#!/usr/bin/env python3
"""
SOFIA Federated Learning Framework
Implements distributed training while preserving data privacy
"""

import os
import json
import pickle
import logging
import asyncio
import threading
from typing import Dict, List, Tuple, Optional, Any, Callable
from datetime import datetime
from collections import defaultdict
import hashlib
import secrets
from concurrent.futures import ThreadPoolExecutor
import numpy as np

# For demonstration - in real implementation, use proper federated learning libraries
try:
    import torch
    import torch.nn as nn
    from torch.utils.data import DataLoader, Dataset
    TORCH_AVAILABLE = True
except ImportError:
    TORCH_AVAILABLE = False
    print("Warning: PyTorch not available. Federated learning will use mock implementation.")

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

class FederatedDataset(Dataset):
    """
    Dataset wrapper for federated learning
    """

    def __init__(self, data: List[Tuple[str, str]], tokenizer=None):
        self.data = data
        self.tokenizer = tokenizer

    def __len__(self):
        return len(self.data)

    def __getitem__(self, idx):
        text1, text2 = self.data[idx]
        if self.tokenizer:
            # In real implementation, tokenize here
            return {
                'text1': text1,
                'text2': text2,
                'input_ids': torch.tensor([1, 2, 3]),  # Mock
                'attention_mask': torch.tensor([1, 1, 1])  # Mock
            }
        return {
            'text1': text1,
            'text2': text2,
            'input_ids': torch.tensor([1, 2, 3]) if TORCH_AVAILABLE else [1, 2, 3],  # Always provide input_ids
            'attention_mask': torch.tensor([1, 1, 1]) if TORCH_AVAILABLE else [1, 1, 1]
        }

class LocalModel:
    """
    Represents a local model on a client device
    """

    def __init__(self, client_id: str, model_config: Dict[str, Any]):
        self.client_id = client_id
        self.model_config = model_config
        self.model = None
        self.optimizer = None
        self.local_epochs = 1
        self.batch_size = 32
        self.learning_rate = 2e-5

        # Privacy parameters
        self.noise_multiplier = 0.1
        self.max_grad_norm = 1.0

        # Training state
        self.current_round = 0
        self.local_loss_history = []
        self.samples_processed = 0

    def initialize_model(self):
        """Initialize the local model"""
        if not TORCH_AVAILABLE:
            logger.warning("PyTorch not available, using mock model")
            self.model = MockModel()
            return

        # In real implementation, load SOFIA model architecture
        # For now, use a simple transformer-like model
        self.model = nn.Sequential(
            nn.Linear(768, 512),
            nn.ReLU(),
            nn.Linear(512, 256),
            nn.ReLU(),
            nn.Linear(256, 128)
        )

        self.optimizer = torch.optim.AdamW(
            self.model.parameters(),
            lr=self.learning_rate,
            weight_decay=0.01
        )

    def train_local(self, train_loader: DataLoader, epochs: int = 1) -> Dict[str, Any]:
        """
        Train the local model on client's data

        Args:
            train_loader: DataLoader with client's training data
            epochs: Number of local training epochs

        Returns:
            Training statistics and model updates
        """
        if not self.model:
            self.initialize_model()

        self.model.train()
        total_loss = 0
        num_batches = 0

        for epoch in range(epochs):
            epoch_loss = 0
            for batch in train_loader:
                self.optimizer.zero_grad()

                if TORCH_AVAILABLE:
                    # Mock forward pass - use input_ids shape
                    batch_size = batch['input_ids'].shape[0] if hasattr(batch['input_ids'], 'shape') else len(batch['input_ids'])
                    outputs = self.model(torch.randn(batch_size, 768))
                    loss = torch.nn.functional.mse_loss(outputs, torch.randn_like(outputs))
                else:
                    # Mock loss
                    loss = 0.5

                if TORCH_AVAILABLE and hasattr(loss, 'backward'):
                    loss.backward()

                    # Apply differential privacy (simplified)
                    self._apply_differential_privacy()

                    # Gradient clipping
                    torch.nn.utils.clip_grad_norm_(self.model.parameters(), self.max_grad_norm)

                    self.optimizer.step()

                epoch_loss += loss.item() if TORCH_AVAILABLE and hasattr(loss, 'item') else loss
                num_batches += 1
                batch_size = batch['input_ids'].shape[0] if hasattr(batch['input_ids'], 'shape') else len(batch['input_ids'])
                self.samples_processed += batch_size

            avg_epoch_loss = epoch_loss / num_batches
            self.local_loss_history.append(avg_epoch_loss)
            total_loss += avg_epoch_loss

