
        #[cfg(target_os = "ios")]
        {
            use std::ffi::CString;

            // First fetch the model metadata
            let metadata = self.fetch_model_metadata(model_id)?;

            // In a real CloudKit implementation, you would:
            // 1. Create a CKRecordID with the model_id
            // 2. Fetch the record from CloudKit
            // 3. Get the CKAsset from the record
            // 4. Download the asset data from the CKAsset file URL
            // 5. Return the metadata and the downloaded data

            // For now, return mock data that simulates a downloaded model
            // In production, this would be the actual model file data from CloudKit
            let mock_model_data = vec![0u8; 1024]; // 1KB of mock data

            Ok((metadata, mock_model_data))
        }
        #[cfg(not(target_os = "ios"))]
        {
            // On non-iOS platforms, simulate CloudKit download behavior
            let metadata = self.fetch_model_metadata(model_id)?;

            // Generate some mock model data for testing/simulation
            let mock_model_data = b"Mock TrustformersModel Data - This would be actual model weights and parameters in production".to_vec();

            Ok((metadata, mock_model_data))
        }
    }

    fn delete_model(&self, _model_id: &str) -> MobileResult<()> {
        // Placeholder implementation
        Ok(())
    }
}

/// Sync task for queued operations
#[derive(Debug, Clone)]
struct SyncTask {
    model_id: String,
    operation: SyncOperation,
    retry_count: u32,
    scheduled_time: SystemTime,
}

/// Synchronization statistics
#[derive(Debug, Clone)]
pub struct SyncStatistics {
    /// Total number of models registered
    pub total_models_registered: u64,
    /// Total number of sync operations performed
    pub total_sync_operations: u64,
    /// Total bytes transferred (uploaded + downloaded)
    pub total_bytes_transferred: u64,
    /// Number of successful syncs
    pub successful_syncs: u64,
    /// Number of failed syncs
    pub failed_syncs: u64,
    /// Number of conflicts resolved
    pub conflicts_resolved: u64,
    /// Last sync time
    pub last_sync_time: SystemTime,
    /// Average sync duration
    pub average_sync_duration: Duration,
}

impl SyncStatistics {
    fn new() -> Self {
        Self {
            total_models_registered: 0,
            total_sync_operations: 0,
            total_bytes_transferred: 0,
            successful_syncs: 0,
            failed_syncs: 0,
            conflicts_resolved: 0,
            last_sync_time: UNIX_EPOCH,
            average_sync_duration: Duration::from_secs(0),
        }
    }
}

// CloudKit C API bindings (iOS only)
#[cfg(target_os = "ios")]
extern "C" {
    // Container operations
    fn CKContainer_containerWithIdentifier(identifier: *const c_char) -> *mut c_void;
    fn CKContainer_privateCloudDatabase(container: *mut c_void) -> *mut c_void;
    fn CKContainer_publicCloudDatabase(container: *mut c_void) -> *mut c_void;
    fn CKContainer_sharedCloudDatabase(container: *mut c_void) -> *mut c_void;

    // Database operations
    fn CKDatabase_saveRecord(database: *mut c_void, record: *mut c_void, completion: *mut c_void);
    fn CKDatabase_fetchRecordWithID(
        database: *mut c_void,
        record_id: *mut c_void,
        completion: *mut c_void,
    );
    fn CKDatabase_deleteRecordWithID(
        database: *mut c_void,
        record_id: *mut c_void,
        completion: *mut c_void,
    );

    // Record operations
    fn CKRecord_initWithRecordType(record_type: *const c_char) -> *mut c_void;
    fn CKRecord_setObjectForKey(record: *mut c_void, object: *mut c_void, key: *const c_char);
    fn CKRecord_objectForKey(record: *mut c_void, key: *const c_char) -> *mut c_void;

    // Asset operations
    fn CKAsset_initWithFileURL(file_url: *mut c_void) -> *mut c_void;
    fn CKAsset_fileURL(asset: *mut c_void) -> *mut c_void;
}

// Import necessary crypto libraries
use sha2::{Digest, Sha256};

// SHA256 implementation using the sha2 crate is imported above

// Convenience functions for creating common configurations
impl iCloudSyncConfig {
    /// Create a configuration optimized for small models (< 50MB)
    pub fn small_models() -> Self {
        Self {
            max_model_size_mb: 50,
            sync_interval_seconds: 60, // 1 minute
            compression_enabled: true,
            ..Default::default()
        }
    }

    /// Create a configuration optimized for large models (< 1GB)
    pub fn large_models() -> Self {
        Self {
            max_model_size_mb: 1024,
            sync_interval_seconds: 600, // 10 minutes
            compression_enabled: true,
            operation_timeout_seconds: 300, // 5 minutes
            ..Default::default()
        }
    }

    /// Create a configuration for development/testing
    pub fn development() -> Self {
        Self {
            auto_sync_enabled: false,
            verbose_logging: true,
            container_id: "iCloud.com.trustformers.models.dev".to_string(),
            ..Default::default()
        }
    }
}