        # Generate model update (gradient or weight differences)
        model_update = self._generate_model_update()

        training_stats = {
            'client_id': self.client_id,
            'round': self.current_round,
            'epochs': epochs,
            'avg_loss': total_loss / epochs,
            'samples_processed': self.samples_processed,
            'model_update_size': len(pickle.dumps(model_update))
        }

        self.current_round += 1
        return training_stats, model_update

    def _apply_differential_privacy(self):
        """Apply differential privacy noise to gradients"""
        if not TORCH_AVAILABLE:
            return

        for param in self.model.parameters():
            if param.grad is not None:
                # Add Gaussian noise for differential privacy
                noise = torch.normal(0, self.noise_multiplier, param.grad.shape)
                param.grad.data += noise

    def _generate_model_update(self) -> Dict[str, Any]:
        """Generate model update for aggregation"""
        if not TORCH_AVAILABLE:
            # Mock update
            return {
                'client_id': self.client_id,
                'round': self.current_round,
                'weights': {'layer1': np.random.randn(512, 768)},
                'gradients': {'layer1': np.random.randn(512, 768)}
            }

        # In real implementation, compute weight differences or gradients
        update = {
            'client_id': self.client_id,
            'round': self.current_round,
            'weights': {},
            'gradients': {}
        }

        for name, param in self.model.named_parameters():
            update['weights'][name] = param.data.clone()
            # In practice, you'd send gradients or weight differences
            update['gradients'][name] = param.grad.clone() if param.grad is not None else torch.zeros_like(param)

        return update

    def update_model(self, global_update: Dict[str, Any]):
        """Update local model with global aggregated update"""
        if not TORCH_AVAILABLE:
            logger.info(f"Client {self.client_id}: Mock model update applied")
            return

        # In real implementation, apply the global update
        for name, param in self.model.named_parameters():
            if name in global_update.get('weights', {}):
                param.data = global_update['weights'][name]

        logger.info(f"Client {self.client_id}: Model updated with global parameters")

class MockModel:
    """Mock model for demonstration when PyTorch is not available"""

    def __init__(self):
        self.parameters = lambda: []
        self.training = True

    def train(self):
        self.training = True

    def eval(self):
        self.training = False

    def __call__(self, x):
        return torch.tensor(0.5) if TORCH_AVAILABLE else 0.5

class FederatedAggregator:
    """
    Aggregates model updates from multiple clients
    """

    def __init__(self, aggregation_method: str = 'fedavg'):
        self.aggregation_method = aggregation_method
        self.global_model_state = {}
        self.client_updates = []
        self.round_number = 0

        # Aggregation statistics
        self.aggregation_history = []

    def aggregate_updates(self, client_updates: List[Tuple[Dict[str, Any], Any]]) -> Dict[str, Any]:
        """
        Aggregate model updates from clients

        Args:
            client_updates: List of (training_stats, model_update) tuples

        Returns:
            Aggregated global model update
        """
        if not client_updates:
            return {}

        self.round_number += 1
        self.client_updates = client_updates

        if self.aggregation_method == 'fedavg':
            return self._fedavg_aggregation(client_updates)
        elif self.aggregation_method == 'fedprox':
            return self._fedprox_aggregation(client_updates)
        else:
            return self._fedavg_aggregation(client_updates)

    def _fedavg_aggregation(self, client_updates: List[Tuple[Dict[str, Any], Any]]) -> Dict[str, Any]:
        """Federated Averaging aggregation"""
        if not client_updates:
            return {}

        # Collect all model updates
        model_updates = [update for _, update in client_updates]

        # Calculate total samples for weighted averaging
        total_samples = sum(stats['samples_processed'] for stats, _ in client_updates)

        # Aggregate weights
        aggregated_weights = {}
        aggregated_gradients = {}

        # Get all parameter names from first update
        if model_updates:
            param_names = set()
            for update in model_updates:
                if 'weights' in update:
                    param_names.update(update['weights'].keys())

            # Aggregate each parameter
            for param_name in param_names:
                weights = []
                weight_contributions = []

                for (stats, update) in client_updates:
                    if param_name in update.get('weights', {}):
                        weight = update['weights'][param_name]
                        sample_weight = stats['samples_processed'] / total_samples

                        if TORCH_AVAILABLE and isinstance(weight, torch.Tensor):
                            weights.append(weight * sample_weight)
                        else:
                            weights.append(np.array(weight) * sample_weight)
                        weight_contributions.append(sample_weight)

                # Average the weights
                if weights:
                    if TORCH_AVAILABLE and isinstance(weights[0], torch.Tensor):
                        aggregated_weights[param_name] = torch.stack(weights).sum(dim=0)
                    else:
                        aggregated_weights[param_name] = np.stack(weights).sum(axis=0)

        # Store aggregation statistics
        aggregation_stats = {
            'round': self.round_number,
            'num_clients': len(client_updates),
            'total_samples': total_samples,
            'aggregation_method': self.aggregation_method,
            'timestamp': datetime.now().isoformat()
        }

        self.aggregation_history.append(aggregation_stats)

        return {
            'weights': aggregated_weights,
            'gradients': aggregated_gradients,
            'aggregation_stats': aggregation_stats
        }

    def _fedprox_aggregation(self, client_updates: List[Tuple[Dict[str, Any], Any]]) -> Dict[str, Any]:
        """FedProx aggregation (simplified)"""
        # FedProx adds a proximal term to prevent client drift
        # For simplicity, using same logic as FedAvg but could add regularization
        return self._fedavg_aggregation(client_updates)

    def get_aggregation_stats(self) -> Dict[str, Any]:
        """Get aggregation statistics"""
        if not self.aggregation_history:
            return {'total_rounds': 0}

        recent_stats = self.aggregation_history[-1]
        return {
            'total_rounds': len(self.aggregation_history),
            'last_round_clients': recent_stats['num_clients'],
            'last_round_samples': recent_stats['total_samples'],
            'aggregation_method': self.aggregation_method
        }

class PrivacyController:
    """
    Manages privacy-preserving techniques in federated learning
    """

    def __init__(self, privacy_budget: float = 1.0, delta: float = 1e-5):
        self.privacy_budget = privacy_budget
        self.delta = delta
        self.spent_budget = 0.0

        # Privacy mechanisms
        self.differential_privacy_enabled = True
        self.secure_aggregation_enabled = False

    def check_privacy_budget(self, epsilon: float) -> bool:
        """Check if privacy budget allows the operation"""
        if self.spent_budget + epsilon > self.privacy_budget:
            return False
        return True

    def spend_privacy_budget(self, epsilon: float):
        """Spend privacy budget"""
        self.spent_budget += epsilon

    def apply_secure_aggregation(self, client_updates: List[Any]) -> Any:
        """Apply secure aggregation (simplified)"""
        if not self.secure_aggregation_enabled:
            return client_updates

        # In real implementation, use cryptographic techniques
        # For now, just return updates (no-op)
        logger.info("Secure aggregation applied (simplified)")
        return client_updates

    def generate_privacy_report(self) -> Dict[str, Any]:
        """Generate privacy report"""
        return {
            'total_budget': self.privacy_budget,
            'spent_budget': self.spent_budget,
            'remaining_budget': self.privacy_budget - self.spent_budget,
            'differential_privacy_enabled': self.differential_privacy_enabled,
            'secure_aggregation_enabled': self.secure_aggregation_enabled,
            'privacy_level': 'high' if self.differential_privacy_enabled else 'medium'
        }

class FederatedLearningCoordinator:
    """
    Coordinates federated learning across multiple clients
    """

    def __init__(self, num_clients: int = 3, rounds: int = 5):
        self.num_clients = num_clients
        self.rounds = rounds
        self.clients = {}
        self.aggregator = FederatedAggregator()
        self.privacy_controller = PrivacyController()

        # Communication
        self.client_updates_queue = asyncio.Queue()
        self.global_model_available = asyncio.Event()

        # Statistics
        self.training_stats = []
        self.round_times = []

    async def initialize_clients(self, client_data: Dict[str, List[Tuple[str, str]]]):
        """Initialize federated clients with their data"""
        for client_id, data in client_data.items():
            model_config = {
                'model_type': 'sofia_embedding',
                'input_dim': 768,
                'hidden_dim': 512,
                'output_dim': 256
            }

            client = LocalModel(client_id, model_config)
            client.initialize_model()

            # Create dataset and dataloader
            dataset = FederatedDataset(data)
            dataloader = DataLoader(dataset, batch_size=client.batch_size, shuffle=True)

            self.clients[client_id] = {
                'model': client,
                'dataloader': dataloader,
                'data_size': len(data)
            }

        logger.info(f"Initialized {len(self.clients)} federated clients")

    async def run_federated_training(self) -> Dict[str, Any]:
        """Run federated training for specified rounds"""
        logger.info(f"Starting federated training for {self.rounds} rounds")

        for round_num in range(1, self.rounds + 1):
            round_start = datetime.now()

            logger.info(f"Round {round_num}/{self.rounds} starting")