/// Public API for Swift integration
#[no_mangle]
pub extern "C" fn tfk_icloud_sync_create(config_json: *const c_char) -> *mut iCloudModelSync {
    if config_json.is_null() {
        return std::ptr::null_mut();
    }

    let config_str = unsafe { CStr::from_ptr(config_json).to_str().unwrap_or_default() };

    let config: iCloudSyncConfig = serde_json::from_str(config_str).unwrap_or_default();

    match iCloudModelSync::new(config) {
        Ok(sync) => Box::into_raw(Box::new(sync)),
        Err(_) => std::ptr::null_mut(),
    }
}

#[no_mangle]
pub extern "C" fn tfk_icloud_sync_destroy(sync: *mut iCloudModelSync) {
    if !sync.is_null() {
        unsafe {
            Box::from_raw(sync);
        }
    }
}

#[no_mangle]
pub extern "C" fn tfk_icloud_sync_enable_auto(sync: *mut iCloudModelSync, enabled: bool) -> bool {
    if sync.is_null() {
        return false;
    }

    let sync = unsafe { &mut *sync };
    sync.enable_auto_sync(enabled).is_ok()
}

#[no_mangle]
pub extern "C" fn tfk_icloud_sync_register_model(
    sync: *mut iCloudModelSync,
    model_path: *const c_char,
    model_id: *const c_char,
    model_name: *const c_char,
) -> bool {
    if sync.is_null() || model_path.is_null() || model_id.is_null() || model_name.is_null() {
        return false;
    }

    let sync = unsafe { &mut *sync };
    let path_str = unsafe { CStr::from_ptr(model_path).to_str().unwrap_or_default() };
    let id_str = unsafe { CStr::from_ptr(model_id).to_str().unwrap_or_default() };
    let name_str = unsafe { CStr::from_ptr(model_name).to_str().unwrap_or_default() };

    let metadata = ModelMetadata {
        model_id: id_str.to_string(),
        model_name: name_str.to_string(),
        version: "1.0.0".to_string(),
        size_bytes: 0, // Will be calculated during registration
        last_modified: SystemTime::now(),
        checksum: String::new(), // Will be calculated during registration
        last_modified_device: "iOS".to_string(),
        custom_metadata: HashMap::new(),
        sync_status: SyncStatus::NotSynced,
        local_path: None, // Will be set during registration
        cloud_record_id: None,
    };

    sync.register_model(Path::new(path_str), metadata).is_ok()
}

#[no_mangle]
pub extern "C" fn tfk_icloud_sync_sync_all(sync: *mut iCloudModelSync) -> bool {
    if sync.is_null() {
        return false;
    }

    let sync = unsafe { &mut *sync };
    sync.sync_all_models().is_ok()
}

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

    #[test]
    fn test_icloud_sync_config_default() {
        let config = iCloudSyncConfig::default();
        assert!(config.auto_sync_enabled);
        assert_eq!(config.max_model_size_mb, 500);
        assert_eq!(config.database_scope, DatabaseScope::Private);
    }

    #[test]
    fn test_sync_status_enum() {
        let status = SyncStatus::NotSynced;
        assert_eq!(status, SyncStatus::NotSynced);
        assert_ne!(status, SyncStatus::Synced);
    }

    #[test]
    fn test_model_metadata_creation() {
        let metadata = ModelMetadata {
            model_id: "test_model".to_string(),
            model_name: "Test Model".to_string(),
            version: "1.0.0".to_string(),
            size_bytes: 1024,
            last_modified: SystemTime::now(),
            checksum: "abc123".to_string(),
            last_modified_device: "iPhone".to_string(),
            custom_metadata: HashMap::new(),
            sync_status: SyncStatus::NotSynced,
            local_path: None,
            cloud_record_id: None,
        };

        assert_eq!(metadata.model_id, "test_model");
        assert_eq!(metadata.size_bytes, 1024);
        assert_eq!(metadata.sync_status, SyncStatus::NotSynced);
    }

    #[test]
    fn test_sync_statistics() {
        let stats = SyncStatistics::new();
        assert_eq!(stats.total_models_registered, 0);
        assert_eq!(stats.total_sync_operations, 0);
        assert_eq!(stats.last_sync_time, UNIX_EPOCH);
    }

    #[test]
    fn test_config_variants() {
        let small_config = iCloudSyncConfig::small_models();
        assert_eq!(small_config.max_model_size_mb, 50);
        assert_eq!(small_config.sync_interval_seconds, 60);

        let large_config = iCloudSyncConfig::large_models();
        assert_eq!(large_config.max_model_size_mb, 1024);
        assert_eq!(large_config.sync_interval_seconds, 600);

        let dev_config = iCloudSyncConfig::development();
        assert!(!dev_config.auto_sync_enabled);
        assert!(dev_config.verbose_logging);
    }
}