            # Client training phase
            client_updates = await self._train_clients_in_round(round_num)

            # Aggregation phase
            global_update = self.aggregator.aggregate_updates(client_updates)

            # Update all clients with global model
            await self._update_clients_with_global_model(global_update)

            # Record round statistics
            round_time = (datetime.now() - round_start).total_seconds()
            self.round_times.append(round_time)

            round_stats = {
                'round': round_num,
                'num_clients': len(client_updates),
                'round_time': round_time,
                'aggregation_stats': global_update.get('aggregation_stats', {})
            }
            self.training_stats.append(round_stats)

            logger.info(f"Round {round_num} completed in {round_time:.2f}s")

        # Generate final report
        final_report = self._generate_final_report()
        return final_report

    async def _train_clients_in_round(self, round_num: int) -> List[Tuple[Dict[str, Any], Any]]:
        """Train all clients in parallel for one round"""
        tasks = []

        for client_id, client_info in self.clients.items():
            task = asyncio.create_task(
                self._train_single_client(client_id, client_info, round_num)
            )
            tasks.append(task)

        # Wait for all clients to complete training
        results = await asyncio.gather(*tasks)
        return [r for r in results if r is not None]  # Filter out failed trainings

    async def _train_single_client(self, client_id: str, client_info: Dict[str, Any], round_num: int):
        """Train a single client"""
        try:
            client = client_info['model']
            dataloader = client_info['dataloader']

            # Train locally
            training_stats, model_update = client.train_local(dataloader, epochs=client.local_epochs)

            logger.info(f"Client {client_id}: Training completed - Loss: {training_stats['avg_loss']:.4f}")

            return training_stats, model_update

        except Exception as e:
            logger.error(f"Client {client_id} training failed: {e}")
            return None

    async def _update_clients_with_global_model(self, global_update: Dict[str, Any]):
        """Update all clients with the new global model"""
        tasks = []

        for client_id, client_info in self.clients.items():
            task = asyncio.create_task(
                self._update_single_client(client_id, client_info['model'], global_update)
            )
            tasks.append(task)

        await asyncio.gather(*tasks)

    async def _update_single_client(self, client_id: str, client_model: LocalModel, global_update: Dict[str, Any]):
        """Update a single client with global model"""
        try:
            client_model.update_model(global_update)
            logger.info(f"Client {client_id}: Model updated with global parameters")
        except Exception as e:
            logger.error(f"Failed to update client {client_id}: {e}")

    def _generate_final_report(self) -> Dict[str, Any]:
        """Generate final training report"""
        total_time = sum(self.round_times)
        avg_round_time = total_time / len(self.round_times) if self.round_times else 0

        return {
            'federated_training_completed': True,
            'total_rounds': len(self.training_stats),
            'total_training_time': total_time,
            'average_round_time': avg_round_time,
            'clients_participated': len(self.clients),
            'privacy_report': self.privacy_controller.generate_privacy_report(),
            'aggregation_stats': self.aggregator.get_aggregation_stats(),
            'round_stats': self.training_stats,
            'final_model_available': True
        }

# Example usage and testing
async def demo_federated_learning():
    """Demonstrate federated learning with mock data"""
    print("SOFIA Federated Learning Demo")
    print("=" * 40)

    # Create mock client data
    client_data = {
        'client_1': [
            ("Hello world", "Hi there"),
            ("How are you", "I'm fine"),
            ("Machine learning", "AI models")
        ] * 10,  # Repeat for more data
        'client_2': [
            ("Python programming", "Code development"),
            ("Data science", "Analytics"),
            ("Neural networks", "Deep learning")
        ] * 10,
        'client_3': [
            ("Natural language", "Text processing"),
            ("Computer vision", "Image recognition"),
            ("Reinforcement learning", "RL algorithms")
        ] * 10
    }

    # Initialize coordinator
    coordinator = FederatedLearningCoordinator(num_clients=3, rounds=3)

    # Initialize clients
    await coordinator.initialize_clients(client_data)

    # Run federated training
    print("Starting federated training...")
    final_report = await coordinator.run_federated_training()

    # Print results
    print("\nFederated Training Results:")
    print(f"Total rounds: {final_report['total_rounds']}")
    print(".2f")
    print(".2f")
    print(f"Clients participated: {final_report['clients_participated']}")
    print(f"Privacy level: {final_report['privacy_report']['privacy_level']}")

    return final_report

if __name__ == "__main__":
    # Run demo
    asyncio.run(demo_federated_learning())